title: RAB3GAP1 and RAB3GAP2 modulate basal and rapamycin-induced autophagy.
abstract: 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.
authors.affiliation: a Institute for Pathobiochemistry ; University Medical Center of the Johannes Gutenberg University ; Mainz , Germany.
authors.forename: Natalie
authors.initials: N
authors.lastname: Spang
authors.forename: Anne
authors.initials: A
authors.lastname: Feldmann
authors.forename: Heike
authors.initials: H
authors.lastname: Huesmann
authors.forename: Fazilet
authors.initials: F
authors.lastname: Bekbulat
authors.forename: Verena
authors.initials: V
authors.lastname: Schmitt
authors.forename: Christof
authors.initials: C
authors.lastname: Hiebel
authors.forename: Ingrid
authors.initials: I
authors.lastname: Koziollek-Drechsler
authors.forename: Albrecht M
authors.initials: AM
authors.lastname: Clement
authors.forename: Bernd
authors.initials: B
authors.lastname: Moosmann
authors.forename: Jennifer
authors.initials: J
authors.lastname: Jung
authors.forename: Christian
authors.initials: C
authors.lastname: Behrends
authors.forename: Ivan
authors.initials: I
authors.lastname: Dikic
authors.forename: Andreas
authors.initials: A
authors.lastname: Kern
authors.forename: Christian
authors.initials: C
authors.lastname: Behl
mesh_terms: D000818:Animals; D001343:Autophagy / Q000187:drug effects* / Q000502:physiology; D001692:Biological Transport / Q000502:physiology; D017173:Caenorhabditis elegans; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D006801:Humans; D008247:Lysosomes / Q000378:metabolism; D010588:Phagosomes / Q000378:metabolism; D020123:Sirolimus / Q000494:pharmacology*; D020692:rab3 GTP-Binding Proteins / Q000378:metabolism*
chemical_list: D020690:GTPase-Activating Proteins; C555465:RAB3GAP2 protein, human; C580955:RAB3GAP1 protein, human; D020692:rab3 GTP-Binding Proteins; D020123:Sirolimus
keywords: ATG, autophagy-related; ATG16L1; ATG3; BSA, bovine serum albumin; Bafi, bafilomycin A1; C. elegans, Caenorhabditis elegans; CALCOCO2, calcium binding and coiled-coil domain 2; DAPI, 4’, 6-diamidino-2-phenylindole; DMSO, dimethyl sulfoxide; DPH, 1, 6-diphenyl-1, 3, 5-hexatriene; FEZ, fasciculation and elongation protein zeta; FEZ1; FEZ2; GABARAP, GABA(A) receptor-associated protein; GEF, guanine nucleotide exchange factor; GFP, green fluorescent protein; MAP1LC3, microtubule-associated protein 1 light chain 3; NBR1, neighbor of BRCA1 gene 1; PBS, phosphate-buffered saline; PE, phosphatidylethanolamine; RAB3GAP1; RAB3GAP2; RABGAP, RAB GTPase activating protein; SQSTM1, sequestosome 1; TBC domain, TRE2-BUB2-CDC16 domain; autophagy; eV, empty vector; lipid droplets; proteostasis; siRNA, small interfering RNA