A specific mechanomodulatory role for p38 MAPK in embryonic joint articular surface cell MEK-ERK pathway regulation
A specific mechanomodulatory role for p38 MAPK in embryonic joint articular surface cell MEK-ERK pathway regulation
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DOI：
10.1074/jbc.m510680200
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发表时间：
2006-04-21
影响因子：
4.8
通讯作者：
Pitsillides, AA
中科院分区：
文献类型：
--
作者：
Lewthwaite, JC;Bastow, ER;Pitsillides, AA
机制调节细胞行为和细胞外基质组成响应机械刺激仍未解决。我们之前的研究已经确定，MEK-ERK级联通过促进依赖透明质酸（HA）的细胞周围基质的组装来促进其完整性，在机械依赖的关节形成过程中发挥特定作用。在这里，我们证明：(i) p38 MAPK和MEK-ERK信号通路之间的新型串扰是机械刺激的特异性；（ii） p38 MAPK在促进来自胚胎鸡胫关节关节表面的细胞产生HA方面的作用。我们发现p38 MAPK阻断限制了富HA基质的细胞周围组装，减少了HA的基础和机械应变诱导释放。p38 MAPK阻滞剂增强了早期菌株诱导的增加，但在后期限制了MEK/ERK磷酸化的持续增加；c-Fos在苏氨酸325处的过度磷酸化被发现与p38 mapk介导的ERK活化调节平行。相比之下，p38 MAPK抑制剂对成纤维细胞生长因子2或磷酸酶抑制剂pervanadate诱导的ERK活化没有可检测到的影响，MEK抑制剂不影响p38 MAPK磷酸化，证实了p38 MAPK-ERK串扰的特异性和单向性。免疫化学和免疫印迹研究显示，在发育中的关节表面或来源于发育中的关节表面的细胞中存在组成性p38 MAPK活化。然而，与MEK-ERK途径不同，p38 MAPK在体外没有受到机械刺激的进一步刺激。因此，p38 MAPK特异性地促进ERK的激活和响应机械刺激的下游信号传导。这些结果表明，组成型活性p38 MAPK在机械诱导的ERK激活变化和富含ha的细胞外基质的积累中起着重要的、允许的作用，这些细胞外基质在关节发育中起关键作用。
Mechanisms regulating cell behavior and extracellular matrix composition in response to mechanical stimuli remain unresolved. Our previous studies have established that the MEK-ERK cascade plays a specific role in the mechano-dependent joint formation process by promoting the assembly of pericellular matrices reliant upon hyaluronan (HA) for their integrity. Here we demonstrate: (i) novel cross-talk between p38 MAPK and MEK-ERK signaling pathways that is specific for mechanical stimuli and (ii) a role for p38 MAPK in facilitating HA production by cells derived from the articular surface of embryonic chick tibiotarsal joints. We find that p38 MAPK blockade restricts pericellular assembly of HA-rich matrices and reduces basal as well as mechanical strain-induced release of HA. p38 MAPK blockers potentiated early strain-induced increases but restricted sustained increases in MEK/ERK phosphorylation at later times; c-Fos hyperphosphorylation at threonine 325 was found to parallel this p38 MAPK-mediated modulation of ERK activation. In contrast, p38 MAPK inhibitors had no detectable effect on the ERK activation induced by fibroblast growth factor 2 or pervanadate, a phosphatase inhibitor, and MEK inhibitors did not influence p38 MAPK phosphorylation, confirming both the specificity and unidirectionality of p38 MAPK-ERK cross-talk. Immunochemical and immunoblotting studies revealed constitutive p38 MAPK activation in cells at, or derived from, developing articular joint surfaces. Unlike the MEK-ERK pathway, however, p38 MAPK was not further stimulated by mechanical stimulation in vitro. Thus, p38 MAPK specifically facilitates ERK activation and downstream signaling in response to mechanical stimuli. These results suggest that constitutively active p38 MAPK serves an essential, permissive role in mechanically induced changes in ERK activation and in the accumulation of HA-rich extracellular matrices that serve a key role in joint development.