title: Regulation of ATG4B stability by RNF5 limits basal levels of autophagy and influences susceptibility to bacterial infection.
abstract: Autophagy is the mechanism by which cytoplasmic components and organelles are degraded by the lysosomal machinery in response to diverse stimuli including nutrient deprivation, intracellular pathogens, and multiple forms of cellular stress. Here, we show that the membrane-associated E3 ligase RNF5 regulates basal levels of autophagy by controlling the stability of a select pool of the cysteine protease ATG4B. RNF5 controls the membranal fraction of ATG4B and limits LC3 (ATG8) processing, which is required for phagophore and autophagosome formation. The association of ATG4B with-and regulation of its ubiquitination and stability by-RNF5 is seen primarily under normal growth conditions. Processing of LC3 forms, appearance of LC3-positive puncta, and p62 expression are higher in RNF5(-/-) MEF. RNF5 mutant, which retains its E3 ligase activity but does not associate with ATG4B, no longer affects LC3 puncta. Further, increased puncta seen in RNF5(-/-) using WT but not LC3 mutant, which bypasses ATG4B processing, substantiates the role of RNF5 in early phases of LC3 processing and autophagy. Similarly, RNF-5 inactivation in Caenorhabditis elegans increases the level of LGG-1/LC3::GFP puncta. RNF5(-/-) mice are more resistant to group A Streptococcus infection, associated with increased autophagosomes and more efficient bacterial clearance by RNF5(-/-) macrophages. Collectively, the RNF5-mediated control of membranalATG4B reveals a novel layer in the regulation of LC3 processing and autophagy.
authors.affiliation: Signal Transduction and Cell Death Programs, Sanford-Burnham Medical Research Institute, La Jolla, California, USA.
authors.forename: Ersheng
authors.initials: E
authors.lastname: Kuang
authors.forename: Cheryl Y M
authors.initials: CY
authors.lastname: Okumura
authors.forename: Sharon
authors.initials: S
authors.lastname: Sheffy-Levin
authors.forename: Tal
authors.initials: T
authors.lastname: Varsano
authors.forename: Vincent Chih-Wen
authors.initials: VC
authors.lastname: Shu
authors.forename: Jianfei
authors.initials: J
authors.lastname: Qi
authors.forename: Ingrid R
authors.initials: IR
authors.lastname: Niesman
authors.forename: Huei-Jiun
authors.initials: HJ
authors.lastname: Yang
authors.forename: Carlos
authors.initials: C
authors.lastname: López-Otín
authors.forename: Wei Yuan
authors.initials: WY
authors.lastname: Yang
authors.forename: John C
authors.initials: JC
authors.lastname: Reed
authors.forename: Limor
authors.initials: L
authors.lastname: Broday
authors.forename: Victor
authors.initials: V
authors.lastname: Nizet
authors.forename: Ze'ev A
authors.initials: ZA
authors.lastname: Ronai
mesh_terms: D000818:Animals; D001343:Autophagy; D001424:Bacterial Infections / Q000235:genetics / Q000378:metabolism* / Q000401:mortality; D017173:Caenorhabditis elegans / Q000378:metabolism; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004795:Enzyme Stability; D020022:Genetic Predisposition to Disease; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D010588:Phagosomes / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport; D059748:Proteolysis; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: C480860:Map1lc3b protein, mouse; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; C529960:RNF5 protein, mouse; D044767:Ubiquitin-Protein Ligases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex