PKA-dependent phosphorylation of LIMK1 and Cofilin is essential for mouse sperm acrosomal exocytosis.
PKA-dependent phosphorylation of LIMK1 and Cofilin is essential for mouse sperm acrosomal exocytosis.
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DOI：
10.1016/j.ydbio.2015.07.008
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发表时间：
2015-09-15
影响因子：
2.7
通讯作者：
Buffone MG
中科院分区：
文献类型：
--
作者：
Romarowski A;Battistone MA;La Spina FA;Puga Molina Ldel C;Luque GM;Vitale AM;Cuasnicu PS;Visconti PE;Krapf D;Buffone MG
哺乳动物精子必须在雌性生殖道中经过一系列生物化学修饰（统称为获能）后才能获得可受精性，以进行顶体胞吐作用，这是受精所必需的过程。肌动蛋白动力学在控制体细胞和几种哺乳动物精子的胞吐过程中起着重要作用。在体细胞中，Rho家族的小GTP酶被广泛认为是肌动蛋白动力学的主要调节因子。然而，这些蛋白质在精子中的作用尚未详细研究。在目前的工作中，我们的特点是参与小GTP酶的Rho家族的信号通路，导致肌动蛋白聚合在小鼠精子获能。我们观察到，这种信号级联的大多数蛋白质及其效应蛋白在小鼠精子中表达。cAMP/PKA、RhoA/C和Rac 1信号通路的激活对于通过Threatenin 508上的磷酸化激活LIMK 1是必需的。Cofilin的丝氨酸3在获能过程中被LIMK 1以瞬时方式磷酸化。特异性抑制剂（BMS-3）对LIMK 1的抑制导致获能过程中肌动蛋白聚合水平降低，精子顶体胞吐的百分比急剧下降。因此，我们第一次证明了体细胞中肌动蛋白动力学的主调节因子在小鼠精子中存在并活跃。结合我们目前的研究结果与其他文献中的结果，我们提出了一个工作模型，关于LIMK 1和Cofilin如何控制小鼠精子顶体胞吐。
Mammalian sperm must acquire their fertilizing ability after a series of biochemical modifications in the female reproductive tract collectively called capacitation to undergo acrosomal exocytosis, a process that is essential for fertilization. Actin dynamics play a central role in controlling the process of exocytosis in somatic cells as well as in sperm from several mammalian species. In somatic cells, small GTPases of the Rho family are widely known as master regulators of actin dynamics. However, the role of these proteins in sperm has not been studied in detail. In the present work we characterized the participation of small GTPases of the Rho family in the signaling pathway that leads to actin polymerization during mouse sperm capacitation. We observed that most of the proteins of this signaling cascade and their effector proteins are expressed in mouse sperm. The activation of the signaling pathways of cAMP/PKA, RhoA/C and Rac1 is essential for LIMK1 activation by phosphorylation on Threonine 508. Serine 3 of Cofilin is phosphorylated by LIMK1 during capacitation in a transiently manner. Inhibition of LIMK1 by specific inhibitors (BMS-3) resulted in lower levels of actin polymerization during capacitation and a dramatic decrease in the percentage of sperm that undergo acrosomal exocytosis. Thus, we demonstrated for the first time that the master regulators of actin dynamics in somatic cells are present and active in mouse sperm. Combining the results of our present study with other results from the literature, we have proposed a working model regarding how LIMK1 and Cofilin control acrosomal exocytosis in mouse sperm.