Zhang Jun, Basu Sharmila, Rigamonti Daniele, Dietz Harry C, Clatterbuck Richard E
Department of Neurosurgery, University of Mississippi Medical Center, Jackson, Mississippi 39216-4505, USA.
Neurosurgery. 2008 Sep;63(3):571-8; discussion 578. doi: 10.1227/01.NEU.0000325255.30268.B0.
Using ribonucleic acid interference on cultured cell lines, we examined the role of Krev interaction trapped 1 (krit1) and integrin cytoplasmic domain-associated protein-1 alpha (icap1alpha) in beta1-integrin-mediated cell proliferation.
Upon depletion of either krit1 or icap1alpha in the HeLa cells, umbilical vein endothelial cells, and microvascular endothelial cells, we examined the cell number and proliferation changes in the cells, followed by the evaluation of beta1-integrin-mediated mitogen-activated protein kinase signal pathway and microscopic study.
Depletion of krit1 reduces cell number and decreases endothelial cell proliferation. Examination of beta1-integrin signaling downstream of focal adhesion kinase reveals decreased phosphorylation along the extracellular signal-regulated kinase/mitogen-activated protein kinase pathway. Depletion of icap1alpha, a protein known to interact with krit1, has similar effects, suggesting synergistic function. We also show that krit1 colocalizes with icap1alpha in both the nucleus and the cytoplasm; however, most of icap1alpha is found in the nucleus and most of krit1 is found in the cytoplasm at steady state. On depletion of krit1, icap1alpha decreases in the cytoplasm and is no longer detected in the nucleus.
Both krit1 and icap1alpha act concordantly to play a critical role in beta1-integrin-mediated cell proliferation. Our data further suggest that krit1 both stabilizes and shuttles icap1alpha and thus modulates its regulation of beta1-integrin-mediated signal transduction.
通过对培养细胞系进行核糖核酸干扰，我们研究了Krev相互作用捕获蛋白1（krit1）和整合素细胞质结构域相关蛋白-1α（icap1α）在β1整合素介导的细胞增殖中的作用。
在HeLa细胞、脐静脉内皮细胞和微血管内皮细胞中分别敲低krit1或icap1α后，我们检测细胞数量和细胞增殖变化，随后评估β1整合素介导的丝裂原活化蛋白激酶信号通路并进行显微镜观察。
敲低krit1可减少细胞数量并降低内皮细胞增殖。对粘着斑激酶下游的β1整合素信号进行检测发现，细胞外信号调节激酶/丝裂原活化蛋白激酶通路的磷酸化水平降低。已知与krit1相互作用的蛋白icap1α敲低后有类似作用，提示二者具有协同功能。我们还发现，krit1与icap1α在细胞核和细胞质中均共定位；然而，在稳态时，大部分icap1α位于细胞核中，大部分krit1位于细胞质中。敲低krit1后，icap1α在细胞质中减少，在细胞核中不再检测到。
krit1和icap1α共同作用，在β1整合素介导的细胞增殖中起关键作用。我们的数据进一步表明，krit1既能稳定icap1α又能使其穿梭移动，从而调节其对β1整合素介导的信号转导的调控。
