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 language | English |
|---|---|
| Pages (from-to) | 1856-1867 |
| Number of pages | 12 |
| Journal | Molecular Endocrinology |
| Volume | 17 |
| Issue number | 9 |
| DOIs | |
| State | Published - Sep 1 2003 |
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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 journal › Article
}
TY - JOUR
T1 - Disruption of a receptor-mediated mechanism for intracellular sorting of proinsulin in familial hyperproinsulinemia
AU - Dhanvantari, Savita
AU - Shen, Fu Sheng
AU - Adams, Tiffany
AU - Snell, Christopher R.
AU - Zhang, Chunfa
AU - Mackin, Robert
AU - Morris, Stephen J.
AU - Loh, Y. Peng
PY - 2003/9/1
Y1 - 2003/9/1
N2 - 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.
AB - 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.
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UR - http://www.scopus.com/inward/citedby.url?scp=0042835761&partnerID=8YFLogxK
U2 - 10.1210/me.2002-0380
DO - 10.1210/me.2002-0380
M3 - Article
C2 - 12829804
AN - SCOPUS:0042835761
VL - 17
SP - 1856
EP - 1867
JO - Molecular Endocrinology
JF - Molecular Endocrinology
SN - 0888-8809
IS - 9
ER -