Secretion of misfolded cytosolic proteins from mammalian cells is independent of chaperone-mediated autophagy

Lee, Juhyung1; Xu, Yue1; Zhang, Ting2; Cui, Lei3; Saidi, Layla1; Ye, Yihong1

2018-09-14

10.1074/jbc.RA118.003660

JOURNAL OF BIOLOGICAL CHEMISTRY   影响因子和分区

0021-9258

1083-351X

In eukaryotic cells, elimination of misfolded proteins is essential for maintaining protein homeostasis and cell viability. Misfolding-associated protein secretion (MAPS) is a protein quality-control mechanism that exports misfolded cytosolic proteins via a compartment characteristic of late endosomes, but how cytosolic proteins enter this compartment is unclear. Because chaperone-mediated autophagy (CMA) is a known mechanism that imports cytosolic proteins bearing a specific CMA motif to lysosomes for degradation and because late endosomes and lysosomes overlap significantly in mammalian cells, we determined here whether CMA is involved in targeting protein cargoes to the lumen of late endosomes in MAPS. Using HEK293T and COS-7 cells and immunoblotting and -staining and coimmunoprecipitation methods, we show that, unlike CMA, the secretion of misfolded proteins in MAPS does not require cargo unfolding, is inhibited by serum starvation, and is not dependent on the CMA motif in cargo. Intriguingly, knockdown of lysosome-associated membrane protein 2 (LAMP2), which consists of three isoforms, including a variant proposed to form a protein channel on lysosomes for CMA, attenuated MAPS. However, this could not be attributed to the proposed channel function of the LAMP2a isoform because overexpression of a cytosolic MAPS stimulator, DnaJ heat shock protein family (Hsp40) member C5 (DNAJC5), fully rescued the secretion defect associated with LAMP2 deficiency. We conclude that, in MAPS, cargoes use a CMA-independent mechanism to enter a nondegradative prelysosomal compartment.

protein misfolding protein secretion chaperone autophagy endosome lysosome -synuclein chaperone-mediated autophagy CMA DNAJC5 CSP misfolding-associated protein secretion MAPS protein quality control unconventional protein secretion UPS

SCI ; EI

英语

其他

National Institutes of Health[] ; National Institute of Diabetes and Digestive and Kidney Diseases[]

Biochemistry & Molecular Biology

Biochemistry & Molecular Biology

WOS:000444671500016

AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

20183805833113

Biological membranes ; Cells ; Cytology ; Mammals ; Optical projectors ; Physiology

Biological Materials and Tissue Engineering:461.2 ; Biology:461.9 ; Optical Devices and Systems:741.3 ; Organic Compounds:804.1

BIOLOGY & BIOCHEMISTRY

Web of Science

1.NIDDK, Lab Mol Biol, NIH, Bethesda, MD 20892 USA
2.Southern Univ Sci & Technol, SUSTech Acad Adv Interdisciplinary Studies, Shenzhen 518055, Peoples R China
3.Capital Med Univ, Beijing Childrens Hosp, Beijing Pediat Res Inst, Hematol & Oncol Lab, Beijing 100045, Peoples R China

Lee, Juhyung,Xu, Yue,Zhang, Ting,et al. Secretion of misfolded cytosolic proteins from mammalian cells is independent of chaperone-mediated autophagy[J]. JOURNAL OF BIOLOGICAL CHEMISTRY,2018,293(37):14359-14370.

Lee, Juhyung,Xu, Yue,Zhang, Ting,Cui, Lei,Saidi, Layla,&Ye, Yihong.(2018).Secretion of misfolded cytosolic proteins from mammalian cells is independent of chaperone-mediated autophagy.JOURNAL OF BIOLOGICAL CHEMISTRY,293(37),14359-14370.

Lee, Juhyung,et al."Secretion of misfolded cytosolic proteins from mammalian cells is independent of chaperone-mediated autophagy".JOURNAL OF BIOLOGICAL CHEMISTRY 293.37(2018):14359-14370.