Title

Glycosylation and Processing of Pro-B-Type Natriuretic Peptide in Cardiomyocytes

Document Type

Article

Publication Date

8-5-2011

Publication Title

Biochemical and Biophysical Research Communications

Abstract

B-type natriuretic peptide (BNP) and its related peptides are biomarkers for the diagnosis of heart failure. Recent studies identified several O-glycosylation sites, including Thr-71, on human pro-BNP but the functional significance was unclear. In this study, we analyzed glycosylation and proteolytic processing of pro-BNP in cardiomyocytes. Human pro-BNP wild-type (WT) and mutants were expressed in HEK 293 cells and murine HL-1 cardiomyocytes. Pro-BNP and BNP were analyzed by immunoprecipitation and Western blotting. Glycosidases and glycosylation inhibitors were used to examine carbohydrates on pro-BNP. The effects of furin and corin expression on pro-BNP processing in cells also were examined. We found that in HEK 293 cells, recombinant pro-BNP contained significant amounts of O-glycans with terminal oligosialic acids. Mutation at Thr-71 reduced O-glycans on pro-BNP and increased pro-BNP processing. In HL-1 cardiomyocytes, residue Thr-71 contained little O-glycans, and pro-BNP WT and T71A mutant were processed similarly. In HEK 293 cells, pro-BNP was processed by furin. Mutations at Arg-73 and Arg-76, but not Lys-79, prevented pro-BNP processing. In HL-1 cardiomyocytes, which express furin and corin, single or double mutations at Arg-73, Arg-76 and Lys-79 did not prevent pro-BNP processing. Only when all these three residues were mutated, was pro-BNP processing completely blocked. Our data indicate that pro-BNP glycosylation in cardiomyocytes differed significantly from that in HEK 293 cells. In HEK 293 cells, furin cleaved pro-BNP at Arg-76 whereas in cardiomyocytes corin cleaved pro-BNP at multiple residues including Arg-73, Arg-76 and Lys-79.

Comments

This work was supported in part by grants from the Bakken Heart-Brain Institute,
the National Institutes of Health (HL089298, HL089298-S1, HD064634), the National Natural Science Foundation of China (31070716), and the Priority Academic Program Development of Jiangsu Higher Education Institutions.

DOI

10.1016/j.bbrc.2011.06.192

Volume

411

Issue

3