title: Bovine brain ribonuclease is the functional homolog of human ribonuclease 1.
abstract: Mounting evidence suggests that human pancreatic ribonuclease (RNase 1) plays important roles in vivo, ranging from regulating blood clotting and inflammation to directly counteracting tumorigenic cells. Understanding these putative roles has been pursued with continual comparisons of human RNase 1 to bovine RNase A, an enzyme that appears to function primarily in the ruminant gut. Our results imply a different physiology for human RNase 1. We demonstrate distinct functional differences between human RNase 1 and bovine RNase A. Moreover, we characterize another RNase 1 homolog, bovine brain ribonuclease, and find pronounced similarities between that enzyme and human RNase 1. We report that human RNase 1 and bovine brain ribonuclease share high catalytic activity against double-stranded RNA substrates, a rare quality among ribonucleases. Both human RNase 1 and bovine brain RNase are readily endocytosed by mammalian cells, aided by tight interactions with cell surface glycans. Finally, we show that both human RNase 1 and bovine brain RNase are secreted from endothelial cells in a regulated manner, implying a potential role in vascular homeostasis. Our results suggest that brain ribonuclease, not RNase A, is the true bovine homolog of human RNase 1, and provide fundamental insight into the ancestral roles and functional adaptations of RNase 1 in mammals.
authors: Departments of Biochemistry and University of Wisconsin, Madison, Wisconsin 53706.
authors: Chelcie H
authors: CH
authors: Eller
authors: Graduate Program in Cellular and Molecular Biology, University of Wisconsin, Madison, Wisconsin 53706.
authors: Jo E
authors: JE
authors: Lomax
authors: Departments of Biochemistry and University of Wisconsin, Madison, Wisconsin 53706; Departments of Chemistry, and University of Wisconsin, Madison, Wisconsin 53706. Electronic address: rtraines@wisc.edu.
authors: Ronald T
authors: RT
authors: Raines
mesh_terms: D000818:Animals; D001921:Brain / Q000201:enzymology; D002417:Cattle; D002478:Cells, Cultured; D061307:Human Umbilical Vein Endothelial Cells / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008081:Liposomes / Q000737:chemistry; D011485:Protein Binding; D021381:Protein Transport; D020871:RNA Stability; D012330:RNA, Double-Stranded / Q000737:chemistry; D012259:Ribonuclease, Pancreatic / Q000737:chemistry* / Q000502:physiology
chemical_list: D008081:Liposomes; D012330:RNA, Double-Stranded; D012259:Ribonuclease, Pancreatic
keywords: Double-stranded RNA (dsRNA); Enzyme Catalysis; Heparin-binding Protein; RNA; Ribonuclease