Disruption of a receptor-mediated mechanism for intracellular sorting of proinsulin in familial hyperproinsulinemia

Savita Dhanvantari, Fu Sheng Shen, Tiffany Adams, Christopher R. Snell, Chunfa Zhang, Robert Mackin, Stephen J. Morris, Y. Peng Loh

Research output: Contribution to journalArticle

31 Citations (Scopus)

Abstract

In familial hyperproinsulinemia, specific mutations in the proinsulin gene are linked with a profound increase in circulating plasma proinsulin levels. However, the molecular and cellular basis for this disease remains uncharacterized. Here we investigated how these mutations may disrupt the sorting signal required to target proinsulin to the secretory granules of the regulated secretory pathway, resulting in the unregulated release of proinsulin. Using a combination of molecular modeling and site-directed mutagenesis, we have identified structural molecular motifs in proinsulin that are necessary for correct sorting into secretory granules of endocrine cells. We show that membrane carboxypeptidase E (CPE), previously identified as a prohormone-sorting receptor, is essential for proinsulin sorting. This was demonstrated through short interfering RNA-mediated depletion of CPE and transfection with a dominant negative mutant of CPE in a β-cell line. Mutant proinsulins found in familial hyperproinsulinemia failed to bind to CPE and were not sorted efficiently. These findings provide evidence that the elevation of plasma proinsulin levels found in patients with familial hyperproinsulinemia is caused by the disruption of CPE-mediated sorting of mutant proinsulins to the regulated secretory pathway.

Original languageEnglish
Pages (from-to)1856-1867
Number of pages12
JournalMolecular Endocrinology
Volume17
Issue number9
DOIs
StatePublished - Sep 1 2003

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Proinsulin
Carboxypeptidase H
Secretory Pathway
Secretory Vesicles
Hyperproinsulinemia
Mutation
Endocrine Cells
Site-Directed Mutagenesis
Small Interfering RNA
Transfection
Cell Line
Membranes

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Endocrinology, Diabetes and Metabolism

Cite this

Disruption of a receptor-mediated mechanism for intracellular sorting of proinsulin in familial hyperproinsulinemia. / Dhanvantari, Savita; Shen, Fu Sheng; Adams, Tiffany; Snell, Christopher R.; Zhang, Chunfa; Mackin, Robert; Morris, Stephen J.; Loh, Y. Peng.

In: Molecular Endocrinology, Vol. 17, No. 9, 01.09.2003, p. 1856-1867.

Research output: Contribution to journalArticle

Dhanvantari, Savita ; Shen, Fu Sheng ; Adams, Tiffany ; Snell, Christopher R. ; Zhang, Chunfa ; Mackin, Robert ; Morris, Stephen J. ; Loh, Y. Peng. / Disruption of a receptor-mediated mechanism for intracellular sorting of proinsulin in familial hyperproinsulinemia. In: Molecular Endocrinology. 2003 ; Vol. 17, No. 9. pp. 1856-1867.
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