Publications by authors named "Agnieszka Karkucinska-Wieckowska"

32 Publications

Western Diet Causes Obesity-Induced Nonalcoholic Fatty Liver Disease Development by Differentially Compromising the Autophagic Response.

Antioxidants (Basel) 2020 Oct 15;9(10). Epub 2020 Oct 15.

Nencki Institute of Experimental Biology of Polish Academy of Sciences, 02-093 Warsaw, Poland.

Nonalcoholic fatty liver disease (NAFLD) is characterized by the development of steatosis, which can ultimately compromise liver function. Mitochondria are key players in obesity-induced metabolic disorders; however, the distinct role of hypercaloric diet constituents in hepatic cellular oxidative stress and metabolism is unknown. Male mice were fed either a high-fat (HF) diet, a high-sucrose (HS) diet or a combined HF plus HS (HFHS) diet for 16 weeks. This study shows that hypercaloric diets caused steatosis; however, the HFHS diet induced severe fibrotic phenotype. At the mitochondrial level, lipidomic analysis showed an increased cardiolipin content for all tested diets. Despite this, no alterations were found in the coupling efficiency of oxidative phosphorylation and neither in mitochondrial fatty acid oxidation (FAO). Consistent with unchanged mitochondrial function, no alterations in mitochondrial-induced reactive oxygen species (ROS) and antioxidant capacity were found. In contrast, the HF and HS diets caused lipid peroxidation and provoked altered antioxidant enzyme levels/activities in liver tissue. Our work provides evidence that hepatic oxidative damage may be caused by augmented levels of peroxisomes and consequently higher peroxisomal FAO-induced ROS in the early NAFLD stage. Hepatic damage is also associated with autophagic flux impairment, which was demonstrated to be diet-type dependent. The HS diet induced a reduction in autophagosomal formation, while the HF diet reduced levels of cathepsins. The accumulation of damaged organelles could instigate hepatocyte injuries and NAFLD progression.
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http://dx.doi.org/10.3390/antiox9100995DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7602470PMC
October 2020

Molecular identification of CNS NB-FOXR2, CNS EFT-CIC, CNS HGNET-MN1 and CNS HGNET-BCOR pediatric brain tumors using tumor-specific signature genes.

Acta Neuropathol Commun 2020 07 10;8(1):105. Epub 2020 Jul 10.

Department of Experimental and Clinical Neuropathology, Mossakowski Medical Research Centre, Polish Academy of Sciences, A. Pawińskiego 5 Street, 02-106, Warsaw, Poland.

Four molecular types of rare central nervous system (CNS) tumors have been recently identified by gene methylation profiling: CNS Neuroblastoma with FOXR2 activation (CNS NB-FOXR2), CNS Ewing Sarcoma Family Tumor with CIC alteration (CNS EFT-CIC), CNS high grade neuroepithelial tumor with MN1 alteration (CNS HGNET-MN1) and CNS high grade neuroepithelial tumor with BCOR alteration (CNS HGNET-BCOR). Although they are not represented in 2016 updated WHO classification of CNS tumors, their diagnostic recognition is important because of clinical consequences. We have introduced a diagnostic method based on transcription profiling of tumor specific signature genes from formalin-fixed, paraffin-embedded tumor blocks using NanoString nCounter Technology. Altogether, 14 out of 187 (7.4%) high grade pediatric brain tumors were diagnosed with either of four new CNS categories. Histopathological examination of the tumors confirmed, that they demonstrate a spectrum of morphology mimicking other CNS high grade tumors. However, they also exhibit some suggestive histopathological and immunohistochemical features that allow for a presumptive diagnosis prior to molecular assessment. Clinical characteristics of patients corroborated with the previous findings for CNS EFT-CIC, CNS NB-FOXR2 and CNS HGNET-MN1 patients, with a favorable survival rate for the latter two groups. Among six CNS HGNET-BCOR patients, three patients are long term survivors, suggesting possible heterogeneity within this molecular category of tumors. In summary, we confirmed the effectiveness of NanoString method using a single, multi-gene tumor specific signature and recommend this novel approach for identification of either one of the four newly described CNS tumor entities.
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http://dx.doi.org/10.1186/s40478-020-00984-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7350623PMC
July 2020

Fat and Sugar-A Dangerous Duet. A Comparative Review on Metabolic Remodeling in Rodent Models of Nonalcoholic Fatty Liver Disease.

Nutrients 2019 Nov 24;11(12). Epub 2019 Nov 24.

Nencki Institute of Experimental Biology of Polish Academy of Sciences, 02-093 Warsaw, Poland.

Nonalcoholic fatty liver disease (NAFLD) is a common disease in Western society and ranges from steatosis to steatohepatitis to end-stage liver disease such as cirrhosis and hepatocellular carcinoma. The molecular mechanisms that are involved in the progression of steatosis to more severe liver damage in patients are not fully understood. A deeper investigation of NAFLD pathogenesis is possible due to the many different animal models developed recently. In this review, we present a comparative overview of the most common dietary NAFLD rodent models with respect to their metabolic phenotype and morphological manifestation. Moreover, we describe similarities and controversies concerning the effect of NAFLD-inducing diets on mitochondria as well as mitochondria-derived oxidative stress in the progression of NAFLD.
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http://dx.doi.org/10.3390/nu11122871DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6950566PMC
November 2019

A Diet Induced Maladaptive Increase in Hepatic Mitochondrial DNA Precedes OXPHOS Defects and May Contribute to Non-Alcoholic Fatty Liver Disease.

Cells 2019 10 8;8(10). Epub 2019 Oct 8.

Nencki Institute of Experimental Biology, Polish Academy of Sciences, Pasteur 3 Str., 02-093 Warsaw, Poland.

Non-alcoholic fatty liver disease (NAFLD), an increasingly prevalent and underdiagnosed disease, is postulated to be caused by hepatic fat mediated pathological mechanisms. Mitochondrial dysfunction is proposed to be involved, but it is not known whether this is a pathological driver or a consequence of NAFLD. We postulate that changes to liver mitochondrial DNA (mtDNA) are an early event that precedes mitochondrial dysfunction and irreversible liver damage. To test this hypothesis, we evaluated the impact of diet on liver steatosis, hepatic mtDNA content, and levels of key mitochondrial proteins. Liver tissues from C57BL/6 mice fed with high fat (HF) diet (HFD) and Western diet (WD, high fat and high sugar) for 16 weeks were used. Steatosis/fibrosis were assessed using haematoxylin and eosin (H&E) Oil Red and Masson's trichome staining and collagen content. Total DNA was isolated, and mtDNA content was determined by quantifying absolute mtDNA copy number/cell using quantitative PCR. Selected mitochondrial proteins were analysed from a proteomics screen. As expected, both HFD and WD resulted in steatosis. Mouse liver contained a high mtDNA content (3617 ± 233 copies per cell), which significantly increased in HFD diet, but this increase was not functional, as indicated by changes in mitochondrial proteins. In the WD fed mice, liver dysfunction was accelerated alongside downregulation of mitochondrial oxidative phosphorylation (OXPHOS) and mtDNA replication machinery as well as upregulation of mtDNA-induced inflammatory pathways. These results demonstrate that diet induced changes in liver mtDNA can occur in a relatively short time; whether these contribute directly or indirectly to subsequent mitochondrial dysfunction and the development of NAFLD remains to be determined. If this hypothesis can be substantiated, then strategies to prevent mtDNA damage in the liver may be needed to prevent development and progression of NAFLD.
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http://dx.doi.org/10.3390/cells8101222DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6830072PMC
October 2019

OLIG2 is a novel immunohistochemical marker associated with the presence of PAX3/7-FOXO1 translocation in rhabdomyosarcomas.

Diagn Pathol 2019 Sep 7;14(1):103. Epub 2019 Sep 7.

Department of Pathology, The Children's Memorial Health Institute, Av. Dzieci Polskich 20, 04-730, Warsaw, Poland.

Background: The most frequent histological types of rhabdomyosarcoma (RMS) in children are embryonal (ERMS) and alveolar (ARMS) tumours. The majority of ARMS are characterized by the presence of PAX3/7-FOXO1 gene fusion and have a worse prognosis than fusion gene-negative ARMS. However, identification of PAX3/7-FOXO1 fusion status is challenging when using formalin-fixed, paraffin-embedded (FFPE) material. Microarray analyses revealed that high expression of several genes is associated with PAX3/7-FOXO1 fusion status. Therefore, we investigated if immunohistochemical approach may detect surrogate marker genes as indicators of fusion gene-positive RMS.

Methods: Forty five RMS patients were included in the analysis and immunohistochemistry was applied to FFPE tissues collected at diagnosis. Protein expression of OLIG2, a novel marker in RMS, was investigated using antibody EP112 (Cell Marque). In addition already known two markers were also analyzed: TFAP2B using rabbit anti-TFAP2β antibody (Santa Cruz Biotechnology) and ALK using anti-ALK antibody clone D5F3 #3633 (Cell Signalling). Fluorescence in situ hybridization (FISH) was performed on FFPE sections with FOXO1/PAX3 and/or FOXO1/PAX7 probes (Dual Colour Single Fusion Probe, Zytovision).

Results: Our analysis revealed that all three immunohistochemical markers are associated with the presence of PAX3/7-FOXO1 fusion: TFAP2B (p < 0.00001), OLIG2 (p = 0.0001) and ALK (p = 0.0007). Four ARMS had negative PAX3/7-FOXO1 status and none of them displayed positive reaction with the analysed markers. Positive reaction with OLIG2 (6 tumours) was always associated with the presence of PAX3/7-FOXO1 rearrangement. Two additional OLIG2 positive cases showed inconclusive FISH results, but were positive for TFAP2B and ALK, what suggests that these tumours expressed fusion positive signature.

Conclusion: Our results indicate that TFAP2B, ALK and a novel marker OLIG2 may serve as surrogate markers for PAX3/7-FOXO1 status what is especially beneficial in cases where poor quality tumour tissue is not suitable for reliable genetic analyses or shows inconclusive result.
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http://dx.doi.org/10.1186/s13000-019-0883-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6731563PMC
September 2019

Differential Expression of Mitochondrial Biogenesis Markers in Mouse and Human SHH-Subtype Medulloblastoma.

Cells 2019 03 5;8(3). Epub 2019 Mar 5.

Centre of New Technologies, University of Warsaw, Banacha 2c, 02-097 Warsaw, Poland.

Medulloblastoma is a brain tumor that arises predominantly in infants and children. It is the most common pediatric brain malignancy. Around 25% of medulloblastomas are driven by constitutive activation of the Hedgehog signaling pathway. Hedgehog-driven medulloblastoma is often studied in the laboratory using genetic mouse models with overactive Hedgehog signaling, which recapitulate many of the pathological features of human Hedgehog-dependent tumors. However, we show here that on a molecular level the human and mouse HH-dependent MB are quite distinct, with human, but not mouse, tumors characterized by the presence of markers of increased oxidative phosphorylation and mitochondrial biogenesis. The latter suggests that, unlike for many other types of tumors, a switch to glycolytic metabolism might not be co-opted by human SHH-MB to perpetuate their survival and growth. This needs to be taken into consideration and could potentially be exploited in the design of therapies.
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http://dx.doi.org/10.3390/cells8030216DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6468894PMC
March 2019

Immunohistochemical detection of ALK protein identifies APC mutated medulloblastoma and differentiates the WNT-activated medulloblastoma from other types of posterior fossa childhood tumors.

Brain Tumor Pathol 2019 Jan 6;36(1):1-6. Epub 2018 Dec 6.

Department of Experimental and Clinical Pathology, Mossakowski Medical Research Centre, Polish Academy of Sciences, A. Pawińskiego 5 Street, 02-106, Warsaw, Poland.

Expression of the ALK gene strongly correlates with the WNT-activated medulloblastomas, which are routinely identified by detection of CTNNB1 mutation. However, some tumors have mutations in other than CTNNB1 genes. Therefore, we investigated if ALK expression may identify WNT-activated tumors without CTNNB1 mutation. In addition, we examined if ALK expression may differentiate WNT-activated medulloblastoma from other malignant posterior fossa tumors. ALK expression was analyzed using immunohistochemistry (clone D5F3) in 70 patients with posterior fossa tumours. Among 55 medulloblastomas, 6 tumors showed ALK expression in > 50% of tumor cells. In one tumor, with ALK positive reaction, negative nuclear reaction against β-catenin and the lack of CTNNB1 mutation, next generation sequencing revealed a presence of pathogenic variant c.3366_3369del in the APC gene, with homozygous deletion leading to inactivation of both copies in tumor cells. MLPA analysis displayed the presence of chromosome 6 monosomy, therefore, confirming the WNT type of this tumor. All analyzed 19 anaplastic ependymomas, 4 choroid plexus carcinomas and 2 atypical teratoid rhabdoid tumors were immunonegative for ALK expression. Therefore, we propose, that immunohistochemical detection of ALK protein should be highly recommended in routine investigation, in parallel to already established methods for identification and differentiation of WNT-activated medulloblastoma.
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http://dx.doi.org/10.1007/s10014-018-0331-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6514113PMC
January 2019

Mitochondria and Reactive Oxygen Species in Aging and Age-Related Diseases.

Int Rev Cell Mol Biol 2018 22;340:209-344. Epub 2018 Jun 22.

Department of Biochemistry, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland.

Aging has been linked to several degenerative processes that, through the accumulation of molecular and cellular damage, can progressively lead to cell dysfunction and organ failure. Human aging is linked with a higher risk for individuals to develop cancer, neurodegenerative, cardiovascular, and metabolic disorders. The understanding of the molecular basis of aging and associated diseases has been one major challenge of scientific research over the last decades. Mitochondria, the center of oxidative metabolism and principal site of reactive oxygen species (ROS) production, are crucial both in health and in pathogenesis of many diseases. Redox signaling is important for the modulation of cell functions and several studies indicate a dual role for ROS in cell physiology. In fact, high concentrations of ROS are pathogenic and can cause severe damage to cell and organelle membranes, DNA, and proteins. On the other hand, moderate amounts of ROS are essential for the maintenance of several biological processes, including gene expression. In this review, we provide an update regarding the key roles of ROS-mitochondria cross talk in different fundamental physiological or pathological situations accompanying aging and highlighting that mitochondrial ROS may be a decisive target in clinical practice.
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http://dx.doi.org/10.1016/bs.ircmb.2018.05.006DOI Listing
April 2019

Role of Mitochondria-Associated ER Membranes in Calcium Regulation in Cancer-Specific Settings.

Neoplasia 2018 05 5;20(5):510-523. Epub 2018 Apr 5.

Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology and LTTA center, University of Ferrara, Ferrara, Italy; Cecilia Hospital, GVM Care & Research, E.S.: Health Science Foundation, Cotignola, Italy; CNR Institute of Cell Biology and Neurobiology, Monterotondo, Italy. Electronic address:

Mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs) are highly specialized subcellular compartments that are shaped by ER subdomains juxtaposed to mitochondria but are biochemically distinct from pure ER and pure mitochondria. MAMs are enriched in enzymes involved in lipid synthesis and transport, channels for calcium transfer, and proteins with oncogenic/oncosuppressive functions that modulate cell signaling pathways involved in physiological and pathophysiological processes. The term "cancer" denotes a group of disorders that result from uncontrolled cell growth driven by a mixture of genetic and environmental components. Alterations in MAMs are thought to account for the onset as well as the progression and metastasis of cancer and have been a focus of investigation in recent years. In this review, we present the current state of the art regarding MAM-resident proteins and their relevance, alterations, and deregulating functions in different types of cancer from a cell biology and clinical perspective.
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http://dx.doi.org/10.1016/j.neo.2018.03.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5916088PMC
May 2018

Medulloblastoma with transitional features between Group 3 and Group 4 is associated with good prognosis.

J Neurooncol 2018 Jun 9;138(2):231-240. Epub 2018 Feb 9.

Department of Experimental and Clinical Neuropathology, Mossakowski Medical Research Centre Polish Academy of Sciences, A. Pawińskiego 5 Street, 02-106, Warsaw, Poland.

Medulloblastoma, the most common malignant pediatric brain tumor, is a heterogeneous disease, with the existence of at least four molecular types: Wingless (WNT), Sonic Hedgehog (SHH), Group 3 and Group 4 tumors. The latter two groups, which can be identified by an application of multi-gene expression or methylation profiling, show sometimes ambiguous categorization and are still classified for diagnostic reason as non-SHH/non-WNT medulloblastomas in updated WHO 2016 classification. In order to better characterize non-SHH/non-WNT tumors, we applied the method based on the Nanostring nCounter Technology, using the 26 genes codeset in 68 uniformly treated medulloblastoma patients. This allowed for identification of tumors, which shared common Group 3 and Group 4 gene signatures. We recognized three transcriptional groups within non-WNT/non-SHH tumors: Group 3, Group 4 and the Intermediate 3/4 Group. Group 3, in line with previously published results, showed poor prognosis with survival rate < 40%, frequent metastases, large cell/anaplastic pathology and presence of tumors with MYCC amplification. This is in contrast to patients from the Intermediate 3/4 Group who showed the best survival rate (100%). Overall and progression free survival were better for this group than for Group 3 (p = 0.001, for both) and Group 4 (p = 0.064 and p = 0.066, respectively). Our work supports the view that within the non-WNT/non-SHH tumors different risk groups exist and that the current two groups classifier may be not sufficient for proper clinical categorization of individual patients.
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http://dx.doi.org/10.1007/s11060-018-2797-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5942343PMC
June 2018

Constitutional mosaicism of a de novo TP53 mutation in a patient with bilateral choroid plexus carcinoma.

Cancer Genet 2017 Oct 20;216-217:79-85. Epub 2017 Jul 20.

Department of Oncology, The Children's Memorial Health Institute, 04-730 Warsaw, Poland.

Choroid plexus tumors (CPT) constitute 2%-5% of all pediatric brain tumors and include high grade choroid plexus carcinoma (CPC). About 40% of CPC patients harbor germline TP53 mutations, associated with diminished survival rates. However, the number of TP53 carriers might be underestimated due to suboptimal ability of Sanger sequencing to identify mosaicism. We describe an 18-month-old boy with ultra-rare, bilateral disseminated CPC and negative family history of cancer. Next generation sequencing (NGS) revealed constitutional mosaicism of de novo TP53 mutation, which was barely detectable by Sanger sequencing. This is the first description of a de novo TP53 mutation mosaicism in a patient with CPC. Up to now four cases of de novo TP53 mutations in CPC patients have been described but none of them were mosaic. Since TP53 mutation mosaicism may have an impact on management of patients and predisposition to other cancers, a reliable method of identification is important. Our results highlight the utility of high-throughput technologies in detection of potentially important genetic markers.
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http://dx.doi.org/10.1016/j.cancergen.2017.07.001DOI Listing
October 2017

Modulation of mitochondrial dysfunction-related oxidative stress in fibroblasts of patients with Leigh syndrome by inhibition of prooxidative p66Shc pathway.

Mitochondrion 2017 11 21;37:62-79. Epub 2017 Jul 21.

Department of Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland. Electronic address:

The mitochondrial respiratory chain, and in particular, complex I, is a major source of reactive oxygen species (ROS) in cells. Elevated levels of ROS are associated with an imbalance between the rate of ROS formation and the capacity of the antioxidant defense system. Increased ROS production may lead to oxidation of DNA, lipids and proteins and thus can affect fundamental cellular processes. The aim of this study was to investigate the magnitude of intracellular oxidative stress in fibroblasts of patients with Leigh syndrome with defined mutations in complex I. Moreover, we hypothesized that activation of the p66Shc protein (phosphorylation of p66Shc at Ser36 by PKCβ), being part of the oxidative stress response pathway, is partially responsible for the increased ROS production in cells with dysfunctional complex I. Characterization of bioenergetic parameters and ROS production showed that the cellular model of Leigh syndrome is described by increased intracellular oxidative stress and oxidative damage to DNA and proteins, which correlate with increased p66Shc phosphorylation at Ser36. Treatment of patients' fibroblasts with hispidin (an inhibitor of the protein kinase PKCβ), in addition to decreasing ROS production and intracellular oxidative stress, resulted in restoration of complex I activity.
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http://dx.doi.org/10.1016/j.mito.2017.07.002DOI Listing
November 2017

Dietary Polyphenols and Mitochondrial Function: Role in Health and Disease.

Curr Med Chem 2019 ;26(19):3376-3406

CNC - Center for Neuroscience and Cell Biology, UC-Biotech, Biocant Park - Cantanhede, University of Coimbra, Portugal.

Mitochondria are cytoplasmic double-membraned organelles that are involved in a myriad of key cellular regulatory processes. The loss of mitochondrial function is related to the pathogenesis of several human diseases. Over the last decades, an increasing number of studies have shown that dietary polyphenols can regulate mitochondrial redox status, and in some cases, prevent or delay disease progression. This paper aims to review the role of four dietary polyphenols - resveratrol, curcumin, epigallocatechin-3-gallate nd quercetin - in molecular pathways regulated by mitochondria and their potential impact on human health. Cumulative evidence showed that the aforementioned polyphenols improve mitochondrial functions in different in vitro and in vivo experiments. The mechanisms underlying the polyphenols' beneficial effects include, among others, the attenuation of oxidative stress, the regulation of mitochondrial metabolism and biogenesis and the modulation of cell-death signaling cascades, among other mitochondrial-independent effects. The understanding of the chemicalbiological interactions of dietary polyphenols, namely with mitochondria, may have a huge impact on the treatment of mitochondrial dysfunction-related disorders.
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http://dx.doi.org/10.2174/0929867324666170529101810DOI Listing
December 2019

ALK Expression Is a Novel Marker for the WNT-activated Type of Pediatric Medulloblastoma and an Indicator of Good Prognosis for Patients.

Am J Surg Pathol 2017 Jun;41(6):781-787

*Department of Pathology §Clinic of Oncology, The Children's Memorial Health Institute †Department of Experimental and Clinical Pathology, Mossakowski Medical Research Centre Polish Academy of Sciences, Warsaw ‡Clinical Research Centre ∥Department of Endocrinology, Diabetology and Internal Medicine, Medical University of Białystok, Białystok, Poland.

ALK gene rearrangements were identified in a variety of cancers, including neuroblastoma, where the presence of ALK expression is associated with adverse prognosis. ALK mutations have recently been found in the pediatric brain tumor medulloblastoma, and microarray data indicate that ALK is highly expressed in a subset of these tumors. Therefore, we investigated whether ALK expression correlates with transcriptional profiles and clinical features of medulloblastoma. Tumors from 116 medulloblastoma patients were studied at diagnosis for the detection of ALK expression at the RNA level by an application of NanoString technology and at the protein level by immunohistochemistry using antibody ALK clone D5F3. The results indicate that ALK expression, at both the RNA and the protein levels, is strongly associated with the WNT-activated type of tumors and therefore may serve as a useful marker for the detection of this type of medulloblastoma. Importantly, ALK protein expression alone is also an indicator of good prognosis for medulloblastoma patients.
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http://dx.doi.org/10.1097/PAS.0000000000000847DOI Listing
June 2017

New perspective in diagnostics of mitochondrial disorders: two years' experience with whole-exome sequencing at a national paediatric centre.

J Transl Med 2016 06 12;14(1):174. Epub 2016 Jun 12.

Department of Medical Genetics, Warsaw Medical University, Pawińskiego str, 02-106, Warsaw, Poland.

Background: Whole-exome sequencing (WES) has led to an exponential increase in identification of causative variants in mitochondrial disorders (MD).

Methods: We performed WES in 113 MD suspected patients from Polish paediatric reference centre, in whom routine testing failed to identify a molecular defect. WES was performed using TruSeqExome enrichment, followed by variant prioritization, validation by Sanger sequencing, and segregation with the disease phenotype in the family.

Results: Likely causative mutations were identified in 67 (59.3 %) patients; these included variants in mtDNA (6 patients) and nDNA: X-linked (9 patients), autosomal dominant (5 patients), and autosomal recessive (47 patients, 11 homozygotes). Novel variants accounted for 50.5 % (50/99) of all detected changes. In 47 patients, changes in 31 MD-related genes (ACAD9, ADCK3, AIFM1, CLPB, COX10, DLD, EARS2, FBXL4, MTATP6, MTFMT, MTND1, MTND3, MTND5, NAXE, NDUFS6, NDUFS7, NDUFV1, OPA1, PARS2, PC, PDHA1, POLG, RARS2, RRM2B, SCO2, SERAC1, SLC19A3, SLC25A12, TAZ, TMEM126B, VARS2) were identified. The ACAD9, CLPB, FBXL4, PDHA1 genes recurred more than twice suggesting higher general/ethnic prevalence. In 19 cases, variants in 18 non-MD related genes (ADAR, CACNA1A, CDKL5, CLN3, CPS1, DMD, DYSF, GBE1, GFAP, HSD17B4, MECP2, MYBPC3, PEX5, PGAP2, PIGN, PRF1, SBDS, SCN2A) were found. The percentage of positive WES results rose gradually with increasing probability of MD according to the Mitochondrial Disease Criteria (MDC) scale (from 36 to 90 % for low and high probability, respectively). The percentage of detected MD-related genes compared with non MD-related genes also grew with the increasing MD likelihood (from 20 to 97 %). Molecular diagnosis was established in 30/47 (63.8 %) neonates and in 17/28 (60.7 %) patients with basal ganglia involvement. Mutations in CLPB, SERAC1, TAZ genes were identified in neonates with 3-methylglutaconic aciduria (3-MGA) as a discriminative feature. New MD-related candidate gene (NDUFB8) is under verification.

Conclusions: We suggest WES rather than targeted NGS as the method of choice in diagnostics of MD in children, including neonates with 3-MGA aciduria, who died without determination of disease cause and with limited availability of laboratory data. There is a strong correlation between the degree of MD diagnosis by WES and MD likelihood expressed by the MDC scale.
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http://dx.doi.org/10.1186/s12967-016-0930-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4903158PMC
June 2016

Leigh disease due to SCO2 mutations revealed at extended autopsy.

J Clin Pathol 2015 May 26;68(5):397-9. Epub 2015 Feb 26.

Department of Pathology, The Children's Memorial Health Institute, Warsaw, Poland.

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http://dx.doi.org/10.1136/jclinpath-2014-202606DOI Listing
May 2015

Case report of an adolescent girl with limb-girdle muscular dystrophy type 2B - the usefulness of muscle protein immunostaining in the diagnosis of dysferlinopathies.

Folia Neuropathol 2014 ;52(4):452-6

Maciej Pronicki, Department of Pathology, The Children's Memorial Health Institute, Al. Dzieci Polskich 20, 04-730 Warsaw, Poland, phone: +48 228151960, fax: +48 228151975, e-mail:

Dysferlinopathies are rare disorders of muscle that present two main phenotypes: Miyoshi myopathy with primarily distal weakness and limb-girdle muscular dystrophy type 2B (LGMD2B) with primarily proximal weakness. They are caused by mutations in the gene encoding the skeletal muscle protein dysferlin, which is involved in muscle repair. The clinical presentation of the disease is rather uncharacteristic, and molecular genetic testing is long-lasting; thus muscle biopsy may be essential in the diagnostic process. Histology itself reveals non-specific changes, but a variety of currently available muscle protein immunostains may be very helpful. We present a 19-year-old girl with epilepsy and elevated creatine phosphokinase (CPK) concentration. Due to increased CPK, myopathy was suspected and muscle biopsy was performed. Light microscopy showed no distinctive myopathic changes, and electron microscopy showed no abnormalities. Extended immunohistochemistry, performed much later, showed complete absence of dysferlin immunostaining. Based on that result, the diagnosis of LGMD2B was made, with subsequent genetic testing to be done. Two known pathogenic variants were found in the DYSF gene, confirming the diagnosis of LGMD2B and allowing proper genetic counseling.
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http://dx.doi.org/10.5114/fn.2014.47847DOI Listing
December 2015

The interplay between p66Shc, reactive oxygen species and cancer cell metabolism.

Eur J Clin Invest 2015 Jan;45 Suppl 1:25-31

Department of Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland.

The adaptor protein p66Shc links membrane receptors to intracellular signalling pathways and has the potential to respond to energy status changes and regulate mitogenic signalling. Initially reported to mediate growth signals in normal and cancer cells, p66Shc has also been recognized as a pro-apoptotic protein involved in the cellular response to oxidative stress. Moreover, it is a key element in processes such as cancer cell proliferation, tumor progression, metastasis and metabolic reprogramming. Recent findings on the role of p66Shc in the above-mentioned processes have been obtained through the use of various tumor cell types, including prostate, breast, ovarian, lung, colon, skin and thyroid cancer cells. Interestingly, the impact of p66Shc on the proliferation rate was mainly observed in prostate tumors, while its impact on metastasis was mainly found in breast cancers. In this review, we summarize the current knowledge about the possible roles of p66Shc in different cancers.
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http://dx.doi.org/10.1111/eci.12364DOI Listing
January 2015

Histoenzymatic methods for visualization of the activity of individual mitochondrial respiratory chain complexes in the muscle biopsies from patients with mitochondrial defects.

Methods Mol Biol 2015 ;1241:85-93

Department of Pathology, The Children's Memorial Health Institute, Warsaw, Poland.

Investigation of mitochondrial metabolism perturbations and successful diagnosis of patients with mitochondrial abnormalities often requires assessment of human samples like muscle biopsy. Immunohistochemical and histochemical examination of muscle biopsy is an important technique to investigate mitochondrial dysfunction that combined with spectrophotometric and Blue Native electrophoresis techniques can be an important tool to provide diagnosis of mitochondrial disorders. In this chapter we focus on technical description of the methods that are suitable to detect the activity of complex I, II, and IV of mitochondrial respiratory chain in muscle biopsies. The protocols provided can be useful not only for general assessment of mitochondrial activity in studied material, but they are also successfully used in the diagnostic procedures in case of suspicion of mitochondrial disorders.
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http://dx.doi.org/10.1007/978-1-4939-1875-1_8DOI Listing
June 2015

Methods to monitor and compare mitochondrial and glycolytic ATP production.

Methods Enzymol 2014 ;542:313-32

Section of Pathology, Oncology and Experimental Biology, Laboratory for Technologies of Advanced Therapies (LTTA), Department of Morphology, Surgery and Experimental Medicine, Ferrara, Italy. Electronic address:

ATP is commonly considered as the main energy unit of the cell and participates in a variety of cellular processes. Thus, intracellular ATP concentrations rapidly vary in response to a wide variety of stimuli, including nutrients, hormones, cytotoxic agents, and hypoxia. Such alterations not necessarily affect cytosolic and mitochondrial ATP to similar extents. From an oncological perspective, this is particularly relevant in the course of tumor progression as well as in the response of cancer cells to therapy. In normal cells, mitochondrial oxidative phosphorylation (OXPHOS) is the predominant source of ATP. Conversely, many cancer cells exhibit an increased flux through glycolysis irrespective of oxygen tension. Assessing the relative contribution of glycolysis and OXPHOS to intracellular ATP production is fundamental not only for obtaining further insights into the peculiarities and complexities of oncometabolism but also for developing therapeutic and diagnostic tools. Several techniques have been developed to measure intracellular ATP levels including enzymatic methods based on hexokinase, glucose-6-phosphate dehydrogenase, and firefly luciferase. Here, we summarize conventional methods for measuring intracellular ATP levels and we provide a detailed protocol based on cytosol- and mitochondrion-targeted variants of firefly luciferase to determine the relative contribution of glycolysis and OXPHOS to ATP synthesis.
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http://dx.doi.org/10.1016/B978-0-12-416618-9.00016-9DOI Listing
May 2015

"Drop attacks" as first clinical symptoms in a child carrying MTTK m.8344A>G mutation.

Folia Neuropathol 2013 ;51(4):347-54

Katarzyna Kotulska, Department of Child Neurology and Epileptology, The Children's Memorial Health Institute, Al. Dzieci Polskich, 04-730 Warsaw, Poland, phone: +48 22 815 74 04, fax: 48-22-815 74 02, e-mail:

Unlabelled: We describe a child with dyslexia and difficulty in school who, at the age of 13 years, began to suffer from several head injuries resulting from falls of uncertain cause. Two years later, the patient developed symptoms of a severe mitochondrial disorder (involving bulbar-pyramidal paralysis, ophthalmoplegia, and hyperlactatemia) that coincided with VPA administration. Brain MR imaging revealed rapidly developing Leigh syndrome (LS), and muscle biopsy showed ragged blue fibres (RBF). A diminished expression of the E1α subunit of pyruvate dehydrogenase was found in muscle homogenate (signal 28.7% of normal). The accurate diagnosis of mitochondrially inherited LS (MILS) and the identification of an almost homoplasmic m.8344G>A mutation in the MTTK gene was delayed due to an initial incorrect diagnosis of epilepsy, misdiagnosis of neuroinfection, and failure to note LS on the first brain MRI. Periods of exacerbation or improvement were observed in association with the administration of certain drugs or procedures (VPA administration or intensive rehabilitation associated with worsening; ketogenic diet associated with remission). However, the random association of these factors with natural disease fluctuations cannot be excluded.

Conclusions: 1) To improve the early detection of mitochondrial disorder, we recommend screening for mtDNA (and nDNA) mutations in all patients with LS present on brain MRI. 2) Brain MRI protocols should include diffusion-weighted and T2-weighted imaging, and LS-like changes should be analysed by a neuroradiologist experienced in the field. 3) Additional controlled studies are urgently needed to assess the causal relationship between management strategies and the natural history of the disease. Until the association between VPA and disease exacerbation can be ruled out, VPA should be avoided in patients with these symptoms unless the mitochondrial disorder has been excluded.
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http://dx.doi.org/10.5114/fn.2013.39726DOI Listing
July 2014

The natural history of SCO2 deficiency in 36 Polish children confirmed the genotype-phenotype correlation.

Mitochondrion 2013 Nov 26;13(6):810-6. Epub 2013 May 26.

Department of Metabolic Diseases, The Children's Memorial Health Institute, Warsaw, Poland; Department of Medical Genetics, The Children's Memorial Health Institute, Warsaw, Poland. Electronic address:

The aim of this study was to assess the natural history of the SCO2 deficiency in relation to the genotype in a cohort of 62 patients with SCO2 mutations (36 this study, 26 previous reports). A novel, milder phenotype (disease onset delayed until one year after birth, nonspecific encephalomyopathy, and 2-4 year survival period) associated with compound heterozygosity of the common p.E140K and a novel p.M177T mutations extends the range of symptoms of the SCO2 deficiency. The prevalence of SCO2 deficiency in Poland is relatively high. A search for SCO2 mutations in patients with histology resembling SMA appears to efficiently improve the detection rate.
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http://dx.doi.org/10.1016/j.mito.2013.05.007DOI Listing
November 2013

Left ventricular noncompaction (LVNC) and low mitochondrial membrane potential are specific for Barth syndrome.

J Inherit Metab Dis 2013 Nov 30;36(6):929-37. Epub 2013 Jan 30.

Department of Pathology, The Children's Memorial Health Institute, Warsaw, Poland.

Barth syndrome (BTHS) is an X-linked mitochondrial defect characterised by dilated cardiomyopathy, neutropaenia and 3-methylglutaconic aciduria (3-MGCA). We report on two affected brothers with c.646G > A (p.G216R) TAZ gene mutations. The pathogenicity of the mutation, as indicated by the structure-based functional analyses, was further confirmed by abnormal monolysocardiolipin/cardiolipin ratio in dry blood spots of the patients as well as the occurrence of this mutation in another reported BTHS proband. In both brothers, 2D-echocardiography revealed some features of left ventricular noncompaction (LVNC) despite marked differences in the course of the disease; the eldest child presented with isolated cardiomyopathy from late infancy, whereas the youngest showed severe lactic acidosis without 3-MGCA during the neonatal period. An examination of the patients' fibroblast cultures revealed that extremely low mitochondrial membrane potentials (mtΔΨ about 50 % of the control value) dominated other unspecific mitochondrial changes detected (respiratory chain dysfunction, abnormal ROS production and depressed antioxidant defense). 1) Our studies confirm generalised mitochondrial dysfunction in the skeletal muscle and the fibroblasts of BTHS patients, especially a severe impairment in the mtΔΨ and the inhibition of complex V activity. It can be hypothesised that impaired mtΔΨ and mitochondrial ATP synthase activity may contribute to episodes of cardiac arrhythmia that occurred unexpectedly in BTHS patients. 2) Severe lactic acidosis without 3-methylglutaconic aciduria in male neonates as well as an asymptomatic mild left ventricular noncompaction may characterise the ranges of natural history of Barth syndrome.
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http://dx.doi.org/10.1007/s10545-013-9584-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3825551PMC
November 2013

Disrupted ATP synthase activity and mitochondrial hyperpolarisation-dependent oxidative stress is associated with p66Shc phosphorylation in fibroblasts of NARP patients.

Int J Biochem Cell Biol 2013 Jan 31;45(1):141-50. Epub 2012 Jul 31.

Nencki Institute of Experimental Biology, Warsaw, Poland.

p66Shc is an adaptor protein involved in cell proliferation and differentiation that undergoes phosphorylation at Ser36 in response to oxidative stimuli, consequently inducing a burst of reactive oxygen species (ROS), mitochondrial disruption and apoptosis. Its role during several pathologies suggests that p66Shc mitochondrial signalling can perpetuate a primary mitochondrial defect, thus contributing to the pathophysiology of that condition. Here, we show that in the fibroblasts of neuropathy, ataxia and retinitis pigmentosa (NARP) patients, the p66Shc phosphorylation pathway is significantly induced in response to intracellular oxidative stress related to disrupted ATP synthase activity and mitochondrial membrane hyperpolarisation. We postulate that the increased phosphorylation of p66Shc at Ser36 is partially responsible for further increasing ROS production, resulting in oxidative damage of proteins. Oxidative stress and p66Shc phosphorylation at Ser36 may be mitigated by antioxidant administration or the use of a p66Shc phosphorylation inhibitor. This article is part of a Directed Issue entitled: Bioenergetic dysfunction, adaptation and therapy.
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http://dx.doi.org/10.1016/j.biocel.2012.07.020DOI Listing
January 2013

Cardiac mitochondrial dysfunction during hyperglycemia--the role of oxidative stress and p66Shc signaling.

Int J Biochem Cell Biol 2013 Jan 7;45(1):114-22. Epub 2012 Jul 7.

CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Portugal.

Diabetes mellitus is a chronic disease caused by a deficiency in the production of insulin and/or by the effects of insulin resistance. Insulin deficiency leads to hyperglycemia which is the major initiator of diabetic cardiovascular complications escalating with time and driven by many complex biochemical and molecular processes. Four hypotheses, which propose mechanisms of diabetes-associated pathophysiology, are currently considered. Cardiovascular impairment may be caused by an increase in polyol pathway flux, by intracellular advanced glycation end-products formation or increased flux through the hexosamine pathway. The latter of these mechanisms involves activation of the protein kinase C. Cellular and mitochondrial metabolism alterations observed in the course of diabetes are partially associated with an excessive production of reactive oxygen species (ROS). Among many processes and factors involved in ROS production, the 66 kDa isoform of the growth factor adaptor shc (p66Shc protein) is of particular interest. This protein plays a key role in the control of mitochondria-dependent oxidative balance thus it involvement in diabetic complications and other oxidative stress based pathologies is recently intensively studied. In this review we summarize the current understanding of hyperglycemia induced cardiac mitochondrial dysfunction with an emphasis on the oxidative stress and p66Shc protein. This article is part of a Directed Issue entitled: Bioenergetic dysfunction, adaptation and therapy.
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http://dx.doi.org/10.1016/j.biocel.2012.07.004DOI Listing
January 2013

PGC-1 family coactivators and cell fate: roles in cancer, neurodegeneration, cardiovascular disease and retrograde mitochondria-nucleus signalling.

Mitochondrion 2012 Jan 29;12(1):86-99. Epub 2011 Sep 29.

Department of Cell and Developmental Biology, Consortium for Mitochondrial Research, University College London, London, UK.

Over the past two decades, a complex nuclear transcriptional machinery controlling mitochondrial biogenesis and function has been described. Central to this network are the PGC-1 family coactivators, characterised as master regulators of mitochondrial biogenesis. Recent literature has identified a broader role for PGC-1 coactivators in both cell death and cellular adaptation under conditions of stress, here reviewed in the context of the pathology associated with cancer, neurodegeneration and cardiovascular disease. Moreover, we propose that these studies also imply a novel conceptual framework on the general role of mitochondrial dysfunction in disease. It is now well established that the complex nuclear transcriptional control of mitochondrial biogenesis allows for adaptation of mitochondrial mass and function to environmental conditions. On the other hand, it has also been suggested that mitochondria alter their function according to prevailing cellular energetic requirements and thus function as sensors that generate signals to adjust fundamental cellular processes through a retrograde mitochondria-nucleus signalling pathway. Therefore, altered mitochondrial function can affect cell fate not only directly by modifying cellular energy levels or redox state, but also indirectly, by altering nuclear transcriptional patterns. The current literature on such retrograde signalling in both yeast and mammalian cells is thus reviewed, with an outlook on its potential contribution to disease through the regulation of PGC-1 family coactivators. We propose that further investigation of these pathways will lead to the identification of novel pharmacological targets and treatment strategies to combat disease.
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http://dx.doi.org/10.1016/j.mito.2011.09.009DOI Listing
January 2012

p66Shc aging protein in control of fibroblasts cell fate.

Int J Mol Sci 2011 22;12(8):5373-89. Epub 2011 Aug 22.

Department of Biochemistry, Nencki Institute of Experimental Biology, Warsaw 02-093, Poland; E-Mails: (J.M.S.); (M.L.); (J.S.); (J.D.).

Reactive oxygen species (ROS) are wieldy accepted as one of the main factors of the aging process. These highly reactive compounds modify nucleic acids, proteins and lipids and affect the functionality of mitochondria in the first case and ultimately of the cell. Any agent or genetic modification that affects ROS production and detoxification can be expected to influence longevity. On the other hand, genetic manipulations leading to increased longevity can be expected to involve cellular changes that affect ROS metabolism. The 66-kDa isoform of the growth factor adaptor Shc (p66Shc) has been recognized as a relevant factor to the oxygen radical theory of aging. The most recent data indicate that p66Shc protein regulates life span in mammals and its phosphorylation on serine 36 is important for the initiation of cell death upon oxidative stress. Moreover, there is strong evidence that apart from aging, p66Shc may be implicated in many oxidative stress-associated pathologies, such as diabetes, mitochondrial and neurodegenerative disorders and tumorigenesis. This article summarizes recent knowledge about the role of p66Shc in aging and senescence and how this protein can influence ROS production and detoxification, focusing on studies performed on skin and skin fibroblasts.
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http://dx.doi.org/10.3390/ijms12085373DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3179172PMC
January 2015

Increased reactive oxygen species (ROS) production and low catalase level in fibroblasts of a girl with MEGDEL association (Leigh syndrome, deafness, 3-methylglutaconic aciduria).

Folia Neuropathol 2011 ;49(1):56-63

Department of Pathology, Children’s Memorial Health Institute, Warsaw, Poland.

Unlabelled: Association of 3-methylglutaconic aciduria (3-MGCA) with sensorineural deafness and Leigh-like encephalopathy (MEGDEL) was described as a very rare mitochondrial disorder without a known molecular background. We present clinical and biochemical characteristics of a 4.5-year-old girl with a similar association. The clinical course of the disease was as follows: in the neonatal period transient adaptation troubles; at 4-5 mo failure to thrive and hypotonia; at 13 mo: extrapyramidal symptoms, sensorineural deafness, Leigh syndrome on MRI, pigmentary degeneration of retina, episodes of respiratory alkalosis, increased lactate in plasma, urine and brain, and increased excretion of 3-MGCA. Mitochondrial encephalopathy was suspected and muscle biopsy performed. Only mild lipid accumulation was found by muscle histopathology and histochemistry. Unspecific decrease of respiratory chain complexes was revealed by muscle homogenate spectrophotometry. The in-gel activity assay in the patient's muscle confirmed a combined defect of OXPHOS, particularly indicating suppression of mitochondrial ATP synthase (complex V) activity. Measurements of functional mitochondrial bioenergetic parameters in the patient's fibroblasts revealed a decrease in the mitochondrial membrane potential and activity of the mitochondrial respiratory chain. At the same time, a significant increase of ROS production (cytosolic and mitochondrial superoxide and H2O2) with signs of protein damage (protein carbonylation), and decreased antioxidant defence (SOD1 and SOD2) were observed. Additionally, the catalase amount was surprisingly low in comparison with healthy control and other reference 3-MGCA cases (Barth syndrome).

Conclusion: (1) the natural history of the disease in the presented patient confirms the existence of previously reported clinical phenotype of MEGDEL (2) antioxidant defence impairment due to abnormal catalase metabolism/transport may characterize an unknown basic defect which led to the development of MEGDEL association.
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July 2011

Post mortem identification of deoxyguanosine kinase (DGUOK) gene mutations combined with impaired glucose homeostasis and iron overload features in four infants with severe progressive liver failure.

J Appl Genet 2011 Feb 16;52(1):61-6. Epub 2010 Nov 16.

Department of Metabolic Diseases, Endocrinology and Diabetology, Children's Memorial Health Institute (CMHI), Aleja Dzieci Polskich 20, 04-730, Warsaw, Poland.

Deoxyguanosine kinase deficiency (dGK) is a frequent cause of the hepatocerebral form of mitochondrial depletion syndrome (MDS). A group of 28 infants with severe progressive liver failure of unknown cause was recruited for post mortem search for deoxyguanosine kinase (DGUOK) gene mutations. Four affected patients (14% of the studied group), two homozygotes, one compound heterozygote, and one heterozygote, with DGUOK mutation found on only one allele, were identified. Three known pathogenic mutations in the DGUOK gene were detected, c.3G>A (p.Met1Ile), c.494A>T (p.Glu165Val), and c.766_767insGATT (p.Phe256X), and one novel molecular variant of unknown pathogenicity, c.813_814insTTT (p.Asn271_Thr272insPhe). Profound mitochondrial DNA depletion was confirmed in available specimens of the liver (4%, 15%, and 10% of the normal value) and in the muscle (4%, 23%, 45%, and 6%, respectively). The patients were born with low weights for gestational age and they presented adaptation trouble during the first days of life. Subsequently, liver failure developed, leading to death at the ages of 18, 6, 5.5, and 2.25 months, respectively. Mild neurological involvement was observed in all children (hypotonia, psychomotor retardation, and ptosis). Hypoglycemia (hypoketotic) and lactic acidosis were the constant laboratory findings. Elevated transferrin saturation, high ferritin, and alpha-fetoprotein levels resembled, in two cases, a neonatal hemochromatosis. Liver histopathology showed severe hepatic damage ranging from micronodular formation and cirrhosis to the total loss of liver architecture with diffuse fibrosis and neocholangiolar proliferation. Pancreatic islet cell hyperplasia with numerous confluent giant islets was found in both autopsied infants. Analysis of the natural history of the disease in our patients and the literature data led us to the following observations: (i) islet cell hyperplasia (and hyperinsulinism) may contribute to MDS-associated hypoglycemia; (ii) iron overload may additionally damage mtDNA-depleted tissues; (iii) low birth weight, adaptation trouble, and abnormal amino acids in newborn screening are frequent in dGK-deficient neonates.
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http://dx.doi.org/10.1007/s13353-010-0008-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3026684PMC
February 2011

Oxidative stress-dependent p66Shc phosphorylation in skin fibroblasts of children with mitochondrial disorders.

Biochim Biophys Acta 2010 Jun-Jul;1797(6-7):952-60. Epub 2010 Mar 10.

Nencki Institute of Experimental Biology, Warsaw, Poland.

p66Shc, the growth factor adaptor protein, can have a substantial impact on mitochondrial metabolism through regulation of cellular response to oxidative stress. We investigated relationships between the extent of p66Shc phosphorylation at Ser36, mitochondrial dysfunctions and an antioxidant defense reactions in fibroblasts derived from five patients with various mitochondrial disorders (two with mitochondrial DNA mutations and three with methylglutaconic aciduria and genetic defects localized, most probably, in nuclear genes). We found that in all these fibroblasts, the extent of p66Shc phosphorylation at Ser36 was significantly increased. This correlated with a substantially decreased level of mitochondrial superoxide dismutase (SOD2) in these cells. This suggest that SOD2 is under control of the Ser36 phosphorylation status of p66Shc protein. As a consequence, an intracellular oxidative stress and accumulation of damages caused by oxygen free radicals are observed in the cells.
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http://dx.doi.org/10.1016/j.bbabio.2010.03.005DOI Listing
January 2011