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Title 

UBR box N-recognin-4 (UBR4), an N-recognin of the N-end rule pathway, and its role in yolk sac vascular development and autophagy

Authors 

T TasakiS T KimA ZakrzewskaB E LeeM J KangY D YooHyun Joo Cha-MolstadJoonsung HwangNak Kyun SoungK S SungSu Hyeon KimM D NguyenM SunE C YiBo Yeon KimY T Kwon

Publisher 

National Academy of Sciences

Issue Date 

2013

Citation 

Proceedings of the National Academy of Sciences of the United States of America, vol. 110, no. 10, pp. 3800-3805

Keywords 

Cardiovascular systemUbiquitin ligase

Abstract 

The N-end rule pathway is a proteolytic system in which destabilizing N-terminal residues of short-lived proteins act as degradation determinants (N-degrons). Substrates carrying N-degrons are recognized by N-recognins that mediate ubiquitylation-dependent selective proteolysis through the proteasome. Our previous studies identified the mammalian N-recognin family consisting of UBR1/ E3α, UBR2, UBR4/p600, and UBR5, which recognize destabilizing N-terminal residues through the UBR box. In the current study, we addressed the physiological function of a poorly characterized N-recognin, 570-kDa UBR4, in mammalian development. UBR4-deficient mice die during embryogenesis and exhibit pleiotropic abnormalities, including impaired vascular development in the yolk sac (YS). Vascular development in UBR4-deficient YS normally advances through vasculogenesis but is arrested during angiogenic remodeling of primary capillary plexus associated with accumulation of autophagic vacuoles. In the YS, UBR4 marks endoderm-derived, autophagy-enriched cells that coordinate differentiation of mesoderm- derived vascular cells and supply autophagy-generated amino acids during early embryogenesis. UBR4 of the YS endoderm is associated with a tissue-specific autophagic pathway that mediates bulk lysosomal proteolysis of endocytosed maternal proteins into amino acids. In cultured cells, UBR4 subpopulation is degraded by autophagy through its starvation-induced association with cellular cargoes destined to autophagic double membrane structures. UBR4 loss results in multiple misregulations in autophagic induction and flux, including synthesis and lipidation/activation of the ubiquitin-like protein LC3 and formation of autophagic double membrane structures. Our results suggest that UBR4 plays an important role in mammalian development, such as angiogenesis in the YS, in part through regulation of bulk degradation by lysosomal hydrolases.

ISSN 

0027-8424

Link 

http://dx.doi.org/10.1073/pnas.1217358110

Appears in Collections

1. Journal Articles > Journal Articles

Registered Date

2019-05-02


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