Highlights of glycosylation and adhesion related genes involved in myogenesis

Abstract

BackgroundMyogenesis is initiated by myoblast differentiation and fusion to form myotubes and muscle fibres. A population of myoblasts, known as satellite cells, is responsible for post-natal growth of muscle and for its regeneration. This differentiation requires many changes in cell behaviour and its surrounding environment. These modifications are tightly regulated over time and can be characterized through the study of changes in gene expression associated with this process. During the initial myogenesis steps, using the myoblast cell line C2C12 as a model, Janot et al. (2009) showed significant variations in expression for genes involved in pathways of glycolipid synthesis. In this study we used murine satellite cells (MSC) and their ability to differentiate into myotubes or early fat storage cells to select glycosylation related genes whose variation of expression is myogenesis specific.ResultsThe comparison of variant genes in both MSC differentiation pathways identified 67 genes associated with myogenesis. Comparison with data obtained for C2C12 revealed that only 14 genes had similar expression profiles in both cell types and that 17 genes were specifically regulated in MSC. Results were validated statistically by without a priori clustering. Classification according to protein function encoded by these 31 genes showed that the main regulated cellular processes during this differentiation were (i) remodeling of the extracellular matrix, particularly, sulfated structures, (ii) down-regulation of O-mannosyl glycan biosynthesis, and (iii) an increase in adhesion protein expression. A functional study was performed on Itga11 and Chst5 encoding two highly up-regulated proteins. The inactivation of Chst5 by specific shRNA delayed the fusion of MSC. By contrast, the inactivation of Itga11 by specific shRNA dramatically decreased the fusion ability of MSC. This result was confirmed by neutralization of Itga11 product by specific antibodies.ConclusionsOur screening method detected 31 genes specific for myogenic differentiation out of the 383 genes studied. According to their function, interaction networks of the products of these selected genes converged to cell fusion. Functional studies on Itga11 and Chst5 demonstrated the robustness of this screening.

The Histone Variant MacroH2A1 Regulates Key Genes for Myogenic Cell Fusion in a Splice-Isoform Dependent Manner

“…Interestingly, in our hands, Fmod was the most downregulated gene in cells treated with si macroH2A1.1 (log2 fold change of -4.45) and at the same time the most upregulated in cells treated with si macroH2A1.2 (log2 fold-changes of 4.80). Similarly, knockdown of the cell adhesion receptor-encoding gene Itga11 inhibits the fusion capacity of muscle satellite cells and myotube formation [47]. The specific role of the fibronectin 1 and the thrombospondin 1 encoded by Fn1 and Thbs1, respectively, in muscle fusion is still unclear.…”

A tale of two niches: differential functions for VCAM-1 in satellite cells under basal and injured conditions

“…Multiple types of cell-cell adhesion molecules are expressed on SC including cadherins, integrins, claudins, and immunoglobulin (Ig) superfamily molecules, although most of these have only been identified at the mRNA level (4,15,19,42,46). Although the in vitro roles for some of these molecules have been studied using muscle cell lines and primary myoblasts (42,46,57), the in vivo roles on SC are unknown as mice with SC-specific deletion of these cell-cell adhesion molecules have not been generated.…”

Selective Expansion of Skeletal Muscle Stem Cells from Bulk Muscle Cells in Soft Three-Dimensional Fibrin Gel

“…D), indicating diverse adaptations to different substrates of fibrin gel and Matrigel. Particularly, Itga6 and B4galt1 [62], two genes specific for myogenic differentiation , were also upregulated in Matrigel‐expanded satellite cells. Substrate rigidity modifies the activation of integrin clustering, which is considered as the initial step in subsequent signal transduction in stem cell genomic regulation .…”