Differential regulation of macropinocytosis by Abi1/Hssh3bp1 isoforms.
Differential regulation of macropinocytosis by Abi1/Hssh3bp1 isoforms.
复制标题
DOI：
10.1371/journal.pone.0010430
复制
发表时间：
2010-05-10
期刊：
影响因子：
3.7
通讯作者：
Kotula L
中科院分区：
文献类型：
--
作者：
Dubielecka PM;Cui P;Xiong X;Hossain S;Heck S;Angelov L;Kotula L
巨胞饮作用是一种细胞内液体和大分子的摄取过程，受细胞膜附近肌动蛋白骨架重排的调节。Rac 1的激活被认为作用于肌动蛋白聚合调节波2复合物的上游，已发现与巨胞饮作用的增强相关。Wave 2复合体的一个组成部分是Abi 1。Abi 1的多种选择性剪接异构体在哺乳动物细胞中表达，但各种异构体的功能意义尚不清楚。在这里，使用流式细胞术分析Alexa Fluor 647，我们证明Abi 1亚型2和3差异调节巨胞饮。与表达同种型2的细胞相比，表达同种型3的LNCaP细胞具有与增强的细胞铺展和更高的Rac 1活化相关的增加的巨胞饮摄取。表达亚型2的细胞具有降低的巨胞饮摄取，但表现出对Rac 1活化的更大敏感性。此外，与亚型3相比，更多的亚型2位于细胞质内，亚型3与质膜更相关。发现激活的Rac1在体外特异性结合于亚型2的外显子10中的位点。由于选择性mRNA剪接，外显子10不存在于亚型3中，排除了激活的Rac 1的类似结合。然而，这两种亚型通过相同的非外显子10位点与无活性Rac1结合。因此，含有Abi 1同种型3的Wave 2复合物表现出与活化的与失活的Rac 1的差异结合，而含有同种型2的Wave 2复合物结合活化的或失活的Rac 1 β。基于这些观察结果，我们假设Abi1亚型差异调节巨胞饮作用，这是由于它们对波2复合物中激活的Rac1具有不同的相对亲和力。这些发现也提高了亚型特异性作用发生在其他Abi1功能中的可能性。
Macropinocytosis, which is a constitutive cellular process of fluid and macromolecule uptake, is regulated by actin cytoskeleton rearrangements near the plasma membrane. Activation of Rac1, which is proposed to act upstream of the actin polymerization regulatory Wave 2 complex, has been found to correlate with enhanced macropinocytosis. One of the components of the Wave 2 complex is Abi1. Multiple, alternatively spliced isoforms of Abi1 are expressed in mammalian cells, but the functional significance of the various isoforms is unknown. Here, using flow cytometric assay analysis for Alexa Fluor 647, we demonstrate that Abi1 isoforms 2 and 3 differentially regulate macropinocytosis. LNCaP cells expressing isoform 3 had increased macropinocytic uptake that correlated with enhanced cell spreading and higher Rac1 activation in comparison to cells expressing isoform 2. Isoform 2 expressing cells had decreased macropinocytic uptake, but demonstrated greater sensitivity to Rac1 activation. Moreover, more isoform 2 was localized within the cytoplasm in comparison to isoform 3, which was more associated with the plasma membrane. Activated Rac1 was found to specifically bind to a site in exon 10 of isoform 2 in vitro. Because of alternative mRNA splicing, exon 10 is absent from isoform 3, precluding similar binding of activated Rac1. Both isoforms, however, bound to inactive Rac1 through the same non-exon 10 site. Thus, Abi1 isoform 3-containing Wave 2 complex exhibited a differential binding to activated vs. inactive Rac1, whereas isoform 2-containing Wave 2 complex bound activated or inactive Rac1 comparably. Based on these observations, we postulate that Abi1 isoforms differentially regulate macropinocytosis as a consequence of their different relative affinities for activated Rac1 in Wave 2 complex. These findings also raise the possibility that isoform-specific roles occur in other Abi1 functions.
登录
查看更多内容
影响因子：
4.8
作者：
Kobayashi, K;Kuroda, S;Kaibuchi, K
通讯作者：
Kaibuchi, K
影响因子：
4
作者：
Bryant, David M.;Kerr, Markus C.;Stow, Jennifer L.
通讯作者：
Stow, Jennifer L.
DOI：
10.1038/nsb0297-147
发表时间：
1997-02-01
期刊：
NATURE STRUCTURAL BIOLOGY
影响因子：
--
作者：
Hirshberg, M;Stockley, RW;Webb, MR
通讯作者：
Webb, MR
DOI：
10.1083/jcb.200206079
发表时间：
2003-01-06
期刊：
The Journal of cell biology
影响因子：
--
作者：
Innocenti M;Frittoli E;Ponzanelli I;Falck JR;Brachmann SM;Di Fiore PP;Scita G
通讯作者：
Scita G
DOI：
10.1083/jcb.83.1.82
发表时间：
1979-10
期刊：
The Journal of cell biology
影响因子：
--
作者：
Haigler HT;McKanna JA;Cohen S
通讯作者：
Cohen S