GPM6B regulates osteoblast function and induction of mineralization by controlling cytoskeleton and matrix vesicle release

• Published in: Journal of bone and mineral research Vol. 26; no. 9; pp. 2045 - 2051
• Main Authors: Drabek, Ksenija, van de Peppel, Jeroen, Eijken, Marco, van Leeuwen, Johannes PTM
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.09.2011; Wiley; Oxford University Press
• Subjects: ACTIN FILAMENTS; Actins - metabolism; Alkaline Phosphatase - metabolism; Biological and medical sciences; Bone Matrix - metabolism; Calcification, Physiologic - genetics; Cell Differentiation - genetics; Cytoplasmic Vesicles - metabolism; Cytoskeleton - metabolism; EXTRACELLULAR MATRIX; Focal Adhesions - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression Profiling; Gene Expression Regulation; GENE SILENCING; GPM6B; Humans; Membrane Glycoproteins - genetics; Membrane Glycoproteins - metabolism; Mesenchymal Stromal Cells - cytology; Mesenchymal Stromal Cells - enzymology; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Oligonucleotide Array Sequence Analysis; Osteoblasts - cytology; Osteoblasts - metabolism; Osteogenesis - genetics; OSTEOGENIC HMSCS; Skeleton and joints; Vertebrates: osteoarticular system, musculoskeletal system; OSTEOGENIC HMSCS; Induction; ACTIN FILAMENTS; Osteoarticular system; Vertebrata; Mammalia; Gene; Actin; Mineralization; Osteoblast; Cytoskeleton; Extracellular matrix; Bone; GENE SILENCING; Release; GPM6B
• ISSN: 0884-0431; 1523-4681; 1523-4681
• DOI: 10.1002/jbmr.435

Neuronal membrane glycoprotein gene (GPM6B) encodes a membrane glycoprotein that belongs to the proteolipid protein family. We identified GPM6B as a gene that is strongly upregulated during osteoblast differentiation. To investigate the role of GPM6B in the process of bone formation, we silenced GPM6B expression during osteogenic differentiation of human mesenchymal stem cells (hMSCs). GPM6B silencing in hMSCs resulted in reduced alkaline phosphate (ALP) activity along with reduced mineralization of extracellular matrix (ECM). Microarray expression analysis of GPM6B‐depleted osteogenic hMSCs revealed significant changes in genes involved in cytoskeleton organization and biogenesis. Immunocytochemistry results confirm changes in the distribution of actin filaments, as well as the shape and size of focal adhesions on GPM6B silencing. Moreover, we demonstrated that production and release of ALP‐positive matrix vesicles (MVs) were reduced. In conclusion, we identified GPM6B as a novel regulator of osteoblast function and bone formation. This finding demonstrates the significance of cytoskeleton organization for MV production and subsequent mineralization. © 2011 American Society for Bone and Mineral Research