Involvement of G Protein-Coupled Receptor Kinase (GRK) 3 and GRK2 in Down-Regulation of the α<sub>2B</sub>-Adrenoceptor

Desai, Aarti N.; Salim, Samina; Standifer, Kelly M.; Eikenburg, Douglas C.

doi:10.1124/jpet.105.098996

Cited by 15 publications

(11 citation statements)

References 35 publications

(51 reference statements)

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“…Experimental examination of signaling processes at different spatial and temporal scales, for example the motion of individual molecules or the formation of particular signaling complexes, may require a more detailed model than that used here. Indeed, mechanisms other than variation in receptor or G-protein number, including the formation of multi-protein signaling complexes, clustering of receptors via dimerization or regulation of the numbers of other signaling proteins, may play roles in regulating crosstalk (Hall and Lefkowitz, 2002; Breitwieser, 2004; Woolf and Linderman, 2004; Desai et al , 2006). While we found it was not necessary to incorporate compartments to explain the signaling data explored here, compzartments may indeed exist and play a role at other levels.…”

Section: Discussionmentioning

confidence: 99%

Collision coupling, crosstalk, and compartmentalization in G-protein coupled receptor systems: Can a single model explain disparate results?

Brinkerhoff

Traynor

Linderman

2008

Journal of Theoretical Biology

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The collision coupling model describes interactions between receptors and G-proteins as first requiring the molecules to find each other by diffusion. A variety of experimental data on Gprotein activation have been interpreted as suggesting (or not) the compartmentalization of receptors and/or G-proteins in addition to a collision coupling mechanism. In this work, we use a mathematical model of G-protein activation via collision coupling but without compartmentalization to demonstrate that these disparate observations do not imply the existence of such compartments. In experiments with GTP analogs (commonly GTPγS), the extent of Gprotein activation is predicted to be a function of both receptor number and the rate of GTP analog hydrolysis. The sensitivity of G-protein activation to receptor number is shown to be dependent upon the assay used, with the sensitivity of phosphate production assays (GTPase) > GTPγS binding assays > cAMP inhibition assays. Finally, the amount of competition or crosstalk between receptor species activating the same type of G-proteins is predicted to depend on receptor and Gprotein number, but in some (common) experimental regimes this dependence is expected to be minimal. Taken together, these observations suggest that the collision coupling model, without compartments of receptors and/or G-proteins, is sufficient to explain a variety of observations in literature data.

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Section: Discussionmentioning

confidence: 99%

Collision coupling, crosstalk, and compartmentalization in G-protein coupled receptor systems: Can a single model explain disparate results?

Brinkerhoff

Traynor

Linderman

2008

Journal of Theoretical Biology

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“…The cells were processed for immunofluorescence as described previously (Desai et al, 2006). In brief, BE(2)-C cells were grown on poly-D-lysine-coated 20-ϫ 20-mm glass cover slips to 40 to 70% confluence.…”

Section: Methodsmentioning

confidence: 99%

“…BE(2)-C cells were treated with EPI (0.3 M) or vehicle for 5 and 15 min. After the treatment, cells were processed for immunofluorescence as described previously (Desai et al, 2006). In separate samples, Sp-1 or Ap-2 were visualized with Alexa-488, whereas cell nuclei were stained with DAPI for visualization (blue).…”

Section: Regulation Of Grk3 Expression 53mentioning

confidence: 99%

Extracellular Signal-Regulated Kinase 1/2-Mediated Transcriptional Regulation of G-Protein-Coupled Receptor Kinase 3 Expression in Neuronal Cells

Salim

Standifer²,

Eikenburg³

2007

J Pharmacol Exp Ther

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Relatively small changes in G-protein-coupled receptor kinase (GRK) 3 expression (ϳ2-fold) profoundly affect ␣ 2 -adrenergic receptor (AR) function and preferentially regulate neuronal ␣ 2A -and ␣ 2B -AR signaling. In the present study, we provide evidence that epinephrine (EPI)-induced up-regulation of GRK3 protein expression in two neuronal cell lines, BE(2)-C cells (endogenously express ␣ 2A -and ␤ 2 -AR) and BN17 cells [endogenously express ␣ 2B (NG108) and transfected to express ␤ 2 -AR] is due in part to increased GRK3 gene expression. In both cell lines, the increase in GRK3 transcription occurred via an extracellular signal-regulated kinase (ERK) 1/2-dependent mechanism because the increase in GRK3 mRNA is eliminated in the presence of the mitogen-activated protein kinase/ERK kinase 1/2 inhibitor, U0126 [1,4-diamino-2,3-dicyano-1,4-bis (2-amino phenylthiobutadiene)]. EPI-induced GRK3 mRNA upregulation also is prevented in the presence of propranolol or phentolamine. Moreover, GRK3 mRNA did not increase in response to EPI treatment in NG108 cells (endogenously express ␣ 2B -AR with no ␤ 2 -AR). Both these results suggest that simultaneous activation of ␣ 2 -and ␤ 2 -AR by EPI is required for the ERK1/2-dependent increase in GRK3 mRNA. The EPI-induced increase in GRK3 mRNA was unaffected in the presence of the protein kinase C inhibitor, chelerythrine chloride. Finally, EPI treatment resulted in increased nuclear translocation and accumulation of the transcription factors, Sp-1 and Ap-2, in BE(2)-C cells. Taken together, our results demonstrate the involvement of the ERK1/2 pathway in selective up-regulation of GRK3 mRNA expression, possibly via activation of Sp-1 and Ap-2 transcription factors in neuronal cells.G-protein-coupled receptor kinases (GRKs) specifically interact with agonist-occupied G-protein-coupled receptors (GPCRs) to mediate receptor phosphorylation. This phosphorylation increases the affinity of the receptor for arrestin, and receptor/G-protein interaction is inhibited even in the presence of agonist. The resulting rapid loss of receptor responsiveness is termed desensitization and in many instances is followed by the removal of the receptor from the plasma membrane via clathrin-mediated endocytosis (Penn et al

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“…G proteincoupled receptor kinase (GRK) 2 binds to and phosphorylates the agonist-activated ␣ 2 AR (Jewell-Motz and Liggett, 1996;Pao and Benovic, 2005), which subsequently interacts with arrestin (Wu et al, 1997;DeGraff et al, 2002;Wang and Limbird, 2002). GRK phosphorylation represents one major mechanism for ␣ 2 AR desensitization after agonist stimulation (Eason et al, 1995;Jewell-Motz and Liggett, 1996;Desai et al, 2006). Whether or not heterologous desensitization pathways Jewell-Motz et al, 1998;Liang et al, 1998) and sensitization pathways (Jones et al, 1987;Bylund, 1988, 1990) reported in vitro also contribute to desensitization of this receptor in vivo is not yet known.…”

mentioning

confidence: 99%

Enhanced Hypotensive, Bradycardic, and Hypnotic Responses to α₂-Adrenergic Agonists in Spinophilin-Null Mice Are Accompanied by Increased G Protein Coupling to the α_2A-Adrenergic Receptor

Lu¹,

Chen²,

Cottingham³

et al. 2010

Mol Pharmacol

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We previously identified spinophilin as a regulator of ␣ 2 adrenergic receptor (␣ 2 AR) trafficking and signaling in vitro and in vivo (Science 304:1940(Science 304: -1944(Science 304: , 2004. To assess the generalized role of spinophilin in regulating ␣ 2 AR functions in vivo, the present study examined the impact of eliminating spinophilin on ␣ 2 AR-evoked cardiovascular and hypnotic responses, previously demonstrated to be mediated by the ␣ 2A AR subtype, after systemic administration of the ␣ 2 -agonists 5-bromo-N-(4,5-dihydro-1H-imidazol-2-yl)-6-quinoxalinamine (UK14,304) and clonidine in spinophilin-null mice. Mice lacking spinophilin expression display dramatically enhanced and prolonged hypotensive, bradycardic, and sedative-hypnotic responses to ␣ 2 AR stimulation. Whereas these changes in sensitivity to ␣ 2 AR agonists occur independent of any changes in ␣ 2A AR density or intrinsic affinity for agonist in the brains of spinophilin-null mice compared with wild-type control mice, the coupling of the ␣ 2A AR to cognate G proteins is enhanced in spinophilin-null mice. Thus, brain preparations from spinophilin-null mice demonstrate enhanced guanine nucleotide regulation of UK14,304 binding and evidence of a larger fraction of ␣ 2A AR in the guanine-nucleotide-sensitive higher affinity state compared with those from wild-type mice. These findings suggest that eliminating spinophilin expression in native tissues leads to an enhanced receptor/G protein coupling efficiency that contributes to sensitization of receptor mediated responses in vivo.The ␣ 2 -adrenergic receptor (AR) is a prototypical G protein-coupled receptor (GPCR) that couples to the G i/o subfamily of G proteins (Wang and Limbird, 2007). In native cells, stimulation of the ␣ 2 AR leads to inhibition of adenylyl cyclase and voltage-gated Ca 2ϩ currents and to activation of receptor-operated K ϩ currents and mitogen activated protein kinase (

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Involvement of G Protein-Coupled Receptor Kinase (GRK) 3 and GRK2 in Down-Regulation of the α_2B-Adrenoceptor

Cited by 15 publications

References 35 publications

Collision coupling, crosstalk, and compartmentalization in G-protein coupled receptor systems: Can a single model explain disparate results?

Collision coupling, crosstalk, and compartmentalization in G-protein coupled receptor systems: Can a single model explain disparate results?

Extracellular Signal-Regulated Kinase 1/2-Mediated Transcriptional Regulation of G-Protein-Coupled Receptor Kinase 3 Expression in Neuronal Cells

Enhanced Hypotensive, Bradycardic, and Hypnotic Responses to α₂-Adrenergic Agonists in Spinophilin-Null Mice Are Accompanied by Increased G Protein Coupling to the α_2A-Adrenergic Receptor

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Involvement of G Protein-Coupled Receptor Kinase (GRK) 3 and GRK2 in Down-Regulation of the α2B-Adrenoceptor

Cited by 15 publications

References 35 publications

Collision coupling, crosstalk, and compartmentalization in G-protein coupled receptor systems: Can a single model explain disparate results?

Collision coupling, crosstalk, and compartmentalization in G-protein coupled receptor systems: Can a single model explain disparate results?

Extracellular Signal-Regulated Kinase 1/2-Mediated Transcriptional Regulation of G-Protein-Coupled Receptor Kinase 3 Expression in Neuronal Cells

Enhanced Hypotensive, Bradycardic, and Hypnotic Responses to α2-Adrenergic Agonists in Spinophilin-Null Mice Are Accompanied by Increased G Protein Coupling to the α2A-Adrenergic Receptor

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Involvement of G Protein-Coupled Receptor Kinase (GRK) 3 and GRK2 in Down-Regulation of the α_2B-Adrenoceptor

Enhanced Hypotensive, Bradycardic, and Hypnotic Responses to α₂-Adrenergic Agonists in Spinophilin-Null Mice Are Accompanied by Increased G Protein Coupling to the α_2A-Adrenergic Receptor