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Exendin-4, a glucagon-like peptide receptor agonist, facilitates osteoblast differentiation via connexin43

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Abstract

Purpose

To investigate whether exendin-4 (Ex-4), a glucagon-like peptide 1 receptor (GLP-1R) agonist, affects connexin 43 (Cx43) expression in osteoblasts, and determine the specific mechanism underlying Cx43 modulation by Ex-4.

Methods

Osteoblast-like MC3T3-E1 cells were treated with Ex-4 with or without GLP-1R antagonist. We assessed Cx43 expression using RT-PCR, western blotting, and confocal microscopy; visualized intercellular communication using Lucifer yellow dye transfer assay; evaluated osteoblast differentiation using alkaline phosphatase and Alizarin red S (ARS) staining. Cx43 silencing or overexpression was investigated via RNA-interference or adenovirus infection. The mechanism underlying Cx43 regulation by Ex-4 was determined via treatment with either Src kinase inhibitor, KX2–391, Akt activator, sc79, or inhibitor, LY294002.

Results

Ex-4 treatment enhanced Cx43 expression and gap junctional intercellular communication in MC3T3-E1 cells. GLP-1R antagonist pretreatment abrogated the induction of Cx43 expression. Cx43 silencing significantly decreased ARS staining intensity in Ex-4-treated cells, whereas overexpression enhanced cell differentiation. Treatment with KX2–391 reduced both the Ex-4-induced increase of Cx43 expression and p-Akt protein levels. sc79 upregulated Cx43 expression, while LY294002 attenuated Cx43 upregulation by Ex-4.

Conclusions

Induced Cx43 expression in osteoblasts via the Src-Akt signaling pathway illustrates the underlying mechanism for promoting osteoblast differentiation by Ex-4.

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Funding

This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2017R1D1A3B04028873), and by the Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital.

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Authors and Affiliations

  1. Division of Endocrinology and Metabolism, Department of Internal Medicine, Jeonbuk National University Medical School, Research Institute of Clinical Medicine of Jeonbuk National University-Biomedical Research Institute of Jeonbuk National University Hospital, Jeonju, Republic of Korea

    Jin Hong Chen, Chen Shen, Haram Oh & Ji Hyun Park

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  1. Jin Hong Chen
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  2. Chen Shen
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Correspondence to Ji Hyun Park.

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Chen, J.H., Shen, C., Oh, H. et al. Exendin-4, a glucagon-like peptide receptor agonist, facilitates osteoblast differentiation via connexin43. Endocrine 72, 672–680 (2021). https://doi.org/10.1007/s12020-021-02664-7

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