Novel Pathogenic Mutation of P209L in TRPC6 Gene Causes Adult Focal Segmental Glomerulosclerosis.

Focal segmental glomerulosclerosis (FSGS) is a leading kidney disease, clinically associated with proteinuria and progressive renal failure. The occurrence of this disease is partly related to gene mutations. We describe a single affected family member who presented with FSGS. We used high-throughput sequencing, sanger sequencing to identify the pathogenic mutations, and a systems genetics analysis in the BXD mice was conducted to explore the genetic regulatory mechanisms of pathogenic genes in the development of FSGS. We identified high urinary protein (++++) and creatinine levels (149 µmol/L) in a 29-year-old male diagnosed with a 5-year history of grade 2 hypertension. Histopathology of the kidney biopsy showed stromal hyperplasia at the glomerular segmental sclerosis and endothelial cell vacuolation degeneration. Whole-exome sequencing followed by Sanger sequencing revealed a heterozygous missense mutation (c.643C > T) in exon 2 of TRPC6, leading to the substitution of arginine with tryptophan at position 215 (p.Arg215Trp). Systems genetics analysis of the 53 BXD mice kidney transcriptomes identified Pygm as the upstream regulator of Trpc6. Those two genes are jointly involved in the regulation of FSGS mainly via Wnt and Hippo signaling pathways. We present a novel variant in the TRPC6 gene that causes FSGS. Moreover, our data suggested TRPC6 works with PYGM, as well as Wnt and Hippo signaling pathways to regulate renal function, which could guide future clinical prevention and targeted treatment for FSGS outcomes.

Recurrent atraumatic compartment syndrome as a manifestation of genetic neuromuscular disease.

Compartment syndrome (CS) is a medical emergency that occurs secondary to excessively high pressures within a confined fibro-osseous space, resulting in reduced perfusion and subsequent tissue injury. CS can be divided into acute forms, most commonly due to trauma and considered an orthopaedic emergency, and chronic forms, most commonly presenting in athletes with recurrent exercise-induced pain. Downstream pathophysiological mechanisms are complex but do share commonalities with mechanisms implicated in genetic neuromuscular disorders. Here we present 3 patients with recurrent CS in the context of a RYR1-related disorder (n = 1) and PYGM-related McArdle disease (n = 2), two of whom presented many years before the diagnosis of an underlying neuromuscular disorder was suspected. We also summarize the literature on previously published cases with CS in the context of a genetically confirmed neuromuscular disorder and outline how the calcium signalling alterations in RYR1-related disorders and the metabolic abnormalities in McArdle disease may feed into CS-causative mechanisms. These findings expand the phenotypical spectrum of RYR1-related disorders and McArdle disease; whilst most forms of recurrent CS will be sporadic, above and other genetic backgrounds ought to be considered in particular in patients where other suggestive clinical features are present.

Clinical and Laboratory Findings on Glycogen Storage Disease Type V: Results from a Retrospective Observational Study in a Tertiary Hospital.

Introduction - Glycogen storage disease type V (GSDV, MIM #232600) is an autosomal recessive metabolic myopathy caused by pathogenic variants in the PYGM gene. The characteristic symptoms of exercise intolerance, myalgia, and cramps, which improve after a few minutes of rest, are frequently unrecognized in affected children. When there is clinical suspicion, the initial approach with a forearm exercise test has diagnostic value by detecting low post-exercise plasma lactate-to-ammonia ratio values. The diagnostic algorithm is followed by genetic testing if the results suggest myophosphorylase deficiency. Methods - This was a retrospective observational study conducted based on reviewing medical records of patients with GSDV in a tertiary hospital. We assessed demographic variables, including the timing of onset and diagnosis, relevant clinical characteristics, and whether genetic testing was performed, including its results. Results/Case Report - Our goal was to review the GSDV cases in our center to assess our cohort's diagnostic timing and clinical and genetic characteristics. We identified 28 patients from 24 families, three with consanguinity. The mean age at the time of the study was 43 years. While most (26/28; 93%) recalled their first symptoms in childhood/adolescence, only 25% (7/28) were diagnosed then. All patients had exercise intolerance and CK elevation, while about half reported the second wind phenomenon. Genetic testing was performed in 22 patients, revealing biallelic PYGM variants (9 homozygous, 13 compound heterozygous) as the most common (p.R50*). Conclusion - GSDV is rare and presents in the pediatric age, with subtle manifestations often underestimated for decades. A late diagnosis may negatively impact the psychosocial development of affected children. It is essential to recognize some unique features that facilitate diagnosis: history of exercise intolerance, the second wind sign, and high resting serum CK levels. Identifying the disease-causing variants in PYGM is currently the gold standard for diagnosis as it is less invasive than performing a muscle biopsy, and may promptly diagnose the condition and avoid wrongful labelling of patients.

Creation of an iPSC-Based Skeletal Muscle Model of McArdle Disease Harbouring the Mutation c.2392T>C (p.Trp798Arg) in the PYGM Gene.

McArdle disease is a rare autosomal recessive condition caused by mutations in the PYGM gene. This gene encodes the skeletal muscle isoform of glycogen phosphorylase or myophosphorylase. Patients with McArdle disease have an inability to obtain energy from their muscle glycogen stores, which manifests as a marked exercise intolerance. Nowadays, there is no cure for this disorder and recommendations are intended to prevent and mitigate symptoms. There is great heterogeneity among the pathogenic variants found in the PYGM gene, and there is no obvious correlation between genotypes and phenotypes. Here, we present the generation of the first human iPSC-based skeletal muscle model harbouring the second most frequent mutation in PYGM in the Spanish population: NM_005609.4: c.2392T>C (p.Trp798Arg). To this end, iPSCs derived from a McArdle patient and a healthy control were both successfully differentiated into skeletal muscle cells using a small molecule-based protocol. The created McArdle skeletal muscle model was validated by confirming distinctive biochemical aspects of the disease such as the absence of myophosphorylase, the most typical biochemical feature of these patients. This model will be very valuable for use in future high-throughput pharmacological screenings.

Fluoride as a Potential Repressor of Glycogen Metabolism in Skeletal Muscle Cell Line CCL136.

The exposure of humans to fluorine is connected with its presence in the air, food and water. It is well known that fluorides even at a low concentration but with long time exposure accumulate in the body and lead to numerous metabolic disorders. Fluoride is recognised as a factor modulating the energy metabolism of cells. This interaction is of particular importance in muscle cells, which are cells with high metabolic activity related to the metabolism of glucose and glycogen. In someone suffering from chronic fluoride poisoning, frequent symptoms are chronic fatigue not relieved by extra sleep or rest, muscular weakness, muscle spasms, involuntary twitching. The aim of this study was to examine the effect of fluorine at concentrations determined in blood of people environmentally exposed to fluorides on activity and expression of enzymes taking part in metabolism of muscle glycogen. CCL136 cells were cultured under standard conditions with the addition of NaF. The amount of ATP produced by the cells was determined using the HPLC method, the amount and expression of genes responsible for glycogen metabolism using WB and RT PCR methods and the amount of glycogen in cells using the fluorimetric and PAS methods. It has been shown that in CCL136 cells exposed to 1, 3 and 10 µM NaF there is a change in the energy state and expression pattern of enzymes involved in the synthesis and breakdown of glycogen. It was observed that NaF caused a decrease in ATP content in CCL136 cells. Fluoride exposure also increased glycogen deposition. These changes were accompanied by a decrease in gene expression and the level of enzymatic proteins related to glycogen metabolism: glycogen synthase, glycogen synthase kinase and glycogen phosphorylase. The results obtained shed new light on the molecular mechanisms by which fluoride acts as an environmental toxin.

Long-term potentiation-based screening identifies neuronal PYGM as a synaptic plasticity regulator participating in Alzheimer's disease.

Synaptic dysfunction is an important pathological hallmark and cause of Alzheimer's disease (AD). High-frequency stimulation (HFS)-induced long-term potentiation (LTP) has been widely used to study synaptic plasticity, with impaired LTP found to be associated with AD. However, the exact molecular mechanism underlying synaptic plasticity has yet to be completely elucidated. Whether genes regulating synaptic plasticity are altered in AD and contribute to disease onset also remains unclear. Herein, we induced LTP in the hippocampal CA1 region of wild-type (WT) and AD model mice by administering HFS to the CA3 region and then studied transcriptome changes in the CA1 region. We identified 89 genes that may participate in normal synaptic plasticity by screening HFS-induced differentially expressed genes (DEGs) in mice with normal LTP, and 43 genes that may contribute to synaptic dysfunction in AD by comparing HFS-induced DEGs in mice with normal LTP and AD mice with impaired LTP. We further refined the 43 genes down to 14 by screening for genes with altered expression in pathological-stage AD mice without HFS induction. Among them, we found that the expression of Pygm, which catabolizes glycogen, was also decreased in AD patients. We further demonstrated that down-regulation of PYGM in neurons impaired synaptic plasticity and cognition in WT mice, while its overexpression attenuated synaptic dysfunction and cognitive deficits in AD mice. Moreover, we showed that PYGM directly regulated energy generation in neurons. Our study not only indicates that PYGM-mediated energy production in neurons plays an important role in synaptic function, but also provides a novel LTP-based strategy to systematically identify genes regulating synaptic plasticity under physiological and pathological conditions.

Generation of the First Human In Vitro Model for McArdle Disease Based on iPSC Technology.

McArdle disease is a rare autosomal recessive disorder caused by mutations in the PYGM gene. This gene encodes for the skeletal muscle isoform of glycogen phosphorylase (myophosphorylase), the first enzyme in glycogenolysis. Patients with this disorder are unable to obtain energy from their glycogen stored in skeletal muscle, prompting an exercise intolerance. Currently, there is no treatment for this disease, and the lack of suitable in vitro human models has prevented the search for therapies against it. In this article, we have established the first human iPSC-based model for McArdle disease. For the generation of this model, induced pluripotent stem cells (iPSCs) from a patient with McArdle disease (harbouring the homozygous mutation c.148C>T; p.R50* in the PYGM gene) were differentiated into myogenic cells able to contract spontaneously in the presence of motor neurons and generate calcium transients, a proof of their maturity and functionality. Additionally, an isogenic skeletal muscle model of McArdle disease was created. As a proof-of-concept, we have tested in this model the rescue of PYGM expression by two different read-through compounds (PTC124 and RTC13). The developed model will be very useful as a platform for testing drugs or compounds with potential pharmacological activity.

Diagnosis and genetic analysis of a case with glycogen storage disease type V caused by compound heterozygous mutations in the PYGM gene.

Glycogen storage disease type V is an autosomal recessive genetic disorder caused by muscle glycogen phosphorylase (PYGM) deficiency, which is characterized by exercise intolerance, second wind phenomena and high level of serum creatine kinase. In this study, we reported a Chinese young man with glycogen storage disease type V, with lower extremity weakness after exercise, increased creatine kinase, and slight fat infiltration in the posterior group of thigh muscle by magnetic resonance imaging (MRI). The proband had complex heterozygous PYGM disease-causing mutations, including c.308T>C (p.L103P) variant transmitted from the mother and c.260_261delCT (p.S87Ffs*23) from the father, of which the former was a novel PYGM mutation. This study enriched the PYGM pathogenic gene mutation spectrum, contributed to improve clinicians' understanding of glycogen storage disease type V and provided a reference for further genetic study of the disease.

Analysis of the expression, function and signaling of glycogen phosphorylase isoforms in hepatocellular carcinoma.

Glycogen phosphorylase (GP) is an essential enzyme for glycolysis via the glycogen degradation pathway. It consists of three isoforms: PYGB (brain form), PYGL (liver form) and PYGM (muscle form). Although the abnormal expression of GP is associated with a variety of tumors, its relationship with hepatocellular carcinoma (HCC) and whether it can be used as a prognostic marker of HCC remains unclear. In the present study, the expression levels of PYGB, PYGL and PYGM were analyzed. It was found that the expression levels of PYGB in tumor tissues were higher than those in normal tissues, particularly in HCC. The high expression of PYGB (hazard ratios=1.801; 95% confidence interval: 1.266-2.562) could predict the poor prognosis of HCC patients but not PYGL and PYGM. Inhibition of PYGB with GP inhibitor CP91149 significantly suppressed the HCC cell proliferation in the HCC cell model. In addition, combination treatment with sorafenib, a standard treatment for HCC, showed a great inhibition on tumor growth and angiogenesis. These findings suggested that PYGB may be used as a therapeutic and prognostic indicator for HCC.

Identification of Potential Muscle Biomarkers in McArdle Disease: Insights from Muscle Proteome Analysis.

Glycogen storage disease type V (GSDV, McArdle disease) is a rare genetic myopathy caused by deficiency of the muscle isoform of glycogen phosphorylase (PYGM). This results in a block in the use of muscle glycogen as an energetic substrate, with subsequent exercise intolerance. The pathobiology of GSDV is still not fully understood, especially with regard to some features such as persistent muscle damage (i.e., even without prior exercise). We aimed at identifying potential muscle protein biomarkers of GSDV by analyzing the muscle proteome and the molecular networks associated with muscle dysfunction in these patients. Muscle biopsies from eight patients and eight healthy controls showing none of the features of McArdle disease, such as frequent contractures and persistent muscle damage, were studied by quantitative protein expression using isobaric tags for relative and absolute quantitation (iTRAQ) followed by artificial neuronal networks (ANNs) and topology analysis. Protein candidate validation was performed by Western blot. Several proteins predominantly involved in the process of muscle contraction and/or calcium homeostasis, such as myosin, sarcoplasmic/endoplasmic reticulum calcium ATPase 1, tropomyosin alpha-1 chain, troponin isoforms, and alpha-actinin-3, showed significantly lower expression levels in the muscle of GSDV patients. These proteins could be potential biomarkers of the persistent muscle damage in the absence of prior exertion reported in GSDV patients. Further studies are needed to elucidate the molecular mechanisms by which PYGM controls the expression of these proteins.

A novel compound heterozygous mutation in PYGM gene associated with McArdle's disease.

McArdle's disease is an autosomal recessive glycogenosis due to mutation in the myophosphorylase gene (PYGM) resulting in a pure myopathy. The clinical onset typically occurs in childhood with cramps, myalgia, and intolerance to physical exercise, although late onset forms are also reported. We describe a case of a 17-year-old male complaining of cramps and myalgia following brief and intense exercise. The patient reported marked improvement in muscle fatigability few minutes after starting aerobic exercise. When he was a child, he had experienced few episodes of vomiting, nausea, and black colored urine following physical activity. Laboratory testings revealed high creatine kinase serum levels. Genetic testings for metabolic myopathies demonstrated a compound heterozygous for two PYGM mutations (p.R570Q and p.K754Nfs*49) allowing the diagnosis of McArdle's disease. To date, 183 mutations in the PYGM gene are listed in Human Gene Mutation Database Professional 2021.2, but this novel compound heterozygosis has never been reported before.

Sequencing refractory regions in bird genomes are hotspots for accelerated protein evolution.

BACKGROUND: Approximately 1000 protein encoding genes common for vertebrates are still unannotated in avian genomes. Are these genes evolutionary lost or are they not yet found for technical reasons? Using genome landscapes as a tool to visualize large-scale regional effects of genome evolution, we reexamined this question. RESULTS: On basis of gene annotation in non-avian vertebrate genomes, we established a list of 15,135 common vertebrate genes. Of these, 1026 were not found in any of eight examined bird genomes. Visualizing regional genome effects by our sliding window approach showed that the majority of these "missing" genes can be clustered to 14 regions of the human reference genome. In these clusters, an additional 1517 genes (often gene fragments) were underrepresented in bird genomes. The clusters of "missing" genes coincided with regions of very high GC content, particularly in avian genomes, making them "hidden" because of incomplete sequencing. Moreover, proteins encoded by genes in these sequencing refractory regions showed signs of accelerated protein evolution. As a proof of principle for this idea we experimentally characterized the mRNA and protein products of four "hidden" bird genes that are crucial for energy homeostasis in skeletal muscle: ALDOA, ENO3, PYGM and SLC2A4. CONCLUSIONS: A least part of the "missing" genes in bird genomes can be attributed to an artifact caused by the difficulty to sequence regions with extreme GC% ("hidden" genes). Biologically, these "hidden" genes are of interest as they encode proteins that evolve more rapidly than the genome wide average. Finally we show that four of these "hidden" genes encode key proteins for energy metabolism in flight muscle.

Molecular diagnosis of McArdle disease using whole-exome sequencing.

Whole-exome sequencing (WES) analysis has been used recently as a diagnostic tool for finding molecular defects. In the present study, researchers attempted to analyze molecular defects through WES in a 13-year-old female patient who had not been diagnosed through a conventional genetic approach. DNA was extracted and subjected to WES analysis to identify the genetic defect. A total of 106,728 exons and splicing variants were selected, and synonymous single nucleotide variants (SNVs) and general single nucleotide polymorphisms (SNPs) were filtered out. Finally, nonsynonymous SNVs (c.C415T and c.C389T) of the PYGM gene were identified in nine compound heterozygous mutations. PYGM encodes myophosphorylase and degrades glycogen in the muscle to supply energy to muscle cells. The present study revealed that the patient's father had a c.C389T mutation and the mother had a c.C415T mutation, resulting in A130V and R139W missense mutations, respectively. To the best of our knowledge, the A130V variant in PYGM has not been reported in the common variant databases. All variations of the patient's family detected using WES were verified by Sanger sequencing. Because the patient had compound heterozygous mutations in the PYGM gene, the patient was presumed to exhibit markedly decreased muscle phosphorylase activity. To assess the function of myophosphorylase, an ischemic forearm exercise test was performed. The blood ammonia level sharply increased and the lactate level maintained a flat curve shape similar to the typical pattern of McArdle disease. Therefore, the diagnosis of the patient was confirmed to be McArdle disease, a glycogen storage disease. Through WES analysis, accurate and early diagnosis could be made in the present study. This report describes a novel compound heterozygous mutation of the PYGM gene in a Korean patient.

Muscle Glycogen Phosphorylase and Its Functional Partners in Health and Disease.

Glycogen phosphorylase (PG) is a key enzyme taking part in the first step of glycogenolysis. Muscle glycogen phosphorylase (PYGM) differs from other PG isoforms in expression pattern and biochemical properties. The main role of PYGM is providing sufficient energy for muscle contraction. However, it is expressed in tissues other than muscle, such as the brain, lymphoid tissues, and blood. PYGM is important not only in glycogen metabolism, but also in such diverse processes as the insulin and glucagon signaling pathway, insulin resistance, necroptosis, immune response, and phototransduction. PYGM is implicated in several pathological states, such as muscle glycogen phosphorylase deficiency (McArdle disease), schizophrenia, and cancer. Here we attempt to analyze the available data regarding the protein partners of PYGM to shed light on its possible interactions and functions. We also underline the potential for zebrafish to become a convenient and applicable model to study PYGM functions, especially because of its unique features that can complement data obtained from other approaches.

Longitudinal case study and phenotypic multimodal characterization of McArdle disease-linked retinopathy: insight into pathomechanisms.

Background: We present a longitudinal clinical characterization of PYGM-linked pattern dystrophy in an adult male patient.Materials and Methods: A patient affected by McArdle disease (glycogen storage disease type V) and homozygous for the nonsense variant PYGM c.148C>T p.(Arg50*) underwent ophthalmic examinations over a 9-year-interval, including fundus photography, fundus autofluorescence, optical coherence tomography (OCT), OCT-angiography and electroretinography (ERG).Results: At age 52, the patient was asymptomatic but yellow flecks were first observed in the macula of both eyes. This yellow flecks at the posterior pole progressed towards a pattern-like dystrophy over a 5-year-period. By fundus autofluorescence imaging the appearance of new hyperautofluorescent flecks and the extension of existing ones was observed over time. Concomitantly, a slow progression of the size of atrophic areas was seen at the posterior pole. Scotopic ERGs were within normal limits, but photopic Flicker responses were decreased, indicating reduced cone function.Conclusions: This additional case of PYGM-linked pattern dystrophy further confirms retinopathy as a clinical phenotype associated with McArdle disease. PYGM expression pattern suggests a disease mechanism involving impaired glycogen metabolism both in the retinal pigment epithelium and in cone photoreceptors.

The effect of muscle glycogen phosphorylase (Pygm) knockdown on zebrafish morphology.

Muscle glycogen phosphorylase (PYGM) is a key enzyme in the first step of glycogenolysis. Mutation in the PYGM gene leads to autosomal recessive McArdle disease. Patients suffer from exercise intolerance with premature fatigue, muscle cramps and myalgia due to lack of available glucose in muscles. So far, no efficient treatment has been found. The zebrafish has many experimental advantages, and was successfully implemented as an animal model of human myopathies. Since zebrafish skeletal muscles share high similarity with human skeletal muscles, it is our animal of choice to investigate the impact of Pygm knockdown on skeletal muscle tissue. The two forms of the zebrafish enzyme, Pygma and Pygmb, share more than 80% amino acid sequence identity with human PYGM. We show that the Pygm level varies at both the mRNA and protein level in distinct stages of zebrafish development, which is correlated with glycogen level. The Pygm distribution in muscles varies from dispersed to highly organized at 72 hpf. The pygma and pygmb morpholino knockdown resulted in a reduced Pygm level in zebrafish morphants, which exhibited altered, disintegrated muscle structure and accumulation of glycogen granules in the subsarcolemmal region. Thus, lowering the Pygm level in zebrafish larvae leads to an elevated glycogen level and to morphological muscle changes mimicking the symptoms of human McArdle disease. The zebrafish model of this human disease might contribute to further understanding of its molecular mechanisms and to the development of appropriate treatment.

Bioinformatics-based discovery of PYGM and TNNC2 as potential biomarkers of head and neck squamous cell carcinoma.

Head and neck squamous cell carcinoma (HNSCC) is an aggressive malignancy with high morbidity and mortality rates and ranks as the sixth most common cancer all over the world. Despite numerous advancements in therapeutic methods, the prognosis of HNSCC patients still remains poor. Therefore, there is an urgent need to have a better understanding of the molecular mechanisms underlying HNSCC progression and to identify essential genes that could serve as effective biomarkers and potential treatment targets. In the present study, original data of three independent datasets were downloaded from the Gene Expression Omnibus database (GEO) and R language was applied to screen out the differentially expressed genes (DEGs). PYGM and TNNC2 were finally selected from the overlapping DEGs of three datasets for further analyses. Transcriptional and survival data related to PYGM and TNNC2 was detected through multiple online databases such as Oncomine, Gene Expression Profiling Interactive Analysis (GEPIA), cBioportal, and UALCAN. Quantitative real-time polymerase chain reaction (qPCR) analysis was adopted for the validation of PYGM and TNNC2 mRNA level in HNSCC tissues and cell lines. Survival curves were plotted to evaluate the association of these two genes with HNSCC prognosis. It was demonstrated that PYGM and TNNC2 were significantly down-regulated in HNSCC and the aberrant expression of PYGM and TNNC2 were correlated with HNSCC prognosis, implying the potential of exploiting them as therapeutic targets for HNSCC treatment or potential biomarkers for diagnosis and prognosis.

Novel variant in the PYGM gene causing late-onset limb-girdle myopathy, ptosis, and camptocormia.

INTRODUCTION: McArdle disease is a glycogen storage disease caused by mutations in the PYGM gene encoding myophosphorylase. It manifests classically with childhood-onset exercise-induced pain. METHODS: We report the characteristics of 2 unrelated patients with a new homozygous mutation of the PYGM gene. RESULTS: Two patients, aged 76 and 79 years, presented with severe upper and lower limb atrophy and weakness. Additionally, 1 patient presented with bilateral ptosis, and the other with camptocormia. In both patients, symptoms had developed progressively in the 2 preceding years, and there was no history of exercise intolerance. Both patients demonstrated myogenic abnormalities on electromyography, multiple glycogen-containing vacuoles and undetectable muscle myophosphorylase activity on muscle biopsy, and a novel homozygous frameshift p.Lys42Profs*48 PYGM mutation. CONCLUSIONS: This report expands the phenotype and genotype of McArdle disease and suggests that PYGM mutations should be looked for in patients with very late-onset myopathy with no previous history of exercise intolerance. Muscle Nerve 57: 157-160, 2018.

Glycogen metabolism in brain and neurons - astrocytes metabolic cooperation can be altered by pre- and neonatal lead (Pb) exposure.

Lead (Pb) is an environmental neurotoxin which particularly affects the developing brain but the molecular mechanism of its neurotoxicity still needs clarification. The aim of this paper was to examine whether pre- and neonatal exposure to Pb (concentration of Pb in rat offspring blood below the "threshold level") may affect the brain's energy metabolism in neurons and astrocytes via the amount of available glycogen. We investigated the glycogen concentration in the brain, as well as the expression of the key enzymes involved in glycogen metabolism in brain: glycogen synthase 1 (Gys1), glycogen phosphorylase (PYGM, an isoform active in astrocytes; and PYGB, an isoform active in neurons) and phosphorylase kinase ß (PHKB). Moreover, the expression of connexin 43 (Cx43) was evaluated to analyze whether Pb poisoning during the early phase of life may affect the neuron-astrocytes' metabolic cooperation. This work shows for the first time that exposure to Pb in early life can impair brain energy metabolism by reducing the amount of glycogen and decreasing the rate of its metabolism. This reduction in brain glycogen level was accompanied by a decrease in Gys1 expression. We noted a reduction in the immunoreactivity and the gene expression of both PYGB and PYGM isoform, as well as an increase in the expression of PHKB in Pb-treated rats. Moreover, exposure to Pb induced decrease in connexin 43 immunoexpression in all the brain structures analyzed, both in astrocytes as well as in neurons. Our data suggests that exposure to Pb in the pre- and neonatal periods results in a decrease in the level of brain glycogen and a reduction in the rate of its metabolism, thereby reducing glucose availability, which as a further consequence may lead to the impairment of brain energy metabolism and the metabolic cooperation between neurons and astrocytes.

Whole exome sequencing of rare aggressive breast cancer histologies.

Little is known about mutational landscape of rare breast cancer (BC) subtypes. The aim of the study was to apply next generation sequencing to three different subtypes of rare BCs in order to identify new genes related to cancer progression. We performed whole exome and targeted sequencing of 29 micropapillary, 23 metaplastic, and 27 pleomorphic lobular BCs. Micropapillary BCs exhibit a profile comparable to common BCs: PIK3CA, TP53, GATA3, and MAP2K4 were the most frequently mutated genes. Metaplastic BCs presented a high frequency of TP53 (78 %) and PIK3CA (48 %) mutations and were recurrently mutated on KDM6A (13 %), a gene involved in histone demethylation. Pleomorphic lobular carcinoma exhibited high mutation rate of PIK3CA (30 %), TP53 (22 %), and CDH1 (41 %) and also presented mutations in PYGM, a gene involved in glycogen metabolism, in 8 out of 27 samples (30 %). Further analyses of publicly available datasets showed that PYGM is dramatically underexpressed in common cancers as compared to normal tissues and that low expression in tumors is correlated with poor relapse-free survival. Immunohistochemical staining on formalin-fixed paraffin-embedded tissues available in our cohort of patients confirmed higher PYGM expression in normal breast tissue compared to equivalent tumoral zone. Next generation sequencing methods applied on rare cancer subtypes can serve as a useful tool in order to uncover new potential therapeutic targets. Sequencing of pleomorphic lobular carcinoma identified a high rate of alterations in PYGM. These findings emphasize the role of glycogen metabolism in cancer progression.