Spang Natalie, Feldmann Anne, Huesmann Heike, Bekbulat Fazilet, Schmitt Verena, Hiebel Christof, Koziollek-Drechsler Ingrid, Clement Albrecht M, Moosmann Bernd, Jung Jennifer, Behrends Christian, Dikic Ivan, Kern Andreas, Behl Christian
a Institute for Pathobiochemistry ; University Medical Center of the Johannes Gutenberg University ; Mainz , Germany.
Autophagy. 2014;10(12):2297-309. doi: 10.4161/15548627.2014.994359.
Macroautophagy is a degradative pathway that sequesters and transports cytosolic cargo in autophagosomes to lysosomes, and its deterioration affects intracellular proteostasis. Membrane dynamics accompanying autophagy are mostly elusive and depend on trafficking processes. RAB GTPase activating proteins (RABGAPs) are important factors for the coordination of cellular vesicle transport systems, and several TBC (TRE2-BUB2-CDC16) domain-containing RABGAPs are associated with autophagy. Employing C. elegans and human primary fibroblasts, we show that RAB3GAP1 and RAB3GAP2, which are components of the TBC domain-free RAB3GAP complex, influence protein aggregation and affect autophagy at basal and rapamycin-induced conditions. Correlating the activity of RAB3GAP1/2 with ATG3 and ATG16L1 and analyzing ATG5 punctate structures, we illustrate that the RAB3GAPs modulate autophagosomal biogenesis. Significant levels of RAB3GAP1/2 colocalize with members of the Atg8 family at lipid droplets, and their autophagy modulatory activity depends on the GTPase-activating activity of RAB3GAP1 but is independent of the RAB GTPase RAB3. Moreover, we analyzed RAB3GAP1/2 in relation to the previously reported suppressive autophagy modulators FEZ1 and FEZ2 and demonstrate that both reciprocally regulate autophagy. In conclusion, we identify RAB3GAP1/2 as novel conserved factors of the autophagy and proteostasis network.
巨自噬是一种降解途径，它将胞质货物隔离并运输到自噬体中，再转运至溶酶体，其功能退化会影响细胞内蛋白质稳态。自噬过程中的膜动力学大多难以捉摸，且依赖于运输过程。RAB GTP酶激活蛋白（RABGAPs）是协调细胞囊泡运输系统的重要因素，一些含TBC（TRE2-BUB2-CDC16）结构域的RABGAPs与自噬相关。利用秀丽隐杆线虫和人类原代成纤维细胞，我们发现不含TBC结构域的RAB3GAP复合物的组成成分RAB3GAP1和RAB3GAP2，在基础状态和雷帕霉素诱导的条件下影响蛋白质聚集并影响自噬。通过将RAB3GAP1/2的活性与ATG3和ATG16L1相关联，并分析ATG5点状结构，我们阐明了RAB3GAPs调节自噬体的生物发生。RAB3GAP1/2的显著水平与Atg8家族成员在脂滴处共定位，并且它们的自噬调节活性取决于RAB3GAP1的GTP酶激活活性，但不依赖于RAB GTP酶RAB3。此外，我们分析了RAB3GAP1/2与先前报道的自噬抑制调节剂FEZ1和FEZ2的关系，并证明两者相互调节自噬。总之，我们确定RAB3GAP1/2是自噬和蛋白质稳态网络的新型保守因子。
