beta-Arrestin1 interacts with the G-protein subunits beta1gamma2 and promotes beta1gamma2-dependent Akt signalling for NF-kappaB activation.
beta-Arrestins are known to regulate G-protein signalling through interactions with their downstream effectors. In the present study, we report that beta-arrestin1 associates with the G-protein beta1gamma2 subunits in transfected cells, and purified beta-arrestin1 interacts with G(beta1gamma2) derived from in vitro translation. Deletion mutagenesis of beta-arrestin1 led to the identification of a region, comprising amino acids 181-280, as being responsible for its interaction with G(beta1gamma2). Overexpression of beta-arrestin1 facilitates G(beta1gamma2)-mediated Akt phosphorylation, and inhibition of endogenous beta-arrestin1 expression by siRNA (small interfering RNA) diminishes this effect. Through investigation of NF-kappaB (nuclear factor kappaB), a transcription factor regulated by Akt signalling, we have found that overexpression of beta-arrestin1 significantly enhances G(beta1gamma2)-mediated nuclear translocation of NF-kappaB proteins and expression of a NF-kappaB-directed luciferase reporter. Overexpression of beta-arrestin1 also promotes bradykinin-induced, G(betagamma)-mediated NF-kappaB luciferase-reporter expression, which is reverted by silencing the endogenous beta-arrestin1 with a specific siRNA. These results identify novel functions of beta-arrestin1 in binding to the beta1gamma2 subunits of heterotrimeric G-proteins and promoting G(betagamma)-mediated Akt signalling for NF-kappaB activation.
Yang
Ming
M
Department of Pharmacology, College of Medicine, University of Illinois, Chicago, IL 60612, USA. ming.yang@cvt.com
He
Rong L
RL
Benovic
Jeffrey L
JL
Ye
Richard D
RD
D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002460:Cell Line; D024202:Electrophoretic Mobility Shift Assay; D044387:GTP-Binding Protein beta Subunits / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D016328:NF-kappa B / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D017384:Sequence Deletion; D015398:Signal Transduction; D000071557:beta-Arrestins
D019390:Arrestins; C410342:GNG2 protein, human; D044387:GTP-Binding Protein beta Subunits; D016328:NF-kappa B; D034741:RNA, Small Interfering; D000071557:beta-Arrestins; D051057:Proto-Oncogene Proteins c-akt; D019204:GTP-Binding Proteins