在秀丽隐杆线虫外阴诱导过程中，AGEF-1/Arf GTP酶/AP-1复合体拮抗LET-23表皮生长因子受体的基底外侧定位和信号传导。
An AGEF-1/Arf GTPase/AP-1 ensemble antagonizes LET-23 EGFR basolateral localization and signaling during C. elegans vulva induction.
作者信息
Skorobogata Olga, Escobar-Restrepo Juan M, Rocheleau Christian E
机构信息
Division of Endocrinology and Metabolism, Department of Medicine, Research Institute of the McGill University Health Centre, McGill University, Montreal, Quebec, Canada; Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada.
Institute of Molecular Life Sciences, University of Zürich, Zürich, Switzerland.
出版信息
PLoS Genet. 2014 Oct 16;10(10):e1004728. doi: 10.1371/journal.pgen.1004728. eCollection 2014 Oct.
LET-23 Epidermal Growth Factor Receptor (EGFR) signaling specifies the vulval cell fates during C. elegans larval development. LET-23 EGFR localization on the basolateral membrane of the vulval precursor cells (VPCs) is required to engage the LIN-3 EGF-like inductive signal. The LIN-2 Cask/LIN-7 Veli/LIN-10 Mint (LIN-2/7/10) complex binds LET-23 EGFR, is required for its basolateral membrane localization, and therefore, vulva induction. Besides the LIN-2/7/10 complex, the trafficking pathways that regulate LET-23 EGFR localization have not been defined. Here we identify vh4, a hypomorphic allele of agef-1, as a strong suppressor of the lin-2 mutant Vulvaless (Vul) phenotype. AGEF-1 is homologous to the mammalian BIG1 and BIG2 Arf GTPase guanine nucleotide exchange factors (GEFs), which regulate secretory traffic between the Trans-Golgi network, endosomes and the plasma membrane via activation of Arf GTPases and recruitment of the AP-1 clathrin adaptor complex. Consistent with a role in trafficking we show that AGEF-1 is required for protein secretion and that AGEF-1 and the AP-1 complex regulate endosome size in coelomocytes. The AP-1 complex has previously been implicated in negative regulation of LET-23 EGFR, however the mechanism was not known. Our genetic data indicate that AGEF-1 is a strong negative regulator of LET-23 EGFR signaling that functions in the VPCs at the level of the receptor. In line with AGEF-1 being an Arf GEF, we identify the ARF-1.2 and ARF-3 GTPases as also negatively regulating signaling. We find that the agef-1(vh4) mutation results in increased LET-23 EGFR on the basolateral membrane in both wild-type and lin-2 mutant animals. Furthermore, unc-101(RNAi), a component of the AP-1 complex, increased LET-23 EGFR on the basolateral membrane in lin-2 and agef-1(vh4); lin-2 mutant animals. Thus, an AGEF-1/Arf GTPase/AP-1 ensemble functions opposite the LIN-2/7/10 complex to antagonize LET-23 EGFR basolateral membrane localization and signaling.
LET-23表皮生长因子受体（EGFR）信号通路在秀丽隐杆线虫幼虫发育过程中决定了外阴细胞的命运。LET-23 EGFR定位于外阴前体细胞（VPC）的基底外侧膜对于激活LIN-3 EGF样诱导信号是必需的。LIN-2 Cask/LIN-7 Veli/LIN-10 Mint（LIN-2/7/10）复合物与LET-23 EGFR结合，是其基底外侧膜定位所必需的，因此也是外阴诱导所必需的。除了LIN-2/7/10复合物外，调节LET-23 EGFR定位的运输途径尚未明确。在这里，我们鉴定出vh4，它是agef-1的一个亚效等位基因，是lin-2突变体无外阴（Vul）表型的强抑制子。AGEF-1与哺乳动物的BIG1和BIG2 Arf GTPase鸟嘌呤核苷酸交换因子（GEF）同源，它们通过激活Arf GTPase和招募AP-1网格蛋白适配复合物来调节反式高尔基体网络、内体和质膜之间的分泌运输。与在运输中的作用一致，我们表明AGEF-1是蛋白质分泌所必需的，并且AGEF-1和AP-1复合物调节体腔细胞中的内体大小。AP-1复合物先前已被证明与LET-23 EGFR的负调控有关，但其机制尚不清楚。我们的遗传数据表明，AGEF-1是LET-23 EGFR信号通路的强负调控因子，在受体水平上在VPC中发挥作用。与AGEF-1作为Arf GEF一致，我们鉴定出ARF-1.2和ARF-3 GTPase也负调控信号通路。我们发现agef-1（vh4）突变导致野生型和lin-2突变体动物的基底外侧膜上LET-23 EGFR增加。此外，unc-101（RNAi），AP-1复合物的一个组分，在lin-2和agef-1（vh4）；lin-2突变体动物的基底外侧膜上增加了LET-23 EGFR。因此，一个AGEF-1/Arf GTPase/AP-1组合与LIN-2/7/10复合物起相反作用，拮抗LET-23 EGFR的基底外侧膜定位和信号通路。
Zotero 插件