Publications by authors named "Martin Hrabe de Angelis"

463 Publications

A comprehensive phenotypic characterization of a whole-body Wdr45 knock-out mouse.

Mamm Genome 2021 May 27. Epub 2021 May 27.

Institute of Human Genetics, Technische Universität München, 81675, Munich, Germany.

Pathogenic variants in the WDR45 (OMIM: 300,526) gene on chromosome Xp11 are the genetic cause of a rare neurological disorder characterized by increased iron deposition in the basal ganglia. As WDR45 encodes a beta-propeller scaffold protein with a putative role in autophagy, the disease has been named Beta-Propeller Protein-Associated Neurodegeneration (BPAN). BPAN represents one of the four most common forms of Neurodegeneration with Brain Iron Accumulation (NBIA). In the current study, we generated and characterized a whole-body Wdr45 knock-out (KO) mouse model. The model, developed using TALENs, presents a 20-bp deletion in exon 2 of Wdr45. Homozygous females and hemizygous males are viable, proving that systemic depletion of Wdr45 does not impair viability and male fertility in mice. The in-depth phenotypic characterization of the mouse model revealed neuropathology signs at four months of age, neurodegeneration progressing with ageing, hearing and visual impairment, specific haematological alterations, but no brain iron accumulation. Biochemically, Wdr45 KO mice presented with decreased complex I (CI) activity in the brain, suggesting that mitochondrial dysfunction accompanies Wdr45 deficiency. Overall, the systemic Wdr45 KO described here complements the two mouse models previously reported in the literature (PMIDs: 26,000,824, 31,204,559) and represents an additional robust model to investigate the pathophysiology of BPAN and to test therapeutic strategies for the disease.
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http://dx.doi.org/10.1007/s00335-021-09875-3DOI Listing
May 2021

Disruption of paternal circadian rhythm affects metabolic health in male offspring via nongerm cell factors.

Sci Adv 2021 May 26;7(22). Epub 2021 May 26.

Institute of Experimental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health Neuherberg, Germany.

Circadian rhythm synchronizes each body function with the environment and regulates physiology. Disruption of normal circadian rhythm alters organismal physiology and increases disease risk. Recent epidemiological data and studies in model organisms have shown that maternal circadian disruption is important for offspring health and adult phenotypes. Less is known about the role of paternal circadian rhythm for offspring health. Here, we disrupted circadian rhythm in male mice by night-restricted feeding and showed that paternal circadian disruption at conception is important for offspring feeding behavior, metabolic health, and oscillatory transcription. Mechanistically, our data suggest that the effect of paternal circadian disruption is not transferred to the offspring via the germ cells but initiated by corticosterone-based parental communication at conception and programmed during in utero development through a state of fetal growth restriction. These findings indicate paternal circadian health at conception as a newly identified determinant of offspring phenotypes.
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http://dx.doi.org/10.1126/sciadv.abg6424DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8153725PMC
May 2021

Creld1 regulates myocardial development and function.

J Mol Cell Cardiol 2021 Jul 24;156:45-56. Epub 2021 Mar 24.

Institute of Innate Immunity, Biophysical Imaging, Medical Faculty, University of Bonn, 53127 Bonn, Germany. Electronic address:

CRELD1 (Cysteine-Rich with EGF-Like Domains 1) is a risk gene for non-syndromic atrioventricular septal defects in human patients. In a mouse model, Creld1 has been shown to be essential for heart development, particularly in septum and valve formation. However, due to the embryonic lethality of global Creld1 knockout (KO) mice, its cell type-specific function during peri- and postnatal stages remains unknown. Here, we generated conditional Creld1 KO mice lacking Creld1 either in the endocardium (KO) or the myocardium (KO). Using a combination of cardiac phenotyping, histology, immunohistochemistry, RNA-sequencing, and flow cytometry, we demonstrate that Creld1 function in the endocardium is dispensable for heart development. Lack of myocardial Creld1 causes extracellular matrix remodeling and trabeculation defects by modulation of the Notch1 signaling pathway. Hence, KO mice die early postnatally due to myocardial hypoplasia. Our results reveal that Creld1 not only controls the formation of septa and valves at an early stage during heart development, but also cardiac maturation and function at a later stage. These findings underline the central role of Creld1 in mammalian heart development and function.
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http://dx.doi.org/10.1016/j.yjmcc.2021.03.008DOI Listing
July 2021

Author Correction: Endogenous FGF21-signaling controls paradoxical obesity resistance of UCP1-deficient mice.

Nat Commun 2021 Mar 16;12(1):1804. Epub 2021 Mar 16.

Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), 85764, Neuherberg, Germany.

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http://dx.doi.org/10.1038/s41467-021-22119-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7966759PMC
March 2021

Unbiased analysis of obesity related, fat depot specific changes of adipocyte volumes and numbers using light sheet fluorescence microscopy.

PLoS One 2021 16;16(3):e0248594. Epub 2021 Mar 16.

Research Unit Analytical Pathology, Helmholtz Zentrum München, Neuherberg, Germany.

In translational obesity research, objective assessment of adipocyte sizes and numbers is essential to characterize histomorphological alterations linked to obesity, and to evaluate the efficacies of experimental medicinal or dietetic interventions. Design-based quantitative stereological techniques based on the analysis of 2D-histological sections provide unbiased estimates of relevant 3D-parameters of adipocyte morphology, but often involve complex and time-consuming tissue processing and analysis steps. Here we report the application of direct 3D light sheet fluorescence microscopy (LSFM) for effective and accurate analysis of adipocyte volumes and numbers in optically cleared adipose tissue samples from a porcine model of diet-induced obesity (DIO). Subcutaneous and visceral adipose tissue samples from DIO-minipigs and lean controls were systematically randomly sampled, optically cleared with 3DISCO (3-dimensional imaging of solvent cleared organs), stained with eosin, and subjected to LSFM for detection of adipocyte cell membrane autofluorescence. Individual adipocytes were unbiasedly sampled in digital 3D reconstructions of the adipose tissue samples, and their individual cell volumes were directly measured by automated digital image analysis. Adipocyte numbers and mean volumes obtained by LSFM analysis did not significantly differ from the corresponding values obtained by unbiased quantitative stereological analysis techniques performed on the same samples, thus proving the applicability of LSFM for efficient analysis of relevant morphological adipocyte parameters. The results of the present study demonstrate an adipose tissue depot specific plasticity of adipocyte growth responses to nutrient oversupply. This was characterized by an exclusively hypertrophic growth of visceral adipocytes, whereas adipocytes in subcutaneous fat tissue depots also displayed a marked (hyperplastic) increase in cell number. LSFM allows for accurate and efficient determination of relevant quantitative morphological adipocyte parameters. The applied stereological methods and LSFM protocols are described in detail and can serve as a guideline for unbiased quantitative morphological analyses of adipocytes in other studies and species.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0248594PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7963095PMC
March 2021

On the Nature of Murine Radiation-Induced Subcapsular Cataracts: Optical Coherence Tomography-Based Fine Classification, In Vivo Dynamics and Impact on Visual Acuity.

Radiat Res 2021 Feb 25. Epub 2021 Feb 25.

Institute of Developmental Genetics, Helmholtz Zentrum München GmbH - German Research Center for Environmental Health, Neuherberg, Germany.

Ionizing radiation is widely known to induce various kinds of lens cataracts, of which posterior subcapsular cataracts (PSCs) have the highest prevalence. Despite some studies regarding the epidemiology and biology of radiation-induced PSCs, the mechanism underscoring the formation of this type of lesions and their dose dependency remain uncertain. Within the current study, our team investigated the in vivo characteristics of PSCs in B6C3F1 mice (F1-hybrids of BL6 × C3H) that received 0.5-2 Gy γ-ray irradiation after postnatal day 70. For purposes of assessing lenticular damages, spectral domain optical coherence tomography was utilized, and the visual acuity of the mice was measured to analyze their levels of visual impairment, and histological sections were then prepared in to characterize in vivo phenotypes. Three varying in vivo phenotype anterior and posterior lesions were thus revealed and correlated with the applied doses to understand their marginal influence on the visual acuity of the studied mice. Histological data indicated no significantly increased odds ratios for PSCs below a dose of 1 Gy at the end of the observation time. Furthermore, our team demonstrated that when the frequencies of the posterior and anterior lesions were calculated at early time points, their responses were in accordance with a deterministic model, whereas at later time points, their responses were better described via a stochastic model. The current study will aid in honing the current understanding of radiation-induced cataract formation and contributes greatly to addressing the fundamental questions of lens dose response within the field of radiation biology.
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http://dx.doi.org/10.1667/RADE-20-00163.1DOI Listing
February 2021

Validation of Candidate Phospholipid Biomarkers of Chronic Kidney Disease in Hyperglycemic Individuals and Their Organ-Specific Exploration in Leptin Receptor-Deficient db/db Mouse.

Metabolites 2021 Feb 3;11(2). Epub 2021 Feb 3.

Research Unit of Molecular Epidemiology, Helmholtz Zentrum München, 85764 Neuherberg, Germany.

Biological exploration of early biomarkers for chronic kidney disease (CKD) in (pre)diabetic individuals is crucial for personalized management of diabetes. Here, we evaluated two candidate biomarkers of incident CKD (sphingomyelin (SM) C18:1 and phosphatidylcholine diacyl (PC aa) C38:0) concerning kidney function in hyperglycemic participants of the Cooperative Health Research in the Region of Augsburg (KORA) cohort, and in two biofluids and six organs of leptin receptor-deficient (db/db) mice and wild type controls. Higher serum concentrations of SM C18:1 and PC aa C38:0 in hyperglycemic individuals were found to be associated with lower estimated glomerular filtration rate (eGFR) and higher odds of CKD. In db/db mice, both metabolites had a significantly lower concentration in urine and adipose tissue, but higher in the lungs. Additionally, db/db mice had significantly higher SM C18:1 levels in plasma and liver, and PC aa C38:0 in adrenal glands. This cross-sectional human study confirms that SM C18:1 and PC aa C38:0 associate with kidney dysfunction in pre(diabetic) individuals, and the animal study suggests a potential implication of liver, lungs, adrenal glands, and visceral fat in their systemic regulation. Our results support further validation of the two phospholipids as early biomarkers of renal disease in patients with (pre)diabetes.
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http://dx.doi.org/10.3390/metabo11020089DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7913334PMC
February 2021

Systemic Jak1 activation provokes hepatic inflammation and imbalanced FGF23 production and cleavage.

FASEB J 2021 02;35(2):e21302

Institute of Physiology, University of Zurich (UZH), and National Center of Competence in Research NCCR Kidney.CH, Zurich, Switzerland.

Fibroblast growth factor 23 (FGF23) is a main regulator of mineral homeostasis. Low and high circulating FGF23 levels are associated with bone, renal, cardiovascular diseases, and increased mortality. Understanding the factors and signaling pathways affecting FGF23 levels is crucial for the management of these diseases and their complications. Here, we show that activation of the Jak1/Stat3 signaling pathway leads to inflammation in liver and to an increase in hepatic FGF23 synthesis, a key hormone in mineral metabolism. This increased synthesis leads to massive C-terminal FGF23 circulating levels, the inactive C-terminal fragment, and increased intact FGF23 levels, the active form, resulting in imbalanced production and cleavage. Liver inflammation does not lead to activation of the calcineurin-NFAT pathway, and no signs of systemic inflammation could be observed. Despite the increase of active intact FGF23, excessive C-terminal FGF23 levels block the phosphaturic activity of FGF23. Therefore, kidney function and renal αKlotho expression are normal and no activation of the MAPK pathway was detected. In addition, activation of the Jak1/Stat3 signaling pathway leads to high calcitriol levels and low parathyroid hormone production. Thus, JAK1 is a central regulator of mineral homeostasis. Moreover, this study also shows that in order to assess the impact of high FGF23 levels on disease and kidney function, the source and the balance in FGF23 production and cleavage are critical.
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http://dx.doi.org/10.1096/fj.202002113RDOI Listing
February 2021

Ionising radiation causes vision impairment in neonatal B6C3F1 mice.

Exp Eye Res 2021 Mar 14;204:108432. Epub 2021 Jan 14.

Helmholtz Zentrum München GmbH - German Research Center for Environmental Health, Institute of Developmental Genetics, Neuherberg, Germany. Electronic address:

Ionising radiation interacts with lenses and retinae differently. In human lenses, posterior subcapsular cataracts are the predominant observation, whereas retinae of adults are comparably resistant to even relatively high doses. In this study, we demonstrate the effects of 2 Gy of low linear energy transfer ionising radiation on eyes of B6C3F1 mice aged postnatal day 2. Optical coherence tomography and Scheimpflug imaging were utilised for the first time to monitor murine lenses and retinae in vivo. The visual acuity of the mice was determined and histological analysis was conducted. Our results demonstrated that visual acuity was reduced by as much as 50 % approximately 9 months after irradiation in irradiated mice. Vision impairment was caused by retinal atrophy and inner cortical cataracts. These results help to further our understanding of the risk of ionising radiation for human foeti (∼ 8 mo), which follow the same eye development stages as neonatal mice.
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http://dx.doi.org/10.1016/j.exer.2020.108432DOI Listing
March 2021

Pathophysiology-based subphenotyping of individuals at elevated risk for type 2 diabetes.

Nat Med 2021 01 4;27(1):49-57. Epub 2021 Jan 4.

Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany.

The state of intermediate hyperglycemia is indicative of elevated risk of developing type 2 diabetes. However, the current definition of prediabetes neither reflects subphenotypes of pathophysiology of type 2 diabetes nor is predictive of future metabolic trajectories. We used partitioning on variables derived from oral glucose tolerance tests, MRI-measured body fat distribution, liver fat content and genetic risk in a cohort of extensively phenotyped individuals who are at increased risk for type 2 diabetes to identify six distinct clusters of subphenotypes. Three of the identified subphenotypes have increased glycemia (clusters 3, 5 and 6), but only individuals in clusters 5 and 3 have imminent diabetes risks. By contrast, those in cluster 6 have moderate risk of type 2 diabetes, but an increased risk of kidney disease and all-cause mortality. Findings were replicated in an independent cohort using simple anthropomorphic and glycemic constructs. This proof-of-concept study demonstrates that pathophysiological heterogeneity exists before diagnosis of type 2 diabetes and highlights a group of individuals who have an increased risk of complications without rapid progression to overt type 2 diabetes.
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http://dx.doi.org/10.1038/s41591-020-1116-9DOI Listing
January 2021

Mouse mutant phenotyping at scale reveals novel genes controlling bone mineral density.

PLoS Genet 2020 12 28;16(12):e1009190. Epub 2020 Dec 28.

Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America.

The genetic landscape of diseases associated with changes in bone mineral density (BMD), such as osteoporosis, is only partially understood. Here, we explored data from 3,823 mutant mouse strains for BMD, a measure that is frequently altered in a range of bone pathologies, including osteoporosis. A total of 200 genes were found to significantly affect BMD. This pool of BMD genes comprised 141 genes with previously unknown functions in bone biology and was complementary to pools derived from recent human studies. Nineteen of the 141 genes also caused skeletal abnormalities. Examination of the BMD genes in osteoclasts and osteoblasts underscored BMD pathways, including vesicle transport, in these cells and together with in silico bone turnover studies resulted in the prioritization of candidate genes for further investigation. Overall, the results add novel pathophysiological and molecular insight into bone health and disease.
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http://dx.doi.org/10.1371/journal.pgen.1009190DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7822523PMC
December 2020

Dose-dependent long-term effects of a single radiation event on behaviour and glial cells.

Int J Radiat Biol 2021 15;97(2):156-169. Epub 2020 Dec 15.

Institute of Developmental Genetics, Helmholtz Zentrum München, German Research Centre for Environmental Health, Neuherberg, Germany.

Purpose: The increasing use of low-dose ionizing radiation in medicine requires a systematic study of its long-term effects on the brain, behaviour and its possible association with neurodegenerative disease vulnerability. Therefore, we analysed the long-term effects of a single low-dose irradiation exposure at 10 weeks of age compared to medium and higher doses on locomotor, emotion-related and sensorimotor behaviour in mice as well as on hippocampal glial cell populations.

Materials And Methods: We determined the influence of radiation dose (0, 0.063, 0.125 or 0.5 Gy), time post-irradiation (4, 12 and 18 months p.i.), sex and genotype (wild type versus mice with DNA repair gene point mutation) on behaviour.

Results: The high dose (0.5 Gy) had early-onset adverse effects at 4 months p.i. on sensorimotor recruitment and late-onset negative locomotor effects at 12 and 18 months p.i. Notably, the low dose (0.063 Gy) produced no early effects but subtle late-onset (18 months) protective effects on sensorimotor recruitment and exploratory behaviour. Quantification and morphological characterization of the microglial and the astrocytic cells of the dentate gyrus 24 months p.i. indicated heightened immune activity after high dose irradiation (0.125 and 0.5 Gy) while conversely, low dose (0.063 Gy) induced more neuroprotective features.

Conclusion: This is one of the first studies demonstrating such long-term and late-onset effects on brain and behaviour after a single radiation event in adulthood.
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http://dx.doi.org/10.1080/09553002.2021.1857455DOI Listing
December 2020

Growth hormone receptor knockout to reduce the size of donor pigs for preclinical xenotransplantation studies.

Xenotransplantation 2021 Mar 25;28(2):e12664. Epub 2020 Nov 25.

Department of Veterinary Sciences, Chair for Molecular Animal Breeding and Biotechnology, Gene Center, LMU Munich, Munich, Germany.

Background: Many genetically multi-modified donor lines for xenotransplantation have a background of domestic pigs with rapid body and organ growth. The intrinsic growth potential of porcine xeno-organs may impair their long-term function after orthotopic transplantation in non-human primate models. Since growth hormone is a major stimulator of postnatal growth, we deleted its receptor (GHR-KO) to reduce the size of donor pigs in one step.

Methods: Heart weight and proteome profile of myocardium were investigated in GHR-KO and control pigs. GHR-KO mutations were introduced using CRISPR/Cas9 in an α1,3-galactosyltransferase (GGTA1)-deficient background expressing the human cluster of differentiation (hCD46) and human thrombomodulin (hTHBD) to generate quadruple-modified (4GM) pigs.

Results: At age 6 months, GHR-KO pigs had a 61% reduced body weight and a 63% reduced heart weight compared with controls. The mean minimal diameter of cardiomyocytes was 28% reduced. A holistic proteome study of myocardium samples from the two groups did not reveal prominent differences. Two 4GM founder sows had low serum insulin-like growth factor 1 (IGF1) levels (24 ± 1 ng/mL) and reached body weights of 70.3 and 73.4 kg at 9 months. Control pigs with IGF1 levels of 228 ± 24 ng/mL reached this weight range three months earlier. The 4GM sows showed normal sexual development and were mated with genetically multi-modified boars. Offspring revealed the expected Mendelian transmission of the genetic modifications and consistent expression of the transgenes.

Conclusion: GHR-KO donor pigs can be used at an age beyond the steepest phase of their growth curve, potentially reducing the problem of xeno-organ overgrowth in preclinical studies.
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http://dx.doi.org/10.1111/xen.12664DOI Listing
March 2021

Mouse Age Matters: How Age Affects the Murine Plasma Metabolome.

Metabolites 2020 Nov 19;10(11). Epub 2020 Nov 19.

Research Unit Molecular Endocrinology and Metabolism, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), 85764 Neuherberg, Germany.

A large part of metabolomics research relies on experiments involving mouse models, which are usually 6 to 20 weeks of age. However, in this age range mice undergo dramatic developmental changes. Even small age differences may lead to different metabolomes, which in turn could increase inter-sample variability and impair the reproducibility and comparability of metabolomics results. In order to learn more about the variability of the murine plasma metabolome, we analyzed male and female C57BL/6J, C57BL/6NTac, 129S1/SvImJ, and C3HeB/FeJ mice at 6, 10, 14, and 20 weeks of age, using targeted metabolomics (BIOCRATES Absolute™ p150 Kit). Our analysis revealed high variability of the murine plasma metabolome during adolescence and early adulthood. A general age range with minimal variability, and thus a stable metabolome, could not be identified. Age-related metabolomic changes as well as the metabolite profiles at specific ages differed markedly between mouse strains. This observation illustrates the fact that the developmental timing in mice is strain specific. We therefore stress the importance of deliberate strain choice, as well as consistency and precise documentation of animal age, in metabolomics studies.
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http://dx.doi.org/10.3390/metabo10110472DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7699431PMC
November 2020

Increased Expressions of Matrix Metalloproteinases (MMPs) in Prostate Cancer Tissues of Men with Type 2 Diabetes.

Biomedicines 2020 Nov 16;8(11). Epub 2020 Nov 16.

Department of Internal Medicine IV, Division of Diabetology, Endocrinology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany.

Type 2 diabetes (T2D) is associated with worse prognosis of prostate cancer (PCa). The molecular mechanisms behind this association are still not fully understood. The aim of this study was to identify key factors, which contribute to the more aggressive PCa phenotype in patients with concurrent T2D. Therefore, we investigated benign and PCa tissue of PCa patients with and without diabetes using real time qPCR. Compared to patients without diabetes, patients with T2D showed a decreased E-cadherin/N-cadherin (CDH1/CDH2) ratio in prostate tissue, indicating a switch of epithelial-mesenchymal transition (EMT), which is a pivotal process in carcinogenesis. In addition, the gene expression levels of matrix metalloproteinases () and CC chemokine ligands () were higher in prostate samples of T2D patients. Next, prostate adenocarcinoma PC3 cells were treated with increasing glucose concentrations to replicate hyperglycemia in vitro. In these cells, high glucose induced expressions of and , which showed significant positive associations with the proliferation marker proliferating cell nuclear antigen (). These results indicate that in prostate tissue of men with T2D, hyperglycemia may induce EMT, increase and gene expressions, which in turn activate invasion and inflammatory processes accelerating the progression of PCa.
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http://dx.doi.org/10.3390/biomedicines8110507DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7696165PMC
November 2020

Inhibition of LTβR signalling activates WNT-induced regeneration in lung.

Nature 2020 12 4;588(7836):151-156. Epub 2020 Nov 4.

German Cancer Research Center (DKFZ), Division of Chronic Inflammation and Cancer, Heidelberg, Germany.

Lymphotoxin β-receptor (LTβR) signalling promotes lymphoid neogenesis and the development of tertiary lymphoid structures, which are associated with severe chronic inflammatory diseases that span several organ systems. How LTβR signalling drives chronic tissue damage particularly in the lung, the mechanism(s) that regulate this process, and whether LTβR blockade might be of therapeutic value have remained unclear. Here we demonstrate increased expression of LTβR ligands in adaptive and innate immune cells, enhanced non-canonical NF-κB signalling, and enriched LTβR target gene expression in lung epithelial cells from patients with smoking-associated chronic obstructive pulmonary disease (COPD) and from mice chronically exposed to cigarette smoke. Therapeutic inhibition of LTβR signalling in young and aged mice disrupted smoking-related inducible bronchus-associated lymphoid tissue, induced regeneration of lung tissue, and reverted airway fibrosis and systemic muscle wasting. Mechanistically, blockade of LTβR signalling dampened epithelial non-canonical activation of NF-κB, reduced TGFβ signalling in airways, and induced regeneration by preventing epithelial cell death and activating WNT/β-catenin signalling in alveolar epithelial progenitor cells. These findings suggest that inhibition of LTβR signalling represents a viable therapeutic option that combines prevention of tertiary lymphoid structures and inhibition of apoptosis with tissue-regenerative strategies.
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http://dx.doi.org/10.1038/s41586-020-2882-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7718297PMC
December 2020

Diabetes type 2 risk gene Dusp8 is associated with altered sucrose reward behavior in mice and humans.

Brain Behav 2021 01 1;11(1):e01928. Epub 2020 Nov 1.

Research Unit Neurobiology of Diabetes, Helmholtz Zentrum München, Neuherberg, Germany.

Background: Dusp8 is the first GWAS-identified gene that is predominantly expressed in the brain and has previously been linked with the development of diabetes type 2 in humans. In this study, we unravel how Dusp8 is involved in the regulation of sucrose reward behavior.

Methods: Female, chow-fed global Dusp8 WT and KO mice were tested in an observer-independent IntelliCage setup for self-administrative sucrose consumption and preference followed by a progressive ratio task with restricted sucrose access to monitor seeking and motivation behavior. Sixty-three human carriers of the major C and minor T allele of DUSP8 SNP rs2334499 were tested for their perception of food cues by collecting a rating score for sweet versus savory high caloric food.

Results: Dusp8 KO mice showed a comparable preference for sucrose, but consumed more sucrose compared to WT mice. In a progressive ratio task, Dusp8 KO females switched to a "trial and error" strategy to find sucrose while control Dusp8 WT mice kept their previously established seeking pattern. Nonetheless, the overall motivation to consume sucrose, and the levels of dopaminergic neurons in the brain areas NAcc and VTA were comparable between genotypes. Diabetes-risk allele carriers of DUSP8 SNP rs2334499 preferred sweet high caloric food compared to the major allele carriers, rating scores for savory food remained comparable between groups.

Conclusion: Our data suggest a novel role for Dusp8 in the perception of sweet high caloric food as well as in the control of sucrose consumption and foraging in mice and humans.
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http://dx.doi.org/10.1002/brb3.1928DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7821601PMC
January 2021

PAX6 mutation alters circadian rhythm and β cell function in mice without affecting glucose tolerance.

Commun Biol 2020 10 30;3(1):628. Epub 2020 Oct 30.

Helmholtz Zentrum München, Institute of Experimental Genetics and German Mouse Clinic, Neuherberg, Germany.

The transcription factor PAX6 is involved in the development of the eye and pancreatic islets, besides being associated with sleep-wake cycles. Here, we investigated a point mutation in the RED subdomain of PAX6, previously described in a human patient, to present a comprehensive study of a homozygous Pax6 mutation in the context of adult mammalian metabolism and circadian rhythm. Pax6 mice lack appropriate retinal structures for light perception and do not display normal daily rhythmic changes in energy metabolism. Despite β cell dysfunction and decreased insulin secretion, mutant mice have normal glucose tolerance. This is associated with reduced hepatic glucose production possibly due to altered circadian variation in expression of clock and metabolic genes, thereby evading hyperglycemia. Hence, our findings show that while the RED subdomain is important for β cell functional maturity, the Leca2 mutation impacts peripheral metabolism via loss of circadian rhythm, thus revealing pleiotropic effects of PAX6.
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http://dx.doi.org/10.1038/s42003-020-01337-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7599253PMC
October 2020

Increased estrogen to androgen ratio enhances immunoglobulin levels and impairs B cell function in male mice.

Sci Rep 2020 10 27;10(1):18334. Epub 2020 Oct 27.

Institute of Biomedicine, University of Turku, Turku, Finland.

Sex steroids, such as estrogens and androgens, are important regulators of the humoral immune response. Studies in female mice have demonstrated that alteration of circulating estrogen concentration regulates antibody-mediated immunity. As males have normally little endogenous estrogen, we hypothesized that in males high estrogens and low androgens affect the immune system and enhance the allergic inflammatory response. Here, we studied transgenic male mice expressing human aromatase (AROM+). These animals have a high circulating estrogen to androgen ratio (E/A), causing female traits such as gynecomastia. We found that AROM+ male mice had significantly higher plasma immunoglobulin levels, particularly IgE. Flow cytometry analyses of splenocytes revealed changes in mature/immature B cell ratio together with a transcriptional upregulation of the Igh locus. Furthermore, higher proliferation rate and increased IgE synthesis after IgE class-switching was found. Subsequently, we utilized an ovalbumin airway challenge model to test the allergic response in AROM+ male mice. In line with above observations, an increase in IgE levels was measured, albeit no impact on immune cell infiltration into the lungs was detected. Together, our findings suggest that high circulating E/A in males significantly alters B cell function without any significant enhancement in allergic inflammation.
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http://dx.doi.org/10.1038/s41598-020-75059-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7591566PMC
October 2020

Murine tissue factor disulfide mutation causes a bleeding phenotype with sex specific organ pathology and lethality.

Haematologica 2020 10 1;105(10):2484-2495. Epub 2020 Oct 1.

Department of Cardiology, University Heart Center, University Hospital, Zurich, Switzerland.

Tissue factor is highly expressed in sub-endothelial tissue. The extracellular allosteric disulfide bond Cys186-Cys209 of human tissue factor shows high evolutionary conservation and in vitro evidence suggests that it significantly contributes to tissue factor procoagulant activity. To investigate the role of this allosteric disulfide bond in vivo, we generated a C213G mutant tissue factor mouse by replacing Cys213 of the corresponding disulfide Cys190-Cys213 in murine tissue factor. A bleeding phenotype was prominent in homozygous C213G tissue factor mice. Pre-natal lethality of 1/3rd of homozygous offspring was observed between E9.5 and E14.5 associated with placental hemorrhages. After birth, homozygous mice suffered from bleedings in different organs and reduced survival. Homozygous C213G tissue factor male mice showed higher incidence of lung bleedings and lower survival rates than females. In both sexes, C213G mutation evoked a reduced protein expression (about 10-fold) and severely reduced pro-coagulant activity (about 1000-fold). Protein glycosylation was impaired and cell membrane exposure decreased in macrophages in vivo. Single housing of homozygous C213G tissue factor males reduced the occurrence of severe bleeding and significantly improved survival, suggesting that inter-male aggressiveness might significantly account for the sex differences. These experiments show that the tissue factor allosteric disulfide bond is of crucial importance for normal in vivo expression, post-translational processing and activity of murine tissue factor. Although C213G tissue factor mice do not display the severe embryonic lethality of tissue factor knock-out mice, their postnatal bleeding phenotype emphasizes the importance of fully functional tissue factor for hemostasis.
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http://dx.doi.org/10.3324/haematol.2019.218818DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7556672PMC
October 2020

Ectopic fat accumulation in human astrocytes impairs insulin action.

R Soc Open Sci 2020 Sep 16;7(9):200701. Epub 2020 Sep 16.

Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Center Munich at the University of Tübingen, Tübingen, Germany.

Astrocytes provide neurons with structural support and energy in form of lactate, modulate synaptic transmission, are insulin sensitive and act as gatekeeper for water, ions, glutamate and second messengers. Furthermore, astrocytes are important for glucose sensing, possess neuroendocrine functions and also play an important role in cerebral lipid metabolism. To answer the question, if there is a connection between lipid metabolism and insulin action in human astrocytes, we investigated if storage of ectopic lipids in human astrocytes has an impact on insulin signalling in those cells. Human astrocytes were cultured in the presence of a lipid emulsion, consisting of fatty acids and triglycerides, to induce ectopic lipid storage. After several days, cells were stimulated with insulin and gene expression profiling was performed. In addition, phosphorylation of Akt as well as glycogen synthesis and cell proliferation was assessed. Ectopic lipid storage was detected in human astrocytes after lipid exposure and lipid storage was persistent even when the fat emulsion was removed from the cell culture medium. Chronic exposure to lipids induced profound changes in the gene expression profile, whereby some genes showed a reversible gene expression profile upon removal of fat, and some did not. This included FOXO-dependent expression patterns. Furthermore, insulin-induced phosphorylation of Akt was diminished and also insulin-induced glycogen synthesis and proliferation was impaired in lipid-laden astrocytes. Chronic lipid exposure induces lipid storage in human astrocytes accompanied by insulin resistance. Analyses of the gene expression pattern indicated the potential of a partially reversible gene expression profile. Targeting astrocytic insulin resistance by reducing ectopic lipid load might represent a promising treatment target for insulin resistance of the brain in obesity, diabetes and neurodegeneration.
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http://dx.doi.org/10.1098/rsos.200701DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7540778PMC
September 2020

Characterization of Hormone-Dependent Pathways in Six Human Prostate-Cancer Cell Lines: A Gene-Expression Study.

Genes (Basel) 2020 10 7;11(10). Epub 2020 Oct 7.

Department of Internal Medicine IV, Division of Diabetology, Endocrinology, and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany.

Prostate cancer (PCa), the most incident cancer in men, is tightly regulated by endocrine signals. A number of different PCa cell lines are commonly used for in vitro experiments, but these are of diverse origin, and have very different cell-proliferation rates and hormone-response capacities. By analyzing the gene-expression pattern of main hormone pathways, we systematically compared six PCa cell lines and parental primary cells. We compared these cell lines (i) with each other and (ii) with PCa tissue samples from 11 patients. We found major differences in the gene-expression levels of androgen, insulin, estrogen, and oxysterol signaling between PCa tissue and cell lines, and between different cell lines. Our systematic characterization gives researchers a solid basis to choose the appropriate PCa cell model for the hormone pathway of interest.
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http://dx.doi.org/10.3390/genes11101174DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7599530PMC
October 2020

Machine Learning Approaches Reveal Metabolic Signatures of Incident Chronic Kidney Disease in Individuals With Prediabetes and Type 2 Diabetes.

Diabetes 2020 12 6;69(12):2756-2765. Epub 2020 Oct 6.

Research Unit of Molecular Epidemiology, Helmholtz Zentrum München - German Research Center for Environmental Health, Neuherberg, Germany

Early and precise identification of individuals with prediabetes and type 2 diabetes (T2D) at risk for progressing to chronic kidney disease (CKD) is essential to prevent complications of diabetes. Here, we identify and evaluate prospective metabolite biomarkers and the best set of predictors of CKD in the longitudinal, population-based Cooperative Health Research in the Region of Augsburg (KORA) cohort by targeted metabolomics and machine learning approaches. Out of 125 targeted metabolites, sphingomyelin C18:1 and phosphatidylcholine diacyl C38:0 were identified as candidate metabolite biomarkers of incident CKD specifically in hyperglycemic individuals followed during 6.5 years. Sets of predictors for incident CKD developed from 125 metabolites and 14 clinical variables showed highly stable performances in all three machine learning approaches and outperformed the currently established clinical algorithm for CKD. The two metabolites in combination with five clinical variables were identified as the best set of predictors, and their predictive performance yielded a mean area value under the receiver operating characteristic curve of 0.857. The inclusion of metabolite variables in the clinical prediction of future CKD may thus improve the risk prediction in people with prediabetes and T2D. The metabolite link with hyperglycemia-related early kidney dysfunction warrants further investigation.
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http://dx.doi.org/10.2337/db20-0586DOI Listing
December 2020

Transcript Levels of Aldo-Keto Reductase Family 1 Subfamily C (AKR1C) Are Increased in Prostate Tissue of Patients with Type 2 Diabetes.

J Pers Med 2020 Sep 12;10(3). Epub 2020 Sep 12.

Department of Internal Medicine IV, Division of Endocrinology, Diabetology and Nephrology, University Hospital Tübingen, 72076 Tübingen, Germany.

Aldo-keto reductase family 1 (AKR1) enzymes play a crucial role in diabetic complications. Since type 2 diabetes (T2D) is associated with cancer progression, we investigated the impact of diabetes on gene expression in the context of prostate cancer (PCa) development. In this study, we analyzed benign (BEN) prostate and PCa tissue of patients with and without T2D. Furthermore, to replicate hyperglycemia in vitro, we treated the prostate adenocarcinoma cell line PC3 with increasing glucose concentrations. Gene expression was quantified using real-time qPCR. In the prostate tissue of patients with T2D, and transcripts were higher compared to samples of patients without diabetes. In PC3 cells, high glucose treatment induced the gene expression levels of , and . Furthermore, both in human tissue and in PC3 cells, the transcript levels of and showed positive associations with oncogenes, which are involved in proliferation processes and HIF1α and NFκB pathways. These results indicate that in the prostate glands of patients with T2D, hyperglycemia could play a pivotal role by inducing the expression of and . The higher transcript level of was furthermore associated with upregulated HIF1α and NFκB pathways, which are major drivers of PCa carcinogenesis.
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http://dx.doi.org/10.3390/jpm10030124DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7564141PMC
September 2020

METTL6 is a tRNA mC methyltransferase that regulates pluripotency and tumor cell growth.

Sci Adv 2020 Aug 26;6(35):eaaz4551. Epub 2020 Aug 26.

Institute of Functional Epigenetics, Helmholtz Zentrum München, 85764 Neuherberg, Germany.

Recently, covalent modifications of RNA, such as methylation, have emerged as key regulators of all aspects of RNA biology and have been implicated in numerous diseases, for instance, cancer. Here, we undertook a combination of in vitro and in vivo screens to test 78 potential methyltransferases for their roles in hepatocellular carcinoma (HCC) cell proliferation. We identified methyltransferase-like protein 6 (METTL6) as a crucial regulator of tumor cell growth. We show that METTL6 is a bona fide transfer RNA (tRNA) methyltransferase, catalyzing the formation of 3-methylcytidine at C32 of specific serine tRNA isoacceptors. Deletion of in mouse stem cells results in changes in ribosome occupancy and RNA levels, as well as impaired pluripotency. In mice, knockout results in reduced energy expenditure. We reveal a previously unknown pathway in the maintenance of translation efficiency with a role in maintaining stem cell self-renewal, as well as impacting tumor cell growth profoundly.
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http://dx.doi.org/10.1126/sciadv.aaz4551DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7449687PMC
August 2020

Phosphorylation Control of p53 DNA-Binding Cooperativity Balances Tumorigenesis and Aging.

Cancer Res 2020 12 1;80(23):5231-5244. Epub 2020 Sep 1.

Institute of Molecular Oncology, Member of the German Center for Lung Research (DZL), Philipps-University Marburg, Marburg, Germany.

Posttranslational modifications are essential for regulating the transcription factor p53, which binds DNA in a highly cooperative manner to control expression of a plethora of tumor-suppressive programs. Here we show at the biochemical, cellular, and organismal level that the cooperative nature of DNA binding is reduced by phosphorylation of highly conserved serine residues (human S183/S185, mouse S180) in the DNA-binding domain. To explore the role of this inhibitory phosphorylation , new phosphorylation-deficient p53-S180A knock-in mice were generated. Chromatin immunoprecipitation sequencing and RNA sequencing studies of S180A knock-in cells demonstrated enhanced DNA binding and increased target gene expression. , this translated into a tissue-specific vulnerability of the bone marrow that caused depletion of hematopoietic stem cells and impaired proper regeneration of hematopoiesis after DNA damage. Median lifespan was significantly reduced by 20% from 709 days in wild type to only 568 days in S180A littermates. Importantly, lifespan was reduced by a loss of general fitness and increased susceptibility to age-related diseases, not by increased cancer incidence as often seen in other p53-mutant mouse models. For example, S180A knock-in mice showed markedly reduced spontaneous tumorigenesis and increased resistance to -driven lymphoma and -driven lung cancer. Preventing phosphorylation of S183/S185 in human cells boosted p53 activity and allowed tumor cells to be killed more efficiently. Together, our data identify p53 DNA-binding domain phosphorylation as a druggable mechanism that balances tumorigenesis and aging. SIGNIFICANCE: These findings demonstrate that p53 tumor suppressor activity is reduced by DNA-binding domain phosphorylation to prevent aging and identify this phosphorylation as a potential target for cancer therapy..
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http://dx.doi.org/10.1158/0008-5472.CAN-20-2002DOI Listing
December 2020

Type 2 diabetes risk gene Dusp8 regulates hypothalamic Jnk signaling and insulin sensitivity.

J Clin Invest 2020 11;130(11):6093-6108

Neurobiology of Stress Resilience, Max Planck Institute of Psychiatry, Munich, Germany.

Recent genome-wide association studies (GWAS) identified DUSP8, encoding a dual-specificity phosphatase targeting mitogen-activated protein kinases, as a type 2 diabetes (T2D) risk gene. Here, we reveal that Dusp8 is a gatekeeper in the hypothalamic control of glucose homeostasis in mice and humans. Male, but not female, Dusp8 loss-of-function mice, either with global or corticotropin-releasing hormone neuron-specific deletion, had impaired systemic glucose tolerance and insulin sensitivity when exposed to high-fat diet (HFD). Mechanistically, we found impaired hypothalamic-pituitary-adrenal axis feedback, blunted sympathetic responsiveness, and chronically elevated corticosterone levels driven by hypothalamic hyperactivation of Jnk signaling. Accordingly, global Jnk1 ablation, AAV-mediated Dusp8 overexpression in the mediobasal hypothalamus, or metyrapone-induced chemical adrenalectomy rescued the impaired glucose homeostasis of obese male Dusp8-KO mice, respectively. The sex-specific role of murine Dusp8 in governing hypothalamic Jnk signaling, insulin sensitivity, and systemic glucose tolerance was consistent with functional MRI data in human volunteers that revealed an association of the DUSP8 rs2334499 risk variant with hypothalamic insulin resistance in men. Further, expression of DUSP8 was increased in the infundibular nucleus of T2D humans. In summary, our findings suggest the GWAS-identified gene Dusp8 as a novel hypothalamic factor that plays a functional role in the etiology of T2D.
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http://dx.doi.org/10.1172/JCI136363DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7598066PMC
November 2020

Increased mitochondrial respiration of adipocytes from metabolically unhealthy obese compared to healthy obese individuals.

Sci Rep 2020 07 24;10(1):12407. Epub 2020 Jul 24.

Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Nephrology, University Hospital Tübingen, Eberhard Karls University Tübingen, Otfried-Müller-Str. 10, 72076, Tübingen, Germany.

Among obese subjects, metabolically healthy (MHO) and unhealthy obese (MUHO) subjects exist, the latter being characterized by whole-body insulin resistance, hepatic steatosis, and subclinical inflammation. Insulin resistance and obesity are known to associate with alterations in mitochondrial density, morphology, and function. Therefore, we assessed mitochondrial function in human subcutaneous preadipocytes as well as in differentiated adipocytes derived from well-matched donors. Primary subcutaneous preadipocytes from 4 insulin-resistant (MUHO) versus 4 insulin-sensitive (MHO), non-diabetic, morbidly obese Caucasians (BMI > 40 kg/m), matched for sex, age, BMI, and percentage of body fat, were differentiated in vitro to adipocytes. Real-time cellular respiration was measured using an XF24 Extracellular Flux Analyzer (Seahorse). Lipolysis was stimulated by forskolin (FSK) treatment. Mitochondrial respiration was fourfold higher in adipocytes versus preadipocytes (p = 1.6*10). In adipocytes, a negative correlation of mitochondrial respiration with donors' insulin sensitivity was shown (p = 0.0008). Correspondingly, in adipocytes of MUHO subjects, an increased basal respiration (p = 0.002), higher proton leak (p = 0.04), elevated ATP production (p = 0.01), increased maximal respiration (p = 0.02), and higher spare respiratory capacity (p = 0.03) were found, compared to MHO. After stimulation with FSK, the differences in ATP production, maximal respiration and spare respiratory capacity were blunted. The differences in mitochondrial respiration between MUHO/MHO were not due to altered mitochondrial content, fuel switch, or lipid metabolism. Thus, despite the insulin resistance of MUHO, we could clearly show an elevated mitochondrial respiration of MUHO adipocytes. We suggest that the higher mitochondrial respiration reflects a compensatory mechanism to cope with insulin resistance and its consequences. Preserving this state of compensation might be an attractive goal for preventing or delaying the transition from insulin resistance to overt diabetes.
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http://dx.doi.org/10.1038/s41598-020-69016-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7382448PMC
July 2020
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