INVESTIGADORES
DAVIO Carlos Alberto
artículos
Título:
Roles of phosphorylation dependent and independent mechanisms in the regulation of Histamine H2 receptor by G Protein-coupled Receptor Kinase
Autor/es:
FERNADEZ NATALIA; GOTARDO FEDERICO; ALONSO NATALIA; MONCZOR FEDERICO; SHAYO CARINA; CARLOS DAVIO
Revista:
JOURNAL OF BIOLOGICAL CHEMISTRY
Editorial:
AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Referencias:
Lugar: Bethesda, Maryland; Año: 2011 vol. 286 p. 28697 - 28706
ISSN:
0021-9258
Resumen:
It is widely assumed that G protein-coupled receptor kinase 2
(GRK2)-mediated specific inhibition of G protein-coupled
receptors (GPCRs) response involves GRK-mediated receptor
phosphorylation followed by-arrestin binding and subsequent
uncoupling from the heterotrimeric G protein. It has recently
become evident that GRK2-mediated GPCRs regulation also
involves phosphorylation-independent mechanisms. In the
present study we investigated whether the histamine H2
receptor (H2R), a Gs-coupled GPCR known to be desensitized
by GRK2, needs to be phosphorylated for its desensitization
and/or internalization and resensitization. For this
purpose we evaluated the effect of the phosphorylating-deficient
GRK2K220R mutant on H2R signaling in U937, COS7,
and HEK293T cells. We found that although this mutant
functioned as dominant negative concerning receptor internalization
and resensitization, it desensitized H2R signaling
in the same degree as the GRK2 wild type. To identify the
domains responsible for the kinase-independent receptor
desensitization, we co-transfected the receptor with constructions
encoding the GRK2 RGS-homology domain (RH)
and the RH or the kinase domain fused to the pleckstrinhomology
domain. Results demonstrated that the RH domain
of GRK2 was sufficient to desensitize the H2R. Moreover,
disruption of RGS functions by the use of GRK2D110A/
K220R double mutant, although coimmunoprecipitating
with the H2R, reversed GRK2K220R-mediated H2R desensitization.
Overall, these results indicate that GRK2 induces desensitization
of H2R through a phosphorylation-independent and
RGS-dependent mechanism and extends the GRK2 RH domainmediated
regulation ofGPCRsbeyondGq-coupled receptors.On
the other hand, GRK2 kinase activity proved to be necessary for
receptor internalization and the resulting resensitization.