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ODDD-linked Cx43 mutants reduce endogenous Cx43 expression and function in osteoblasts and inhibit late stage differentiation.
J Bone Miner Res. 2008 Jun; 23(6):928-38.JB

Abstract

INTRODUCTION

Bone development and modeling requires precise gap junctional intercellular communication (GJIC). Oculodentodigital dysplasia (ODDD) is an autosomal dominant human disease caused by mutations in the gene (GJA1) encoding the gap junction protein, connexin43 (Cx43). The disease is characterized by craniofacial bone deformities and limb abnormalities. It is our hypothesis that Cx43 mutation causes osteoblast dysfunction, which may contribute to the bone phenotype of ODDD.

MATERIALS AND METHODS

We expressed human and mouse ODDD-linked Cx43 mutants in MC3T3-E1 cells and primary mouse osteoblasts by retroviral infection and evaluated their in vitro differentiation as an index of osteoblast function. We compared these findings to the differentiation of osteoblasts isolated from a mouse model of ODDD that harbors a germ line Cx43 mutation and exhibits craniofacial and limb defects mimicking human ODDD. We determined the differentiation status of osteoblasts by analyzing alkaline phosphatase activity and the expression levels of osteoblast markers including bone sialoprotein and osteocalcin.

RESULTS

We showed that ODDD-linked Cx43 mutants are loss-of-function and dominant-negative to co-expressed Cx43 and, furthermore, greatly inhibit functional GJIC in osteoblasts. Surprisingly, the mutants had only a minor effect on osteoblast differentiation when introduced into lineage committed cells. In contrast, osteoblasts isolated from the ODDD mouse model exhibited impaired late stage differentiation.

CONCLUSIONS

Expression of human and mouse ODDD-linked Cx43 mutants failed to significantly impair differentiation in cells predisposed to the osteoblast lineage; however, germ line reduction of Cx43-based GJIC leads to impaired osteoblast differentiation, which may account for the bone phenotypes observed in ODDD patients.

Authors+Show Affiliations

Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

18269311

Citation

McLachlan, Elizabeth, et al. "ODDD-linked Cx43 Mutants Reduce Endogenous Cx43 Expression and Function in Osteoblasts and Inhibit Late Stage Differentiation." Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research, vol. 23, no. 6, 2008, pp. 928-38.
McLachlan E, Plante I, Shao Q, et al. ODDD-linked Cx43 mutants reduce endogenous Cx43 expression and function in osteoblasts and inhibit late stage differentiation. J Bone Miner Res. 2008;23(6):928-38.
McLachlan, E., Plante, I., Shao, Q., Tong, D., Kidder, G. M., Bernier, S. M., & Laird, D. W. (2008). ODDD-linked Cx43 mutants reduce endogenous Cx43 expression and function in osteoblasts and inhibit late stage differentiation. Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research, 23(6), 928-38. https://doi.org/10.1359/jbmr.080217
McLachlan E, et al. ODDD-linked Cx43 Mutants Reduce Endogenous Cx43 Expression and Function in Osteoblasts and Inhibit Late Stage Differentiation. J Bone Miner Res. 2008;23(6):928-38. PubMed PMID: 18269311.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - ODDD-linked Cx43 mutants reduce endogenous Cx43 expression and function in osteoblasts and inhibit late stage differentiation. AU - McLachlan,Elizabeth, AU - Plante,Isabelle, AU - Shao,Qing, AU - Tong,Dan, AU - Kidder,Gerald M, AU - Bernier,Suzanne M, AU - Laird,Dale W, PY - 2008/2/14/pubmed PY - 2008/8/13/medline PY - 2008/2/14/entrez SP - 928 EP - 38 JF - Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research JO - J. Bone Miner. Res. VL - 23 IS - 6 N2 - INTRODUCTION: Bone development and modeling requires precise gap junctional intercellular communication (GJIC). Oculodentodigital dysplasia (ODDD) is an autosomal dominant human disease caused by mutations in the gene (GJA1) encoding the gap junction protein, connexin43 (Cx43). The disease is characterized by craniofacial bone deformities and limb abnormalities. It is our hypothesis that Cx43 mutation causes osteoblast dysfunction, which may contribute to the bone phenotype of ODDD. MATERIALS AND METHODS: We expressed human and mouse ODDD-linked Cx43 mutants in MC3T3-E1 cells and primary mouse osteoblasts by retroviral infection and evaluated their in vitro differentiation as an index of osteoblast function. We compared these findings to the differentiation of osteoblasts isolated from a mouse model of ODDD that harbors a germ line Cx43 mutation and exhibits craniofacial and limb defects mimicking human ODDD. We determined the differentiation status of osteoblasts by analyzing alkaline phosphatase activity and the expression levels of osteoblast markers including bone sialoprotein and osteocalcin. RESULTS: We showed that ODDD-linked Cx43 mutants are loss-of-function and dominant-negative to co-expressed Cx43 and, furthermore, greatly inhibit functional GJIC in osteoblasts. Surprisingly, the mutants had only a minor effect on osteoblast differentiation when introduced into lineage committed cells. In contrast, osteoblasts isolated from the ODDD mouse model exhibited impaired late stage differentiation. CONCLUSIONS: Expression of human and mouse ODDD-linked Cx43 mutants failed to significantly impair differentiation in cells predisposed to the osteoblast lineage; however, germ line reduction of Cx43-based GJIC leads to impaired osteoblast differentiation, which may account for the bone phenotypes observed in ODDD patients. SN - 1523-4681 UR - https://www.unboundmedicine.com/medline/citation/18269311/ODDD_linked_Cx43_mutants_reduce_endogenous_Cx43_expression_and_function_in_osteoblasts_and_inhibit_late_stage_differentiation_ L2 - https://doi.org/10.1359/jbmr.080217 DB - PRIME DP - Unbound Medicine ER -