Collagen integrin receptors regulate early osteoblast differentiation induced by BMP-2
Collagen integrin receptors regulate early osteoblast differentiation induced by BMP-2
复制标题
DOI：
10.1359/jbmr.1999.14.7.1075
复制
发表时间：
1999-07-01
影响因子：
6.2
通讯作者：
Damsky, CH
中科院分区：
文献类型：
--
作者：
Jikko, A;Harris, SE;Damsky, CH
在几种细胞类型中的研究表明，细胞外基质的整合素受体和生长因子受体的作用在调节细胞分化和功能中是协同的。我们研究了α 1 β 1和α 2 β 1整合素胶原受体在调节2 T3成骨细胞响应骨形态发生蛋白（BMP）-2的分化中的作用。永生化2 T3细胞系是从驱动SV 40 T抗原的BMP-2启动子转基因小鼠的颅盖骨建立的，这些细胞需要外源性BMP-2，以及抗坏血酸和β-甘油磷酸盐，用于成熟成骨细胞表型的表达和矿化基质的形成。为了确定I型胶原的整联蛋白受体如何影响BMP-2信号传导、功能干扰性抗大鼠α 1和/或α 2整联蛋白亚基或抗I型胶原（Col-I），在汇合（CO）或汇合后4或8天（C4，C8）将抗体加入人重组（hr）BMP-2处理的2 T3培养物中。培养物仅测定碱性磷酸酶（ALP）mRNA水平和酶活性以及对甲状旁腺激素应答的cAMP产生。向CO培养物中加入抗胶原蛋白-I或抗整合素-α 1和α 2抗体阻断这些早期成骨细胞标志物的表达超过90%，并且还阻断这些细胞的矿化（0.5-1.8%对照）。在所有情况下，分别添加抗α 1或抗α 2抗体产生部分效应，而它们的组合效应接近抗胶原蛋白I。当将抗体加入到更分化的2 T3细胞中时，抑制作用降低。携带组成型活性BMP受体（caBMPR-IB）的2 T3细胞在没有hrBMP-2的情况下显示出升高的ALP活性;这种组成型活性也被α 1和α 2整联蛋白抗体以及抗Col-I抗体抑制。总之，我们的数据表明，来自胶原整联蛋白受体的信号调节BMPR-IB下游和ALP mRNA和成骨细胞分化的其他早期标志物的调节上游对BMP的反应。
Studies in several cell types indicate that the actions of integrin receptors for extracellular matrix and receptors for growth factors are synergistic in regulating cellular differentiation and function. We studied the roles of the alpha 1 beta 1 and alpha 2 beta 1 integrin collagen receptors in regulating the differentiation of 2T3 osteoblastic cells in response to bone morphogenetic protein (BMP)-2 The immortalized 2T3 cell line was established from the calvaria of mice transgenic for a BMP-2 promoter driving SV40 T-antigen, These cells require exogenous BMP-2, as well as ascorbic acid and beta-glycerolphosphate, for expression of a mature osteoblast phenotype and formation of a mineralized matrix. To determine how integrin receptors for collagen-I affect BMP-2 signaling, function-perturbing anti-rat alpha 1 and/or alpha 2 integrin subunit, or anti-type I collagen (Col-I), antibodies mere added to human recombinant (hr)BMP-2-treated 2T3 cultures at confluence (CO) or at 4 or 8 days postconfluenee (C4, C8), After 4 days of exposure to the antibodies, cultures mere assayed for alkaline phosphatase (ALP) mRNA levels and enzyme activity and for cAMP production in response to parathyroid hormone. Addition of anti-collagen-I or both anti-integrin-alpha 1 and -alpha 2 antibodies to CO cultures blocked expression of these early osteoblast markers by more than 90%, and also blocked mineralization (0.5-1.8% control) of these cells. In all cases, adding anti-alpha 1 or anti-alpha 2 antibodies separately produced partial effects, while their combined effect approached that of anti-collagen-I. When antibodies were added to more differentiated 2T3 cells, the inhibitory effects decreased. 2T3 cells carrying constitutively active BMP receptor (caBMPR-IB) showed elevated ALP activity without hrBMP-2; this constitutive activity was also suppressed by alpha 1 and alpha 2 integrin antibodies and by anti-Col-I antibody. Together, our data suggest that a signal(s) from collagen integrin receptors regulates the response to BMP downstream of BMPR-IB and upstream of the regulation of ALP mRNA and other early markers of osteoblast differentiation.