title: Characterization of arginylation branch of N-end rule pathway in G-protein-mediated proliferation and signaling of cardiomyocytes.
abstract: The N-end rule pathway is a proteolytic system in which destabilizing N-terminal amino acids of short lived proteins are recognized by recognition components (N-recognins) as an essential element of degrons, called N-degrons. In eukaryotes, the major way to generate N-degrons is through arginylation by ATE1 arginyl-tRNA-protein transferases, which transfer Arg from aminoacyl-tRNA to N-terminal Asp and Glu (and Cys as well in mammals). We have shown previously that ATE1-deficient mice die during embryogenesis with defects in cardiac and vascular development. Here, we characterized the arginylation-dependent N-end rule pathway in cardiomyocytes. Our results suggest that the cardiac and vascular defects in ATE1-deficient embryos are independent from each other and cell-autonomous. ATE1-deficient myocardium and cardiomyocytes therein, but not non-cardiomyocytes, showed reduced DNA synthesis and mitotic activity ~24 h before the onset of cardiac and vascular defects at embryonic day 12.5 associated with the impairment in the phospholipase C/PKC-MEK1-ERK axis of Gα(q)-mediated cardiac signaling pathways. Cardiac overexpression of Gα(q) rescued ATE1-deficient embryos from thin myocardium and ventricular septal defect but not from vascular defects, genetically dissecting vascular defects from cardiac defects. The misregulation in cardiovascular signaling can be attributed in part to the failure in hypoxia-sensitive degradation of RGS4, a GTPase-activating protein for Gα(q). This study is the first to characterize the N-end rule pathway in cardiomyocytes and reveals the role of its arginylation branch in Gα(q)-mediated signaling of cardiomyocytes in part through N-degron-based, oxygen-sensitive proteolysis of G-protein regulators.
authors.affiliation: Department of Applied Chemistry, College of Applied Sciences, Kyung Hee University, Yongin 446-701, Korea.
authors.forename: Min Jae
authors.initials: MJ
authors.lastname: Lee
authors.forename: Dong Eun
authors.initials: DE
authors.lastname: Kim
authors.forename: Adriana
authors.initials: A
authors.lastname: Zakrzewska
authors.forename: Young Dong
authors.initials: YD
authors.lastname: Yoo
authors.forename: Su-Hyeon
authors.initials: SH
authors.lastname: Kim
authors.forename: Sung Tae
authors.initials: ST
authors.lastname: Kim
authors.forename: Jai Wha
authors.initials: JW
authors.lastname: Seo
authors.forename: Young Sook
authors.initials: YS
authors.lastname: Lee
authors.forename: Gerald W
authors.initials: GW
authors.lastname: Dorn
authors.forename: Uhtaek
authors.initials: U
authors.lastname: Oh
authors.forename: Bo Yeon
authors.initials: BY
authors.lastname: Kim
authors.forename: Yong Tae
authors.initials: YT
authors.lastname: Kwon
mesh_terms: D019881:Aminoacyltransferases / Q000172:deficiency* / Q000235:genetics; D000818:Animals; D001120:Arginine / Q000378:metabolism; D049109:Cell Proliferation; D002478:Cells, Cultured; D004622:Embryo, Mammalian / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000378:metabolism; D006321:Heart / Q000196:embryology; D015151:Immunoblotting; D008297:Male; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009206:Myocardium / Q000166:cytology / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D059748:Proteolysis; D020710:RGS Proteins / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D020690:GTPase-Activating Proteins; D009363:Neoplasm Proteins; D020710:RGS Proteins; C021081:recognins; C098799:RGS4 protein; D001120:Arginine; D019881:Aminoacyltransferases; C019727:arginyltransferase; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D019204:GTP-Binding Proteins; D010100:Oxygen