Publications by authors named "Martin Bilban"

116 Publications

Down-regulation of A20 promotes immune escape of lung adenocarcinomas.

Sci Transl Med 2021 07;13(601)

Institute of Pharmacology, Center of Physiology and Pharmacology, Medical University of Vienna, AT-1090 Vienna, Austria.

Inflammation is a well-known driver of lung tumorigenesis. One strategy by which tumor cells escape tight homeostatic control is by decreasing the expression of the potent anti-inflammatory protein tumor necrosis factor alpha-induced protein 3 (TNFAIP3), also known as A20. We observed that tumor cell intrinsic loss of A20 markedly enhanced lung tumorigenesis and was associated with reduced CD8 T cell-mediated immune surveillance in patients with lung cancer and in mouse models. In mice, we observed that this effect was completely dependent on increased cellular sensitivity to interferon-γ (IFN-γ) signaling by aberrant activation of TANK-binding kinase 1 (TBK1) and increased downstream expression and activation of signal transducer and activator of transcription 1 (STAT1). Interrupting this autocrine feed forward loop by knocking out IFN-α/β receptor completely restored infiltration of cytotoxic T cells and rescued loss of A20 depending tumorigenesis. Downstream of STAT1, programmed death ligand 1 (PD-L1) was highly expressed in A20 knockout lung tumors. Accordingly, immune checkpoint blockade (ICB) treatment was highly efficient in mice harboring A20-deficient lung tumors. Furthermore, an A20 loss-of-function gene expression signature positively correlated with survival of melanoma patients treated with anti-programmed cell death protein 1. Together, we have identified A20 as a master immune checkpoint regulating the TBK1-STAT1-PD-L1 axis that may be exploited to improve ICB therapy in patients with lung adenocarcinoma.
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http://dx.doi.org/10.1126/scitranslmed.abc3911DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7611502PMC
July 2021

Pumilio2 and Staufen2 selectively balance the synaptic proteome.

Cell Rep 2021 Jun;35(12):109279

Biomedical Center (BMC), Department for Cell Biology & Anatomy, Medical Faculty, Ludwig-Maximilians-University, 82152 Planegg-Martinsried, Germany. Electronic address:

Neurons have the capacity to adapt to environmental stimuli, a phenomenon termed cellular plasticity. The underlying processes are controlled by a network of RNA-binding proteins (RBPs). Their precise impact, however, is largely unknown. To address this important question, we chose Pumilio2 (Pum2) and Staufen2 (Stau2), which both regulate synaptic transmission. Surprisingly, even though both RBPs dynamically interact with each other in neurons, their respective impact on the transcriptome and proteome is highly selective. Although Pum2 deficiency leads to reduced translation and protein expression, Stau2 depletion preferentially impacts RNA levels and increases protein abundance. Furthermore, we show that Pum2 activates expression of key GABAergic synaptic components, e.g., the GABA receptor scaffold protein Gephyrin. Consequently, Pum2 depletion selectively reduced the amplitude of miniature inhibitory postsynaptic currents. Together, our data argue for an important role of RBPs to maintain proteostasis in order to control distinct aspects of synaptic transmission.
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http://dx.doi.org/10.1016/j.celrep.2021.109279DOI Listing
June 2021

LMO3 reprograms visceral adipocyte metabolism during obesity.

J Mol Med (Berl) 2021 08 20;99(8):1151-1171. Epub 2021 May 20.

Department of Laboratory Medicine, Medical University of Vienna, 1090, Vienna, Austria.

Obesity and body fat distribution are important risk factors for the development of type 2 diabetes and metabolic syndrome. Evidence has accumulated that this risk is related to intrinsic differences in behavior of adipocytes in different fat depots. We recently identified LIM domain only 3 (LMO3) in human mature visceral adipocytes; however, its function in these cells is currently unknown. The aim of this study was to determine the potential involvement of LMO3-dependent pathways in the modulation of key functions of mature adipocytes during obesity. Based on a recently engineered hybrid rAAV serotype Rec2 shown to efficiently transduce both brown adipose tissue (BAT) and white adipose tissue (WAT), we delivered YFP or Lmo3 to epididymal WAT (eWAT) of C57Bl6/J mice on a high-fat diet (HFD). The effects of eWAT transduction on metabolic parameters were evaluated 10 weeks later. To further define the role of LMO3 in insulin-stimulated glucose uptake, insulin signaling, adipocyte bioenergetics, as well as endocrine function, experiments were conducted in 3T3-L1 adipocytes and newly differentiated human primary mature adipocytes, engineered for transient gain or loss of LMO3 expression, respectively. AAV transduction of eWAT results in strong and stable Lmo3 expression specifically in the adipocyte fraction over a course of 10 weeks with HFD feeding. LMO3 expression in eWAT significantly improved insulin sensitivity and healthy visceral adipose tissue expansion in diet-induced obesity, paralleled by increased serum adiponectin. In vitro, LMO3 expression in 3T3-L1 adipocytes increased PPARγ transcriptional activity, insulin-stimulated GLUT4 translocation and glucose uptake, as well as mitochondrial oxidative capacity in addition to fatty acid oxidation. Mechanistically, LMO3 induced the PPARγ coregulator Ncoa1, which was required for LMO3 to enhance glucose uptake and mitochondrial oxidative gene expression. In human mature adipocytes, LMO3 overexpression promoted, while silencing of LMO3 suppressed mitochondrial oxidative capacity. LMO3 expression in visceral adipose tissue regulates multiple genes that preserve adipose tissue functionality during obesity, such as glucose metabolism, insulin sensitivity, mitochondrial function, and adiponectin secretion. Together with increased PPARγ activity and Ncoa1 expression, these gene expression changes promote insulin-induced GLUT4 translocation, glucose uptake in addition to increased mitochondrial oxidative capacity, limiting HFD-induced adipose dysfunction. These data add LMO3 as a novel regulator improving visceral adipose tissue function during obesity. KEY MESSAGES: LMO3 increases beneficial visceral adipose tissue expansion and insulin sensitivity in vivo. LMO3 increases glucose uptake and oxidative mitochondrial activity in adipocytes. LMO3 increases nuclear coactivator 1 (Ncoa1). LMO3-enhanced glucose uptake and mitochondrial gene expression requires Ncoa1.
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http://dx.doi.org/10.1007/s00109-021-02089-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8313462PMC
August 2021

The energy sensor AMPK orchestrates metabolic and translational adaptation in expanding T helper cells.

FASEB J 2021 04;35(4):e21217

Institute of Immunology, Center of Pathophysiology, Infectiology and Immunology, Medical University of Vienna, Vienna, Austria.

The importance of cellular metabolic adaptation in inducing robust T cell responses is well established. However, the mechanism by which T cells link information regarding nutrient supply to clonal expansion and effector function is still enigmatic. Herein, we report that the metabolic sensor adenosine monophosphate-activated protein kinase (AMPK) is a critical link between cellular energy demand and translational activity and, thus, orchestrates optimal expansion of T cells in vivo. AMPK deficiency did not affect T cell fate decision, activation, or T effector cell generation; however, the magnitude of T cell responses in murine in vivo models of T cell activation was markedly reduced. This impairment was global, as all T helper cell subsets were similarly sensitive to loss of AMPK which resulted in reduced T cell accumulation in peripheral organs and reduced disease severity in pathophysiologically as diverse models as T cell transfer colitis and allergic airway inflammation. T cell receptor repertoire analysis confirmed similar clonotype frequencies in different lymphoid organs, thereby supporting the concept of a quantitative impairment in clonal expansion rather than a skewed qualitative immune response. In line with these findings, in-depth metabolic analysis revealed a decrease in T cell oxidative metabolism, and gene set enrichment analysis indicated a major reduction in ribosomal biogenesis and mRNA translation in AMPK-deficient T cells. We, thus, provide evidence that through its interference with these delicate processes, AMPK orchestrates the quantitative, but not the qualitative, manifestation of primary T cell responses in vivo.
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http://dx.doi.org/10.1096/fj.202001763RRDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8252394PMC
April 2021

Beneficial Metabolic Effects of TREM2 in Obesity Are Uncoupled From Its Expression on Macrophages.

Diabetes 2021 Sep 24;70(9):2042-2057. Epub 2021 Feb 24.

Department of Medicine I, Laboratory of Infection Biology, Medical University of Vienna, Vienna, Austria

Obesity-induced white adipose tissue (WAT) hypertrophy is associated with elevated adipose tissue macrophage (ATM) content. Overexpression of the triggering receptor expressed on myeloid cells 2 (TREM2) reportedly increases adiposity, worsening health. Paradoxically, using insulin resistance, elevated fat mass, and hypercholesterolemia as hallmarks of unhealthy obesity, a recent report demonstrated that ATM-expressed TREM2 promoted health. Here, we identified that in mice, TREM2 deficiency aggravated diet-induced insulin resistance and hepatic steatosis independently of fat and cholesterol levels. Metabolomics linked TREM2 deficiency with elevated obesity-instigated serum ceramides that correlated with impaired insulin sensitivity. Remarkably, while inhibiting ceramide synthesis exerted no influences on TREM2-dependent ATM remodeling, inflammation, or lipid load, it restored insulin tolerance, reversing adipose hypertrophy and secondary hepatic steatosis of TREM2-deficient animals. Bone marrow transplantation experiments revealed unremarkable influences of immune cell-expressed TREM2 on health, instead demonstrating that WAT-intrinsic mechanisms impinging on sphingolipid metabolism dominate in the systemic protective effects of TREM2 on metabolic health.
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http://dx.doi.org/10.2337/db20-0572DOI Listing
September 2021

Delineation of target expression profiles in CD34+/CD38- and CD34+/CD38+ stem and progenitor cells in AML and CML.

Blood Adv 2020 10;4(20):5118-5132

Ludwig Boltzmann Institute for Hematology and Oncology.

In an attempt to identify novel markers and immunological targets in leukemic stem cells (LSCs) in acute myeloid leukemia (AML) and chronic myeloid leukemia (CML), we screened bone marrow (BM) samples from patients with AML (n = 274) or CML (n = 97) and controls (n = 288) for expression of cell membrane antigens on CD34+/CD38- and CD34+/CD38+ cells by multicolor flow cytometry. In addition, we established messenger RNA expression profiles in purified sorted CD34+/CD38- and CD34+/CD38+ cells using gene array and quantitative polymerase chain reaction. Aberrantly expressed markers were identified in all cohorts. In CML, CD34+/CD38- LSCs exhibited an almost invariable aberration profile, defined as CD25+/CD26+/CD56+/CD93+/IL-1RAP+. By contrast, in patients with AML, CD34+/CD38- cells variably expressed "aberrant" membrane antigens, including CD25 (48%), CD96 (40%), CD371 (CLL-1; 68%), and IL-1RAP (65%). With the exception of a subgroup of FLT3 internal tandem duplication-mutated patients, AML LSCs did not exhibit CD26. All other surface markers and target antigens detected on AML and/or CML LSCs, including CD33, CD44, CD47, CD52, CD105, CD114, CD117, CD133, CD135, CD184, and roundabout-4, were also found on normal BM stem cells. However, several of these surface targets, including CD25, CD33, and CD123, were expressed at higher levels on CD34+/CD38- LSCs compared with normal BM stem cells. Moreover, antibody-mediated immunological targeting through CD33 or CD52 resulted in LSC depletion in vitro and a substantially reduced LSC engraftment in NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ (NSG) mice. Together, we have established surface marker and target expression profiles of AML LSCs and CML LSCs, which should facilitate LSC enrichment, diagnostic LSC phenotyping, and development of LSC-eradicating immunotherapies.
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http://dx.doi.org/10.1182/bloodadvances.2020001742DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7594398PMC
October 2020

STAT3 in the dorsal raphe gates behavioural reactivity and regulates gene networks associated with psychopathology.

Mol Psychiatry 2021 Jul 12;26(7):2886-2899. Epub 2020 Oct 12.

Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstraße 17, 1090, Vienna, Austria.

The signal transducer and activator of transcription 3 (STAT3) signalling pathway is activated through phosphorylation by Janus kinases in response to a diverse set of immunogenic and non-immunogenic triggers. Several distinct lines of evidence propose an intricate involvement of STAT3 in neural function relevant to behaviour in health and disease. However, in part due to the pleiotropic effects resulting from its DNA binding activity and the consequent regulation of expression of a variety of genes with context-dependent cellular consequences, the precise nature of STAT3 involvement in the neural mechanisms underlying psychopathology remains incompletely understood. Here, we focused on the midbrain serotonergic system, a central hub for the regulation of emotions, to examine the relevance of STAT3 signalling for emotional behaviour in mice by selectively knocking down raphe STAT3 expression using germline genetic (STAT3 KO) and viral-mediated approaches. Mice lacking serotonergic STAT3 presented with reduced negative behavioural reactivity and a blunted response to the sensitising effects of amphetamine, alongside alterations in midbrain neuronal firing activity of serotonergic neurons and transcriptional control of gene networks relevant for neuropsychiatric disorders. Viral knockdown of dorsal raphe (DR) STAT3 phenocopied the behavioural alterations of STAT3 KO mice, excluding a developmentally determined effect and suggesting that disruption of STAT3 signalling in the DR of adult mice is sufficient for the manifestation of behavioural traits relevant to psychopathology. Collectively, these results suggest DR STAT3 as a molecular gate for the control of behavioural reactivity, constituting a mechanistic link between the upstream activators of STAT3, serotonergic neurotransmission and psychopathology.
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http://dx.doi.org/10.1038/s41380-020-00904-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8505245PMC
July 2021

Intact vitamin A transport is critical for cold-mediated adipose tissue browning and thermogenesis.

Mol Metab 2020 12 28;42:101088. Epub 2020 Sep 28.

Clinical Division of Endocrinology and Metabolism, Department of Medicine III, Medical University of Vienna, Vienna, Austria. Electronic address:

Objective: Transformation of white into brown fat ("browning") reduces obesity in many preclinical models and holds great promise as a therapeutic concept in metabolic disease. Vitamin A metabolites (retinoids) have been linked to thermogenic programming of adipose tissue; however, the physiologic importance of systemic retinoid transport for adipose tissue browning and adaptive thermogenesis is unknown.

Methods: We performed cold exposure studies in mice and humans and used a genetic model of defective vitamin A transport, the retinol binding protein deficient (Rbp) mouse, to study the effects of cooling on systemic vitamin A and the relevance of intact retinoid transport on cold-induced adipose tissue browning.

Results: We show that cold stimulation in mice and humans leads to an increase in circulating retinol and its plasma transporter, Rbp. In Rbp mice, thermogenic programming of adipocytes and oxidative mitochondrial function are dramatically impaired in subcutaneous white fat, which renders Rbp mice more cold-sensitive. In contrast, retinol stimulation in primary human adipocytes promotes thermogenic gene expression and mitochondrial respiration. In humans, cold-mediated retinol increase is associated with a shift in oxidative substrate metabolism suggestive of higher lipid utilisation.

Conclusions: Systemic vitamin A levels are regulated by cold exposure in mice and humans, and intact retinoid transport is essential for cold-induced adipose tissue browning and adaptive thermogenesis.
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http://dx.doi.org/10.1016/j.molmet.2020.101088DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7585949PMC
December 2020

Revealing the Venomous Secrets of the Spider's Web.

J Proteome Res 2020 08 30;19(8):3044-3059. Epub 2020 Jun 30.

Center of the Study of Social Insects, Department of General and Applied Biology, Institute of Biosciences of Rio Claro, University of São Paulo State (UNESP), Rio Claro, SP 13506-900, Brazil.

Orb-weaving spiders use a highly strong, sticky and elastic web to catch their prey. These web properties alone would be enough for the entrapment of prey; however, these spiders may be hiding venomous secrets in the web, which current research is revealing. Here, we provide strong proteotranscriptomic evidence for the presence of toxin/neurotoxin-like proteins, defensins, and proteolytic enzymes on the web silk from spider. The results from quantitative-based transcriptomic and proteomic approaches showed that silk-producing glands produce an extensive repertoire of toxin/neurotoxin-like proteins, similar to those already reported in spider venoms. Meanwhile, the insect toxicity results demonstrated that these toxic components can be lethal and/or paralytic chemical weapons used for prey capture on the web, and the presence of fatty acids in the web may be a responsible mechanism opening the way to the web toxins for accessing the interior of prey's body, as shown here. Comparative phylogenomic-level evolutionary analyses revealed orthologous genes among two spider groups, Araneomorphae and Mygalomorphae, and the findings showed protein sequences similar to toxins found in the taxa Scorpiones and Hymenoptera in addition to Araneae. Overall, these data represent a valuable resource to further investigate other spider web toxin systems and also suggest that web is not a passive mechanical trap for prey capture, but it exerts an active role in prey paralysis/killing using a series of neurotoxins.
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http://dx.doi.org/10.1021/acs.jproteome.0c00086DOI Listing
August 2020

PIWIL-2 and piRNAs are regularly expressed in epithelia of the skin and their expression is related to differentiation.

Arch Dermatol Res 2020 Dec 12;312(10):705-714. Epub 2020 Mar 12.

Department of Dermatology, Medical University of Vienna, Vienna, Austria.

PIWI proteins play multiple roles in germline stem cell maintenance and self-renewal. PIWI-interacting RNAs (piRNAs) associate with PIWI proteins, form effector complexes and maintain genome integrity and function in the regulation of gene expression by epigenetic modifications. Both are involved in cancer development. In this study, we investigated the expression of PIWIL-2 and piRNAs in normal human skin and epithelial tumors and its regulation during keratinocyte (KC) differentiation. Immunohistochemistry showed that PIWIL-2 was regularly expressed in the epidermis and adnexal tissue with strongest expression in sebaceous glands. Cell culture studies revealed an association of PIWIL-2 expression with the state of differentiated KC. In contrast, the PIWIL-2 expression pattern did not correlate with stem cell compartments or malignancy. piRNAs were consistently detected in KC in vitro by next-generation sequencing and the expression levels of numerous piRNAs were regulated during KC differentiation. Epidermal piRNAs were predominantly derived from processed snoRNAs (C/D-box snoRNAs), tRNAs and protein coding genes. Our data indicate that components of the PIWIL-2-piRNA pathway are present in epithelial cells of the skin and are regulated in the context of KC differentiation, suggesting a role of somatic gene regulation. However, putative roles in the maintenance of stem cell compartments or the development of malignancy in the skin were not supported by this study.
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http://dx.doi.org/10.1007/s00403-020-02052-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7548280PMC
December 2020

Lmo3 deficiency in the mouse is associated with alterations in mood-related behaviors and a depression-biased amygdala transcriptome.

Psychoneuroendocrinology 2020 01 19;111:104480. Epub 2019 Oct 19.

Department of Neurophysiology and Neuropharmacology, Center for Physiology and Pharmacology, Medical University of Vienna, Schwarzspanierstraße 17, 1090, Vienna, Austria. Electronic address:

The highly conserved transcription factor LIM-only 3 (Lmo3) is involved in important neurodevelopmental processes in several brain areas including the amygdala, a central hub for the generation and regulation of emotions. Accordingly, a role for Lmo3 in the behavioral responses to ethanol and in the display of anxiety-like behavior in mice has been demonstrated while the potential involvement of Lmo3 in the control of mood-related behavior has not yet been explored. Using a mouse model of Lmo3 depletion (Lmo3), we here report that genetic Lmo3 deficiency is associated with altered performance in behavioral paradigms assessing anxiety-like and depression-like traits and additionally accompanied by impairments in learned fear. Importantly, long-term potentiation (LTP) in the basolateral amygdala (BLA), a proposed cellular correlate of fear learning, is impaired in Lmo3 mice. RNA-Seq analysis of BLA tissue and gene set enrichment analysis (GSEA) of differentially expressed genes in Lmo3 mice reveals a significant overlap between genes overexpressed in Lmo3 mice and those enriched in the amygdala of a cohort of patients suffering from major depressive disorder. Consequently, we propose that Lmo3 may play a role in the regulation of gene networks that are relevant to the regulation of emotions. Future work may aid to further explore the role of Lmo3 in the pathophysiology of affective disorders and its genetic foundations.
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http://dx.doi.org/10.1016/j.psyneuen.2019.104480DOI Listing
January 2020

JAK-STAT inhibition impairs K-RAS-driven lung adenocarcinoma progression.

Int J Cancer 2019 12 10;145(12):3376-3388. Epub 2019 Sep 10.

Department of Physiology, Center of Physiology and Pharmacology & Comprehensive Cancer Center (CCC), Medical University of Vienna, Vienna, Austria.

Oncogenic K-RAS has been difficult to target and currently there is no K-RAS-based targeted therapy available for patients suffering from K-RAS-driven lung adenocarcinoma (AC). Alternatively, targeting K-RAS-downstream effectors, K-RAS-cooperating signaling pathways or cancer hallmarks, such as tumor-promoting inflammation, has been shown to be a promising therapeutic strategy. Since the JAK-STAT pathway is considered to be a central player in inflammation-mediated tumorigenesis, we investigated here the implication of JAK-STAT signaling and the therapeutic potential of JAK1/2 inhibition in K-RAS-driven lung AC. Our data showed that JAK1 and JAK2 are activated in human lung AC and that increased activation of JAK-STAT signaling correlated with disease progression and K-RAS activity in human lung AC. Accordingly, administration of the JAK1/2 selective tyrosine kinase inhibitor ruxolitinib reduced proliferation of tumor cells and effectively reduced tumor progression in immunodeficient and immunocompetent mouse models of K-RAS-driven lung AC. Notably, JAK1/2 inhibition led to the establishment of an antitumorigenic tumor microenvironment, characterized by decreased levels of tumor-promoting chemokines and cytokines and reduced numbers of infiltrating myeloid derived suppressor cells, thereby impairing tumor growth. Taken together, we identified JAK1/2 inhibition as promising therapy for K-RAS-driven lung AC.
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http://dx.doi.org/10.1002/ijc.32624DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6856680PMC
December 2019

A proteotranscriptomic study of silk-producing glands from the orb-weaving spiders.

Mol Omics 2019 08;15(4):256-270

Center of the Study of Social Insects, Department of Biology, Institute of Biosciences of Rio Claro, São Paulo State University, Rio Claro, SP 13500-900, Brazil.

Orb-weaving spiders can produce different silk fibers, which constitute outstanding materials characterized by their high strength and elasticity. Researchers have tried to reproduce the fibers of these proteins synthetically and/or by using recombinant DNA technology, but only a few of the natural physicochemical and biophysical properties have been obtained to date. Female orb-web-spiders present seven silk-glands, which synthesize the spidroins and a series of other proteins, which interact with the spidroins, resulting in silk fibers with notable physicochemical properties. Despite the recognized importance of the silk-glands for understanding how the fibers are produced and processed, the investigation of these glands is at a nascent stage. In the current study we present the assembled transcriptome of silk-producing glands from the orb-weaving spider Nephila clavipes, as well as develop a large-scale proteomic approach for in-depth analyses of silk-producing glands. The present investigation revealed an extensive repertoire of hitherto undescribed proteins involved in silk secretion and processing, such as prevention of degradation during the silk spinning process, transportation, protection against proteolytic autolysis and against oxidative stress, molecular folding and stabilization, and post-translational modifications. Comparative phylogenomic-level evolutionary analyses revealed orthologous genes among three groups of silk-producing organisms - (i) Araneomorphae spiders, (ii) Mygalomorphae spiders, and (iii) silk-producing insects. A common orthologous gene, which was annotated as silk gland factor-3 is present among all species analysed. This protein belongs to a transcription factor family, that is important and related to the development of the silk apparatus synthesis in the silk glands of silk-producing arthropods.
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http://dx.doi.org/10.1039/c9mo00087aDOI Listing
August 2019

Altered Glutamate Receptor Ionotropic Delta Subunit 2 Expression in Stau2-Deficient Cerebellar Purkinje Cells in the Adult Brain.

Int J Mol Sci 2019 Apr 11;20(7). Epub 2019 Apr 11.

Biomedical Center (BMC), Department for Cell Biology & Anatomy, Medical Faculty, Ludwig-Maximilians- University, 82152 Martinsried, Germany.

Staufen2 (Stau2) is an RNA-binding protein that is involved in dendritic spine morphogenesis and function. Several studies have recently investigated the role of Stau2 in the regulation of its neuronal target mRNAs, with particular focus on the hippocampus. Here, we provide evidence for Stau2 expression and function in cerebellar Purkinje cells. We show that Stau2 downregulation (Stau2) led to an increase of glutamate receptor ionotropic delta subunit 2 (GluD2) in Purkinje cells when animals performed physical activity by voluntary wheel running compared with the age-matched wildtype (WT) mice (C57Bl/6J). Furthermore, Stau2 mice showed lower performance in motor coordination assays but enhanced motor learning abilities than did WT mice, concomitantly with an increase in dendritic GluD2 expression. Together, our results suggest the novel role of Stau2 in Purkinje cell synaptogenesis in the mouse cerebellum.
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http://dx.doi.org/10.3390/ijms20071797DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6480955PMC
April 2019

Identification of a leukemia-initiating stem cell in human mast cell leukemia.

Leukemia 2019 11 5;33(11):2673-2684. Epub 2019 Apr 5.

Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of Vienna, 1090, Vienna, Austria.

Mast cell leukemia (MCL) is a highly fatal malignancy characterized by devastating expansion of immature mast cells in various organs. Although considered a stem cell disease, little is known about MCL-propagating neoplastic stem cells. We here describe that leukemic stem cells (LSCs) in MCL reside within a CD34/CD38 fraction of the clone. Whereas highly purified CD34/CD38 cells engrafted NSG mice with fully manifesting MCL, no MCL was produced by CD34/CD38 progenitors or the bulk of KIT/CD34 mast cells. CD34/CD38 MCL cells invariably expressed CD13 and CD133, and often also IL-1RAP, but did not express CD25, CD26 or CLL-1. CD34/CD38 MCL cells also displayed several surface targets, including CD33, which was homogenously expressed on MCL LSCs in all cases, and the D816V mutant form of KIT. Although CD34/CD38 cells were resistant against single drugs, exposure to combinations of CD33-targeting and KIT-targeting drugs resulted in LSC-depletion and markedly reduced engraftment in NSG mice. Together, MCL LSCs are CD34/CD38 cells that express distinct profiles of markers and target antigens. Characterization of MCL LSCs should facilitate their purification and should support the development of LSC-eradicating curative treatment approaches in this fatal type of leukemia.
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http://dx.doi.org/10.1038/s41375-019-0460-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6839966PMC
November 2019

Cytokine-Like 1 Is a Novel Proangiogenic Factor Secreted by and Mediating Functions of Endothelial Progenitor Cells.

Circ Res 2019 01;124(2):243-255

From the Department of Vascular Biology and Thrombosis Research (D.S., C.S., K.L., B.G., M.S., M. Wen, J.T., E.H.), Medical University of Vienna, Austria.

Rationale: Endothelial colony forming cells (ECFCs) or late blood outgrowth endothelial cells can be isolated from human cord or peripheral blood, display properties of endothelial progenitors, home into ischemic tissues and support neovascularization in ischemic disease models.

Objective: To assess the functions of CYTL1 (cytokine-like 1), a factor we found preferentially produced by ECFCs, in regard of vessel formation.

Methods And Results: We show by transcriptomic analysis that ECFCs are distinguished from endothelial cells of the vessel wall by production of high amounts of CYTL1. Modulation of expression demonstrates that the factor confers increased angiogenic sprouting capabilities to ECFCs and can also trigger sprouting of mature endothelial cells. The data further display that CYTL1 can be induced by hypoxia and that it functions largely independent of VEGF-A (vascular endothelial growth factor-A). By recombinant production of CYTL1 we confirm that the peptide is indeed a strong proangiogenic factor and induces sprouting in cellular assays and functional vessel formation in animal models comparable to VEGF-A. Mass spectroscopy corroborates that CYTL1 is specifically O-glycosylated on 2 neighboring threonines in the C-terminal part and this modification is important for its proangiogenic bioactivity. Further analyses show that the factor does not upregulate proinflammatory genes and strongly induces several metallothionein genes encoding anti-inflammatory and antiapoptotic proteins.

Conclusions: We conclude that CYTL1 can mediate proangiogenic functions ascribed to endothelial progenitors such as ECFCs in vivo and may be a candidate to support vessel formation and tissue regeneration in ischemic pathologies.
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http://dx.doi.org/10.1161/CIRCRESAHA.118.313645DOI Listing
January 2019

Parathyroid hormone induces a browning program in human white adipocytes.

Int J Obes (Lond) 2019 06 5;43(6):1319-1324. Epub 2018 Dec 5.

Clinical Division of Endocrinology and Metabolism, Department of Medicine III, Medical University of Vienna, Vienna, Austria.

Energy dissipation through the promotion of brown adipose tissue (BAT) or browning of white adipose tissue has recently evolved as novel promising concept in the fight against metabolic disease. New evidence suggests that hormones can contribute to the thermogenic programming of adipocytes through paracrine or endocrine actions. Recent studies in rodents identified parathyroid hormone (PTH) and PTH-related peptide as mediators of energy wasting in cachexia models due to adipocyte browning. However, the effects of PTH on human adipocyte thermogenesis and metabolic activity are unknown. Here we isolated subcutaneous white adipocyte precursor cells (APCs) from human donors followed by stimulation with recombinant PTH. Our data show that acute and chronic PTH administration in primary in vitro differentiated human subcutaneous adipocytes induces a molecular thermogenic program with increased mitochondrial activity and oxidative respiratory capacity. PTH also enhances hormone sensitive lipase activity and lipolysis in human adipocytes which may contribute to the observed thermogenic effects. In summary, we demonstrate here that PTH is a novel mediator of human adipocyte browning, suggesting a hitherto unknown endocrine axis between the parathyroid gland and adipose tissue in humans.
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http://dx.doi.org/10.1038/s41366-018-0266-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6411131PMC
June 2019

A novel role for NUPR1 in the keratinocyte stress response to UV oxidized phospholipids.

Redox Biol 2019 01 13;20:467-482. Epub 2018 Nov 13.

Department of Dermatology, Medical University of Vienna, Vienna, Austria; Christian Doppler Laboratory for Biotechnology of Skin Aging, Austria. Electronic address:

Ultraviolet light is the dominant environmental oxidative skin stressor and a major skin aging factor. We studied which oxidized phospholipid (OxPL) mediators would be generated in primary human keratinocytes (KC) upon exposure to ultraviolet A light (UVA) and investigated the contribution of OxPL to UVA responses. Mass spectrometric analysis immediately or 24 h post UV stress revealed significant changes in abundance of 173 and 84 lipid species, respectively. We identified known and novel lipid species including known bioactive and also potentially reactive carbonyl containing species. We found indication for selective metabolism and degradation of selected reactive lipids. Exposure to both UVA and to in vitro UVA - oxidized phospholipids activated, on transcriptome and proteome level, NRF2/antioxidant response signaling, lipid metabolizing enzyme expression and unfolded protein response (UPR) signaling. We identified NUPR1 as an upstream regulator of UVA/OxPL transcriptional stress responses and found this protein to be expressed in the epidermis. Silencing of NUPR1 resulted in augmented expression of antioxidant and lipid detoxification genes and disturbed the cell cycle, making it a potential key factor in skin reactive oxygen species (ROS) responses intimately involved in aging and pathology.
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http://dx.doi.org/10.1016/j.redox.2018.11.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6243031PMC
January 2019

Intravenous Heme Arginate Induces HO-1 (Heme Oxygenase-1) in the Human Heart.

Arterioscler Thromb Vasc Biol 2018 11;38(11):2755-2762

Department of Clinical Pharmacology (M.B., M.W.), Medical University of Vienna, Austria.

Objective- HO-1 (heme oxygenase-1) induction may prevent or reduce ischemia-reperfusion injury. We previously evaluated its in vivo induction after a single systemic administration of heme arginate in peripheral blood mononuclear cells. The current trial was designed to assess the pharmacological tissue induction of HO-1 in the human heart with heme arginate in vivo. Approach and Results- Patients planned for conventional aortic valve replacement received placebo (n=8), 1 mg/kg (n=7) or 3 mg/kg (n=9) heme arginate infused intravenously 24 hours before surgery. A biopsy of the right ventricle was performed directly before aortic cross-clamping and after cross-clamp release. In addition, the right atrial appendage was partially removed for analysis. HO-1 protein and mRNA concentrations were measured in tissue samples and in peripheral blood mononuclear cells before to and up to 72 hours after surgery. No study medication-related adverse events occurred. A strong, dose-dependent effect on myocardial HO-1 mRNA levels was observed (right ventricle: 7.9±5.0 versus 88.6±49.1 versus 203.6±148.7; P=0.002 and right atrium: 10.8±8.8 versus 229.8±173.1 versus 392.7±195.7; P=0.001). This was paralleled by a profound increase of HO-1 protein concentration in atrial tissue (8401±3889 versus 28 585±10 692 versus 29 022±8583; P<0.001). Surgery and heme arginate infusion significantly increased HO-1 mRNA concentration in peripheral blood mononuclear cells ( P<0.001). HO-1 induction led to a significant increase of postoperative carboxyhemoglobin (1.7% versus 1.4%; P=0.041). No effect on plasma HO-1 protein levels could be detected. Conclusions- Myocardial HO-1 mRNA and protein can be dose-dependently induced by heme arginate. Protective effects of this therapeutic strategy should be evaluated in upcoming clinical trials. Clinical Trial Registration- URL: http://www.clinicaltrials.gov . Unique identifier: NCT02314780.
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http://dx.doi.org/10.1161/ATVBAHA.118.311832DOI Listing
November 2018

LincRNA H19 protects from dietary obesity by constraining expression of monoallelic genes in brown fat.

Nat Commun 2018 09 6;9(1):3622. Epub 2018 Sep 6.

Max Planck Institute for Metabolism Research, Gleueler Strasse 50, 50931, Köln, Germany.

Increasing brown adipose tissue (BAT) thermogenesis in mice and humans improves metabolic health and understanding BAT function is of interest for novel approaches to counteract obesity. The role of long noncoding RNAs (lncRNAs) in these processes remains elusive. We observed maternally expressed, imprinted lncRNA H19 increased upon cold-activation and decreased in obesity in BAT. Inverse correlations of H19 with BMI were also observed in humans. H19 overexpression promoted, while silencing of H19 impaired adipogenesis, oxidative metabolism and mitochondrial respiration in brown but not white adipocytes. In vivo, H19 overexpression protected against DIO, improved insulin sensitivity and mitochondrial biogenesis, whereas fat H19 loss sensitized towards HFD weight gains. Strikingly, paternally expressed genes (PEG) were largely absent from BAT and we demonstrated that H19 recruits PEG-inactivating H19-MBD1 complexes and acts as BAT-selective PEG gatekeeper. This has implications for our understanding how monoallelic gene expression affects metabolism in rodents and, potentially, humans.
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http://dx.doi.org/10.1038/s41467-018-05933-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6127097PMC
September 2018

FOXF1 Mediates Endothelial Progenitor Functions and Regulates Vascular Sprouting.

Front Bioeng Biotechnol 2018 14;6:76. Epub 2018 Jun 14.

Department of Vascular Biology and Thrombosis Research, Center for Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria.

Endothelial colony forming cells (ECFC) or late blood outgrowth endothelial cells (BOEC) have been proposed to contribute to neovascularization in humans. Exploring genes characteristic for the progenitor status of ECFC we have identified the forkhead box transcription factor FOXF1 to be selectively expressed in ECFC compared to mature endothelial cells isolated from the vessel wall. Analyzing the role of FOXF1 by gain- and loss-of-function studies we detected a strong impact of FOXF1 expression on the particularly high sprouting capabilities of endothelial progenitors. This apparently relates to the regulation of expression of several surface receptors. First, FOXF1 overexpression specifically induces the expression of Notch2 receptors and induces sprouting. Vice versa, knock-down of FOXF1 and Notch2 reduces sprouting. In addition, FOXF1 augments the expression of VEGF receptor-2 and of the arterial marker ephrin B2, whereas it downmodulates the venous marker EphB4. In line with these findings on human endothelial progenitors, we further show that knockdown of FOXF1 in the zebrafish model alters, during embryonic development, the regular formation of vasculature by sprouting. Hence, these findings support a crucial role of FOXF1 for endothelial progenitors and connected vascular sprouting as it may be relevant for tissue neovascularization. It further implicates Notch2, VEGF receptor-2, and ephrin B2 as downstream mediators of FOXF1 functions.
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http://dx.doi.org/10.3389/fbioe.2018.00076DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6010557PMC
June 2018

mTOR Senses Environmental Cues to Shape the Fibroblast-like Synoviocyte Response to Inflammation.

Cell Rep 2018 05;23(7):2157-2167

CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, 1090 Vienna, Austria; Center for Physiology and Pharmacology, Medical University of Vienna, 1090 Vienna, Austria. Electronic address:

Accumulating evidence suggests that metabolic master regulators, including mTOR, regulate adaptive and innate immune responses. Resident mesenchymal tissue components are increasingly recognized as key effector cells in inflammation. Whether mTOR also controls the inflammatory response in fibroblasts is insufficiently studied. Here, we show that TNF signaling co-opts the mTOR pathway to shift synovial fibroblast (FLS) inflammation toward an IFN response. mTOR pathway activation is associated with decreased NF-κB-mediated gene expression (e.g., PTGS2, IL-6, and IL-8) but increased STAT1-dependent gene expression (e.g., CXCL11 and TNFSF13B). We further demonstrate how metabolic inputs, such as amino acids, impinge on TNF-mTORC1 signaling to differentially regulate pro-inflammatory signaling circuits. Our results define a critical role for mTOR in the regulation of the pro-inflammatory response in FLSs and unfold its pathogenic involvement in TNF-driven diseases, such as rheumatoid arthritis (RA).
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http://dx.doi.org/10.1016/j.celrep.2018.04.044DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5972226PMC
May 2018

Mesenchyme-derived factors enhance preneoplastic growth by non-genotoxic carcinogens in rat liver.

Arch Toxicol 2018 Feb 21;92(2):953-966. Epub 2017 Dec 21.

Department of Medicine I, Comprehensive Cancer Center, Institute of Cancer Research, Medical University of Vienna, Borschkegasse 8a, 1090, Vienna, Austria.

Many frequently prescribed drugs are non-genotoxic carcinogens (NGC) in rodent liver. Their mode of action and health risks for humans remain to be elucidated. Here, we investigated the impact of two model NGC, the anti-epileptic drug phenobarbital (PB) and the contraceptive cyproterone acetate (CPA), on intrahepatic epithelial-mesenchymal crosstalk and on growth of first stages of hepatocarcinogenesis. Unaltered hepatocytes (HC) and preneoplastic HC (HC) were isolated from rat liver for primary culture. DNA replication of HC and HC was increased by in vitro treatment with 10 µM CPA, but not 1 mM PB. Next, mesenchymal cells (MC) obtained from liver of rats treated with either PB (50 mg/kg bw/day) or CPA (100 mg/kg bw/day), were cultured. Supernatants from both types of MC raised DNA synthesis of HC and HC. This indicates that PB induces replication of HC and HC only indirectly, via growth factors secreted by MC. CPA, however, acts on HC and HC directly as well as indirectly via mesenchymal factors. Transcriptomics and bio-informatics revealed that PB and CPA induce extensive changes in the expression profile of MC affecting many growth factors and pathways. MC from PB-treated rats produced and secreted enhanced levels of HBEGF and GDF15, factors found to suppress apoptosis and/or induce DNA synthesis in cultured HC and HC. MC from CPA-treated animals showed enhanced expression and secretion of HGF, which strongly raised DNA replication of HC and HC. In conclusion, our findings reveal profound effects of two prototypical NGC on the hepatic mesenchyme. The resulting release of factors, which suppress apoptosis and/or enhance cell replication preferentially in cancer prestages, appears to be crucial for tumor promotion by NGC in the liver.
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http://dx.doi.org/10.1007/s00204-017-2080-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5818586PMC
February 2018

Pumilio2-deficient mice show a predisposition for epilepsy.

Dis Model Mech 2017 11 18;10(11):1333-1342. Epub 2017 Oct 18.

Biomedical Center (BMC), Department for Cell Biology, Faculty of Medicine, LMU, Munich, 82152 Planegg-Martinsried, Germany

Epilepsy is a neurological disease that is caused by abnormal hypersynchronous activities of neuronal ensembles leading to recurrent and spontaneous seizures in human patients. Enhanced neuronal excitability and a high level of synchrony between neurons seem to trigger these spontaneous seizures. The molecular mechanisms, however, regarding the development of neuronal hyperexcitability and maintenance of epilepsy are still poorly understood. Here, we show that pumilio RNA-binding family member 2 (Pumilio2; Pum2) plays a role in the regulation of excitability in hippocampal neurons of weaned and 5-month-old male mice. Almost complete deficiency of Pum2 in adult gene-trap mice (Pum2 GT) causes misregulation of genes involved in neuronal excitability control. Interestingly, this finding is accompanied by the development of spontaneous epileptic seizures in Pum2 GT mice. Furthermore, we detect an age-dependent increase in (Na1.1) and (Na1.6) mRNA levels together with a decrease in (Na1.2) transcript levels in weaned Pum2 GT that is absent in older mice. Moreover, field recordings of CA1 pyramidal neurons show a tendency towards a reduced paired-pulse inhibition after stimulation of the Schaffer-collateral-commissural pathway in Pum2 GT mice, indicating a predisposition to the development of spontaneous seizures at later stages. With the onset of spontaneous seizures at the age of 5 months, we detect increased protein levels of Na1.1 and Na1.2 as well as decreased protein levels of Na1.6 in those mice. In addition, GABA receptor subunit alpha-2 () mRNA levels are increased in weaned and adult mice. Furthermore, we observe an enhanced GABRA2 protein level in the dendritic field of the CA1 subregion in the Pum2 GT hippocampus. We conclude that altered expression levels of known epileptic risk factors such as Na1.1, Na1.2, Na1.6 and GABRA2 result in enhanced seizure susceptibility and manifestation of epilepsy in the hippocampus. Thus, our results argue for a role of Pum2 in epileptogenesis and the maintenance of epilepsy.
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http://dx.doi.org/10.1242/dmm.029678DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5719250PMC
November 2017

Oxidative stress mediates an increased formation of vascular endothelial growth factor in human hepatocarcinoma cells exposed to erlotinib.

Oncotarget 2017 Aug 6;8(34):57109-57120. Epub 2017 Jul 6.

Division of Gastroenterology and Hepatology, Department of Internal Medicine III, Medical University of Vienna, A-1090 Vienna, Austria.

The tyrosine kinase inhibitor erlotinib targets the receptor of epidermal growth factor (EGFR) involved in development of hepatocellular carcinoma (HCC). Although inefficient in established HCC, erlotinib has been recently proposed for HCC chemoprevention. Since Cyp3A4 and Cyp1A2 enzymes metabolize erlotinib in the liver, the insights into the mechanisms of erlotinib effects on liver cells with maintained drug metabolizing activity are needed. We applied erlotinib to both commercially available (SNU398, Huh7) and established in Austria HCC cell lines (HCC-1.2, HCC-3). Cyp3A4 and Cyp1A2, microarray gene expression, cell viability, LDH release, DHFC fluorescence were assessed. VEGF expression was analysed by real-time RT-PCR and ELISA. Higher cumulative expression of erlotinib metabolizing enzymes was observed in HCC-1.2 and HCC-3 cells. Gene expression microarray analysis showed upregulation of VEGF signalling by erlotinib. VEGF was increased up to 134 ± 14% ( = 5, = 0.002) in HCC-1.2, HCC-3 and Huh7 cells. Interventions by Cyp1A2 and Mek2siRNA, MEK inhibitor UO126, diphenylene iodonium, as well as a combination of N-acetylcysteine with selenium all inhibited VEGF upregulation caused by erlotinib. Thus, erlotinib increases VEGF production by mechanisms involving Cyp1A2, oxidative stress and MEK1/2. VEGF may favour angiogenesis and growth of early HCC tumours limiting the therapeutic and chemopreventive effects of erlotinib.
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http://dx.doi.org/10.18632/oncotarget.19055DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5593629PMC
August 2017

APMAP interacts with lysyl oxidase-like proteins, and disruption of leads to beneficial visceral adipose tissue expansion.

FASEB J 2017 09 30;31(9):4088-4103. Epub 2017 May 30.

Institute of Biochemistry, Graz University of Technology, Graz, Austria;

Adipocyte plasma membrane-associated protein (APMAP) has been described as an adipogenic factor in 3T3-L1 cells with unknown biochemical function; we therefore aimed to investigate the physiologic function of APMAP We generated Apmapknockout mice and challenged them with an obesogenic diet to investigate their metabolic phenotype. We identified a novel truncated adipocyte-specific isoform of APMAP in mice that is produced by alternative transcription. Mice lacking the full-length APMAP protein, the only isoform that is expressed in humans, have an improved metabolic phenotype upon diet-induced obesity, indicated by enhanced insulin sensitivity, preserved glucose tolerance, increased respiratory exchange ratio, decreased inflammatory marker gene expression, and reduced adipocyte size. At the molecular level, APMAP interacts with the extracellular collagen cross-linking matrix proteins lysyl oxidase-like 1 and 3. On a high-fat diet, the expression of lysyl oxidase-like 1 and 3 is strongly decreased in Apmap-knockout mice, paralleled by reduced expression of profibrotic collagens and total collagen content in epididymal white adipose tissue, indicating decreased fibrotic potential. Together, our data suggest that APMAP is a novel regulator of extracellular matrix components, and establish that APMAP is a potential target to mitigate obesity-associated insulin resistance.-Pessentheiner, A. R., Huber, K., Pelzmann, H. J., Prokesch, A., Radner, F. P. W., Wolinski, H., Lindroos-Christensen, J., Hoefler, G., Rülicke, T., Birner-Gruenberger, R., Bilban, M., Bogner-Strauss, J. G. APMAP interacts with lysyl oxidase-like proteins, and disruption of leads to beneficial visceral adipose tissue expansion.
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http://dx.doi.org/10.1096/fj.201601337RDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5566180PMC
September 2017

The Transcription Factor ZNF683/HOBIT Regulates Human NK-Cell Development.

Front Immunol 2017 15;8:535. Epub 2017 May 15.

Institute of Vascular Biology and Thrombosis Research, Center of Physiology and Pharmacology, Medical University of Vienna, Vienna, Austria.

We identified as the most highly upregulated transcription factor gene during differentiation of human CD34 cord blood progenitor cells to CD56 natural killer (NK) cells. ZNF683/HOBIT mRNA was preferentially expressed in NK cells compared to other human peripheral blood lymphocytes and monocytes. During differentiation, ZNF683/HOBIT mRNA started to increase shortly after addition of IL-15 and further accumulated in parallel to the generation of CD56 NK cells. shRNA-mediated knockdown of ZNF683/HOBIT resulted in a substantial reduction of CD56CD14 NK-cell progenitors and the following generation of CD56 NK cells was largely abrogated. The few CD56 NK cells, which escaped the developmental inhibition in the ZNF683/HOBIT knockdown cultures, displayed normal levels of NKG2A and KIR receptors. Functional analyses of these cells showed no differences in degranulation capacity from control cultures. However, the proportion of IFN-γ-producing cells appeared to be increased upon ZNF683/HOBIT knockdown. These results indicate a key role of ZNF683/HOBIT for the differentiation of the human NK-cell lineage and further suggest a potential negative control on IFN-γ production in more mature human NK cells.
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http://dx.doi.org/10.3389/fimmu.2017.00535DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5430038PMC
May 2017

The recipient's heme oxygenase-1 promoter region polymorphism is associated with cardiac allograft vasculopathy.

Transpl Int 2017 May 15;30(5):510-518. Epub 2017 Mar 15.

Division of Cardiac Surgery, Medical University of Vienna, Vienna, Austria.

Heme oxygenase-1 (HO-1) catalyses the degradation of heme to biliverdin, free iron, and carbon monoxide. The promoter region contains a highly polymorphic (GT) repeat, where shorter (GT) repeat sequences are linked to higher transcriptional activity, which was shown to correlate with a cytoprotective effect. Higher HO-1 levels may protect from cardiac allograft vasculopathy. Cardiac allograft recipients transplanted between 1988 and 2012 were analyzed for the HO-1 (GT) repeat polymorphism using PCR and DNA fragment analysis with capillary electrophoresis. A relation to cardiac allograft vasculopathy (CAV) was analyzed using Cox regression including common risk factors for CAV and the occurrence of rejection episodes as explanatory variables. A total of 344 patients were analyzed, of which 127 patients were positive for CAV (36.9%). In our multivariable Cox regression analysis, the short homozygous HO-1 (GT) genotype with <27 repeats (S/S) revealed a higher risk for CAV (P = 0.032). Donor age (P = 0.001) and donor weight (P = 0.005) were significant predictors for CAV. A potential risk for CAV was associated with rejection episodes (P = 0.058) and history of smoking (P = 0.06). The recipient HO-1 (GT) genotype may contribute to CAV development. This finding has to be evaluated in larger series including studies targeting the underlying disease mechanism.
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http://dx.doi.org/10.1111/tri.12935DOI Listing
May 2017

Expression profiling of colorectal cancer cells reveals inhibition of DNA replication licensing by extracellular calcium.

Biochim Biophys Acta Mol Cell Res 2017 Jun 1;1864(6):987-996. Epub 2017 Feb 1.

Department of Pathophysiology and Allergy Research, Medical University of Vienna, Austria; Radcliffe Department of Medicine, University of Oxford, UK. Electronic address:

Colorectal cancer is one of the most common cancers in industrialised societies. Epidemiological studies, animal experiments, and randomized clinical trials have shown that dietary factors can influence all stages of colorectal carcinogenesis, from initiation through promotion to progression. Calcium is one of the factors with a chemoprophylactic effect in colorectal cancer. The aim of this study was to understand the molecular mechanisms of the anti-tumorigenic effects of extracellular calcium ([Ca]) in colon cancer cells. Gene expression microarray analysis of colon cancer cells treated for 1, 4, and 24h with 2mM [Ca] identified significant changes in expression of 1571 probe sets (ANOVA, p<10). The main biological processes affected by [Ca] were DNA replication, cell division, and regulation of transcription. All factors involved in DNA replication-licensing were significantly downregulated by [Ca]. Furthermore, we show that the calcium-sensing receptor (CaSR), a G protein-coupled receptor is a mediator involved in this process. To test whether these results were physiologically relevant, we fed mice with a standard diet containing low (0.04%), intermediate (0.1%), or high (0.9%) levels of dietary calcium. The main molecules regulating replication licensing were inhibited also in vivo, in the colon of mice fed high calcium diet. We show that among the mechanisms behind the chemopreventive effect of [Ca] is inhibition of replication licensing, a process often deregulated in neoplastic transformation. Our data suggest that dietary calcium is effective in preventing replicative stress, one of the main drivers of cancer and this process is mediated by the calcium-sensing receptor.
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http://dx.doi.org/10.1016/j.bbamcr.2017.01.017DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5424886PMC
June 2017

HO-1 inhibits preadipocyte proliferation and differentiation at the onset of obesity via ROS dependent activation of Akt2.

Sci Rep 2017 01 19;7:40881. Epub 2017 Jan 19.

Department of Laboratory Medicine, Medical University of Vienna, 1090 Vienna, Austria.

Excessive accumulation of white adipose tissue (WAT) is a hallmark of obesity. The expansion of WAT in obesity involves proliferation and differentiation of adipose precursors, however, the underlying molecular mechanisms remain unclear. Here, we used an unbiased transcriptomics approach to identify the earliest molecular underpinnings occuring in adipose precursors following a brief HFD in mice. Our analysis identifies Heme Oxygenase-1 (HO-1) as strongly and selectively being upregulated in the adipose precursor fraction of WAT, upon high-fat diet (HFD) feeding. Specific deletion of HO-1 in adipose precursors of Hmox1Pdgfra mice enhanced HFD-dependent visceral adipose precursor proliferation and differentiation. Mechanistically, HO-1 reduces HFD-induced AKT2 phosphorylation via ROS thresholding in mitochondria to reduce visceral adipose precursor proliferation. HO-1 influences adipogenesis in a cell-autonomous way by regulating events early in adipogenesis, during the process of mitotic clonal expansion, upstream of Cebpα and PPARγ. Similar effects on human preadipocyte proliferation and differentiation in vitro were observed upon modulation of HO-1 expression. This collectively renders HO-1 as an essential factor linking extrinsic factors (HFD) with inhibition of specific downstream molecular mediators (ROS &AKT2), resulting in diminished adipogenesis that may contribute to hyperplastic adipose tissue expansion.
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http://dx.doi.org/10.1038/srep40881DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5244367PMC
January 2017
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