Multiple phosphorylation sites in RGS16 differentially modulate its GAP activity

Chen, Canhe; Wang, Huashan; Fong, Chee Wai; Lin, Sheng-Cai

doi:10.1016/s0014-5793(01)02757-0

Cited by 33 publications

(27 citation statements)

References 28 publications

(49 reference statements)

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“…RGS16, on the other hand, acts as a mechanism for p53 to exert cellular growth control and acts as a negative feedback regulator in response to mitogenic signals (Buckbinder et al, 1997). RGS16 inhibits ERK activation upstream of the RAS-RAF-MEK-ERK pathway by enhancing GTPase-activating protein function and inactivating RAS-GTP (Buckbinder et al, 1997;Chen et al, 2001). Various inhibitors of RAS-RAF-MEK-ERK signalling pathway have been proven to inhibit cancer cell growth and survival, and are already in phase II clinical trials for the treatment of various cancers (Sebolt-Leopold and Herrera, 2004).…”

Section: Discussionmentioning

confidence: 99%

“…Synchronous RA-induced expression of DUSP6 and RGS16 is required for the antiproliferative effect of RA DUSP6 and RGS16 are both inhibitors involved in the ERK MAPK signalling pathway, RGS16 at the level of Ras G proteins (Buckbinder et al, 1997;Chen et al, 2001) and DUSP6 at the level of ERK proteins (Groom et al, 1996;Sah et al, 2002;Nakagawa et al, 2003). Since the growth inhibitory effect of RA is at least partly due to reduction in ERK phosphorylation (Nakagawa et al, 2003), we examined the hypothesis that RA-induced proliferative arrest was dependent on increased expression of DUSP6 or RGS16.…”

Section: Liganded Rarb2 Regulates Ra-induced Cyp26a1 Expressionmentioning

confidence: 99%

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The retinoid anticancer signal: mechanisms of target gene regulation

et al. 2005

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Retinoids induce growth arrest, differentiation, and cell death in many cancer cell types. One factor determining the sensitivity or resistance to the retinoid anticancer signal is the transcriptional response of retinoid-regulated target genes in cancer cells. We used cDNA microarray to identify 31 retinoid-regulated target genes shared by two retinoid-sensitive neuroblastoma cell lines, and then sought to determine the relevance of the target gene responses to the retinoid anticancer signal. The pattern of retinoid responsiveness for six of 13 target genes (RARb2, CYP26A1, CRBP1, RGS16, DUSP6, EGR1) correlated with phenotypic retinoid sensitivity, across a panel of retinoid-sensitive or -resistant lung and breast cancer cell lines. Retinoid treatment of MYCN transgenic mice bearing neuroblastoma altered the expression of five of nine target genes examined (RARb2, CYP26A1, CRBP1, DUSP6, PLAT) in neuroblastoma tumour tissue in vivo. In retinoid-sensitive neuroblastoma, lung and breast cancer cell lines, direct inhibition of retinoid-induced RARb2 expression blocked induction of only one of eight retinoid target genes (CYP26A1). DNA demethylation, histone acetylation, and exogenous overexpression of RARb2 partially restored retinoid-responsive CYP26A1 expression in RA-resistant MDA-MB-231 breast, but not SK-MES-1 lung, cancer cells. Combined, rather than individual, inhibition of DUSP6 and RGS16 was required to block retinoid-induced growth inhibition in neuroblastoma cells, through phosphorylation of extracellularsignal-regulated kinase. In conclusion, sensitivity to the retinoid anticancer signal is determined in part by the transcriptional response of key retinoid-regulated target genes, such as RARb2, DUSP6, and RGS16.

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Section: Discussionmentioning

confidence: 99%

Section: Liganded Rarb2 Regulates Ra-induced Cyp26a1 Expressionmentioning

confidence: 99%

The retinoid anticancer signal: mechanisms of target gene regulation

et al. 2005

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“…Post-translational modifications, such as phosphorylation, can either enhance or inhibit RGS protein function in a rapid, cell state-specific manner. Phosphorylation of RGS14 by PKA at Thr 494 , adjacent to the GoLoco motif, enhances its guanine nucleotide dissociation inhibitory activity towards Gα i , while having no effect on GAP activity (Hollinger et al, 2003).In contrast, GPCR ligand-dependent phosphorylation of RGS16 at Ser 53 has been shown to inhibit GAP activity (Chen et al, 2001), while Src-mediated phosphorylation at Tyr 168 protects RGS16 from degradation leading to enhanced GAP activity in cells (Derrien and Druey, 2001;Derrien et al, 2003). Another member of the R4 family, RGS2, was demonstrated to be phosphorylated by PKC, which inhibited GAP activity of RGS2 in vitro (Cunningham et al, 2001).…”

Section: Regulation Of Function Localization and Expressionmentioning

confidence: 99%

The evolution of regulators of G protein signalling proteins as drug targets – 20 years in the making: IUPHAR Review 21

Sjögren

2017

British J Pharmacology

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Regulators of G protein signalling (RGS) proteins are celebrating the 20th anniversary of their discovery. The unveiling of this new family of negative regulators of G protein signalling in the mid-1990s solved a persistent conundrum in the G protein signalling field, in which the rate of deactivation of signalling cascades in vivo could not be replicated in exogenous systems. Since then, there has been tremendous advancement in the knowledge of RGS protein structure, function, regulation and their role as novel drug targets. RGS proteins play an important modulatory role through their GTPase-activating protein (GAP) activity at active, GTP-bound Gα subunits of heterotrimeric G proteins. They also possess many non-canonical functions not related to G protein signalling. Here, an update on the status of RGS proteins as drug targets is provided, highlighting advances that have led to the inclusion of RGS proteins in the IUPHAR/BPS Guide to PHARMACOLOGY database of drug targets.Abbreviations DEP, Disheveled Egl-10 Pleckstrin; GAP, GTPase-activating protein; GGL, G protein γ-like; PPI, protein-protein interaction; RGS, regulator of G protein signalling; R7BP, R7 binding protein; R9AP, RGS9 associated protein IntroductionG protein-mediated signalling pathways have played a pivotal role in drug discovery and development for many decades. The large family of GPCRs or their downstream effectors are the target of 40% of clinically used drugs and thus represent a multi-billion-dollar industry (Wise et al., 2002). Interestingly, of the more than 300 non-olfactory GPCRs known, only a fraction of them are targeted by drugs. Thus, there is a large untapped area of drug development still available. Moreover, many GPCR drugs are associated with low efficacy and/or side effects. More targeted therapies are therefore required, and as we learn more about the structure and function of GPCRs and their regulators, these goals will be achievable.All biological signals are tightly regulated and for every on-switch there is usually an off-switch. GPCRs are activated by ligands, transmitting signalling information to Gα subunits of heterotrimeric G proteins by enhancing the exchange of GDP for GTP in the Gα nucleotide binding site, which results in the dissociation of Gα from Gβγ dimers and activation of both G protein components. Deactivation of G proteins does not occur by simple reversal of nucleotide exchange, but rather by an independently regulated GTPase activity, hydrolyzing GTP to GDP. Although Gα proteins possess an intrinsic ability to hydrolyze GTP, this process is very slow and cannot account for the transient nature of intracellular signalling cascades in vivo. Hence, additional kinetic mechanisms are required for the physiological timing of signals. One of the most critical of these kinetic mechanisms is mediated through regulator of G protein signalling (RGS) proteins, which have received increasing interest as novel drug targets in the past two decades. As a result, RGS proteins have now been added as the most recent ad...

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“…Because the N terminus of R4 RGS proteins is believed to serve as a scaffold for receptors and signaling proteins (46), it is conceivable that structural differences between RGS2/3 and RGS5/16 contribute to their differential effects. Phosphorylation of RGS proteins may also play a role, but so far little is known about its regulation and functional implications (36,49,50). Changes in post-translational modifications on G␣ subunits, such as an increase in palmitate turnover in constitutively active G␣ q * (51), also have the potential to differentially affect RGS function (52,53).…”

Section: Implications Of Expression Changes Of Key Components Of the mentioning

confidence: 99%

Differential Contribution of GTPase Activation and Effector Antagonism to the Inhibitory Effect of RGS Proteins on Gq-mediated Signaling in Vivo

Anger

Zhang

Mende

2004

Journal of Biological Chemistry

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RGS proteins act as negative regulators of G protein signaling by serving as GTPase-activating proteins (GAP) for ␣ subunits of heterotrimeric G proteins (G␣), thereby accelerating G protein inactivation. RGS proteins can also block G␣-mediated signal production by competing with downstream effectors for G␣ binding. Little is known about the relative contribution of GAP and effector antagonism to the inhibitory effect of RGS proteins on G protein-mediated signaling. By comparing the inhibitory effect of RGS2, RGS3, RGS5, and RGS16 on G␣ q -mediated phospholipase C␤ (PLC␤) activation under conditions where GTPase activation is possible versus nonexistent, we demonstrate that members of the R4 RGS subfamily differ significantly in their dependence on GTPase acceleration. COS-7 cells were transiently transfected with either muscarinic M 3 receptors, which couple to endogenous G q protein and mediate a stimulatory effect of carbachol on PLC␤, or constitutively active G␣ q * , which is inert to GTP hydrolysis and activates PLC␤ independent of receptor activation. In M 3 -expressing cells, all of the RGS proteins significantly blunted the efficacy and potency of carbachol. In contrast, G␣ q * -induced PLC␤ activation was inhibited by RGS2 and RGS3 but not RGS5 and RGS16. The observed differential effects were not due to changes in M 3 , G␣ q / G␣ q * , PLC␤, or RGS expression, as shown by receptor binding assays and Western blots. We conclude that closely related R4 RGS family members differ in their mechanism of action. RGS5 and RGS16 appear to depend on G protein inactivation, whereas GAP-independent mechanisms (such as effector antagonism) are sufficient to mediate the inhibitory effect of RGS2 and RGS3.Many extracellular stimuli elicit intracellular responses by activating seven-transmembrane receptors that are coupled to heterotrimeric G proteins comprising ␣ and ␤␥ subunits (1, 2). The duration of the response of a cell to external signals is largely determined by the activation/inactivation cycle of G proteins. Activated receptors trigger GTP-for-GDP exchange on G␣ subunits, thus dissociating G␣ from G␤ ␥ and subsequent activation of downstream effectors (such as enzymes and ion channels). The duration of G protein activation is limited by GTPase activity intrinsic to G␣ subunits that catalyzes the conversion of active GTP-bound G␣ into inactive GDP-bound G␣, which in turn can reassociate with G␤␥ and receptors.RGS proteins belong to a family of more than 20 proteins with a conserved RGS core domain of ϳ120 amino acids that is necessary and sufficient for binding to G␣ subunits (3). They are divided into several subfamilies based on their structural similarities, gene organization, and function. RGS proteins act as regulators of G protein signaling by limiting the signals generated by G protein-coupled receptors. They markedly increase the rate at which G␣ subunits hydrolyze GTP to GDP, a property that defines them as GTPase-activating proteins (or GAPs) 1 (4). Hastening of G␣ inactivation facilitates the reass...

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Multiple phosphorylation sites in RGS16 differentially modulate its GAP activity

Cited by 33 publications

References 28 publications

The retinoid anticancer signal: mechanisms of target gene regulation

The retinoid anticancer signal: mechanisms of target gene regulation

The evolution of regulators of G protein signalling proteins as drug targets – 20 years in the making: IUPHAR Review 21

Differential Contribution of GTPase Activation and Effector Antagonism to the Inhibitory Effect of RGS Proteins on Gq-mediated Signaling in Vivo

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