Dual lipidation of the brain-specific Cdc42 isoform regulates its functional properties
Dual lipidation of the brain-specific Cdc42 isoform regulates its functional properties
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DOI：
10.1042/bj20130788
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发表时间：
2013-12-15
影响因子：
4.1
通讯作者：
Ponimaskin, Evgeni
中科院分区：
文献类型：
--
作者：
Wirth, Alexander;Chen-Wacker, Chen;Ponimaskin, Evgeni
Cdc42（细胞分裂周期 42）是 Rho GTPase 家族的成员，通过控制肌动蛋白细胞骨架和基因表达来调节多种细胞活动。 Cdc42 以两种剪接变体的形式表达。典型的 Cdc42 同种型是异戊二烯化的 (Cdc42-prenyl)，而大脑特异性同种型可以是棕榈酰化的 (Cdc42-palm)。在本研究中，我们证明了啮齿动物和人类大脑中内源性 Cdc42 的棕榈酰化，并确定 Cys(188) 和 Cys(189) 作为 Cdc42-palm 的酰化位点。此外，我们已经证明Cys(188)也可以被异戊二烯化。对酰化缺陷突变体的分析表明，Cys(188) 的脂化对于 Cdc42-palm 的正确膜结合以及 Cdc42 介导的基因转录调节和神经母细胞瘤细胞中密集丝状伪足的诱导至关重要。我们还发现，Cdc42-prenyl 是多种常用细胞系以及小脑中的主要剪接变体，而 Cdc42-palm 是海马体中主要的 Cdc42 同工型，在海马体中，它与树突丝状伪足和棘的形成至关重要。用其酰化缺陷突变体替换内源性 Cdc42 揭示了 Cdc42-棕榈脂化对其在神经元中的形态发生和突触发生作用的重要性。这些发现表明，Cdc42-palm 的双重脂质化是海马神经元形态发生信号传导的重要调节因子。
Cdc42 (cell division cycle 42) is a member of the Rho GTPase family which regulates a variety of cellular activities by controlling actin cytoskeleton and gene expression. Cdc42 is expressed in the form of two splice variants. The canonical Cdc42 isoform is prenylated (Cdc42-prenyl), whereas the brain-specific isoform can be palmitoylated (Cdc42-palm). In the present study we have demonstrated palmitoylation of endogenous Cdc42 in rodent and human brains and identified Cys(188) and Cys(189) as acylation sites of Cdc42-palm. Moreover, we have shown that Cys(188) can also be prenylated. Analysis of acylation-deficient mutants revealed that lipidation of Cys(188) is essential for proper membrane binding of Cdc42-palm as well as for Cdc42-mediated regulation of gene transcription and induction of densely packed filopodia in neuroblastoma cells. We also found that Cdc42-prenyl is a dominant splice variant in a wide range of commonly used cell lines as well as in the cerebellum, whereas Cdc42-palm is the main Cdc42 isoform in hippocampus, where it is critically involved in the formation of dendritic filopodia and spines. Replacement of endogenous Cdc42 by its acylation-deficient mutants revealed the importance of Cdc42-palm lipidation for its morphogenic and synaptogenic effects in neurons. These findings demonstrate that dual lipidation of Cdc42-palm represents an important regulator of morphogenic signalling in hippocampal neurons.