Protein kinase D activation stimulates the transcription of the insulin receptor gene.
Our previous studies proved that berberine (BBR) up-regulates the insulin receptor (InsR) gene by stimulating its promoter and calphostin C blocks this effect. Here, the present study was designed to discover the specific kinase isoform(s) used by berberine. In the blocking experiment, we found that Gö6976, a kinase inhibitor that potently inhibit PKCμ/protein kinase D 1 (PKD1), effectively and specifically reduced the activity of BBR on InsR. PKD1/PKCμ is a member of the PKD family that also covers PKD2 and PKD3/PKCν with high homology. The role of PKD1 in InsR expression was also proved by using another PKD-activator oligomycin. In the RNA interference experiment, we found that the effects of BBR on InsR expression and on cellular glucose consumption were partially eliminated by silencing any one of the three PKDs and were totally abolished by silencing all of them. BBR enhanced the PKD1 catalytic activity, but not its expression. Along with BBR treatment, PKD1 ser916 autophosphorylation was increased time- and dose-dependently, indicating an activation of PKD1 by BBR. BBR also induces PKD1 translocation from cytosol-to-plasma membrane, further verifying the activation of PKD1. These results suggest that the PKD family is involved in the transcriptional regulation of the InsR gene; we consider it to be a potential new target to discover drugs for sugar-related disorders in the future.
Zhang
Hao
H
Department of Pharmacology, Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences, 1 Tiantan Xili, Beijing 100050, China.
Kong
Wei-Jia
WJ
Shan
Yong-Qiang
YQ
Song
Dan-Qing
DQ
Li
Yi
Y
Wang
Yue-Ming
YM
You
Xue-Fu
XF
Jiang
Jian-Dong
JD
D001599:Berberine / Q000494:pharmacology; D002227:Carbazoles / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D020868:Gene Silencing / Q000187:drug effects; D056945:Hep G2 Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D007527:Isoenzymes / Q000378:metabolism; D009840:Oligomycins / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011972:Receptor, Insulin / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D015854:Up-Regulation / Q000187:drug effects
D002227:Carbazoles; D007527:Isoenzymes; D009840:Oligomycins; D047428:Protein Kinase Inhibitors; D001599:Berberine; C081021:Go 6976; C089212:protein kinase D; D011972:Receptor, Insulin; D011493:Protein Kinase C