Volume 14 Supplement 1

6th International Conference on cGMP: Generators, Effectors and Therapeutic Implications

Open Access

O-glycosylated pro-B-type natriuretic peptide is cleaved intracellularly by furin in ventricular and atrial myocytes: importance of the distance between the O-glycosylation and cleavage sites

  • Toshio Nishikimi1, 5Email author,
  • Yasuaki Nakagawa1,
  • Naoto Minamino4,
  • Masashi Ikeda3,
  • Toshihiko Ishimitsu2,
  • Chinatsu Yamada1,
  • Kazuhiro Nakao1,
  • Takeya Minami1,
  • Yoshihiro Kuwabara1,
  • Hideyuki Kinoshita1,
  • Koichiro Kuwahara1,
  • Kenji Kangawa4 and
  • Kazuwa Nakao1
BMC Pharmacology and Toxicology201314(Suppl 1):P50

DOI: 10.1186/2050-6511-14-S1-P50

Published: 29 August 2013

Background

Our objective was to investigate the molecular mechanism underlying the processing of proBNP, levels of which are increased in heart failure [1, 2].

Methods

Rat neonatal atrial and ventricular myocytes were cultured separately. We examined: (1) the molecular forms of secreted and intracellular BNP in atrial and ventricular myocytes; (2) levels of corin and furin mRNA in atrial and ventricular myocytes and the effect their knockdown on proBNP processing; (3) molecular forms of BNP in plasma from rats and humans with and without heart failure; (4) the structure of proBNP in humans and rats; (5) the impact of the distance between the glycosylation and cleavage sites in wild-type and mutant human proBNP expressed in rat myocytes transfected with lentiviral vectors.

Results

BNP was the major molecular form secreted by atrial (75±9%) and ventricular (85±9%) myocytes, and was the major intracellular form in atrial myocytes (60±5%). ProBNP was the major intracellular form in ventricular myocytes (58±4%). The relative levels of furin mRNA correlated with those of BNP in atrial and ventricular myocytes, and transfection of furin siRNA reduced proBNP processing in both atrial and ventricular myocytes. BNP was the major molecular form in rat plasma (90±10%), whereas proBNP was the major form in human plasma (72±8%). The relative fraction of human BNP in rat myocytes expressing human proBNP was 60±5%, but increasing the distance between the glycosylation and cleavage sites through mutation, increased the processed fraction correspondingly (Figure 1).

Figure 1

Conclusion

These results suggest that proBNP is processed into BNP and N-terminal proBNP intracellularly, most likely by furin in rat. The level of proBNP processing is lower in humans than rats, most likely due to the smaller distance between the O-glycosylation and cleavage sites in humans.

Authors’ Affiliations

(1)
Department of Medicine and Clinical Science, Kyoto Univ. Graduate School of Medicine
(2)
Department of Hypertension and Cardiorenal Medicine, Dokkyo Medical University
(3)
Department of Laboratory Medicine, Dokkyo Medical University
(4)
Research Institute National Cardiovascular Research Center
(5)
Department of Cardiology, Fujii Hospital

References

  1. Nishikimi T, Kuwahara K, Nakagawa Y, Kangawa K, Minamino N, Nakao K: Complexity of molecular forms of B-type natriuretic peptide in heart failure. Heart. 2013, 99: 677-679. 10.1136/heartjnl-2012-302929.View ArticlePubMedGoogle Scholar
  2. Nishikimi T, Ikeda M, Takeda Y, Ishimitsu T, Shibasaki I, Fukuda H, Kinoshita H, Nakagawa Y, Kuwahara K, Nakao K: The effect of glycosylation on plasma N- terminal proBNP-76 levels in patients with heart or renal failure. Heart. 2012, 98: 152-161. 10.1136/heartjnl-2011-300102.View ArticlePubMedGoogle Scholar

Copyright

© Nishikimi et al; licensee BioMed Central Ltd. 2013

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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