Defective collagen VI α6 chain expression in the skeletal muscle of patients with collagen VI-related myopathies

Strategies to improve the design of gapmer antisense oligonucleotide on allele-specific silencing

Gapmer antisense oligonucleotides (ASOs) hold therapeutic promise for allele-specific silencing, but face challenges in distinguishing between mutant and wild-type transcripts. This study explores new design strategies to enhance ASO specificity, focusing on a common dominant mutation in COL6A3 gene associated with Ullrich congenital muscular dystrophy. Initial gapmer ASO design exhibited high efficiency but poor specificity for the mutant allele. We then adopted a mixmer design, incorporating additional RNA bases based on computational predictions of secondary structures for both mutant and wild-type alleles, aiming to enhance ASO accessibility to mutant transcripts. The mixmer ASO design demonstrated up to a 3-fold increase in specificity compared with the classical gapmer design. Further refinement involved introducing a nucleotide mismatch as a structural modification, resulting in a 10-fold enhancement in specificity compared with the gapmer design and a 3-fold over the mixmer design. Additionally, we identified for the first time a potential role of the RNA-induced silencing complex (RISC), alongside RNase H1, in gapmer-mediated silencing, in contrast with what was observed with mixmer ASOs, where only RNase H1 was involved. In conclusion, this study presents a novel design concept for allele-specific ASOs leveraging mRNA secondary structures and nucleotide mismatching and suggests a potential involvement of RISC in gapmer-mediated silencing.

New Clinical and Immunofluoresence Data of Collagen VI-Related Myopathy: A Single Center Cohort of 69 Patients

Pathogenetic mechanism recognition and proof-of-concept clinical trials were performed in our patients affected by collagen VI-related myopathies. This study, which included 69 patients, aimed to identify innovative clinical data to better design future trials. Among the patients, 33 had Bethlem myopathy (BM), 24 had Ullrich congenital muscular dystrophy (UCMD), 7 had an intermediate phenotype (INTM), and five had myosclerosis myopathy (MM). We obtained data on muscle strength, the degree of contracture, immunofluorescence, and genetics. In our BM group, only one third had a knee extension strength greater than 50% of the predicted value, while only one in ten showed similar retention of elbow flexion. These findings should be considered when recruiting BM patients for future trials. All the MM patients had axial and limb contractures that limited both the flexion and extension ranges of motion, and a limitation in mouth opening. The immunofluorescence analysis of collagen VI in 55 biopsies from 37 patients confirmed the correlation between collagen VI defects and the severity of the clinical phenotype. However, biopsies from the same patient or from patients with the same mutation taken at different times showed a progressive increase in protein expression with age. The new finding of the time-dependent modulation of collagen VI expression should be considered in genetic correction trials.

Collagen VI promotes recovery from colitis by inducing lymphangiogenesis and drainage of inflammatory cells

Despite a number of studies providing evidence that the extracellular matrix (ECM) is an active player in the pathogenesis of intestinal inflammation, knowledge on the actual contribution of specific ECM molecules in the progression of inflammatory bowel disease (IBD) remains scant. Here, we investigated the role of a major ECM protein, collagen VI (ColVI), in gut homeostasis and elucidated the impact of its deregulation on the pathophysiology of IBD. To this end, we combined in vivo and ex vivo studies on wild type and ColVI-deficient (Col6a1-/- ) mice both under physiological conditions and during experimentally induced acute colitis and its subsequent recovery, by means of gut histology and immunostaining, gene expression, bone marrow transplantation, flow cytometry of immune cell subpopulations, and lymph flow assessment. We found that ColVI displayed dynamic expression and ECM deposition during the acute inflammatory and recovery phases of experimentally induced colitis, whereas the genetic ablation of ColVI in Col6a1 null mice impaired the functionality of lymphatic vessels, which in turn affected the resolution of inflammation during colitis. Based on these findings, we investigated ColVI expression and deposition in ileal specimens from two cohorts of patients affected by Crohn's disease (CD) and correlated ColVI abundance to clinical outcome. Our results show that high ColVI immunoreactivity in ileal biopsies of CD patients at diagnosis correlates with increased risk of surgery and that ColVI expression in biopsies taken at the resection margin during surgery, and showing inactive disease, predict disease recurrence. Our data unveil a key role for ColVI in the intestinal microenvironment, where it is involved in lymphangiogenesis and intestinal inflammation. Altogether, these findings point at the dysregulation of ColVI expression as a novel factor contributing to the onset and maintenance of inflammation in CD via mechanisms impinging on the modulation of inflammatory cell recruitment and function. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Collagen VI in the Musculoskeletal System

Collagen VI exerts several functions in the tissues in which it is expressed, including mechanical roles, cytoprotective functions with the inhibition of apoptosis and oxidative damage, and the promotion of tumor growth and progression by the regulation of cell differentiation and autophagic mechanisms. Mutations in the genes encoding collagen VI main chains, COL6A1, COL6A2 and COL6A3, are responsible for a spectrum of congenital muscular disorders, namely Ullrich congenital muscular dystrophy (UCMD), Bethlem myopathy (BM) and myosclerosis myopathy (MM), which show a variable combination of muscle wasting and weakness, joint contractures, distal laxity, and respiratory compromise. No effective therapeutic strategy is available so far for these diseases; moreover, the effects of collagen VI mutations on other tissues is poorly investigated. The aim of this review is to outline the role of collagen VI in the musculoskeletal system and to give an update about the tissue-specific functions revealed by studies on animal models and from patients' derived samples in order to fill the knowledge gap between scientists and the clinicians who daily manage patients affected by collagen VI-related myopathies.

A novel variant of COL6A3 c.6817-2(IVS27)A>G causing Bethlem myopathy: A case report

Bethlem myopathy (BM) is a disease that is caused by mutations in the collagen VI genes. It is a mildly progressive disease characterized by proximal muscle weakness and contracture of the fingers, the wrist, the elbow, and the ankle. BM is an autosomal dominant inheritance that is mainly caused by dominant COL6A1, COL6A2, or COL6A3 mutations. However, a few cases of collagen VI mutations with bilateral facial weakness and Beevor's sign have also been reported. This study presents a 50-year-old female patient with symptoms of facial weakness beginning in childhood and with the slow progression of the disease with age. At the age of 30 years, the patient presented with asymmetrical proximal muscle weakness, and the neurological examination revealed bilateral facial weakness and a positive Beevor's sign. Phosphocreatine kinase was slightly elevated with electromyography showing myopathic changes and magnetic resonance imaging (MRI) of the lower limb muscles showing the muscle MRI associated with collagen VI (COL6)-related myopathy (COL6-RM). The whole-genome sequencing technology identified the heterozygous mutation c.6817-2(IVS27)A>G in the COL6A3 gene, which was in itself a novel mutation. The present study reports yet another case of BM, which is caused by the recessive COL6A3 intron variation, widening the clinical spectrum and genetic heterogeneity of BM.

Personalized in vitro Extracellular Matrix Models of Collagen VI-Related Muscular Dystrophies

Collagen VI-related dystrophies (COL6-RDs) are a group of rare congenital neuromuscular dystrophies that represent a continuum of overlapping clinical phenotypes that go from the milder Bethlem myopathy (BM) to the severe Ullrich congenital muscular dystrophy, for which there is no effective treatment. Mutations in one of the three Collagen VI genes alter the incorporation of this protein into the extracellular matrix (ECM), affecting the assembly and the structural integrity of the whole fibrillar network. Clinical hallmarks of COL6-RDs are secondary to the ECM disruption and include muscle weakness, proximal joint contractures, and distal hyperlaxity. Although some traits have been identified in patients’ ECMs, a correlation between the ECM features and the clinical phenotype has not been established, mainly due to the lack of predictive and reliable models of the pathology. Herein, we engineered a new personalized pre-clinical model of COL6-RDs using cell-derived matrices (CDMs) technology to better recapitulate the complexity of the native scenario. We found that CDMs from COL6-RD patients presented alterations in ECM structure and composition, showing a significantly decreased Collagen VI secretion, especially in the more severe phenotypes, and a decrease in Fibrillin-1 inclusion. Next, we examined the Collagen VI-mediated deposition of Fibronectin in the ECM, finding a higher alignment, length, width, and straightness than in patients with COL6-RDs. Overall, these results indicate that CDMs models are promising tools to explore the alterations that arise in the composition and fibrillar architecture due to mutations in Collagen VI genes, especially in early stages of matrix organization. Ultimately, CDMs derived from COL6-RD patients may become relevant pre-clinical models, which may help identifying novel biomarkers to be employed in the clinics and to investigate novel therapeutic targets and treatments.

New COL6A6 Variant Causes Autosomal Dominant Retinitis Pigmentosa in a Four-Generation Family

Purpose

To report that variants in the gene for a large lamina basal component protein, COL6A6 (collagen type VI alpha 6 chain, Col6α6), linked to chromosome 3p22.1 causes retinitis pigmentosa (RP) in patients with autosomal dominant transmission (adRP).

Methods

A positional-cloning approach, whole exome sequencing, and modeling were used. The proband and several affected family members have been phenotyped and followed for over 12 years.

Results

A heterozygous missense variant, c.509C>G (p. Ser170Cys) in exon 2 of COL6A6 (comprised of 36 exons and 2236 amino acids), was observed in a four- generation family and is likely to cause the adRP phenotype. It was identified in 10 affected members. All affected family members had a distinct phenotype: late-onset rod cone dystrophy, with good retained visual acuity, until their late 70s. Immunohistochemistry of human retina showed a dot-like signal at the base of the inner segments of photoreceptors and outer plexiform layer (OPL). The structural modeling of the N7 domain of Col6α6 suggests that the mutant might result in the abnormal cellular localization of collagen VI or malformation of collagen fibers resulting in the loss of its unique filament structure.

Conclusions

COL6A6 is widely expressed in human tissues and evolutionary conserved. It is thought to interact with a range of extracellular matrix components. Our findings suggest that this form of RP has long-term useful central visual acuity and a mild progression, which are important considerations for patient counseling.

Early Morphological Changes of the Rectus Femoris Muscle and Deep Fascia in Ullrich Congenital Muscular Dystrophy

Ullrich congenital muscular dystrophy (UCMD) is a severe form of muscular dystrophy caused by the loss of function of collagen VI, a critical component of the muscle-tendon matrix. Magnetic resonance imaging of UCMD patients’ muscles shows a peculiar rim of abnormal signal at the periphery of each muscle, and a relative sparing of the internal part. The mechanism/s involved in the early fat substitution of muscle fiber at the periphery of muscles remain elusive. We studied a muscle biopsy of the rectus femoris/deep fascia (DF) of a 3-year-old UCMD patient, with a homozygous mutation in the COL6A2 gene. By immunohistochemical and ultrastructural analysis, we found a marked fatty infiltration at the interface of the muscle with the epimysium/DF and an atrophic phenotype, primarily in fast-twitch fibers, which has never been reported before. An unexpected finding was the widespread increase of interstitial cells with long cytoplasmic processes, consistent with the telocyte phenotype. Our study documents for the first time in a muscle biopsy the peculiar pattern of outside-in muscle degeneration followed by fat substitution as already shown by muscle imaging, and an increase of telocytes in the interstitium of the deep fascia, which highlights a potential involvement of this structure in the pathogenesis of UCMD.

The Role of Collagen VI α6 Chain Gene in Atopic Dermatitis

Background

Objective

Methods

Results

Conclusion

Exome Sequencing Reveals Diagnosis of LAMA2-Muscular Dystrophy and Possibility of Coexisting Bethlem Myopathy in a Neonate

We reported a neonate presenting with muscle weakness, hypotonia, and joint contractures since birth. Investigations revealed significantly elevated creatinine-phosphokinase, abnormal electromyography suggestive of muscle disease and normal magnetic resonance imaging (MRI) of the brain. Exome sequencing revealed homozygous pathogenic mutations in LAMA2 (NM_000426.3: c.7881T > G, p.(His2627Gln)) and a heterozygous likely-pathogenic mutation in COL6A2 (NM_001849.3: c.1970–2A > G). Parental segregation by Sanger sequencing confirmed a heterozygous carrier state for the LAMA2 variant in both parents, thus confirming the diagnosis of autosomal recessive LAMA2-muscular dystrophy (LAMA2-MD) in the proband. The COL6A2 variant segregated with the as-yet asymptomatic mother. Musculoskeletal MRI of the proband at 12 months of age revealed peripheral involvement of the vastii, rectus femoris, gastrocnemius and the soleus, with relative central sparing, without areas of fatty infiltration; not serving to distinguish clearly between LAMA-MD and COL6A2- related disease. Reverse phenotyping of a 27-year-old mother revealed a normal musculoskeletal MRI and clinically absent red flags. Potential explanations for the heterozygous likely-pathogenic COL6A2 variant in the proband and the mother include (a) a coexisting diagnosis of autosomal dominant COL6A2-related myopathy, likely Bethlem myopathy, which has a variable clinical phenotype and age of onset; (b) a carrier state for autosomal recessive Ullrich congenital muscular dystrophy; or (c) a heterozygous COL6A2 variant contributing as a synergistic factor along with homozygous LAMA2 mutation. The couple was offered genetic counseling regarding the proband and the future pregnancies.

Surgical treatment of scoliosis in Ullrich Congenital Muscular Dystrophy: a case series of 3 patients

Scoliosis in Ullrich Congenital Muscular Dystrophy (UCMD) is very common, with a reported incidence of more than 50%, and it is rapidly progressive. There are no previous studies which specifically focus on scoliosis surgery in UCMD patients. This article reports three cases of scoliosis surgery in UCMD, focusing on operative course, clinical and radiological results achieved, fusion area and complications, with a 2-year follow-up. The surgical technique adopted for vertebral arthrodesis included: high-density pedicle screw systems, asymmetric rods contouring and direct vertebral rotation. The summary results shown a significative correction of the coronal deformity, with a reduction of the mean Cobb angle from 49° to 25° post-operatively. Mean pelvic tilt remained stable, while L5-tilt showed a decrease from 10° to 6°. Mean screw density was 1.92. None of the patients required extended fixation to S2. No major complications were reported, and patients maintained their pre-operative walking ability. All the patients reported a subjective improvement in quality of life, with a better sitting comfort. In conclusion, posterior spinal fusion with high-density pedicle screw systems and direct vertebral rotation may be safe and effective in surgical correction of scoliosis in UCMD. If pelvic obliquity and L5-tilt are less than 15°, could be possible to achieve an optimal spinal and pelvic balance even without sacral or pelvic fixation.

Congenital muscular dystrophy-associated inflammatory chemokines provide axes for effective recruitment of therapeutic adult stem cell into muscles

Background

Congenital muscular dystrophies (CMD) are a clinically and genetically heterogeneous group of neuromuscular disorders characterized by muscle weakness. The two most prevalent forms of CMD, collagen VI-related myopathies (COL6RM) and laminin α2 deficient CMD type 1A (MDC1A), are both caused by deficiency or dysfunction of extracellular matrix proteins. Previously, we showed that an intramuscular transplantation of human adipose-derived stem cells (ADSC) into the muscle of the Col6a1^−/− mice results in efficient stem cell engraftment, migration, long-term survival, and continuous production of the collagen VI protein, suggesting the feasibility of the systemic cellular therapy for COL6RM. In order for this therapeutic approach to work however, stem cells must be efficiently targeted to the entire body musculature. Thus, the main goal of this study is to test whether muscle homing of systemically transplanted ADSC can be enhanced by employing muscle-specific chemotactic signals originating from CMD-affected muscle tissue.

Methods

Proteomic screens of chemotactic molecules were conducted in the skeletal muscles of COL6RM- and MDC1A-affected patients and CMD mouse models to define the inflammatory and immune activities, thus, providing potential markers of disease activity or treatment effect. Also using a pre-clinical animal model, recapitulating mild Ullrich congenital muscular dystrophy (UCMD), the therapeutic relevance of identified chemotactic pathways was investigated in vivo, providing a basis for future clinical investigations.

Results

Comprehensive proteomic screens evaluating relevant human and mouse skeletal muscle biopsies offered chemotactic axes to enhance directional migration of systemically transplanted cells into CMD-affected muscles, including CCL5-CCR1/3/5, CCL2-CCR2, CXCL1/2-CXCR1,2, and CXCL7-CXCR2. Also, the specific populations of ADSC selected with an affinity for the chemokines being released by damaged muscle showed efficient migration to injured site and presented their therapeutic effect.

Conclusions

Collectively, identified molecules provided insight into the mechanisms governing directional migration and intramuscular trafficking of systemically infused stem cells, thus, permitting broad and effective application of the therapeutic adult stem cells for CMD treatment.

Transcriptome analysis identifies genes involved with the development of umbilical hernias in pigs

Umbilical hernia (UH) is one of the most frequent defects affecting pig production, however, it also affects humans and other mammals. UH is characterized as an abnormal protrusion of the abdominal contents to the umbilical region, causing pain, discomfort and reduced performance in pigs. Some genomic regions associated to UH have already been identified, however, no study involving RNA sequencing was performed when umbilical tissue is considered. Therefore, here, we have sequenced the umbilical ring transcriptome of five normal and five UH-affected pigs to uncover genes and pathways involved with UH development. A total of 13,216 transcripts were expressed in the umbilical ring tissue. From those, 230 genes were differentially expressed (DE) between normal and UH-affected pigs (FDR <0.05), being 145 downregulated and 85 upregulated in the affected compared to the normal pigs. A total of 68 significant biological processes were identified and the most relevant were extracellular matrix, immune system, anatomical development, cell adhesion, membrane components, receptor activation, calcium binding and immune synapse. The results pointed out ACAN, MMPs, COLs, EPYC, VIT, CCBE1 and LGALS3 as strong candidates to trigger umbilical hernias in pigs since they act in the extracellular matrix remodeling and in the production, integrity and resistance of the collagen. We have generated the first transcriptome of the pig umbilical ring tissue, which allowed the identification of genes that had not yet been related to umbilical hernias in pigs. Nevertheless, further studies are needed to identify the causal mutations, SNPs and CNVs in these genes to improve our understanding of the mechanisms of gene regulation.

Tendon Extracellular Matrix Remodeling and Defective Cell Polarization in the Presence of Collagen VI Mutations

Mutations in collagen VI genes cause two major clinical myopathies, Bethlem myopathy (BM) and Ullrich congenital muscular dystrophy (UCMD), and the rarer myosclerosis myopathy. In addition to congenital muscle weakness, patients affected by collagen VI-related myopathies show axial and proximal joint contractures, and distal joint hypermobility, which suggest the involvement of tendon function. To gain further insight into the role of collagen VI in human tendon structure and function, we performed ultrastructural, biochemical, and RT-PCR analysis on tendon biopsies and on cell cultures derived from two patients affected with BM and UCMD. In vitro studies revealed striking alterations in the collagen VI network, associated with disruption of the collagen VI-NG2 (Collagen VI-neural/glial antigen 2) axis and defects in cell polarization and migration. The organization of extracellular matrix (ECM) components, as regards collagens I and XII, was also affected, along with an increase in the active form of metalloproteinase 2 (MMP2). In agreement with the in vitro alterations, tendon biopsies from collagen VI-related myopathy patients displayed striking changes in collagen fibril morphology and cell death. These data point to a critical role of collagen VI in tendon matrix organization and cell behavior. The remodeling of the tendon matrix may contribute to the muscle dysfunction observed in BM and UCMD patients.

Clinical features of collagen VI-related dystrophies: A large Brazilian cohort

OBJECTIVES

Collagen VI-related dystrophies (COL6-RDs) have a broad clinical spectrum and are caused by mutations in the COL6A1, COL6A2 and COL6A3 genes. Despite the clinical variability, two phenotypes are classically recognized: Bethlem myopathy (BM, milder form) and Ullrich congenital muscular dystrophy (UCMD, more severe form), with many patients presenting an intermediate phenotype. In this work, we present clinical and genetic data from 28 patients (27 families), aged 6-38 years (mean of 16.96 years), with COL6-RDs.

PATIENTS AND METHODS

Clinical, muscle histology and genetic data are presented. COL6A1, COL6A2 and COL6A3 genes were analyzed by next-generation sequencing (NGS).

RESULTS

Homozygous or heterozygous variants were found in COL6A1 (12 families), COL6A2 (12 families) and COL6A3 (3 families). Patients with the severe UCMD phenotype (three cases) had a homogeneous clinical picture characterized by neonatal onset of manifestations, no gait acquisition and a stable course, but with severe respiratory involvement. Most of the patients with the mild UCMD phenotype had neonatal onset of manifestations (88.8 %), delayed motor development (66.6 %), slowly progressive course, pulmonary involvement (55.5 %) and loss of the walking capacity before the age of 10 (66.6 %). In the intermediate group (nine patients), some children had neonatal onset of manifestations (44.5 %) and delayed motor development (88.9 %); but all of them achieved the ability to walk and were still ambulatory. Some patients that had the BM phenotype presented neonatal manifestations (57.1 %); however, all of them had normal motor development and normal pulmonary function. Only one patient from the group of BM lost the walking capacity during the evolution of the disease. Other frequent findings observed in all groups were joint retractions, spinal deformities, distal hyperextensibility, congenital hip dislocation and keloid formation.

CONCLUSION

COL6-RDs present variable clinical manifestations, but common findings are helpful for the clinical suspicion. NGS is a valuable approach for diagnosis, providing useful information for the genetic counseling of families.

Collagen VI-related myopathy: Expanding the clinical and genetic spectrum

INTRODUCTION

We aimed to analyze the clinical and genetic characteristics of collagen VI-related myopathy.

METHODS

We analyzed the clinical course and mutation spectrum in patients with collagen VI gene mutations among our congenital muscular dystrophy cohort.

RESULTS

Among 24 patients with mutations in collagen VI coding genes, 13 (54.2%) were categorized as Ullrich type, and 11 (45.8%) as non-Ullrich type. Congenital orthopedic problems were similarly observed in both types, yet multiple joint contractures were found only in the Ullrich type. Clinical courses and pathology findings varied between patients. Mutations in COL6A1, COL6A2, and COL6A3 were found in 15 (65%), 3 (13%), and 5 (22%) patients, respectively, without genotype-phenotype association. Five novel variants were detected.

DISCUSSION

We verified clinical heterogeneity of collagen VI-related myopathy, which emphasizes the importance of genetic testing. Genotype-phenotype association or early predictors for progression were not identified. Multiple joint contractures predict rapid deterioration. Muscle Nerve 58: 381-388, 2018.

Collagen VI disorders: Insights on form and function in the extracellular matrix and beyond

Mutations in the three canonical collagen VI genes, COL6A1, COL6A2 and COL6A3, cause a spectrum of muscle disease from Bethlem myopathy at the mild end to the severe Ullrich congenital muscular dystrophy. Mutations can be either dominant or recessive and the resulting clinical severity is influenced by the way mutations impact the complex collagen VI assembly process. Most mutations are found towards the N-terminus of the triple helical collagenous domain and compromise extracellular microfibril assembly. Outside the triple helix collagen VI is highly polymorphic and discriminating mutations from rare benign changes remains a major diagnostic challenge. Collagen VI deficiency alters extracellular matrix structure and biomechanical properties and leads to increased apoptosis and oxidative stress, decreased autophagy, and impaired muscle regeneration. Therapies that target these downstream consequences have been tested in a collagen VI null mouse and also in small human trials where they show modest clinical efficacy. An important role for collagen VI in obesity, cancer and diabetes is emerging. A major barrier to developing effective therapies is the paucity of information about how collagen VI deficiency in the extracellular matrix signals the final downstream consequences - the receptors involved and the intracellular messengers await further characterization.

Gene expression profiling of breast cancer in Lebanese women

Breast cancer is commonest cancer in women worldwide. Elucidation of underlying biology and molecular pathways is necessary for improving therapeutic options and clinical outcomes. Molecular alterations in breast cancer are complex and involve cross-talk between multiple signaling pathways. The aim of this study is to extract a unique mRNA fingerprint of breast cancer in Lebanese women using microarray technologies. Gene-expression profiles of 94 fresh breast tissue samples (84 cancerous/10 non-tumor adjacent samples) were analyzed using GeneChip Human Genome U133 Plus 2.0 arrays. Quantitative real-time PCR was employed to validate candidate genes. Differentially expressed genes between breast cancer and non-tumor tissues were screened. Significant differences in gene expression were established for COL11A1/COL10A1/MMP1/COL6A6/DLK1/S100P/CXCL11/SOX11/LEP/ADIPOQ/OXTR/FOSL1/ACSBG1 and C21orf37. Pathways/diseases representing these genes were retrieved and linked using PANTHER^®/Pathway Studio^®. Many of the deregulated genes are associated with extracellular matrix, inflammation, angiogenesis, metastasis, differentiation, cell proliferation and tumorigenesis. Characteristics of breast cancers in Lebanese were compared to those of women from Western populations to explain why breast cancer is more aggressive and presents a decade earlier in Lebanese victims. Delineating molecular mechanisms of breast cancer in Lebanese women led to key genes which could serve as potential biomarkers and/or novel drug targets for breast cancer.

Autophagy activation in COL6 myopathic patients by a low-protein-diet pilot trial

A pilot clinical trial based on nutritional modulation was designed to assess the efficacy of a one-year low-protein diet in activating autophagy in skeletal muscle of patients affected by COL6/collagen VI-related myopathies. Ullrich congenital muscular dystrophy and Bethlem myopathy are rare inherited muscle disorders caused by mutations of COL6 genes and for which no cure is yet available. Studies in col6 null mice revealed that myofiber degeneration involves autophagy defects and that forced activation of autophagy results in the amelioration of muscle pathology. Seven adult patients affected by COL6 myopathies underwent a controlled low-protein diet for 12 mo and we evaluated the presence of autophagosomes and the mRNA and protein levels for BECN1/Beclin 1 and MAP1LC3B/LC3B in muscle biopsies and blood leukocytes. Safety measures were assessed, including muscle strength, motor and respiratory function, and metabolic parameters. After one y of low-protein diet, autophagic markers were increased in skeletal muscle and blood leukocytes of patients. The treatment was safe as shown by preservation of lean:fat percentage of body composition, muscle strength and function. Moreover, the decreased incidence of myofiber apoptosis indicated benefits in muscle homeostasis, and the metabolic changes pointed at improved mitochondrial function. These data provide evidence that a low-protein diet is able to activate autophagy and is safe and tolerable in patients with COL6 myopathies, pointing at autophagy activation as a potential target for therapeutic applications. In addition, our findings indicate that blood leukocytes are a promising noninvasive tool for monitoring autophagy activation in patients.

Integrated Analysis of the Roles of Long Noncoding RNA and Coding RNA Expression in Sheep (Ovis aries) Skin during Initiation of Secondary Hair Follicle

Initiation of hair follicle (HF) is the first and most important stage of HF morphogenesis. However the precise molecular mechanism of initiation of hair follicle remains elusive. Meanwhile, in previous study, the more attentions had been paid to the function of genes, while the roles of non-coding RNAs (such as long noncoding RNA and microRNA) had not been described. Therefore, the roles of long noncoding RNA(LncRNA) and coding RNA in sheep skin during the initiation of sheep secondary HF were integrated and analyzed, by using strand-specific RNA sequencing (ssRNA-seq).A total of 192 significant differentially expressed genes were detected, including 67 up-regulated genes and 125 down-regulated genes between stage 0 and stage 1 of HF morphogenesis during HF initiation. Only Wnt2, FGF20 were just significant differentially expressed among Wnt, Shh, Notch and BMP signaling pathways. Further expression profile analysis of lncRNAs showed that 884 novel lncRNAs were discovered in sheep skin expression profiles. A total of 15 lncRNAs with significant differential expression were detected, 6 up-regulated and 9 down-regulated. Among of differentially expressed genes and LncRNA, XLOC002437 lncRNA and potential target gene COL6A6 were all significantly down-regulated in stage 1. Furthermore, by using RNAhybrid, XLOC005698 may be as a competing endogenous RNA ''sponges" oar-miR-3955-5p activity. Gene Ontology and KEGG pathway analyses indicated that the significantly enriched pathway was peroxisome proliferator-activated receptors (PPARs) pathway (corrected P-value < 0.05), indicating that PPAR pathway is likely to play significant roles during the initiation of secondary HF.Results suggest that the key differentially expressed genes and LncRNAs may be considered as potential candidate genes for further study on the molecular mechanisms of HF initiation, as well as supplying some potential values for understanding human hair disorders.

Tendon Extracellular Matrix Alterations in Ullrich Congenital Muscular Dystrophy

Collagen VI (COLVI) is a non-fibrillar collagen expressed in skeletal muscle and most connective tissues. Mutations in COLVI genes cause two major clinical forms, Bethlem myopathy and Ullrich congenital muscular dystrophy (UCMD). In addition to congenital muscle weakness, patients affected by COLVI myopathies show axial and proximal joint contractures and distal joint hypermobility, which suggest the involvement of the tendon function. We examined a peroneal tendon biopsy and tenocyte culture of a 15-year-old patient affected by UCMD with compound heterozygous COL6A2 mutations. In patient’s tendon biopsy, we found striking morphological alterations of tendon fibrils, consisting in irregular profiles and reduced mean diameter. The organization of the pericellular matrix of tenocytes, the primary site of collagen fibril assembly, was severely affected, as determined by immunoelectron microscopy, which showed an abnormal accumulation of COLVI and altered distribution of collagen I (COLI) and fibronectin (FBN). In patient’s tenocyte culture, COLVI web formation and cell surface association were severely impaired; large aggregates of COLVI, which matched with COLI labeling, were frequently detected in the extracellular matrix. In addition, metalloproteinase MMP-2, an extracellular matrix-regulating enzyme, was increased in the conditioned medium of patient’s tenocytes, as determined by gelatin zymography and western blot. Altogether, these data indicate that COLVI deficiency may influence the organization of UCMD tendon matrix, resulting in dysfunctional fibrillogenesis. The alterations of tendon matrix may contribute to the complex pathogenesis of COLVI related myopathies.

Deep RNA profiling identified CLOCK and molecular clock genes as pathophysiological signatures in collagen VI myopathy

Collagen VI myopathies are genetic disorders caused by mutations in collagen 6 A1, A2 and A3 genes, ranging from the severe Ullrich congenital muscular dystrophy to the milder Bethlem myopathy, which is recapitulated by collagen-VI-null (Col6a1(-/-)) mice. Abnormalities in mitochondria and autophagic pathway have been proposed as pathogenic causes of collagen VI myopathies, but the link between collagen VI defects and these metabolic circuits remains unknown. To unravel the expression profiling perturbation in muscles with collagen VI myopathies, we performed a deep RNA profiling in both Col6a1(-/-)mice and patients with collagen VI pathology. The interactome map identified common pathways suggesting a previously undetected connection between circadian genes and collagen VI pathology. Intriguingly, Bmal1(-/-)(also known as Arntl) mice, a well-characterized model displaying arrhythmic circadian rhythms, showed profound deregulation of the collagen VI pathway and of autophagy-related genes. The involvement of circadian rhythms in collagen VI myopathies is new and links autophagy and mitochondrial abnormalities. It also opens new avenues for therapies of hereditary myopathies to modulate the molecular clock or potential gene-environment interactions that might modify muscle damage pathogenesis.

Two novel COLVI long chains in zebrafish that are essential for muscle development

Collagen VI (COLVI), a protein ubiquitously expressed in connective tissues, is crucial for structural integrity, cellular adhesion, migration and survival. Six different genes are recognized in mammalians, encoding six COLVI-chains that assemble as two 'short' (α1, α2) and one 'long' chain (theoretically any one of α3-6). In humans, defects in the most widely expressed heterotrimer (α123), due to mutations in the COL6A1-3 genes, cause a heterogeneous group of neuromuscular disorders, collectively termed COLVI-related muscle disorders. Little is known about the function(s) of the recently described α4-6 chains and no mutations have been detected yet. In this study, we characterized two novel COLVI long chains in zebrafish that are most homologous to the mammalian α4 chain; therefore, we named the corresponding genes col6a4a and col6a4b. These orthologues represent ancestors of the mammalian Col6a4-6 genes. By in situ hybridization and RT-qPCR, we unveiled a distinctive expression kinetics for col6a4b, compared with the other col6a genes. Using morpholino antisense oligonucleotides targeting col6a4a, col6a4b and col6a2, we modelled partial and complete COLVI deficiency, respectively. All morphant embryos presented altered muscle structure and impaired motility. While apoptosis was not drastically increased, autophagy induction was defective in all morphants. Furthermore, motoneuron axon growth was abnormal in these morphants. Importantly, some phenotypical differences emerged between col6a4a and col6a4b morphants, suggesting only partial functional redundancy. Overall, our results further confirm the importance of COLVI in zebrafish muscle development and may provide important clues for potential human phenotypes associated with deficiency of the recently described COLVI-chains.

Novel pathogenic variants and genes for myopathies identified by whole exome sequencing

Neuromuscular diseases (NMD) account for a significant proportion of infant and childhood mortality and devastating chronic disease. Determining the specific diagnosis of NMD is challenging due to thousands of unique or rare genetic variants that result in overlapping phenotypes. We present four unique childhood myopathy cases characterized by relatively mild muscle weakness, slowly progressing course, mildly elevated creatine phosphokinase (CPK), and contractures. We also present two additional cases characterized by severe prenatal/neonatal myopathy. Prior extensive genetic testing and histology of these cases did not reveal the genetic etiology of disease. Here, we applied whole exome sequencing (WES) and bioinformatics to identify likely causal pathogenic variants in each pedigree. In two cases, we identified novel pathogenic variants in COL6A3. In a third case, we identified novel likely pathogenic variants in COL6A6 and COL6A3. We identified a novel splice variant in EMD in a fourth case. Finally, we classify two cases as calcium channelopathies with identification of novel pathogenic variants in RYR1 and CACNA1S. These are the first cases of myopathies reported to be caused by variants in COL6A6 and CACNA1S. Our results demonstrate the utility and genetic diagnostic value of WES in the broad class of NMD phenotypes.

Melanocytes from Patients Affected by Ullrich Congenital Muscular Dystrophy and Bethlem Myopathy have Dysfunctional Mitochondria That Can be Rescued with Cyclophilin Inhibitors

Ullrich congenital muscular dystrophy and Bethlem myopathy are caused by mutations in collagen VI (ColVI) genes, which encode an extracellular matrix protein; yet, mitochondria play a major role in disease pathogenesis through a short circuit caused by inappropriate opening of the permeability transition pore, a high-conductance channel, which causes a shortage in ATP production. We find that melanocytes do not produce ColVI yet they bind it at the cell surface, suggesting that this protein may play a trophic role and that its absence may cause lesions similar to those seen in skeletal muscle. We show that mitochondria in melanocytes of Ullrich congenital muscular dystrophy and Bethlem myopathy patients display increased size, reduced matrix density, and disrupted cristae, findings that suggest a functional impairment. In keeping with this hypothesis, mitochondria (i) underwent anomalous depolarization after inhibition of the F-ATP synthase with oligomycin, and (ii) displayed decreased respiratory reserve capacity. The non-immunosuppressive cyclophilin inhibitor NIM811 prevented mitochondrial depolarization in response to oligomycin in melanocytes from both Ullrich congenital muscular dystrophy and Bethlem myopathy patients, and partially restored the respiratory reserve of melanocytes from one Bethlem myopathy patient. These results match our recent findings on melanocytes from patients affected by Duchenne muscular dystrophy (Pellegrini et al., 2013), and suggest that skin biopsies may represent a minimally invasive tool to investigate mitochondrial dysfunction and to evaluate drug efficacy in ColVI-related myopathies and possibly in other muscle wasting conditions like aging sarcopenia.