Abstract 20850: Secretion of ProBNP is Regulated by Mir30-GALNTs Axis Dependent O-linked Glycosylation in the Pathological Myocardium
Introduction: It has been reported that biological inactive pro-brain natriuretic peptide(proBNP), precursor peptide of bioactive BNP, is circulating in the healthy subject and increased in patients with heart failure, as well as mature BNP-32. However, underlying mechanisms of increased plasma proBNP levels in heart failure remain unclear.
Methods: We used the conventional BNP assay system, which cross-reacts both proBNP and BNP-32, and our recently developed specific human proBNP assay system. We assessed cardiac production of proBNP and BNP(=proBNP+BNP-32) in patients with heart failure. To elucidate the molecular mechanisms underlying the processing and secretion of proBNP, we generated lentivirus vectors carrying several mutations in glycosylation sites of human proBNP. We evaluated the proBNP/BNP ratio, as an efficacy of processing of proBNP to BNP-32.
Results: In coronary sinus, plasma proBNP/BNP ratios were significantly elevated in heart failure patients in accordance with the disease severity. In conditioned medium of cultured ventricular myocytes expressing wild type human proBNP, proBNP/BNP ratio was significantly increased compared to that in those of myocytes expressing glycosylation-resistant mutant of proBNP, demonstrating the essential contribution of glycosylation to the secretion of proBNP. Among 7 glycosylation sites, we found that glycosylation of Thr48 and Thr71 in proBNP is critical for the secretion of proBNP from ventricular myocytes by attenuating proBNP processing. GalNAc-transferase(GALNT) is the glycosyltransferase enyme family, which control O-linked glycosylasion. We identified GALNT 1 and 2 mediated the glycosylation-regulated increase in cardiac secretion of proBNP by screening with siRNAs. Indeed, GALNT1 and 2-expression was increased in FCS-treated ventricular myocytes and failing hearts. We further found that GALNT1 and 2 expression is suppressed by miR-30 family, and that miR-30s expression is decreased in FCS-treated ventricular myocytes and failing hearts.
Conclusions: We have elucidated novel molecular pathways that miR-30-GALNTs axis-mediated O-linked glycosylation in proBNP contributes to increased proportion of proBNP among secreted BNP in the pathological myocardium.
Author Disclosures: Y. Nakagawa: Other Research Support; Modest; Shionogi pharmaceutical company. K. Kuwahara: None. T. Nishikimi: None. H. Kinoshita: None. H. Inazumi: None. K. Moriuchi: None. T. Kato: None. N. Minamino: None. K. Nacho: None. T. Kimura: None.
- © 2016 by American Heart Association, Inc.