Integrin-β1, not integrin-β5, mediates osteoblastic differentiation and ECM formation promoted by mechanical tensile strain.

Qiangcheng Zeng,Xinchang Zhang,Ruixin Li,Yongming Liu,Lu Liu,Yong Guo,Xizheng Zhang,Yang Wang,Xianqiong Zou

doi:10.1186/s40659-015-0014-y

Abstract

BackgroundMechanical strain plays a great role in growth and differentiation of osteoblast. A previous study indicated that integrin-β (β1, β5) mediated osteoblast proliferation promoted by mechanical tensile strain. However, the involvement of integrin-β in osteoblastic differentiation and extracellular matrix (ECM) formation induced by mechanical tensile strain, remains unclear.ResultsAfter transfection with integrin-β1 siRNA or integrin-β5 siRNA, mouse MC3T3-E1 preosteoblasts were cultured in cell culture dishes and stimulated with mechanical tensile strain of 2500 microstrain (με) at 0.5 Hz applied once a day for 1 h over 3 or 5 consecutive days. The cyclic tensile strain promoted osteoblastic differentiation of MC3T3-E1 cells. Transfection with integrin-β1 siRNA attenuated the osteoblastic diffenentiation induced by the tensile strain. By contrast, transfection with integrin-β5 siRNA had little effect on the osteoblastic differentiation induced by the strain. At the same time, the result of ECM formation promoted by the strain, was similar to the osteoblastic differentiation.ConclusionIntegrin-β1 mediates osteoblast differentiation and osteoblastic ECM formation promoted by cyclic tensile strain, and integrin-β5 is not involved in the osteoblasts response to the tensile strain.Electronic supplementary materialThe online version of this article (doi:10.1186/s40659-015-0014-y) contains supplementary material, which is available to authorized users.

Highlights

Mechanical strain plays a great role in growth and differentiation of osteoblast
OCN, OPG, Runx 2, collagen type I (Col I), and Ca content are all markers for osteoblastic differentiation in previous study [14,15,18,19]. These results indicated that the mechanical tensile strain promoted osteoblastic differentiation
GAG and collagen are main components of extracellular matrix (ECM), and Col I is a kind of main collagen, so that the tensile strain increased ECM production of osteoblasts

Summary

Introduction

Mechanical strain plays a great role in growth and differentiation of osteoblast. A previous study indicated that integrin-β (β1, β5) mediated osteoblast proliferation promoted by mechanical tensile strain. The involvement of integrin-β in osteoblastic differentiation and extracellular matrix (ECM) formation induced by mechanical tensile strain, remains unclear. Mechanical forces are important regulators of bone homeostasis [1]. Application of mechanical loading promotes bone formation, whereas lack of loading results in bone loss [2]. Osteoblasts and their precursor cells are sensitive to mechanical strain. Many studies have shown that mechanical strains are crucial for the regulation of osteoblastic proliferation, differentiation, and apoptosis [3,4].

Methods

Results

Discussion

Conclusion