title: Impaired osteoblast differentiation in annexin A2- and -A5-deficient cells.
abstract: Annexins are a class of calcium-binding proteins with diverse functions in the regulation of lipid rafts, inflammation, fibrinolysis, transcriptional programming and ion transport. Within bone, they are well-characterized as components of mineralizing matrix vesicles, although little else is known as to their function during osteogenesis. We employed shRNA to generate annexin A2 (AnxA2)- or annexin A5 (AnxA5)-knockdown pre-osteoblasts, and determined whether proliferation or osteogenic differentiation was altered in knockdown cells, compared to pSiren (Si) controls. We report that DNA content, a marker of proliferation, was significantly reduced in both AnxA2 and AnxA5 knockdown cells. Alkaline phosphatase expression and activity were also suppressed in AnxA2- or AnxA5-knockdown after 14 days of culture. The pattern of osteogenic gene expression was altered in knockdown cells, with Col1a1 expressed more rapidly in knock-down cells, compared to pSiren. In contrast, Runx2, Ibsp, and Bglap all revealed decreased expression after 14 days of culture. In both AnxA2- and AnxA5-knockdown, interleukin-induced STAT6 signaling was markedly attenuated compared to pSiren controls. These data suggest that AnxA2 and AnxA5 can influence bone formation via regulation of osteoprogenitor proliferation, differentiation, and responsiveness to cytokines in addition to their well-studied function in matrix vesicles.
authors.affiliation: Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California Davis, Davis, CA, United States of America.
authors.forename: Damian C
authors.initials: DC
authors.lastname: Genetos
authors.affiliation: Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California Davis, Davis, CA, United States of America.
authors.forename: Alice
authors.initials: A
authors.lastname: Wong
authors.affiliation: Systems Toxicology, Pacific Northwest National Laboratory, Richland, WA, United States of America.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Weber
authors.affiliation: Systems Toxicology, Pacific Northwest National Laboratory, Richland, WA, United States of America.
authors.forename: Norman J
authors.initials: NJ
authors.lastname: Karin
authors.affiliation: Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California Davis, Davis, CA, United States of America.
authors.forename: Clare E
authors.initials: CE
authors.lastname: Yellowley
mesh_terms: D000818:Animals; D017306:Annexin A2 / Q000235:genetics*; D017304:Annexin A5 / Q000235:genetics*; D002454:Cell Differentiation / Q000235:genetics*; D049109:Cell Proliferation / Q000235:genetics; D024042:Collagen Type I / Q000096:biosynthesis; D000090602:Collagen Type I, alpha 1 Chain; D050659:Core Binding Factor Alpha 1 Subunit / Q000096:biosynthesis; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D058574:Integrin-Binding Sialoprotein / Q000096:biosynthesis; D051379:Mice; D010006:Osteoblasts / Q000378:metabolism; D010012:Osteogenesis / Q000235:genetics*; D034741:RNA, Small Interfering; D050800:STAT6 Transcription Factor / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics
chemical_list: D017306:Annexin A2; D017304:Annexin A5; D024042:Collagen Type I; D000090602:Collagen Type I, alpha 1 Chain; D050659:Core Binding Factor Alpha 1 Subunit; C546872:Ibsp protein, mouse; D058574:Integrin-Binding Sialoprotein; D034741:RNA, Small Interfering; C493716:Runx2 protein, mouse; D050800:STAT6 Transcription Factor