A Naturally Occurring Splice Variant of GGA1 Inhibits the Anterograde Post-Golgi Traffic of alpha(2B)-Adrenergic Receptor
A Naturally Occurring Splice Variant of GGA1 Inhibits the Anterograde Post-Golgi Traffic of alpha(2B)-Adrenergic Receptor
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GGA1 的自然剪接变体抑制 α(2B)-肾上腺素受体的顺行后高尔基体运输
DOI：
10.1038/s41598-019-46547-4
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发表时间：
2019
影响因子：
4.6
通讯作者：
Wu Guangyu
中科院分区：
文献类型：
--
作者：
Zhang Maoxiang;Xu Xin;Li Chunman;Huang Wei;Xu Nenggui;Wu Guangyu
新生G蛋白偶联受体（gpcr）从内质网经过高尔基体的细胞表面靶向调控机制尚不清楚。我们最近证明了三个高尔基定位的，γ-适应蛋白耳域同源的，ADP核糖基化因子结合蛋白（GGAs）介导α 2b -肾上腺素能受体（α2B-AR）的高尔基后输出，这是一种原型GPCR，并直接与受体相互作用。特别是，GGA1与α2B-AR的相互作用是通过其铰链结构域介导的。本研究确定了天然存在的GGA1截断形式（GGA1t）在α2B-AR转运中的作用，并阐明了其潜在的机制，GGA1t缺乏铰链结构域的n端部分。我们证明GGA1和GGA1t都是共定位的，主要在高尔基体表达。与GGA1形成鲜明对比的是，GGA1t的表达显著减弱了新合成的α2B-AR从高尔基体和平行受体介导的信号传导的细胞表面输出。此外，我们发现GGA1t与GGA1形成同二聚体和异二聚体。更有趣的是，GGA1t不能结合货物α2B-AR和招募网格蛋白到反式高尔基网络。这些数据提供了证据，表明截断形式的GGA1作为α2B-AR细胞表面输出的显性负调节因子，而GGA1的这种功能归因于其与宽型对偶物二聚体的能力，以及抑制货物相互作用和网格蛋白募集以形成专门的运输囊泡的能力。
The regulatory mechanisms of cell surface targeting of nascent G protein-coupled receptors (GPCRs)en routefrom the endoplasmic reticulum through the Golgi remain poorly understood. We have recently demonstrated that three Golgi-localized, γ-adaptin ear domain homology, ADP ribosylation factor-binding proteins (GGAs) mediate the post-Golgi export of α2B-adrenergic receptor (α2B-AR), a prototypic GPCR, and directly interact with the receptor. In particular, GGA1 interaction with α2B-AR is mediated via its hinge domain. Here we determined the role of a naturally occurring truncated form of GGA1 (GGA1t) which lacks the N-terminal portion of the hinge domain in α2B-AR trafficking and elucidated the underlying mechanisms. We demonstrated that both GGA1 and GGA1t were colocalized and mainly expressed at the Golgi. In marked contrast to GGA1, the expression of GGA1t significantly attenuated the cell surface export of newly synthesized α2B-AR from the Golgi and in parallel receptor-mediated signaling. Furthermore, we found that GGA1t formed homodimers and heterodimers with GGA1. More interestingly, GGA1t was unable to bind the cargo α2B-AR and to recruit clathrin onto the trans-Golgi network. These data provide evidence implicating that the truncated form of GGA1 behaviors as a dominant-negative regulator for the cell surface export of α2B-AR and this function of GGA1t is attributed to its abilities to dimerize with its wide type counterpart and to inhibit cargo interaction and clathrin recruitment to form specialized transport vesicles.