Endo-β-N-acetylglucosaminidase forms N-GlcNAc protein aggregates during ER-associated degradation in Ngly1-defective cells.

Chengcheng Huang, Yoichiro Harada, Akira Hosomi, Yuki Masahara-Negishi, Junichi Seino, Haruhiko Fujihira, Yoko Funakoshi, Takehiro Suzuki, Naoshi Dohmae, Tadashi Suzuki

Proceedings of the National Academy of Sciences of the United States of America 2015 Feb 3

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The cytoplasmic peptide:N-glycanase (PNGase; Ngly1 in mice) is a deglycosylating enzyme involved in the endoplasmic reticulum (ER)-associated degradation (ERAD) process. The precise role of Ngly1 in the ERAD process, however, remains unclear in mammals. The findings reported herein, using mouse embryonic fibroblast (MEF) cells, that the ablation of Ngly1 causes dysregulation of the ERAD process. Interestingly, not only delayed degradation but also the deglycosylation of a misfolded glycoprotein was observed in Ngly1(-/-) MEF cells. The unconventional deglycosylation reaction was found to be catalyzed by the cytosolic endo-β-N-acetylglucosaminidase (ENGase), generating aggregation-prone N-GlcNAc proteins. The ERAD dysregulation in cells lacking Ngly1 was restored by the additional knockout of ENGase gene. Thus, our study underscores the functional importance of Ngly1 in the ERAD process and provides a potential mechanism underlying the phenotypic consequences of a newly emerging genetic disorder caused by mutation of the human NGLY1 gene.

Citation

Chengcheng Huang, Yoichiro Harada, Akira Hosomi, Yuki Masahara-Negishi, Junichi Seino, Haruhiko Fujihira, Yoko Funakoshi, Takehiro Suzuki, Naoshi Dohmae, Tadashi Suzuki. Endo-β-N-acetylglucosaminidase forms N-GlcNAc protein aggregates during ER-associated degradation in Ngly1-defective cells. Proceedings of the National Academy of Sciences of the United States of America. 2015 Feb 3;112(5):1398-403