Dataset Information

The Chaperone BAG6 Regulates Cellular Homeostasis between Autophagy and Apoptosis by Holding LC3B.

ABSTRACT: AMFR/gp78 and USP13 are a pair of ubiquitin ligase and deubiquitinase that ensure the accuracy of endoplasmic reticulum-associated degradation (ERAD). Depletion of USP13 leads to caspase activation and cleavage of the ERAD chaperone BAG6, which is reversed by knockdown of AMFR. However, the mechanism and physiological relevance of this regulation are still unclear. Here, by using the NEDDylator system, we screened out TXN as a substrate of AMFR and USP13 and showed its involvement in regulating CASP3 activation and BAG6 cleavage. Furthermore, we showed that the cleaved N-terminal BAG6 is located in the cytosol and interacts with both LC3B-I and unprocessed form of LC3B (Pro-LC3B) through the LIR1 motif to suppress autophagy. An NMR approach verified the direct interaction between BAG6 LIR1 and LC3B-I or Pro-LC3B. Collectively, our findings uncover a mechanism that converts BAG6 from an ERAD regulator to an autophagy tuner and apoptosis inducer during ER stress.

SUBMITTER: Chu Y

PROVIDER: S-EPMC7674511 | biostudies-literature | 2020 Nov

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

The Chaperone BAG6 Regulates Cellular Homeostasis between Autophagy and Apoptosis by Holding LC3B.

Chu Yuanyuan Y Dong Xingqi X Kang Yingjin Y Liu Jingnan J Zhang Tao T Yang Cuiwei C Wang Zhangshun Z Shen Wangchen W Huo Huanhuan H Zhuang Min M Lu Junxia J Liu Yanfen Y

iScience 20201021 11

AMFR/gp78 and USP13 are a pair of ubiquitin ligase and deubiquitinase that ensure the accuracy of endoplasmic reticulum-associated degradation (ERAD). Depletion of USP13 leads to caspase activation and cleavage of the ERAD chaperone BAG6, which is reversed by knockdown of <i>AMFR</i>. However, the mechanism and physiological relevance of this regulation are still unclear. Here, by using the NEDDylator system, we screened out TXN as a substrate of AMFR and USP13 and showed its involvement in regu ...[more]

PMID: 33241194

Similar Datasets

Project description:The dynein motor protein complex is required for retrograde transport but the functions of the intermediate-light chains that form the cargo-binding complex are not elucidated and the importance of individual subunits in maintaining cellular homeostasis is unknown. Here, using mRNA arrays and protein analysis, we show that the dynein subunit, DYNC1LI2 (dynein, cytoplasmic 1 light intermediate chain 2) is downregulated in cystinosis, a lysosomal storage disorder caused by genetic defects in CTNS (cystinosin, lysosomal cystine transporter). Reconstitution of DYNC1LI2 expression in ctns-/- cells reestablished endolysosomal dynamics. Defective vesicular trafficking in cystinotic cells was rescued by DYNC1LI2 expression which correlated with decreased endoplasmic reticulum stress manifested as decreased expression levels of the chaperone HSPA5/GRP78, and the transcription factors ATF4 and DDIT3/CHOP. Mitochondrial fragmentation, membrane potential and endolysosomal-mitochondrial association in cystinotic cells were rescued by DYNC1LI2. Survival of cystinotic cells to oxidative stress was increased by DYNC1LI2 reconstitution but not by its paralog DYNC1LI1, which also failed to decrease ER stress and mitochondrial fragmentation. DYNC1LI2 expression rescued the localization of the chaperone-mediated autophagy (CMA) receptor LAMP2A, CMA activity, cellular homeostasis and LRP2/megalin expression in cystinotic proximal tubule cells, the primary cell type affected in cystinosis. DYNC1LI2 failed to rescue phenotypes in cystinotic cells when LAMP2A was downregulated or when co-expressed with dominant negative (DN) RAB7 or DN-RAB11, which impaired LAMP2A trafficking. DYNC1LI2 emerges as a regulator of cellular homeostasis and potential target to repair underlying trafficking and CMA in cystinosis, a mechanism that is not restored by lysosomal cystine depletion therapies.Abbreviations: ACTB: actin, beta; ATF4: activating transcription factor 4; CMA: chaperone-mediated autophagy; DYNC1LI1: dynein cytoplasmic 1 light intermediate chain 1; DYNC1LI2: dynein cytoplasmic 1 light intermediate chain 2; ER: endoplasmic reticulum; LAMP1: lysosomal associated membrane protein 1; LAMP2A: lysosomal associated membrane protein 2A; LIC: light-intermediate chains; LRP2/Megalin: LDL receptor related protein 2; PTCs: proximal tubule cells; RAB: RAB, member RAS oncogene family; RAB11FIP3: RAB11 family interacting protein 3; RILP: Rab interacting lysosomal protein.

Project description:Scavenger receptors are pattern recognition receptors that recognize both foreign and self-ligands, and initiate different mechanisms of cellular activation, often as co-receptors. The function of scavenger receptor CD36 in the immune system has mostly been studied in macrophages but it is also highly expressed by innate type B cells where its function is less explored. Here we report that CD36 is involved in macro-autophagy/autophagy in B cells, and in its absence, the humoral immune response is impaired. We found that CD36-deficient B cells exhibit a significantly reduced plasma cell formation, proliferation, mitochondrial mobilization and oxidative phosphorylation. These changes were accompanied by impaired initiation of autophagy, and we found that CD36 regulated autophagy and colocalized with autophagosome membrane protein MAP1LC3/LC3 (microtubule-associated protein 1 light chain 3). When we investigated T-cell-dependent immune responses, we found that mice with CD36 deficiency, specifically in B cells, exhibited attenuated germinal center responses, class switching, and antibody production as well as autophagosome formation. These findings establish a critical role for CD36 in B cell responses and may also contribute to our understanding of CD36-mediated autophagy in other cells as well as in B cell lymphomas that have been shown to express the receptor.Abbreviations: AICDA/AID: activation-induced cytidine deaminase; ATG5: autophagy related 5; ATP: adenosine triphosphate; BCR: B-cell receptor; CPG: unmethylated cytosine-guanosine; CQ: chloroquine; DC: dendritic cells; FOB: follicular B cells; GC: germinal center; Ig: immunoglobulin; LPS: lipopolysaccharide; MAP1LC3/LC3: microtubule-associated protein 1 light chain 3; MFI: mean fluorescence intensity; MZB: marginal zone B cells; NP-CGG: 4-hydroxy-3-nitrophenylacetyl-chicken gamma globulin; OCR: oxygen consumption rate; oxLDL: oxidized low-density lipoprotein; PC: plasma cells; Rapa: rapamycin; SQSTM1/p62: sequestosome 1; SRBC: sheep red blood cells; Tfh: follicular helper T cells; TLR: toll-like receptor.

Dataset Information

The Chaperone BAG6 Regulates Cellular Homeostasis between Autophagy and Apoptosis by Holding LC3B.

Publications

The Chaperone BAG6 Regulates Cellular Homeostasis between Autophagy and Apoptosis by Holding LC3B.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets