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Transcriptome analysis of collagen VI-related muscular dystrophy muscle biopsies [RNA-Seq].

ABSTRACT: Collagen VI-related muscular dystrophies (COL6RD) are a rare, inherited group of congenital muscular dystrophies. The phenotype spans from an early-onset, severe, and rapidly progressive clinical course in Ullrich congenital muscular dystrophy (UCMD), to a late-onset, mild and slowly progressive form in Bethlem muscular dystrophy (BM). COL6RD are caused by pathogenic variants in any of the three collagen type VI genes (COL6A1, COL6A2, COL6A3), which cause absence, reduction, mislocalization, or dysfunction of the collagen VI microfibrils in the skeletal muscle extracellular matrix (myomatrix), leading to yet incompletely understood downstream effects. Pathologic alterations in muscle biopsies of COL6RD varies, ranging from severely dystrophic changes, to mildly myopathic, represented by isolated myofiber atrophy. In this study, we aim to define the pathophysiologic events responsible for the histologic alterations of muscle and their progression in COL6RD. Aided by automated image analysis, we reviewed COL6RD patient muscle biopsies (n=22) and stratified them to three groups based on the degree of fibrosis and muscle fiber atrophy. Using microarray and RNA-Seq, we then performed global gene expression profiling on the same muscle biopsies and compared it with controls (n=14). Different histologic groups were characterized by similar transcriptional signatures predominantly featuring the upregulation of myomatrix component genes and downregulation of skeletal muscle and mitochondrion-specific genes. Our results also identified the TGFβ1 pathway in strong correlation with the development of COL6RD pathology at the histologic level, beginning early in the disease process, preceding fibrosis, and increasing in direct correlation with increased histologic severity. Overall, our study identifies COL6RD as a primary disorder of the myomatrix and posits dysregulation of TGFβ1-dependent pathways as a potential factor in pathogenesis of the disease.

ORGANISM(S): Homo sapiens

PROVIDER: GSE103608 | GEO | 2022/03/22

REPOSITORIES: GEO

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Project description:Transgenic overexpression of Galgt2 in the skeletal muscles of mdx mice inhibits the development of disease pathology associated with muscular dystrophy. This is the case both in transgenic mice, where Galgt2 overexpression occurs from embryonic timepoints onward and in mdx mice where Galgt2 is overexpressed in the early postnatal period using Adeno-associated virus (AAV). Here, we use gene expression profiling to compare transcriptional changes resulting from embryonic and postnatal Galgt2 overexpression in mdx skeletal muscle. A surprising number of changes were in genes known to ameliorate muscular dystrophy when overexpressed (agrin, integrin alpha 7, ADAM12, Bcl2) or to cause muscular dystrophy when mutated (collagen VI (alpha1,alpha2), plectin 1, dystroglycan, selenoprotein N1, integrin alpha7, biglycan, dysferlin). Several genes involved in calcium homeostasis were also changed. In Galgt2 transgenic mice, where embryonic overexpression of Galgt2 in skeletal muscles alters neuromuscular development and muscle growth, the number of gene expression changes was vastly greater, however, 14% of genes altered in postnatal AAV-Galgt2 infected mdx muscles were also changed with embryonic overexpression. These experiments suggest that postnatal overexpression of Galgt2 inhibits muscular dystrophy in mdx mice via induction of a group of genes that, in aggregate, can govern membrane stability, membrane repair, calcium homeostasis, and apoptosis. Transgenic overexpression of Galgt2 in the skeletal muscles of mdx mice inhibits the development of disease pathology associated with muscular dystrophy. This is the case both in transgenic mice, where Galgt2 overexpression occurs from embryonic timepoints onward and in mdx mice where Galgt2 is overexpressed in the early postnatal period using Adeno-associated virus (AAV). Here, we use gene expression profiling to compare transcriptional changes resulting from embryonic and postnatal Galgt2 overexpression in mdx skeletal muscle. A surprising number of changes were in genes known to ameliorate muscular dystrophy when overexpressed (agrin, integrin alpha7, ADAM12, Bcl2) or to cause muscular dystrophy when mutated (collagen VI (alpha1,alpha2), plectin 1, dystroglycan, selenoprotein N1, integrin alpha7, biglycan, dysferlin). Several genes involved in calcium homeostasis were also changed. In Galgt2 transgenic mice, where embryonic overexpression of Galgt2 in skeletal muscles alters neuromuscular development and muscle growth, the number of gene expression changes was vastly greater, however, 14% of genes altered in postnatal AAV-Galgt2 infected mdx muscles were also changed with embryonic overexpression. These experiments suggest that postnatal overexpression of Galgt2 inhibits muscular dystrophy in mdx mice via induction of a group of genes that, in aggregate, can govern membrane stability, membrane repair, calcium homeostasis, and apoptosis. Experiment Overall Design: Microarrays were done in three groups at a time. 1) Transgenic Overexpression of Galgt2 - comprised to Wild Type (WT), Galgt2 Transgenic (CT), Dystrophin-Deficient (mdx), and Galgt2 Transgenic and Dystrophin-Deficient (CTmdx) each in duplicate 2) AAV-Mediated Galgt2 Gene Delivery in to the mdx gastrocnemius muscle in the postnatal period - comprised of AAVGalgt2 and PBS each in duplicate, and 3) Myoblasts and myotubes - comptised of one sample each of C1C12 myoblasts and myotubes, C2C12 myoblasts and myotubes stably transfected with Galgt2

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Transcriptome analysis of collagen VI-related muscular dystrophy muscle biopsies [RNA-Seq].

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