Identification of Differentially Regulated Secretome Components During Skeletal Myogenesis

Abstract

Myogenesis is a well-characterized program of cellular differentiation that is exquisitely sensitive to the extracellular milieu. Systematic characterization of the myogenic secretome (i.e. the ensemble of secreted proteins) is, therefore, warranted for the identification of novel secretome components that regulate both the pluripotency of these progenitor mesenchymal cells, and also their commitment and passage through the differentiation program. Previously, we have successfully identified 26 secreted proteins in the mouse skeletal muscle cell line C2C12 (1). In an effort to attain a more comprehensive picture of the regulation of myogenesis by its extracellular milieu, quantitative profiling employing stable isotope labeling by amino acids in cell culture was implemented in conjunction with two parallel high throughput online reverse phase liquid chromatography-tandem mass spectrometry systems.In summary, 34 secreted proteins were quantified, 30 of which were shown to be differentially expressed during muscle development. Intriguingly, our analysis has revealed several novel up-and down-regulated secretome components that may have critical biological relevance for both the maintenance of pluripotency and the passage of cells through the differentiation program. In particular, the altered regulation of secretome components, including follistatin-like protein-1, osteoglycin, spondin-2, and cytokine-induced apoptosis inhibitor-1, along with consti-

Role of Osteoglycin in the Linkage between Muscle and Bone

“…High expression of OGN inhibits metastatic behavior and decreases gelatinase activity of murine hepatocarcinoma Hca-F cells (23,24). In this study the levels of OGN were elevated during osteoblast differentiation, which was consistent with a previous study (25). Moreover, some comparative microarray studies revealed that OGN is one of the mechanosensitive genes that mediates an anabolic response of mechanical loading in mice and in osteoblasts using a rotating wall vessel and a random positioning machine (26,27).…”

“…In our data the levels of OGN were decreased by activation of ALK2 signaling, which pathologically converts muscle tissues to bone in fibrodysplasia ossificans progressiva, and the levels of OGN increased when myoblastic cells differentiated into myotubes upon horse serum treatment. Moreover, Chan et al (25) recently reported that OGN was included in differentially up-regulated secretome components during skeletal myogenesis in C2C12 cells in a recent study. These findings suggest that OGN might play some important role in muscle.…”

Monosodium Urate Activates Src/Pyk2/PI3 Kinase and Cathepsin Dependent Unconventional Protein Secretion From Human Primary Macrophages

“…At present, different proteomic techniques allow for in-depth analysis of the secretome, the global pattern of secreted proteins. Secretome analysis is important in revealing complex cellular processes that require communication and signaling between the cells, and it has recently been applied to analyze the signaling pathways related to cell differentiation (19,20), cancer (21,22), and immune responses (23)(24)(25). In the present work we have characterized the secretome of human primary macrophages that have been activated simultaneously by microbial signal lipopolysaccharide (LPS) and endogenous danger signal MSU to get a global view of macrophage response to combined PAMP and DAMP stimulation.…”

Proteomic Analysis of the Palmitate-induced Myotube Secretome Reveals Involvement of the Annexin A1-Formyl Peptide Receptor 2 (FPR2) Pathway in Insulin Resistance*

“…As part of its extracellular signaling pathway, skeletal muscle secretes myokines that participate in myogenesis, angiogenesis, and nutrient generation in response to factors such as metabolic disorders, including insulin resistance, and exercise (11)(12)(13). Some myokines, including IL-6, IL-8, IL-15, and fibroblast growth factor 21, and brain-derived neurotrophic factor (14), are induced by exercise.…”