Publications (6)38.38 Total impact
-
Article: The G-protein-coupled receptor kinase 5 inhibits NFkappaB transcriptional activity by inducing nuclear accumulation of IkappaB alpha.
[show abstract] [hide abstract]
ABSTRACT: G-protein-coupled receptor (GPCR) kinases, GRKs, are known as serine/threonine kinases that regulate GPCR signaling, but recent findings propose functions for these kinases besides receptor desensitization. Indeed, GRK5 can translocate to the nucleus by means of a nuclear localization sequence, suggesting that this kinase regulates transcription events in the nucleus. To evaluate the effect of GRK5-IkappaB alpha interaction on NFkappaB signaling, we induced the overexpression and the knockdown of GRK5 in cell cultures. GRK5 overexpression causes nuclear accumulation of IkappaB alpha, leading to the inhibition of NFkappaB transcriptional activity. Opposite results are achieved by GRK5 knockdown through siRNA. A physical interaction between GRK5 and IkappaB alpha, rather than phosphorylative events, appears as the underlying mechanism. We identify the regulator of gene protein signaling homology domain of GRK5 (RH) and the N-terminal domain of IkappaB alpha as the regions involved in such interaction. To confirm the biological relevance of this mechanism of regulation for NFkappaB, we evaluated the effects of GRK5-RH on NFkappaB-dependent phenotypes. In particular, GRK5-RH overexpression impairs apoptosis protection and cytokine production in vitro and inflammation and tissue regeneration in vivo. Our results reveal an unexpected role for GRK5 in the regulation of NFkappaB transcription activity. Placing these findings in perspective, this mechanism may represent a therapeutic target for all those conditions involving excessive NFkappaB activity.Proceedings of the National Academy of Sciences 12/2008; 105(46):17818-23. · 9.68 Impact Factor -
Article: Calmodulin-dependent kinase IV links Toll-like receptor 4 signaling with survival pathway of activated dendritic cells.
[show abstract] [hide abstract]
ABSTRACT: Microbial products, including lipopolysaccharide (LPS), an agonist of Toll-like receptor 4 (TLR4), regulate the lifespan of dendritic cells (DCs) by largely undefined mechanisms. Here, we identify a role for calcium-calmodulin-dependent kinase IV (CaMKIV) in this survival program. The pharmacologic inhibition of CaMKs as well as ectopic expression of kinase-inactive CaMKIV decrease the viability of monocyte-derived DCs exposed to bacterial LPS. The defect in TLR4 signaling includes a failure to accumulate the phosphorylated form of the cAMP response element-binding protein (pCREB), Bcl-2, and Bcl-xL. CaMKIV null mice have a decreased number of DCs in lymphoid tissues and fail to accumulate mature DCs in spleen on in vivo exposure to LPS. Although isolated Camk4-/- DCs are able to acquire the phenotype typical of mature cells and release normal amounts of cytokines in response to LPS, they fail to accumulate pCREB, Bcl-2, and Bcl-xL and therefore do not survive. The transgenic expression of Bcl-2 in CaMKIV null mice results in full recovery of DC survival in response to LPS. These results reveal a novel link between TLR4 and a calcium-dependent signaling cascade comprising CaMKIV-CREB-Bcl-2 that is essential for DC survival.Blood 02/2008; 111(2):723-31. · 9.90 Impact Factor -
Article: Endothelial beta2 adrenergic signaling to AKT: role of Gi and SRC.
[show abstract] [hide abstract]
ABSTRACT: We have recently demonstrated that endothelial beta(2) adrenergic receptors (beta(2)AR) regulate eNOS activity and consequently vascular tone, through means of PKB/AKT. In this work we explored the signal transduction pathway leading to AKT/eNOS activation in endothelial cells (EC). Using pharmacological and molecular inhibitors both in cultured EC cells and in ex vivo rat carotid preparations, we found that G(i) coupling of the beta(2)AR is needed for AKT activation and vasorelaxation. Since endothelial activation is sensitive to pertussis toxin but not to G(ibetagamma) inhibition by betaARKct, we conclude that G(alphai) mediates betaAR induced AKT activation. Downstream, betaAR signalling requires the soluble tyrosine kinase SRC, as both in cultured EC and rat carotid, the mutant dominant negative of SRC prevent beta(2)AR induced endothelial activation and vasodilation. In EC, G(alphai) directly interacts with SRC and this interaction leads to SRC activation and phosphorylation in a manner that is regulated by beta(2)AR stimulation. We propose a novel signal transduction pathway for beta(2)AR stimulation trough G(alphai) and SRC, leading to activation of AKT.Cellular Signalling 10/2007; 19(9):1949-55. · 4.06 Impact Factor -
Article: ADENOVIRAL MEDIATED GENE TRANSFER OF THE β2ADRENERGIC RECEPTOR (β2AR) CORRECTS IMPAIRED ANGIOGENESIS IN THE ISCHEMIC HINDLIMB OF HYPERTENSIVE SHR RATS.
Circulation 01/2005; · 14.74 Impact Factor -
Article: Endothelial β2 adrenergic signaling to AKT: Role of Gi and SRC
[show abstract] [hide abstract]
ABSTRACT: We have recently demonstrated that endothelial β2 adrenergic receptors (β2AR) regulate eNOS activity and consequently vascular tone, through means of PKB/AKT. In this work we explored the signal transduction pathway leading to AKT/eNOS activation in endothelial cells (EC). Using pharmacological and molecular inhibitors both in cultured EC cells and in ex vivo rat carotid preparations, we found that Gi coupling of the β2AR is needed for AKT activation and vasorelaxation. Since endothelial activation is sensitive to pertussis toxin but not to Giβγ inhibition by βARKct, we conclude that Gαi mediates βAR induced AKT activation. Downstream, βAR signalling requires the soluble tyrosine kinase SRC, as both in cultured EC and rat carotid, the mutant dominant negative of SRC prevent β2AR induced endothelial activation and vasodilation. In EC, Gαi directly interacts with SRC and this interaction leads to SRC activation and phosphorylation in a manner that is regulated by β2AR stimulation. We propose a novel signal transduction pathway for β2AR stimulation trough Gαi and SRC, leading to activation of AKT.Cellular Signalling. 19(9):1949-1955. -
Article: Kinase independent inhibition of NFκB transcriptional activity by GRK5 through IκBα stabilization.
[show abstract] [hide abstract]
ABSTRACT: Members of the G protein receptor kinase (GRK) family that regulates receptor desensitization and members of the nuclear transcription factors family NF[kappa]B have been recently and convincingly demonstrated to interact, although the effects on transcription and gene expression have not yet been described. Using overexpression, knockdown (small interfering RNA) and mutagenesis experiments, we demonstrate that GRK5 couples to and stabilizes the NF[kappa]B inhibitor I[kappa]B[alpha], and inhibits NF[kappa]B activity. Studies with minigenes suggest that the N-terminal Regulation of G protein Signaling (RGS) homology (RH) domain confers GRK5 such ability. GRK5-RH domain overexpression affects NF[kappa]B dependent phenotypes, such as apoptosis protection, cytokine production and inflammation and tissue regeneration. Our results reveal a novel, unexpected role of GRK5 in NF[kappa]B transcription activity regulation that represents a possible target for diagnostic and therapeutics.Nature Precedings.
Top co-authors
Top Journals
Institutions
-
2008
-
Centro Biotecnologie Avanzate
Genova, Liguria, Italy
-
-
2007–2008
-
Università degli Studi di Napoli Federico II
- Department of Clinical Medicine, Cardiovascular and Immunological Science
Napoli, Campania, Italy
-
