title: GPM6B regulates osteoblast function and induction of mineralization by controlling cytoskeleton and matrix vesicle release.
abstract: 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.
authors.affiliation: Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands.
authors.forename: Ksenija
authors.initials: K
authors.lastname: Drabek
authors.forename: Jeroen
authors.initials: J
authors.lastname: van de Peppel
authors.forename: Marco
authors.initials: M
authors.lastname: Eijken
authors.forename: Johannes P T M
authors.initials: JP
authors.lastname: van Leeuwen
mesh_terms: D000199:Actins / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000378:metabolism; D001857:Bone Matrix / Q000378:metabolism*; D002113:Calcification, Physiologic / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D022162:Cytoplasmic Vesicles / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism*; D022001:Focal Adhesions / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D020868:Gene Silencing; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000201:enzymology; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism; D010012:Osteogenesis / Q000235:genetics
chemical_list: D000199:Actins; C484160:GPM6B protein, human; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D000469:Alkaline Phosphatase