title: Insulin-like growth factor-1 promotes osteogenic differentiation and collagen I alpha 2 synthesis via induction of mRNA-binding protein LARP6 expression.
abstract: This study explored the mechanism underlying the stimulation of collagen synthesis and osteoblastic differentiation by insulin-like growth factor 1 (IGF1) in primary mouse osteoblasts. Primary mouse calvarial osteoblasts were cultured and treated with various doses of IGF1 before transfection with siRNA targeting the collagen type I alpha 2 (Col1a2) or La ribonucleoprotein domain family member 6 (Larp6) genes. Alkaline phosphatase (ALP) activity, osteocalcin staining, alizarin red quantification and the expression level of runt-related transcription factor 2 (RUNX2) were performed to assess the differentiation of pre-osteoblasts. Based on Western blot analysis, IGF1 up-regulated COL1A2 protein expression in the primary osteoblasts in a dose- and time-dependent manner. In addition, Col1a2 interference inhibited the differentiation and mineralization of osteoblasts. IGF1 also stimulated the differentiation of mouse primary osteoblasts and increased LARP6 expression during osteogenic differentiation. RNA-Immunoprecipitation (IP) indicated that LARP6 could bind to Col1a2 mRNA after IGF1 stimulation. However, transfection of Larp6-specific siRNA significantly reduced collagen and ALP secretion, mineralization and inhibited the expression of osteocalcin and RUNX2, indicating that Larp6 interference inhibited the differentiation ability of primary mouse calvarial osteoblasts, and these effects could not be reversed by IGF1. Thus, IGF1 could promote COL1A2 expression and osteoblast differentiation in primary mouse calvarial pre-osteoblasts by increasing LARP6 expression via a posttranscriptional mechanism.
authors.affiliation: Department of Metabolism & Endocrinology, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital, Central South University, ChangSha, Hunan, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Guo
authors.affiliation: Department of Metabolism & Endocrinology, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital, Central South University, ChangSha, Hunan, China.
authors.forename: Chen-Yi
authors.initials: CY
authors.lastname: Tang
authors.affiliation: Department of Metabolism & Endocrinology, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital, Central South University, ChangSha, Hunan, China.
authors.forename: Xiao-Fei
authors.initials: XF
authors.lastname: Man
authors.affiliation: Department of Metabolism & Endocrinology, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital, Central South University, ChangSha, Hunan, China.
authors.forename: Hao-Neng
authors.initials: HN
authors.lastname: Tang
authors.affiliation: Department of Metabolism & Endocrinology, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital, Central South University, ChangSha, Hunan, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Tang
authors.affiliation: Department of Metabolism & Endocrinology, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital, Central South University, ChangSha, Hunan, China.
authors.forename: Ci-La
authors.initials: CL
authors.lastname: Zhou
authors.affiliation: Department of Metabolism & Endocrinology, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital, Central South University, ChangSha, Hunan, China.
authors.forename: Shu-Wen
authors.initials: SW
authors.lastname: Tan
authors.affiliation: Department of Metabolism & Endocrinology, Xiangya Hospital, Central South University, ChangSha, Hunan, China.
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.affiliation: Department of Stomatology, The Second Xiangya Hospital, Central South University, ChangSha, Hunan, China.
authors.forename: Yun-Zhi
authors.initials: YZ
authors.lastname: Feng
authors.affiliation: Department of Metabolism & Endocrinology, National Clinical Research Center for Metabolic Diseases, The Second Xiangya Hospital, Central South University, ChangSha, Hunan, China.
authors.forename: Hou-De
authors.initials: HD
authors.lastname: Zhou
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D001324:Autoantigens / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002454:Cell Differentiation / Q000187:drug effects* / Q000235:genetics; D002478:Cells, Cultured; D024042:Collagen Type I / Q000096:biosynthesis* / Q000235:genetics; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D008810:Mice, Inbred C57BL; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015675:Osteocalcin / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects* / Q000235:genetics; D011485:Protein Binding; D034622:RNA Interference; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012261:Ribonucleoproteins / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D000097585:SS-B Antigen
chemical_list: D000469:Alkaline Phosphatase; D001324:Autoantigens; D024042:Collagen Type I; D050659:Core Binding Factor Alpha 1 Subunit; D007334:Insulin-Like Growth Factor I; D015675:Osteocalcin; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; D000097585:SS-B Antigen; C493716:Runx2 protein, mouse
keywords: COL1A2; La ribonucleoprotein domain family member 6; insulin-like growth factor 1; osteoblast; osteogenic differentiation