TY - JOUR
T1 - PKCepsilon mediates glucose-regulated insulin production in pancreatic beta-cells
AU - Warwar, Nasim
AU - Dov, Avital
AU - Abramovitch, Eva
AU - Wu, Ren
AU - Jmoudiak, Marina
AU - Haber, Esther
AU - Cerasi, Erol
AU - Nesher, Rafael
N1 - Funding Information:
The authors wish to thank N. Kaiser, D. Gross and Y. Ariav for the technical advice. We are grateful to D. Mochly-Rosen for the εV1-2 plasmid and to T. Tenenbaum and T. Kuroki for the adenoviruses expressing PKCs. This work was supported in part by a grant from the Hadassah Medical Organization and a grant from Les Laboratoires Servier, France. N.W. was a fellow of the Israel Ministry of Science, Culture and Sport and of the Hebrew University Diabetes Center.
PY - 2008/10/1
Y1 - 2008/10/1
N2 - Endocrine cells produce large amounts of one or more peptides. The post-translational control of selective production of a single protein is often unknown. We used 3 unrelated approaches to diminish PKCε in rat islets to evaluate its role in preferential glucose-mediated insulin production. Transfection with siRNA (siR-PKCε) or expression of inactive PKCε (PKCε-KD) resulted in a significant reduction in insulin response to glucose (16.7 mmol/l). Glucose stimulation resulted in concentration of PKCε in the perinuclear region, an area known to be rich in ER-Golgi systems, associated with insulin-containing structures. ß'COP1 (RACK2) is the anchoring protein for PKCε. Glucose-stimulated proinsulin production was diminished by 50% in islets expressing PKCε-KD, and 60% in islets expressing RACK2 binding protein (εV1-2); total protein biosynthesis was not affected. In islets expressing εV1-2, a chase period following glucose stimulus resulted in a reduced proinsulin conversion to mature insulin. We propose that PKCε plays a specific role in mediating the glucose-signal into insulin production: binding to ß'COP1 localizes the activated enzyme to the RER where it modulates the shuttling of proinsulin to the TGN. Subsequently the enzyme may be involved in anterograde trafficking of the prohormone or in its processing within the TGN.
AB - Endocrine cells produce large amounts of one or more peptides. The post-translational control of selective production of a single protein is often unknown. We used 3 unrelated approaches to diminish PKCε in rat islets to evaluate its role in preferential glucose-mediated insulin production. Transfection with siRNA (siR-PKCε) or expression of inactive PKCε (PKCε-KD) resulted in a significant reduction in insulin response to glucose (16.7 mmol/l). Glucose stimulation resulted in concentration of PKCε in the perinuclear region, an area known to be rich in ER-Golgi systems, associated with insulin-containing structures. ß'COP1 (RACK2) is the anchoring protein for PKCε. Glucose-stimulated proinsulin production was diminished by 50% in islets expressing PKCε-KD, and 60% in islets expressing RACK2 binding protein (εV1-2); total protein biosynthesis was not affected. In islets expressing εV1-2, a chase period following glucose stimulus resulted in a reduced proinsulin conversion to mature insulin. We propose that PKCε plays a specific role in mediating the glucose-signal into insulin production: binding to ß'COP1 localizes the activated enzyme to the RER where it modulates the shuttling of proinsulin to the TGN. Subsequently the enzyme may be involved in anterograde trafficking of the prohormone or in its processing within the TGN.
KW - Anchoring proteins
KW - Proinsulin biosynthesis
KW - Translocation inhibiting peptides
KW - siRNA
KW - β′COP1
UR - http://www.scopus.com/inward/record.url?scp=50849130230&partnerID=8YFLogxK
U2 - 10.1016/j.bbamcr.2008.04.007
DO - 10.1016/j.bbamcr.2008.04.007
M3 - Article
C2 - 18486624
AN - SCOPUS:50849130230
SN - 0167-4889
VL - 1783
SP - 1929
EP - 1934
JO - Biochimica et Biophysica Acta - Molecular Cell Research
JF - Biochimica et Biophysica Acta - Molecular Cell Research
IS - 10
ER -