The PI3K-mediated activation of CRAC independently regulates adenylyl cyclase activation and chemotaxis
The PI3K-mediated activation of CRAC independently regulates adenylyl cyclase activation and chemotaxis
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DOI：
10.1016/j.cub.2005.01.007
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发表时间：
2005-01-26
期刊：
影响因子：
9.2
通讯作者：
Parent, CA
中科院分区：
文献类型：
--
作者：
Corner, FI;Lippincott, CK;Parent, CA
细胞检测外部化学信号并沿着梯度启动定向迁移程序的能力包括称为趋化性[1]的基本过程。对盘状盘状盘状体和中性粒细胞的研究已经证实，与PI3K产物PI(3,4)P-2和PI(3,4,5)P-3结合的pleckstrin同源（PH）结构域的蛋白，如腺苷酸环化酶的胞浆调节因子CRAC和Akt/PKB，会特异性地转运到趋化细胞的前沿[2-4]。CRAC对于趋化剂介导的腺苷酸环化酶ACA[5]的激活至关重要，该酶将ATP转化为cAMP， cAMP是盘状田鼠的主要趋化剂。CRAC激活ACA的机制仍有待确定。我们现在表明，除了在ACA的激活中发挥重要作用外，CRAC还参与调节趋化性。通过诱变，我们发现这两种功能是在Pl3K下游独立调控的。失去结合PI3K产物能力的CRAC突变体不支持趋化性，并且显示最小的ACA激活。最后，过表达CRAC和各种CRAC突变体对ACA的激活有很强的影响，而对趋化性的影响很小。这些发现表明，趋化剂介导的PI3K激活对于依赖于crac的趋化性和腺苷酸环化酶激活的调节是重要的。
The ability of a cell to detect an external chemical signal and initiate a program of directed migration along a gradient comprises the fundamental process called chemotaxis [1]. Investigations in Dictyostelium discoideum and neutrophils have established that pleckstrin homology (PH) domain-containing proteins that bind to the PI3K products PI(3,4)P-2 and PI(3,4,5)P-3, such as CRAC (cytosolic regulator of adenylyl cyclase) and Akt/PKB, translocate specifically to the leading edge of chemotaxing cells [2-4]. CRAC is essential for the chemoattractant-mediated activation of the adenylyl cyclase ACA [5], which converts ATP into cAMP, the primary chemoattractant for D. discoideum. The mechanisms by which CRAC activates ACA remain to be determined. We now show that in addition to its essential role in the activation of ACA, CRAC is involved in regulating chemotaxis. Through mutagenesis, we show that these two functions are independently regulated downstream of Pl3K. A CRAC mutant that has lost the capacity to bind PI3K products does not support chemotaxis and shows minimal ACA activation. Finally, overexpression of CRAC and various CRAC mutants show strong effects on ACA activation with little effect on chemotaxis. These findings establish that chemoattractant-mediated activation of PI3K is important for the CRAC-dependent regulation of both chemotaxis and adenylyl cyclase activation.