Calpain-6, a microtubule-stabilizing protein, regulates Rac1 activity and cell motility through interaction with GEF-H1
Calpain-6, a microtubule-stabilizing protein, regulates Rac1 activity and cell motility through interaction with GEF-H1
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DOI：
10.1242/jcs.072561
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发表时间：
2011-04
影响因子：
4
通讯作者：
Kazuo Tonami;Y. Kurihara;S. Arima;Koichi Nishiyama;Y. Uchijima;T. Asano;H. Sorimachi;H. Kurihara
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作者：
Kazuo Tonami;Y. Kurihara;S. Arima;Koichi Nishiyama;Y. Uchijima;T. Asano;H. Sorimachi;H. Kurihara
微管和肌动蛋白丝之间的串扰对于各种细胞功能至关重要，包括细胞迁移、扩散和胞质分裂。 Rac1 GTPase 在迁移细胞前缘的串扰中发挥着关键作用，以促进板状足的形成。然而，微管和 Rac1 激活之间联系的机制仍不清楚。在这里，我们表明钙蛋白酶 6 (CAPN6)，一种具有微管结合和稳定活性的非蛋白水解钙蛋白酶，可能参与了这种串扰。在 NIH 3T3 细胞中，小干扰 RNA (siRNA) 诱导的 Capn6 敲低导致 Rac1 激活，从而促进细胞迁移、扩散和板状足突出。 Rac1 活性的增加通过敲除 Rho 鸟嘌呤核苷酸交换因子 GEF-H1（正式名称为 Arhgef2）而消除。 CAPN6 和 GEF-H1 与微管共定位，并且还通过特定域相互作用。敲低 Capn6 后，GEF-H1 从微管转移到板状足区域并与 Rac1 相互作用。相比之下，RhoA 活性在 Capn6 敲低后降低，尽管 Capn6 敲低诱导的 Rac1 激活似乎需要低水平的活性 RhoA 或 RhoA 分子的存在。我们认为 CAPN6 通过与 GEF-H1 相互作用的机制充当 Rac1 活性的潜在调节剂，以控制片状足的形成和细胞运动。
Crosstalk between microtubules and actin filaments is crucial for various cellular functions, including cell migration, spreading and cytokinesis. The Rac1 GTPase plays a key role in such crosstalk at the leading edge of migrating cells in order to promote lamellipodial formation. However, the mechanism underlying the link between microtubules and Rac1 activation remains unclear. Here, we show that calpain-6 (CAPN6), a non-proteolytic calpain with microtubule-binding and -stabilizing activity, might participate in this crosstalk. Small interfering RNA (siRNA)-induced knockdown of Capn6 in NIH 3T3 cells resulted in Rac1 activation, which promoted cell migration, spreading and lamellipodial protrusion. This increase in Rac1 activity was abolished by knockdown of the Rho guanine nucleotide exchange factor GEF-H1 (officially known as Arhgef2). CAPN6 and GEF-H1 colocalized with microtubules and also interacted with each other through specific domains. Upon knockdown of Capn6, GEF-H1 was shown to translocate from microtubules to the lamellipodial region and to interact with Rac1. By contrast, RhoA activity was decreased upon knockdown of Capn6, although low levels of active RhoA or the presence of RhoA molecules appeared to be required for the Capn6-knockdown-induced Rac1 activation. We suggest that CAPN6 acts as a potential regulator of Rac1 activity, through a mechanism involving interaction with GEF-H1, to control lamellipodial formation and cell motility.