Prohormone convertase 1/3 and 2 together orchestrate the site-speciifc cleavages of progastrin to release gastrin-34 and gastrin-17

Jens F. Rehfeld*, Xiaorong Zhu, Christina Norrbom, Jens R. Bundgaard, Anders H. Johnsen, John E. Nielsen, Jonas Vikesaa, Jeffrey Stein, Arunangsu Dey, Donald F. Steiner, Lennart Friis-Hansen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

Cellular synthesis of peptide hormones requires PCs (prohormone convertases) for the endoproteolysis of prohormones. Antral G-cells synthesize the most gastrin and express PC1/3, 2 and 5/6 in the rat and human. But the cleavage sites in progastrin for each PC have not been determined. Therefore, in the present study, we measured the concentrations of progastrin, processing intermediates and α-amidated gastrins in antral extracts from PC1/3-null mice and compared the results with those in mice lacking PC2 and wild-type controls. The expression of PCs was examined by immunocytochemistry and in situ hybridization of mouse G-cells. Finally, the in vitro effect of recombinant PC5/6 on progastrin and progastrin fragments containing the relevant dibasic cleavage sites was also examined. The results showed that mouse G-cells express PC1/3, 2 and 5/6. The concentration of progastrin in PC1/3-null mice was elevated 3-fold. Chromatography showed that cleavage of the Arg36 Arg37 and Arg73 Arg74 sites were grossly decreased. Accordingly, the concentrations of progastrin products were markedly reduced, α-amidated gastrins (-34 and -17) being 25% of normal. Lack of PC1/3 was without effect on the third dibasic site (Lys53 Lys54), which is the only processing site for PC2. Recombinant PC5/6 did not cleave any of the dibasic processing sites in progastrin and fragments containing the relevant dibasic processing sites. The complementary cleavages of PC1/3 and 2, however, suffice to explain most of the normal endoproteolysis of progastrin. Moreover, the results show that PCs react differently to the same dibasic sequences, suggesting that additional structural factors modulate the substrate specificity.

Original languageEnglish (US)
Pages (from-to)35-43
Number of pages9
JournalBiochemical Journal
Volume415
Issue number1
DOIs
StatePublished - Oct 1 2008

Keywords

  • Gastrin
  • Peptide hormone
  • Post-translational processing
  • Progastrin
  • Prohormone convertase

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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