PDF(Pubmed)
Abstract：
Arf GTPase-activating proteins (ArfGAPs) mediate the hydrolysis of GTP bound to ADP-ribosylation factors. ArfGAPs are critical for cargo sorting in the Golgi-to-ER traffic. However, the role of ArfGAPs in sorting into intralumenal vesicles (ILVs) in multivesicular bodies (MVBs) in post-Golgi traffic remains unclear. Exosomes are extracellular vesicles (EVs) of endosomal origin. CD63 is an EV marker. CD63 is enriched ILVs in MVBs of cells. However, the secretion of CD63 positive EVs has not been consistent with the data on CD63 localization in MVBs, and how CD63-containing EVs are formed is yet to be understood. To elucidate the mechanism of CD63 transport to ILVs, we focused on CD63 localization in MVBs and searched for the ArfGAPs involved in CD63 localization. We observed that ADAP1 and ARAP1 depletion inhibited CD63 localization to enlarged endosomes after Rab5Q79L overexpression. We tested epidermal growth factor (EGF) and CD9 localization in MVBs. We observed that ADAP1 and ARAP1 depletion inhibited CD9 localization in enlarged endosomes but not EGF. Our results indicate ADAP1 and ARAP1, regulate incorporation of CD63 and CD9, but not EGF, in overlapped and different MVBs. Our work will contribute to distinguish heterogenous ILVs and exosomes by ArfGAPs.
摘要：
ArfGTP酶激活蛋白(ArfGAP)介导与ADP-核糖基化因子结合的GTP的水解。ArfGAP对于高尔基到ER交通中的货物分类至关重要。然而,ArfGAP在后高尔基体交通中多囊泡（MVB）中分选腔内囊泡（ILV）的作用尚不清楚。外泌体是内体起源的细胞外囊泡(EV)。CD63是EV标记。CD63富集在细胞MVB的腔内囊泡(ILV)中。然而,CD63阳性EV的分泌与CD63在MVB中的定位数据不一致，含CD63的电动汽车是如何形成的，还有待理解。为了阐明CD63转运到ILV的机制，我们关注CD63在MVB中的定位,并搜索了参与CD63定位的ArfGAP.我们观察到，在Rab5Q79L过表达后，ADAP1和ARAP1耗竭抑制了CD63向扩大的内体的定位。我们测试了表皮生长因子（EGF）和CD9在MVB中的定位。我们观察到ADAP1和ARAP1耗竭抑制了CD9在扩大的内体中的定位，但不抑制EGF。我们的结果表明ADAP1和ARAP1调节CD63和CD9的掺入，但不调节EGF，在重叠和不同的MVB中。我们的工作将有助于通过ArfGAP区分异质ILV和外泌体。
