Activation of caspases is required for osteoblastic differentiation
Activation of caspases is required for osteoblastic differentiation
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DOI：
10.1074/jbc.m307055200
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发表时间：
2003-11-28
影响因子：
4.8
通讯作者：
Togari, A
中科院分区：
文献类型：
--
作者：
Mogi, M;Togari, A
先前的研究表明，小鼠成骨细胞MC 3 T3-E1细胞暴露于促炎细胞因子的混合物时发生凋亡。骨形态发生蛋白（BMP）是成骨细胞分化的重要调节因子。由于成骨细胞分化的调控知之甚少，我们试图确定BMP-4诱导的成骨细胞分化是否依赖于关键凋亡蛋白酶，即半胱天冬酶的活性。BMP-4诱导成骨细胞系MC 3 T3-E1的生长停滞和分化，如成骨细胞表型如碱性磷酸酶（ALP）活化和甲状旁腺激素（PTH）依赖性cAMP产生的出现所证明的。令人惊讶的是，BMP-4以这种顺序诱导半胱天冬酶-8、半胱天冬酶-2和半胱天冬酶-3的瞬时和有效活化。然而，在BMP-4处理的细胞中，没有凋亡或坏死可以通过FACS使用annexin-V/propdium碘双重染色检测。在BMP-4处理的细胞中，胱天蛋白酶活性的肽抑制导致ALP活化和PTH诱导的cAMP产生的急剧减少。虽然BMP-4处理导致细胞周期G（0）/G（1）停滞，但caspase抑制剂（caspase-8、caspase-2和caspase-3抑制剂）可以阻断MC 3 T3-E1细胞的G（0）/G（1）停滞。总之，这些结果证实了一个独特的和意想不到的作用，半胱天冬酶介导的信号级联在成骨细胞的分化。
Previous studies have shown that mouse osteoblastic MC3T3-E1 cells undergo apoptosis when exposed to a mixture of proinflammatory cytokines. Bone morphogenetic protein (BMP) s are important regulators of osteoblast differentiation. Because regulation of osteoblastic differentiation is poorly understood, we sought to determine if BMP-4-induced differentiation of osteoblastic cells depends on the activity of the key apoptotic proteases, i.e. the caspases. BMP-4 induced the growth arrest and differentiation of osteoblastic cell line MC3T3-E1, as evidenced by the appearance of osteoblastic phenotypes such as alkaline phosphatase ( ALP) activation and parathyroid hormone (PTH)-dependent production of cAMP. Surprisingly, BMP-4 induced transient and potent activation of caspase-8, caspase-2, and caspase-3, in this order. However, no apoptosis or necrosis in BMP-4-treated cells could be detected by FACS using annexin-V/propodium iodine double staining. Peptide inhibition of caspase activity led to a dramatic reduction in ALP activation and PTH-induced production of cAMP in BMP-4-treated cells. Although BMP-4 treatment resulted in cell-cycle G(0)/G(1) arrest as detected by FACS cell-cycle analysis, caspase inhibitors (caspase-8, caspase-2, and caspase-3 inhibitors) could block the G(0)/G(1) arrest in MC3T3-E1 cells. Taken together, these results confirm a unique and unanticipated role for the caspase-mediated signal cascade in the differentiation of osteoblasts.