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Midena G, Parrozzani R, Frizziero L, Esposito G, Micera A, Midena E. Expression of GNAQ, BAP1, SF3B1, and EIF1AX Proteins in the Aqueous Humor of Eyes Affected by Uveal Melanoma. Invest Ophthalmol Vis Sci 2024; 65:15. [PMID: 38175637 PMCID: PMC10774693 DOI: 10.1167/iovs.65.1.15] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 12/11/2023] [Indexed: 01/05/2024] Open
Abstract
Purpose The purpose of this study was to quantify specific aqueous humor (AH) proteins in eyes affected by posterior uveal melanoma (UM). Methods Thirty-six eyes affected by primary UM were included. Tumor thickness and largest basal diameter were specific clinical characteristics. Tumors were staged with the American Joint Commission on Cancer Eighth Edition (AJCC) classification. During the brachytherapy (Iodine-125) surgical procedure, both the AH sample collection and the 25-gauge transscleral fine needle aspiration biopsy (FNAB) were performed. AH samples were analyzed by immunoprecipitation and SDS PAGE techniques to quantify GNAQ, BAP1, SF3B1, and EIF1AX proteins. Cytologic material underwent fluorescence in situ hybridization for chromosome 3. The AH of 36 healthy eyes was used as the control group. Cluster analysis of groups was also performed. Results Compared with the control group, significantly higher protein levels of: GNAQ (P = 0.02), BAP1 (P = 0.01), and SF3B1 (P = 0.02) were detected in eyes with UM. Cluster analysis of UM group revealed 2 clusters, one showing higher expression of GNAQ and BAP1 protein and one of EIF1AX protein. Moreover, the 2 clusters corresponded with the chromosome 3 status of UM. Conclusions Specific and selected proteins may be detected in the AH of eyes affected by UM. These findings confirm the possibilities provided by AH analysis in UM.
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Affiliation(s)
| | | | - Luisa Frizziero
- Department of Ophthalmology, University of Padova, Padova, Italy
| | | | | | - Edoardo Midena
- IRCCS–Fondazione Bietti, Rome, Italy
- Department of Ophthalmology, University of Padova, Padova, Italy
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2
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Wang W, Du X, Chu M, He X. Photoperiod Induces the Epigenetic Change of the GNAQ Gene in OVX+E 2 Ewes. Int J Mol Sci 2023; 24:16442. [PMID: 38003630 PMCID: PMC10671395 DOI: 10.3390/ijms242216442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Revised: 11/09/2023] [Accepted: 11/15/2023] [Indexed: 11/26/2023] Open
Abstract
GNAQ, a member of the alpha subunit encoding the q-like G protein, is a critical gene in cell signaling, and multiple studies have shown that upregulation of GNAQ gene expression ultimately inhibits the proliferation of gonadotropin-releasing hormone (GnRH) neurons and GnRH secretion, and ultimately affects mammalian reproduction. Photoperiod is a key inducer which plays an important role in gene expression regulation by affecting epigenetic modification. However, fewer studies have confirmed how photoperiod induces epigenetic modifications of the GNAQ gene. In this study, we examined the expression and epigenetic changes of GNAQ in the hypothalamus in ovariectomized and estradiol-treated (OVX+E2) sheep under three photoperiod treatments (short photoperiod treatment for 42 days, SP42; long photoperiod treatment for 42 days, LP42; 42 days of short photoperiod followed by 42 days of long photoperiod, SP-LP42). The results showed that the expression of GNAQ was significantly higher in SP-LP42 than in SP42 and LP42 (p < 0.05). Whole genome methylation sequencing (WGBS) results showed that there are multiple differentially methylated regions (DMRs) and loci between different groups of GNAQ. Among them, the DNA methylation level of DMRs at the CpG1 locus in SP42 was significantly higher than that of SP-LP42 (p < 0.01). Subsequently, we confirmed that the core promoter region of the GNAQ gene was located with 1100 to 1500 bp upstream, and the DNA methylation level of all eight CpG sites in SP42 was significantly higher than those in LP42 (p < 0.01), and significantly higher than those in SP-LP42 (p < 0.01), except site 2 and site 4 in the first sequencing fragment (p < 0.05) in the core promoter region. The expression of acetylated GNAQ histone H3 was significantly higher than that of the control group under three different photoperiods (p < 0.01); the acetylation level of sheep hypothalamic GNAQ genomic protein H3 was significantly lower under SP42 than under SP-LP42 (p < 0.05). This suggests that acetylated histone H3 binds to the core promoter region of the GNAQ gene, implying that GNAQ is epigenetically regulated by photoperiod through histone acetylation. In summary, the results suggest that photoperiod can induce DNA methylation in the core promoter region and histone acetylation in the promoter region of the GNAQ gene, and hypothesize that the two may be key factors in regulating the differential expression of GNAQ under different photoperiods, thus regulating the hypothalamus-pituitary-gonadal axis (HPGA) through the seasonal estrus in sheep. The results of this study will provide some new information to understand the function of epigenetic modifications in reproduction in sheep.
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Affiliation(s)
| | | | - Mingxing Chu
- State Key Laboratory of Animal Biotech Breeding, Institute of Animal Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing 100193, China; (W.W.); (X.D.)
| | - Xiaoyun He
- State Key Laboratory of Animal Biotech Breeding, Institute of Animal Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing 100193, China; (W.W.); (X.D.)
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3
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Nadel G, Maik-Rachline G, Seger R. JNK Cascade-Induced Apoptosis-A Unique Role in GqPCR Signaling. Int J Mol Sci 2023; 24:13527. [PMID: 37686335 PMCID: PMC10487481 DOI: 10.3390/ijms241713527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 08/27/2023] [Accepted: 08/28/2023] [Indexed: 09/10/2023] Open
Abstract
The response of cells to extracellular signals is mediated by a variety of intracellular signaling pathways that determine stimulus-dependent cell fates. One such pathway is the cJun-N-terminal Kinase (JNK) cascade, which is mainly involved in stress-related processes. The cascade transmits its signals via a sequential activation of protein kinases, organized into three to five tiers. Proper regulation is essential for securing a proper cell fate after stimulation, and the mechanisms that regulate this cascade may involve the following: (1) Activatory or inhibitory phosphorylations, which induce or abolish signal transmission. (2) Regulatory dephosphorylation by various phosphatases. (3) Scaffold proteins that bring distinct components of the cascade in close proximity to each other. (4) Dynamic change of subcellular localization of the cascade's components. (5) Degradation of some of the components. In this review, we cover these regulatory mechanisms and emphasize the mechanism by which the JNK cascade transmits apoptotic signals. We also describe the newly discovered PP2A switch, which is an important mechanism for JNK activation that induces apoptosis downstream of the Gq protein coupled receptors. Since the JNK cascade is involved in many cellular processes that determine cell fate, addressing its regulatory mechanisms might reveal new ways to treat JNK-dependent pathologies.
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Affiliation(s)
| | | | - Rony Seger
- Department of Immunology and Regenerative Biology, Weizmann Institute of Science, Rehovot 7610001, Israel; (G.N.); (G.M.-R.)
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4
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Wang W, Yao J, Li W, Wu Y, Duan H, Xu C, Tian X, Li S, Tan Q, Zhang D. Epigenome-wide association study in Chinese monozygotic twins identifies DNA methylation loci associated with blood pressure. Clin Epigenetics 2023; 15:38. [PMID: 36869404 PMCID: PMC9985232 DOI: 10.1186/s13148-023-01457-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 02/24/2023] [Indexed: 03/05/2023] Open
Abstract
BACKGROUND Hypertension is a crucial risk factor for developing cardiovascular disease and reducing life expectancy. We aimed to detect DNA methylation (DNAm) variants potentially related to systolic blood pressure (SBP) and diastolic blood pressure (DBP) by conducting epigenome-wide association studies in 60 and 59 Chinese monozygotic twin pairs, respectively. METHODS Genome-wide DNA methylation profiling in whole blood of twins was performed using Reduced Representation Bisulfite Sequencing, yielding 551,447 raw CpGs. Association between DNAm of single CpG and blood pressure was tested by applying generalized estimation equation. Differentially methylated regions (DMRs) were identified by comb-P approach. Inference about Causation through Examination of Familial Confounding was utilized to perform the causal inference. Ontology enrichment analysis was performed using Genomic Regions Enrichment of Annotations Tool. Candidate CpGs were quantified using Sequenom MassARRAY platform in a community population. Weighted gene co-expression network analysis (WGCNA) was conducted using gene expression data. RESULTS The median age of twins was 52 years (95% range 40, 66). For SBP, 31 top CpGs (p < 1 × 10-4) and 8 DMRs were identified, with several DMRs within NFATC1, CADM2, IRX1, COL5A1, and LRAT. For DBP, 43 top CpGs (p < 1 × 10-4) and 12 DMRs were identified, with several DMRs within WNT3A, CNOT10, and DAB2IP. Important pathways, such as Notch signaling pathway, p53 pathway by glucose deprivation, and Wnt signaling pathway, were significantly enriched for SBP and DBP. Causal inference analysis suggested that DNAm at top CpGs within NDE1, MYH11, SRRM1P2, and SMPD4 influenced SBP, while SBP influenced DNAm at CpGs within TNK2. DNAm at top CpGs within WNT3A influenced DBP, while DBP influenced DNAm at CpGs within GNA14. Three CpGs mapped to WNT3A and one CpG mapped to COL5A1 were validated in a community population, with a hypermethylated and hypomethylated direction in hypertension cases, respectively. Gene expression analysis by WGCNA further identified some common genes and enrichment terms. CONCLUSION We detect many DNAm variants that may be associated with blood pressure in whole blood, particularly the loci within WNT3A and COL5A1. Our findings provide new clues to the epigenetic modification underlying hypertension pathogenesis.
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Affiliation(s)
- Weijing Wang
- Department of Epidemiology and Health Statistics, Public Health College, Qingdao University, No. 308 Ningxia Road, Qingdao, 266021, Shandong, China
| | - Jie Yao
- Department of Epidemiology and Health Statistics, Public Health College, Qingdao University, No. 308 Ningxia Road, Qingdao, 266021, Shandong, China
- Jiangsu Health Development Research Center, Nanjing, Jiangsu, China
| | - Weilong Li
- Population Research Unit, Faculty of Social Sciences, University of Helsinki, Helsinki, Finland
| | - Yili Wu
- Department of Epidemiology and Health Statistics, Public Health College, Qingdao University, No. 308 Ningxia Road, Qingdao, 266021, Shandong, China
| | - Haiping Duan
- Qingdao Municipal Center for Disease Control and Prevention/Qingdao Institute of Preventive Medicine, Qingdao, Shandong, China
| | - Chunsheng Xu
- Qingdao Municipal Center for Disease Control and Prevention/Qingdao Institute of Preventive Medicine, Qingdao, Shandong, China
| | - Xiaocao Tian
- Qingdao Municipal Center for Disease Control and Prevention/Qingdao Institute of Preventive Medicine, Qingdao, Shandong, China
| | - Shuxia Li
- Unit of Human Genetics, Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Qihua Tan
- Unit of Human Genetics, Department of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Dongfeng Zhang
- Department of Epidemiology and Health Statistics, Public Health College, Qingdao University, No. 308 Ningxia Road, Qingdao, 266021, Shandong, China.
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de Lange MJ, Razzaq L, Versluis M, Verlinde S, Dogrusöz M, Böhringer S, Marinkovic M, Luyten GPM, de Keizer RJW, de Gruijl FR, Jager MJ, van der Velden PA. Distribution of GNAQ and GNA11 Mutation Signatures in Uveal Melanoma Points to a Light Dependent Mutation Mechanism. PLoS One 2015; 10:e0138002. [PMID: 26368812 PMCID: PMC4569098 DOI: 10.1371/journal.pone.0138002] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 08/24/2015] [Indexed: 11/24/2022] Open
Abstract
Uveal melanomas (UM) originate from melanocytes in the interior wall of the eye, namely from the iris, ciliary body and the choroid with marked differences in light exposure (from dark anterior to illuminated posterior). In contrast to UV radiation, focused or converging visible light readily reaches the retina and can damage DNA which possibly contributes to UM development. In this report choroidal, ciliochoroidal and iridociliary melanomas were analyzed for GNAQ and GNA11 mutations which were subsequently correlated to the location of tumor origin. Hotspot mutations in GNAQ and GNA11 can be divided in A>T and in A>C mutation signatures. The GNAQ A626C mutation (Q209P) was almost exclusively observed in choroidal melanomas from the illuminated posterior side. On the other hand, ciliochoroidal UM from the dark anterior side with mostly A>T mutations were clearly associated with light-colored eyes. Combined these data suggest a light and a pigment dependent etiology in UM development.
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Affiliation(s)
- Mark J. de Lange
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - Lubna Razzaq
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - Mieke Versluis
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - Sven Verlinde
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - Mehmet Dogrusöz
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - Stefan Böhringer
- Department of Medical Statistics, Leiden University Medical Center, Leiden, the Netherlands
| | - Marina Marinkovic
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | | | - Rob J. W. de Keizer
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
| | - Frank R. de Gruijl
- Department of Dermatology, Leiden University Medical Center, Leiden, the Netherlands
| | - Martine J. Jager
- Department of Ophthalmology, Leiden University Medical Center, Leiden, the Netherlands
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Abstract
The intestinal microbiome can regulate host energy homeostasis and the development of metabolic disease. Here we identify GPR43, a receptor for bacterially produced short-chain fatty acids (SCFAs), as a modulator of microbiota-host interaction. β-Cell expression of GPR43 and serum levels of acetate, an endogenous SCFA, are increased with a high-fat diet (HFD). HFD-fed GPR43 knockout (KO) mice develop glucose intolerance due to a defect in insulin secretion. In vitro treatment of isolated murine islets, human islets, and Min6 cells with (S)-2-(4-chlorophenyl)-3,3-dimethyl-N-(5-phenylthiazol-2-yl)butanamide (PA), a specific agonist of GPR43, increased intracellular inositol triphosphate and Ca(2+) levels, and potentiated insulin secretion in a GPR43-, Gαq-, and phospholipase C-dependent manner. In addition, KO mice fed an HFD displayed reduced β-cell mass and expression of differentiation genes, and the treatment of Min6 cells with PA increased β-cell proliferation and gene expression. Together these findings identify GPR43 as a potential target for therapeutic intervention.
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Affiliation(s)
- Joanne C McNelis
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Yun Sok Lee
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Rafael Mayoral
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Rik van der Kant
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA
| | - Andrew M F Johnson
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Joshua Wollam
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Jerrold M Olefsky
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, La Jolla, CA
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7
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Lian CG, Sholl LM, Zakka LR, O TM, Liu C, Xu S, Stanek E, Garcia E, Jia Y, MacConaill LE, Murphy GF, Waner M, Mihm MC. Novel genetic mutations in a sporadic port-wine stain. JAMA Dermatol 2015; 150:1336-40. [PMID: 25188413 DOI: 10.1001/jamadermatol.2014.1244] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
IMPORTANCE Port-wine stains (PWSs) are common congenital cutaneous capillary malformations. A somatic GNAQ mutation was recently identified in patients with sporadic PWSs and Sturge-Weber syndrome. However, subsequent studies to confirm or extend this observation are lacking.OBSERVATIONS We report a long-standing, unilateral facial PWS of a man in his early 70s confirmed by histopathological analysis. Staged surgical excision of the vascular malformation was performed, and genomic DNA was extracted from the vascular malformation specimen and normal skin. Targeted next-generation sequencing of the coding sequence of 275 known cancer genes including GNAQ was performed in both specimens. A single-nucleotide variant(c.548G>A, p.Arg183Gln) in GNAQ was identified in the PWS-affected tissue but not in the normal skin sample. In addition, this sequencing approach uncovered several additional novel somatic mutations in the genes SMARCA4, EPHA3, MYB, PDGFR-β, and PIK3CA.CONCLUSIONS AND RELEVANCE Our findings confirm the presence of somatic mutations inGNAQ in the affected skin of a patient with congenital PWS, as well as alterations in several other novel genes of possible importance in the pathogenesis of PWS that may also offer substantial therapeutic targets.
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Abstract
Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) are the major downstream effectors of the Hippo pathway, which regulates tissue homeostasis, organ size, regeneration and tumorigenesis. In this Progress article, we summarize the current understanding of the biological functions of YAP and TAZ, and how the regulation of these two proteins can be disrupted in cancer. We also highlight recent findings on their expanding role in cancer progression and describe the potential of these targets for therapeutic intervention.
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Affiliation(s)
- Toshiro Moroishi
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, California 92093, USA
| | - Carsten Gram Hansen
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, California 92093, USA
| | - Kun-Liang Guan
- Department of Pharmacology and Moores Cancer Center, University of California, San Diego, La Jolla, California 92093, USA
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Posch C, Latorre A, Crosby MB, Celli A, Latorre A, Vujic I, Sanlorenzo M, Green GA, Weier J, Zekhtser M, Ma J, Monico G, Char DH, Jusufbegovic D, Rappersberger K, Somoza Á, Ortiz-Urda S. Detection of GNAQ mutations and reduction of cell viability in uveal melanoma cells with functionalized gold nanoparticles. Biomed Microdevices 2015; 17:15. [PMID: 25653058 PMCID: PMC4586106 DOI: 10.1007/s10544-014-9908-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND Uveal melanoma (UM) is the most common primary intraocular malignancy in adults. Early treatment may improve any chances of preventing metastatic disease, but diagnosis of small UM is challenging. Up to 95 % of all UMs carry somatic mutations in the G-coupled proteins GNAQ and GNA11 promoting anchorage-independent growth and proliferation. About 50 % of UMs are fatal. Once metastatic, patients have limited options for successful therapy. METHODS We have developed functionalized gold nanoparticles (AuNPs) to visualize transcripts of mutant GNAQ mRNA in living cells. In addition to their suitability as a specific tool for GNAQ mutation detection, we have developed a novel linker that enables conjugation of siRNAs to AuNPs allowing for greater and more rapid intracellular release of siRNAs compared to previously described approaches. RESULTS Binding of modified AuNPs to matching target mRNA leads to conformational changes, resulting in a detectable fluorescent signal that can be used for mutation detection in living cells. Knockdown of GNAQ with siRNA-AuNPs effectively reduced downstream signals and decreased cell viability in GNAQ mutant uveal melanoma cells. CONCLUSION AuNPs may in future be developed to serve as sensors for mutations of vital importance. The new release system for siRNA-AuNP improves previous systems, which conceivably will be useful for future therapeutic gene regulatory approaches.
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Affiliation(s)
- Christian Posch
- Department of Dermatology, Mount Zion Cancer Research Center, University of California San Francisco, 2340 Sutter Street N461, 94115, San Francisco, CA, USA,
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10
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Abstract
Purpose To examine whether GNAQ and GNA11 somatic mutations previously identified in uveal melanomas of Caucasians are associated with uveal melanomas in Chinese patients. Methods Uveal melanomas treated by primary enucleation in Chinese patients underwent a mutation analysis of GNAQ and GNA11 with sequencing of exon 5 and exon 4. Results The study included 50 patients with uveal melanoma and with a mean age of 47.6±13.0 years. During the follow-up of at least 3 years, 20 (40%) patients developed extraocular metastases. The frequencies of GNAQ and GNA11 somatic mutations in uveal melanoma were 18% (9/50) and 20% (10/50), respectively. The mutations occurred exclusively in codon 209 of exon 5. No mutations were detected in exon 4. Mutations affecting codon 209 in GNAQ were c.626A>C(Q209P) (78%) and c.626A>T(Q209L) (22%). Mutations affecting codon 209 in GNA11 were exclusively c.626A>T(Q209L) (100%). In none of the tumors, mutations of BRAF and NRAS were detected. GNAQ/11 mutations were marginally (P = 0.045) associated with optic disc involvement. In Kaplan-Meier analysis, metastasis-free survival was not significantly (P = 0.94) associated with GNAQ/11 mutations. Conclusions Mutations of GNAQ and GNA11 can be found in Chinese patients as in Caucasian patients with uveal melanoma, with a higher frequency reported for Caucasian patients.
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Affiliation(s)
- Xiaolin Xu
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, China
| | - Wen Bin Wei
- Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
- * E-mail:
| | - Bin Li
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, China
| | - Fei Gao
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, China
| | - Zhibao Zhang
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, China
| | - Jost B. Jonas
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Laboratory, Beijing, China
- Department of Ophthalmology, Medical Faculty Mannheim of the Ruprecht-Karls-University of Heidelberg, Seegartenklinik Heidelberg, Germany
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11
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Sagoo MS, Harbour JW, Stebbing J, Bowcock AM. Combined PKC and MEK inhibition for treating metastatic uveal melanoma. Oncogene 2014; 33:4722-3. [PMID: 24413085 PMCID: PMC4356624 DOI: 10.1038/onc.2013.555] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 11/15/2013] [Indexed: 12/11/2022]
Abstract
Uveal melanoma (UM) is the most common primary intraocular malignancy and the second most common form of melanoma. UM has a strong tendency for metastatic disease, and no effective treatments have yet been identified. Activating oncogenic mutations are commonly found in GNAQ and GNA11 in UM, and inhibiting key downstream effectors of the GNAQ/11 signaling pathway represents a rational therapeutic approach for treating metastatic UM. Chen et al., doi:10.1038/onc.2013.418, now confirm activation of the MAPK and PKC pathways as a result of GNAQ and GNA11 activating mutations in melanocytes, and they demonstrate that MAPK activation occurs downstream of PKC activation. PKC inhibitors disrupt MAPK signaling and block proliferation of GNAQ/11 mutant UM cell lines and slow the in vivo growth of xenografted UM tumors without inducing their shrinkage. However, a combination of PKC and MEK inhibition led to sustained MAPK pathway inhibition and tumor regression in vivo. Hence, the authors concluded that MEK and PKC inhibition is synergistic, with superior efficacy to treatment of GNAQ/GNA11 mutant UMs with either drug alone.
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Affiliation(s)
- MS Sagoo
- Ocular Oncology Service, Moorfields Eye Hospital and St Bartholomew’s Hospital and UCL Institute of Ophthalmology, London, UK
| | - JW Harbour
- Ocular Oncology Service, Bascom Palmer Eye Institute & Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, FL, USA
| | - J Stebbing
- Department of Oncology, Imperial College, Hammersmith Campus, London, UK
| | - AM Bowcock
- National Heart and Lung Institute (NHLI), Imperial College of Science and Technology, London, UK
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12
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Feng X, Degese MS, Iglesias-Bartolome R, Vaque JP, Molinolo AA, Rodrigues M, Zaidi MR, Ksander BR, Merlino G, Sodhi A, Chen Q, Gutkind JS. Hippo-independent activation of YAP by the GNAQ uveal melanoma oncogene through a trio-regulated rho GTPase signaling circuitry. Cancer Cell 2014; 25:831-45. [PMID: 24882515 PMCID: PMC4074519 DOI: 10.1016/j.ccr.2014.04.016] [Citation(s) in RCA: 397] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2013] [Revised: 03/06/2014] [Accepted: 04/24/2014] [Indexed: 02/05/2023]
Abstract
Mutually exclusive activating mutations in the GNAQ and GNA11 oncogenes, encoding heterotrimeric Gαq family members, have been identified in ∼ 83% and ∼ 6% of uveal and skin melanomas, respectively. However, the molecular events underlying these GNAQ-driven malignancies are not yet defined, thus limiting the ability to develop cancer-targeted therapies. Here, we focused on the transcriptional coactivator YAP, a critical component of the Hippo signaling pathway that controls organ size. We found that Gαq stimulates YAP through a Trio-Rho/Rac signaling circuitry promoting actin polymerization, independently of phospholipase Cβ and the canonical Hippo pathway. Furthermore, we show that Gαq promotes the YAP-dependent growth of uveal melanoma cells, thereby identifying YAP as a suitable therapeutic target in uveal melanoma, a GNAQ/GNA11-initiated human malignancy.
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Affiliation(s)
- Xiaodong Feng
- Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-4340, USA; State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan 610041, China
| | - Maria Sol Degese
- Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-4340, USA
| | - Ramiro Iglesias-Bartolome
- Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-4340, USA
| | - Jose P Vaque
- Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-4340, USA
| | - Alfredo A Molinolo
- Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-4340, USA
| | - Murilo Rodrigues
- Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, MD 21287, USA
| | - M Raza Zaidi
- Fels Institute for Cancer Research and Molecular Biology, Temple University School of Medicine, Philadelphia, PA 19140, USA
| | - Bruce R Ksander
- Schepens Eye Research Institute, Harvard Medical School, Boston, MA 02114, USA
| | - Glenn Merlino
- Laboratory of Cancer Biology and Genetics, National Cancer Institute, Bethesda, MD 20892, USA
| | - Akrit Sodhi
- Wilmer Eye Institute, Johns Hopkins School of Medicine, Baltimore, MD 21287, USA
| | - Qianming Chen
- State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan 610041, China.
| | - J Silvio Gutkind
- Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892-4340, USA.
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Turajlic S, Furney SJ, Stamp G, Rana S, Ricken G, Oduko Y, Saturno G, Springer C, Hayes A, Gore M, Larkin J, Marais R. Whole-genome sequencing reveals complex mechanisms of intrinsic resistance to BRAF inhibition. Ann Oncol 2014; 25:959-67. [PMID: 24504448 PMCID: PMC3999800 DOI: 10.1093/annonc/mdu049] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 02/03/2014] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND BRAF is mutated in ∼42% of human melanomas (COSMIC. http://www.sanger.ac.uk/genetics/CGP/cosmic/) and pharmacological BRAF inhibitors such as vemurafenib and dabrafenib achieve dramatic responses in patients whose tumours harbour BRAF(V600) mutations. Objective responses occur in ∼50% of patients and disease stabilisation in a further ∼30%, but ∼20% of patients present primary or innate resistance and do not respond. Here, we investigated the underlying cause of treatment failure in a patient with BRAF mutant melanoma who presented primary resistance. METHODS We carried out whole-genome sequencing and single nucleotide polymorphism (SNP) array analysis of five metastatic tumours from the patient. We validated mechanisms of resistance in a cell line derived from the patient's tumour. RESULTS We observed that the majority of the single-nucleotide variants identified were shared across all tumour sites, but also saw site-specific copy-number alterations in discrete cell populations at different sites. We found that two ubiquitous mutations mediated resistance to BRAF inhibition in these tumours. A mutation in GNAQ sustained mitogen-activated protein kinase (MAPK) signalling, whereas a mutation in PTEN activated the PI3 K/AKT pathway. Inhibition of both pathways synergised to block the growth of the cells. CONCLUSIONS Our analyses show that the five metastases arose from a common progenitor and acquired additional alterations after disease dissemination. We demonstrate that a distinct combination of mutations mediated primary resistance to BRAF inhibition in this patient. These mutations were present in all five tumours and in a tumour sample taken before BRAF inhibitor treatment was administered. Inhibition of both pathways was required to block tumour cell growth, suggesting that combined targeting of these pathways could have been a valid therapeutic approach for this patient.
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Affiliation(s)
| | - S. J. Furney
- Molecular Oncology Group, Cancer Research UK Manchester Institute, Manchester
| | - G. Stamp
- Experimental Pathology Laboratory, Cancer Research UK London Research Institute, London
| | - S. Rana
- The Institute of Cancer Research, London
| | - G. Ricken
- The Institute of Cancer Research, London
| | - Y. Oduko
- The Institute of Cancer Research, London
| | - G. Saturno
- Molecular Oncology Group, Cancer Research UK Manchester Institute, Manchester
| | - C. Springer
- Division of Cancer Therapeutics, The Institute of Cancer Research, London
| | | | - M. Gore
- Melanoma Unit, Royal Marsden Hospital, London, UK
| | - J. Larkin
- Melanoma Unit, Royal Marsden Hospital, London, UK
| | - R. Marais
- Molecular Oncology Group, Cancer Research UK Manchester Institute, Manchester
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14
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Levasseur SD, Paton KE, Van Raamsdonk CD, Heran MKS, White VA. Mutation of GNAQ in a cytologically unusual choroidal melanoma in an 18-month-old child. JAMA Ophthalmol 2013; 131:810-2. [PMID: 23572156 DOI: 10.1001/jamaophthalmol.2013.2483] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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15
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Shirley MD, Tang H, Gallione CJ, Baugher JD, Frelin LP, Cohen B, North PE, Marchuk DA, Comi AM, Pevsner J. Sturge-Weber syndrome and port-wine stains caused by somatic mutation in GNAQ. N Engl J Med 2013; 368:1971-9. [PMID: 23656586 PMCID: PMC3749068 DOI: 10.1056/nejmoa1213507] [Citation(s) in RCA: 606] [Impact Index Per Article: 55.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND The Sturge-Weber syndrome is a sporadic congenital neurocutaneous disorder characterized by a port-wine stain affecting the skin in the distribution of the ophthalmic branch of the trigeminal nerve, abnormal capillary venous vessels in the leptomeninges of the brain and choroid, glaucoma, seizures, stroke, and intellectual disability. It has been hypothesized that somatic mosaic mutations disrupting vascular development cause both the Sturge-Weber syndrome and port-wine stains, and the severity and extent of presentation are determined by the developmental time point at which the mutations occurred. To date, no such mutation has been identified. METHODS We performed whole-genome sequencing of DNA from paired samples of visibly affected and normal tissue from 3 persons with the Sturge-Weber syndrome. We tested for the presence of a somatic mosaic mutation in 97 samples from 50 persons with the Sturge-Weber syndrome, a port-wine stain, or neither (controls), using amplicon sequencing and SNaPshot assays, and investigated the effects of the mutation on downstream signaling, using phosphorylation-specific antibodies for relevant effectors and a luciferase reporter assay. RESULTS We identified a nonsynonymous single-nucleotide variant (c.548G→A, p.Arg183Gln) in GNAQ in samples of affected tissue from 88% of the participants (23 of 26) with the Sturge-Weber syndrome and from 92% of the participants (12 of 13) with apparently nonsyndromic port-wine stains, but not in any of the samples of affected tissue from 4 participants with an unrelated cerebrovascular malformation or in any of the samples from the 6 controls. The prevalence of the mutant allele in affected tissues ranged from 1.0 to 18.1%. Extracellular signal-regulated kinase activity was modestly increased during transgenic expression of mutant Gαq. CONCLUSIONS The Sturge-Weber syndrome and port-wine stains are caused by a somatic activating mutation in GNAQ. This finding confirms a long-standing hypothesis. (Funded by the National Institutes of Health and Hunter's Dream for a Cure Foundation.).
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Affiliation(s)
- Matthew D Shirley
- Biochemistry, Cellular and Molecular Biology Program, Johns Hopkins School of Medicine, and Department of Neurology and Developmental Medicine, Hugo W. Moser Research Institute at Kennedy Krieger, Baltimore, MD 21205, USA
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16
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Ambrosini G, Pratilas CA, Qin LX, Tadi M, Surriga O, Carvajal RD, Schwartz GK. Identification of unique MEK-dependent genes in GNAQ mutant uveal melanoma involved in cell growth, tumor cell invasion, and MEK resistance. Clin Cancer Res 2012; 18:3552-61. [PMID: 22550165 DOI: 10.1158/1078-0432.ccr-11-3086] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Metastatic uveal melanoma represents the most common intraocular malignancy with very poor prognosis and no effective treatments. Oncogenic mutations in the G-protein α-subunit q and 11 have been described in about 85% of uveal melanomas and confer constitutive activation. Multiple signaling pathways are induced as a consequence of GNAQ/11 activation, which include the MEK/ERK kinase cascade. We analyzed the transcriptional profile of cell lines treated with a mitogen-activated protein (MAP)/extracellular signal-regulated (ERK) kinase (MEK) inhibitor to identify gene targets of activated GNAQ and to evaluate the biologic importance of these genes in uveal melanoma. EXPERIMENTAL DESIGN We conducted microarray analysis of uveal melanoma cell lines with GNAQ mutations treated with the MEK inhibitor selumetinib. For comparison, we used cells carrying BRAF(V600E) and cells without either mutation. Changes in the expression of selected genes were then confirmed by quantitative real-time PCR and immunoblotting. RESULTS We found that GNAQ mutant cells have a MEK-dependent transcriptional output and identified a unique set of genes that are downregulated by MEK inhibition, including the RNA helicase DDX21 and the cyclin-dependent kinase regulator CDK5R1 whereas Jun was induced. We provide evidence that these genes are involved in cell proliferation, tumor cell invasion, and drug resistance, respectively. Furthermore, we show that selumetinib treatment regulates the expression of these genes in tumor tissues of patients with metastatic GNAQ/11 mutant uveal melanoma. CONCLUSIONS Our findings define a subset of transcriptionally regulated genes by selumetinib in GNAQ mutant cells and provide new insights into understanding the biologic effect of MEK inhibition in this disease.
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Affiliation(s)
- Grazia Ambrosini
- Laboratory of New Drug Development and Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York 10065, USA.
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17
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Lovly CM, Dahlman KB, Fohn LE, Su Z, Dias-Santagata D, Hicks DJ, Hucks D, Berry E, Terry C, Duke M, Su Y, Sobolik-Delmaire T, Richmond A, Kelley MC, Vnencak-Jones CL, Iafrate AJ, Sosman J, Pao W. Routine multiplex mutational profiling of melanomas enables enrollment in genotype-driven therapeutic trials. PLoS One 2012; 7:e35309. [PMID: 22536370 PMCID: PMC3335021 DOI: 10.1371/journal.pone.0035309] [Citation(s) in RCA: 148] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 03/13/2012] [Indexed: 01/07/2023] Open
Abstract
Purpose Knowledge of tumor mutation status is becoming increasingly important for the treatment of cancer, as mutation-specific inhibitors are being developed for clinical use that target only sub-populations of patients with particular tumor genotypes. Melanoma provides a recent example of this paradigm. We report here development, validation, and implementation of an assay designed to simultaneously detect 43 common somatic point mutations in 6 genes (BRAF, NRAS, KIT, GNAQ, GNA11, and CTNNB1) potentially relevant to existing and emerging targeted therapies specifically in melanoma. Methods The test utilizes the SNaPshot method (multiplex PCR, multiplex primer extension, and capillary electrophoresis) and can be performed rapidly with high sensitivity (requiring 5–10% mutant allele frequency) and minimal amounts of DNA (10–20 nanograms). The assay was validated using cell lines, fresh-frozen tissue, and formalin-fixed paraffin embedded tissue. Clinical characteristics and the impact on clinical trial enrollment were then assessed for the first 150 melanoma patients whose tumors were genotyped in the Vanderbilt molecular diagnostics lab. Results Directing this test to a single disease, 90 of 150 (60%) melanomas from sites throughout the body harbored a mutation tested, including 57, 23, 6, 3, and 2 mutations in BRAF, NRAS, GNAQ, KIT, and CTNNB1, respectively. Among BRAF V600 mutations, 79%, 12%, 5%, and 4% were V600E, V600K, V600R, and V600M, respectively. 23 of 54 (43%) patients with mutation harboring metastatic disease were subsequently enrolled in genotype-driven trials. Conclusion We present development of a simple mutational profiling screen for clinically relevant mutations in melanoma. Adoption of this genetically-informed approach to the treatment of melanoma has already had an impact on clinical trial enrollment and prioritization of therapy for patients with the disease.
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Affiliation(s)
- Christine M. Lovly
- Division of Hematology-Oncology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Kimberly Brown Dahlman
- Department of Cancer Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Laurel E. Fohn
- Division of Hematology-Oncology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Zengliu Su
- Division of Hematology-Oncology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Dora Dias-Santagata
- Translational Research Laboratory, Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Donna J. Hicks
- Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Donald Hucks
- Vanderbilt-Ingram Cancer Center, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Elizabeth Berry
- Division of Hematology-Oncology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Charles Terry
- Division of Hematology-Oncology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - MarKeesa Duke
- Division of Hematology-Oncology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Yingjun Su
- Department of Cancer Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Tammy Sobolik-Delmaire
- Department of Cancer Biology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Ann Richmond
- Department of Cancer Biology, Department of Veterans Affairs, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Mark C. Kelley
- Division of Surgical Oncology, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - Cindy L. Vnencak-Jones
- Departments of Pathology, Microbiology, Immunology and Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - A. John Iafrate
- Translational Research Laboratory, Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jeffrey Sosman
- Division of Hematology-Oncology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
| | - William Pao
- Division of Hematology-Oncology, Department of Medicine, Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
- * E-mail:
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Wu X, Zhu M, Fletcher JA, Giobbie-Hurder A, Hodi FS. The protein kinase C inhibitor enzastaurin exhibits antitumor activity against uveal melanoma. PLoS One 2012; 7:e29622. [PMID: 22253748 PMCID: PMC3257235 DOI: 10.1371/journal.pone.0029622] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Accepted: 12/02/2011] [Indexed: 01/23/2023] Open
Abstract
GNAQ mutations at codon 209 have been recently identified in approximately 50% of uveal melanomas (UM) and are reported to be oncogenic through activating the MAPK/Erk1/2 pathway. Protein kinase C (PKC) is a component of signaling from GNAQ to Erk1/2. Inhibition of PKC might regulate GNAQ mutation-induced Erk1/2 activation, resulting in growth inhibition of UM cells carrying GNAQ mutations. UM cells carrying wild type or mutant GNAQ were treated with the PKC inhibitor enzastaurin. Effects on proliferation, apoptosis, and signaling events were evaluated. Enzastaurin downregulated the expression of several PKC isoforms including PKCβII PKCθ, PKCε and/or their phosphorylation in GNAQ mutated cells. Downregulation of these PKC isoforms in GNAQ mutated cells by shRNA resulted in reduced viability. Enzastaurin exhibited greater antiproliferative effect on GNAQ mutant cells than wild type cells through induction of G1 arrest and apoptosis. Enzastaurin-induced G1 arrest was associated with inhibition of Erk1/2 phosphorylation, downregulation of cyclin D1, and accumulation of cyclin dependent kinase inhibitor p27Kip1. Furthermore, enzastaurin reduced the expression of antiapoptotic Bcl-2 and survivin in GNAQ mutant cells. Inhibition of Erk1/2 phosphorylation with a MEK specific inhibitor enhanced the sensitivity of GNAQ wild type cells to enzastaurin, accompanied by p27Kip1 accumulation and/or inhibition of enzastaurin-induced survivin and Bcl-2 upregulation. PKC inhibitors such as enzastaurin have activity against UM cells carrying GNAQ mutations through inhibition of the PKC/Erk1/2 pathway and induction of G1 arrest and apoptosis. Inhibition of the PKC pathway provides a basis for clinical investigation in patients with UM.
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Affiliation(s)
- Xinqi Wu
- Department of Medical Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, United States of America
- Melanoma Program, Dana-Farber/Brigham and Women's Cancer Center, Boston, Massachusetts, United States of America
| | - Meijun Zhu
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Jonathan A. Fletcher
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, United States of America
| | - Anita Giobbie-Hurder
- Department of Biostatistics and Computational Biology, Dana-Farber Cancer Institute, Boston, Massachusetts, United States of America
| | - F. Stephen Hodi
- Department of Medical Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, United States of America
- Melanoma Program, Dana-Farber/Brigham and Women's Cancer Center, Boston, Massachusetts, United States of America
- * E-mail:
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Christopher BN, Cebulla CM, Wakely PE, Davidorf FH, Abdel-Rahman MH. Molecular genetic testing of uveal melanoma from routinely processed and stained cytology specimens. Exp Eye Res 2011; 93:720-5. [PMID: 21945171 DOI: 10.1016/j.exer.2011.09.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 08/01/2011] [Accepted: 09/08/2011] [Indexed: 11/20/2022]
Abstract
In the following study we investigated the utility of molecular genetic testing of the DNA extracted from routinely stained and processed smears from uveal melanoma (UM). Smears from five uveal melanoma cell lines and 12 primary tumors were prepared and stained with Papanicolaou and Romanowsky stains. Genotyping was carried out utilizing 14 microsatellite markers on chromosomes 3, 6 and 8. Mutational screening for alterations in GNAQ and GNA11 genes was carried out by restriction fragment length polymorphism. The results were compared to those obtained through direct sequencing of frozen tumor tissues. High quality DNA was extracted from the stained slides with no difference in the efficiency of DNA extraction between the two staining techniques. The extracted DNA was of adequate quality for genotyping and mutational screening. DNA extracted from approximately 200 tumor cells is sufficient for reproducible testing of allelic imbalances and for studying the common somatic mutations in GNAQ and GNA11 genes. In conclusion, we presented the feasibility of utilizing routinely stained cytology smears from UM for molecular genetic testing. The DNA obtained is of sufficient quality to carry out genotyping for markers on chromosome 3, 6 and 8, as well as screening for somatic mutations in GNAQ and GNA11 genes.
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MESH Headings
- Chromosomes, Human, Pair 3/genetics
- Chromosomes, Human, Pair 6/genetics
- Chromosomes, Human, Pair 8/genetics
- DNA Mutational Analysis
- DNA, Neoplasm/analysis
- DNA, Neoplasm/isolation & purification
- Feasibility Studies
- GTP-Binding Protein alpha Subunits/genetics
- GTP-Binding Protein alpha Subunits, Gq-G11
- Genotype
- Genotyping Techniques
- Histocytological Preparation Techniques
- Humans
- Melanoma/genetics
- Melanoma/pathology
- Microsatellite Repeats/genetics
- Molecular Diagnostic Techniques
- Polymorphism, Restriction Fragment Length
- Tumor Cells, Cultured
- Uveal Neoplasms/genetics
- Uveal Neoplasms/pathology
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Abstract
Frequent mutations in the GNAQ, MMP8, Akt3, EGFR, and PIK3R1 genes have been reported in human cancers but mostly have not been well examined in thyroid cancer. Selected exons of GNAQ, MMP8, AKT3, EGFR, and PIK3R1 genes were sequenced in various thyroid cancers. We found a G2203A EGFR mutation, resulting in a G735S amino acid change, in one of 21 (5%) papillary thyroid cancer samples. We did not find any mutation in the MMP8 gene, but observed a frequent SNP A259G (K87E) genotype switch in various types of thyroid cancer samples. We did not find any mutation in the GNAQ, AKT3, and PIK3R1 genes in various types of thyroid cancer. No mutation in these genes was found in 12 cell lines derived from various types of thyroid cancer. Therefore, unlike in other cancers, mutations in these genes are uncommon in thyroid cancer.
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Affiliation(s)
- Avaniyapuram Kannan Murugan
- Laboratory for Cellular and Molecular Thyroid Research, Division of Endocrinology and Metabolism, The Johns Hopkins University School of Medicine, 1830, East Monument Street, Suite 333, Baltimore, MD 21287, USA
| | - Jianli Dong
- Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Jingwu Xie
- Department of Pediatrics, Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Mingzhao Xing
- Laboratory for Cellular and Molecular Thyroid Research, Division of Endocrinology and Metabolism, The Johns Hopkins University School of Medicine, 1830, East Monument Street, Suite 333, Baltimore, MD 21287, USA
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Abstract
Melanoma is an aggressive disease with few standard treatment options. The conventional classification system for this disease is based on histological growth patterns, with division into four subtypes: superficial spreading, lentigo maligna, nodular, and acral lentiginous. Major limitations of this classification system are absence of prognostic importance and little correlation with treatment outcomes. Recent preclinical and clinical findings support the notion that melanoma is not one malignant disorder but rather a family of distinct molecular diseases. Incorporation of genetic signatures into the conventional histopathological classification of melanoma has great implications for development of new and effective treatments. Genes of the mitogen-associated protein kinase (MAPK) pathway harbour alterations sometimes identified in people with melanoma. The mutation Val600Glu in the BRAF oncogene (designated BRAF(V600E)) has been associated with sensitivity in vitro and in vivo to agents that inhibit BRAF(V600E) or MEK (a kinase in the MAPK pathway). Melanomas arising from mucosal, acral, chronically sun-damaged surfaces sometimes have oncogenic mutations in KIT, against which several inhibitors have shown clinical efficacy. Some uveal melanomas have activating mutations in GNAQ and GNA11, rendering them potentially susceptible to MEK inhibition. These findings suggest that prospective genotyping of patients with melanoma should be used increasingly as we work to develop new and effective treatments for this disease.
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Affiliation(s)
- Emanuela Romano
- Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
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22
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Van Raamsdonk CD, Griewank KG, Crosby MB, Garrido MC, Vemula S, Wiesner T, Obenauf AC, Wackernagel W, Green G, Bouvier N, Sozen MM, Baimukanova G, Roy R, Heguy A, Dolgalev I, Khanin R, Busam K, Speicher MR, O'Brien J, Bastian BC. Mutations in GNA11 in uveal melanoma. N Engl J Med 2010; 363:2191-9. [PMID: 21083380 PMCID: PMC3107972 DOI: 10.1056/nejmoa1000584] [Citation(s) in RCA: 1029] [Impact Index Per Article: 73.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Uveal melanoma is the most common intraocular cancer. There are no effective therapies for metastatic disease. Mutations in GNAQ, the gene encoding an alpha subunit of heterotrimeric G proteins, are found in 40% of uveal melanomas. METHODS We sequenced exon 5 of GNAQ and GNA11, a paralogue of GNAQ, in 713 melanocytic neoplasms of different types (186 uveal melanomas, 139 blue nevi, 106 other nevi, and 282 other melanomas). We sequenced exon 4 of GNAQ and GNA11 in 453 of these samples and in all coding exons of GNAQ and GNA11 in 97 uveal melanomas and 45 blue nevi. RESULTS We found somatic mutations in exon 5 (affecting Q209) and in exon 4 (affecting R183) in both GNA11 and GNAQ, in a mutually exclusive pattern. Mutations affecting Q209 in GNA11 were present in 7% of blue nevi, 32% of primary uveal melanomas, and 57% of uveal melanoma metastases. In contrast, we observed Q209 mutations in GNAQ in 55% of blue nevi, 45% of uveal melanomas, and 22% of uveal melanoma metastases. Mutations affecting R183 in either GNAQ or GNA11 were less prevalent (2% of blue nevi and 6% of uveal melanomas) than the Q209 mutations. Mutations in GNA11 induced spontaneously metastasizing tumors in a mouse model and activated the mitogen-activated protein kinase pathway. CONCLUSIONS Of the uveal melanomas we analyzed, 83% had somatic mutations in GNAQ or GNA11. Constitutive activation of the pathway involving these two genes appears to be a major contributor to the development of uveal melanoma. (Funded by the National Institutes of Health and others.).
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Abstract
Activating mutations of GNAq protein in a hotspot at codon 209 have been recently described in uveal melanomas. Since these neoplasms share with thyroid carcinomas a high frequency of MAP kinase pathway-activating mutations, we hypothesized whether GNAq mutations could also play a role in the development of thyroid carcinomas. Additionally, activating mutations of another subtype of G protein (GNAS1) are frequently found in hyperfunctioning thyroid adenomas, making it plausible that GNAq-activating mutations could also be found in some of these nodules. To investigate thyroid papillary carcinomas and thyroid hyperfunctioning nodules for GNAq mutations in exon 5, codon 209, a total of 32 RET/PTC, BRAF, and RAS negative thyroid papillary carcinomas and 13 hyperfunctioning thyroid nodules were evaluated. No mutations were identified. Although plausible, GNAq mutations seem not to play an important role in the development of thyroid follicular neoplasms, either benign hyperfunctioning nodules or malignant papillary carcinomas. Our results are in accordance with the literature, in which no GNAq hotspot mutations were found in thyroid papillary carcinomas, as well as in an extensive panel of other tumors. The molecular basis for MAP-kinase pathway activation in RET-PTC/BRAF/RAS negative thyroid carcinomas remains to be determined.
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Affiliation(s)
- Clarissa A Cassol
- Department of Pathology, University of Toronto, Toronto, ON, Canada.
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Lents NH, Irintcheva V, Goel R, Wheeler LW, Baldassare JJ. The rapid activation of N-Ras by alpha-thrombin in fibroblasts is mediated by the specific G-protein Galphai2-Gbeta1-Ggamma5 and occurs in lipid rafts. Cell Signal 2009; 21:1007-14. [PMID: 19250965 DOI: 10.1016/j.cellsig.2009.02.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Revised: 02/18/2009] [Accepted: 02/18/2009] [Indexed: 11/20/2022]
Abstract
alpha-thrombin is a potent mitogen for fibroblasts and initiates a rapid signal transduction pathway leading to the activation of Ras and the stimulation of cell cycle progression. While the signaling events downstream of Ras have been studied in significant detail and appear well conserved across many species and cell types, the precise molecular events beginning with thrombin receptor activation and leading to the activation of Ras are not as well understood. In this study, we examined the immediate events in the rapid response to alpha-thrombin, in a single cell type, and found that an unexpected degree of specificity exists in the pathway linking alpha-thrombin to Ras activation. Specifically, although IIC9 cells express all three Ras isoforms, only N-Ras is rapidly activated by alpha-thrombin. Further, although several Galpha subunits associate with PAR1 and are released following stimulation, only Galpha(i2) couples to the rapid activation of Ras. Similarly, although IIC9 cells express many Gbeta and Ggamma subunits, only a subset associates with Galpha(i2), and of those, only a single Gbetagamma dimer, Gbeta(1)gamma(5), participates in the rapid activation of N-Ras. We then hypothesized that co-localization into membrane microdomains called lipid rafts, or caveolae, is at least partially responsible for this degree of specificity. Accordingly, we found that all components localize to lipid rafts and that disruption of caveolae abolishes the rapid activation of N-Ras by alpha-thrombin. We thus report the molecular elucidation of an extremely specific and rapid signal transduction pathway linking alpha-thrombin stimulation to the activation of Ras.
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Affiliation(s)
- Nathan H Lents
- Department of Sciences at John Jay College of Criminal Justice, City University of New York, New York, NY 10019, USA.
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Liu J, Joglekar M, Ware J, Fitzgerald MEC, Lowell CA, Berndt MC, Gartner TK. Evaluation of the physiological significance of botrocetin/ von Willebrand factor in vitro signaling. J Thromb Haemost 2008; 6:1915-22. [PMID: 18752568 PMCID: PMC2982674 DOI: 10.1111/j.1538-7836.2008.03135.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND A signaling pathway is difficult, if not impossible, to elucidate in platelets using only in vivo studies. Likewise, the physiological significance of signaling information obtained exclusively from in vitro observations is unknown. Therefore, both in vitro and in vivo experiments are required to establish the physiological significance of a signaling pathway. OBJECTIVE To evaluate the physiological significance of signaling data obtained from botrocetin (bt)/von Willebrand factor (VWF)-stimulated washed platelets. METHOD Stable thrombus formation in response to FeCl(3)-induced injury of the mouse carotid artery was used to evaluate the physiological significance of signaling data obtained from bt/VWF-stimulated washed platelets. RESULTS Syk, PLCgamma2, Galphaq and P2Y12, but not LAT, were found either to be required for or to affect stable thrombus formation. Prior in vitro studies had demonstrated that LAT is not required for bt/VWF-induced platelet aggregation in the presence of exogenous fibrinogen. These data provide the first demonstration of the in vivo role for these signaling molecules in GPIb-dependent/initiated signal transduction and are consistent with the signaling pathway deduced from in vitro studies of bt/VWF-stimulated washed platelets using metabolic inhibitors and knockout mice. CONCLUSION The broad agreement between the in vitro and the in vivo results establish that bt/VWF stimulation of washed platelets can provide physiologically significant glycoprotein Ib-dependent/initiated signaling data.
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Affiliation(s)
- J Liu
- Institutes of Medical Sciences, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
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27
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Gladue DP, Konopka JB. Scanning mutagenesis of regions in the Galpha protein Gpa1 that are predicted to interact with yeast mating pheromone receptors. FEMS Yeast Res 2007; 8:71-80. [PMID: 17892473 DOI: 10.1111/j.1567-1364.2007.00311.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The mechanism by which receptors activate heterotrimeric G proteins was examined by scanning mutagenesis of the Saccharomyces cerevisiae pheromone-responsive Galpha protein (Gpa1). The juxtaposition of high-resolution structures for rhodopsin and its cognate G protein transducin predicted that at least six regions of Galpha are in close proximity to the receptor. Mutagenesis was targeted to residues in these domains in Gpa1, which included four loop regions (beta2-beta3, alpha2-beta4, alpha3-beta5, and alpha4-beta6) as well as the N and C termini. The mutants displayed a range of phenotypes from nonsignaling to constitutive activation of the pheromone pathway. The constitutive activity of some mutants could be explained by decreased production of Gpa1, which permits unregulated signaling by Gbetagamma. However, the constitutive activity caused by the F344C and E335C mutations in the alpha2-beta4 loop and F378C in the alpha3-beta5 loop was not due to decreased protein levels, and was apparently due to defects in sequestering Gbetagamma. The strongest loss of the function mutant, which was not detectably induced by a pheromone, was caused by a K314C substitution in the beta2-beta3 loop. Several other mutations caused weak signaling phenotypes. Altogether, these results suggest that residues in different interface regions of Galpha contribute to activation of signaling.
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Affiliation(s)
- Douglas P Gladue
- Department of Molecular Genetics and Microbiology, State University of New York, Stony Brook, NY 11794-5222, USA
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28
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Abstract
Platelets release insulin-like growth factor-1 (IGF-1) from alpha granules upon activation. We have investigated the regulation of IGF-1 in G(i)-dependent pathways leading to Akt activation and the role of IGF-1 in platelet activation. IGF-1 alone failed to induce platelet aggregation, but IGF-1 potentiated 2-MeSADP-induced platelet aggregation in a concentration-dependent manner. IGF-1 triggered platelet aggregation in combination with selective P2Y(1) receptor activation. IGF-1 also caused platelet aggregation without shape change when combined with selective G(z) stimulation by epinephrine, suggesting the role of IGF-1 in platelet aggregation by supplementing G(i) pathways. The potentiating effect of IGF-1 was not affected by intracellular calcium chelation. Importantly, IGF-1 was unable to potentiate platelet aggregation by the phosphatidylinositol 3-kinase (PI3-K) inhibitor wortmannin, suggesting a critical regulation by PI3-K. Moreover, the potentiating effect of IGF-1 was abolished by the presence of PI3-K p110alpha inhibitor PIK-75. Stimulation of platelets with IGF-1 resulted in phosphorylation of Akt, a downstream effector of PI3-K, which was completely inhibited by wortmannin. IGF-1-induced Akt phosphorylation was abolished by PIK-75 suggesting the contribution of PI3-K p110alpha for activation of Akt by IGF-1. These results demonstrate that IGF-1 plays a role in potentiating platelet aggregation by complementing G(i)- but not G(q)-signaling pathways via PI3-K p110alpha.
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Affiliation(s)
- Soochong Kim
- Department of Physiology and Pharmacology and the Sol Sherry Thrombosis Research Center, Temple University School of Medicine, Philadelphia, PA 19140, USA
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29
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Abstract
Functional genomics relies on two essential parameters: the sensitivity of phenotypic measures and the power to detect genomic perturbations that cause phenotypic variations. In model organisms, two types of perturbations are widely used. Artificial mutations can be introduced in virtually any gene and allow the systematic analysis of gene function via mutants fitness. Alternatively, natural genetic variations can be associated to particular phenotypes via genetic mapping. However, the access to genome manipulation and breeding provided by model organisms is sometimes counterbalanced by phenotyping limitations. Here we investigated the natural genetic diversity of Saccharomyces cerevisiae cellular morphology using a very sensitive high-throughput imaging platform. We quantified 501 morphological parameters in over 50,000 yeast cells from a cross between two wild-type divergent backgrounds. Extensive morphological differences were found between these backgrounds. The genetic architecture of the traits was complex, with evidence of both epistasis and transgressive segregation. We mapped quantitative trait loci (QTL) for 67 traits and discovered 364 correlations between traits segregation and inheritance of gene expression levels. We validated one QTL by the replacement of a single base in the genome. This study illustrates the natural diversity and complexity of cellular traits among natural yeast strains and provides an ideal framework for a genetical genomics dissection of multiple traits. Our results did not overlap with results previously obtained from systematic deletion strains, showing that both approaches are necessary for the functional exploration of genomes.
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Affiliation(s)
- Satoru Nogami
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba, Japan
| | - Yoshikazu Ohya
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba, Japan
- * To whom correspondence should be addressed. E-mail: (image analysis); (all other inquiries)
| | - Gaël Yvert
- Laboratoire de Biotechnologie et Bioprocédés, Institut National des Sciences Appliquées, Centre National de la Recherche Scientifique UMR5504, Toulouse, France
- Université de Lyon, Lyon, France; Université Lyon 1, Lyon, France; Laboratoire de Biologie Moléculaire de la Cellule, Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, Lyon, France; IFR128 BioSciences Lyon-Gerland, Lyon, France
- * To whom correspondence should be addressed. E-mail: (image analysis); (all other inquiries)
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30
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Jones PG, Nawoschik SP, Sreekumar K, Uveges AJ, Tseng E, Zhang L, Johnson J, He L, Paulsen JE, Bates B, Pausch MH. Tissue distribution and functional analyses of the constitutively active orphan G protein coupled receptors, GPR26 and GPR78. Biochim Biophys Acta Gen Subj 2007; 1770:890-901. [PMID: 17363172 DOI: 10.1016/j.bbagen.2007.01.013] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2006] [Revised: 01/12/2007] [Accepted: 01/17/2007] [Indexed: 11/22/2022]
Abstract
GPR26 and GPR78 are orphan GPCRs (oGPCRs) that share 51% amino acid sequence identity and are widely expressed in selected tissues of the human brain as well as the developing and adult mouse brain. Investigation of the functional activity of GPR26 and GPR78 via expression in HEK293 cells showed that both proteins are constitutively active and coupled to elevated cAMP production. Accordingly, in yeast, GPR26 demonstrated apparent agonist-independent coupling to a chimeric Gpa1 protein in which the 5 C-terminal amino acids were from Galphas. A comparison of the proteins revealed an atypical glutamine residue in GPR78 in place of the conserved arginine residue (R3.50) in the so-called DRY box. Site-directed mutants R3.50 in GPR26 were constructed and retained their constitutive activity suggesting that these 2 receptors activate G proteins in a manner that is distinct from other group 1 GPCRs.
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Affiliation(s)
- Philip G Jones
- Neuroscience Discovery Research, Wyeth Research, CN8000, Princeton, NJ 08543, USA
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31
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Abstract
Signaling by cell surface receptors and heterotrimeric guanine nucleotide-binding proteins (G proteins) is one of the most exhaustively studied processes in the cell but remains a major focus of molecular pharmacology research. The pheromone-response system in yeast (see the Connections Map at Science's Signal Transduction Knowledge Environment) has provided numerous major advances in our understanding of G protein signaling and regulation. However, the basic features of this prototypical pathway have remained largely unchanged since the mid-1990s. New tools available in yeast are beginning to uncover new pathway components and interactions and have revealed signaling in unexpected locations within the cell.
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Affiliation(s)
- Janna E Slessareva
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599-7260, USA
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32
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Ooms LS, Koster MJ, Mitchell JR, Pals-Rylaarsdam R. Identification of a second-site suppressor mutation of the GTPase defect associated with McCune-Albright syndrome: a model using the yeast heterotrimeric G protein, GPA1. Arch Physiol Biochem 2006; 112:166-73. [PMID: 17132542 DOI: 10.1080/13813450600935271] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
McCune-Albright syndrome (MAS) causes a variety of bone and endocrine abnormalities due to the post-zygotic mutation of the alpha subunit of the stimulatory G-protein Gsalpha. This mutation causes signal-independent activity of the G-protein in the affected cells. We report the development of a system to study the effects of MAS mutations using Saccharomyces cerevisiae, wherein activation of the yeast G-protein pathway results in growth arrest in a genetically recessive fashion. We introduced the MAS mutation into the analogous site in the yeast Galpha gene, GPA1 and randomly mutated the gene to produce intragenic suppressors. Yeast with normal and mutated G-protein genes were induced to lose the normal gene, and mutations able to intragenically suppress the constitutive activity of the MAS mutation were identified based on their ability to form colonies. We report one mutation in GPA1, also in the active site, that is an intragenic suppressor of the MAS defect.
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Affiliation(s)
- Laura S Ooms
- Trinity Christian College, Biology Department, Palos Heights, IL 60463, USA
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33
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Chasse SA, Flanary P, Parnell SC, Hao N, Cha JY, Siderovski DP, Dohlman HG. Genome-scale analysis reveals Sst2 as the principal regulator of mating pheromone signaling in the yeast Saccharomyces cerevisiae. Eukaryot Cell 2006; 5:330-46. [PMID: 16467474 PMCID: PMC1405904 DOI: 10.1128/ec.5.2.330-346.2006] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
A common property of G protein-coupled receptors is that they become less responsive with prolonged stimulation. Regulators of G protein signaling (RGS proteins) are well known to accelerate G protein GTPase activity and do so by stabilizing the transition state conformation of the G protein alpha subunit. In the yeast Saccharomyces cerevisiae there are four RGS-homologous proteins (Sst2, Rgs2, Rax1, and Mdm1) and two Galpha proteins (Gpa1 and Gpa2). We show that Sst2 is the only RGS protein that binds selectively to the transition state conformation of Gpa1. The other RGS proteins also bind Gpa1 and modulate pheromone signaling, but to a lesser extent and in a manner clearly distinct from Sst2. To identify other candidate pathway regulators, we compared pheromone responses in 4,349 gene deletion mutants representing nearly all nonessential genes in yeast. A number of mutants produced an increase (sst2, bar1, asc1, and ygl024w) or decrease (cla4) in pheromone sensitivity or resulted in pheromone-independent signaling (sst2, pbs2, gas1, and ygl024w). These findings suggest that Sst2 is the principal regulator of Gpa1-mediated signaling in vivo but that other proteins also contribute in distinct ways to pathway regulation.
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Affiliation(s)
- Scott A Chasse
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599-7260, USA
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34
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Hashimotodani Y, Ohno-Shosaku T, Kano M. [Mechanisms of triggering endocannabinoid release]. Seikagaku 2006; 78:126-30. [PMID: 16541803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Affiliation(s)
- Yuki Hashimotodani
- Department of Cellular Neurophysiology, Graduate School of Medical Science, Kanazawa University, Japan
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35
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Arimoto T, Takeishi Y, Takahashi H, Shishido T, Niizeki T, Koyama Y, Shiga R, Nozaki N, Nakajima O, Nishimaru K, Abe JI, Endoh M, Walsh RA, Goto K, Kubota I. Cardiac-Specific Overexpression of Diacylglycerol Kinase ζ Prevents Gq Protein-Coupled Receptor Agonist-Induced Cardiac Hypertrophy in Transgenic Mice. Circulation 2006; 113:60-6. [PMID: 16380548 DOI: 10.1161/circulationaha.105.560771] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
Diacylglycerol is a lipid second messenger that accumulates in cardiomyocytes when stimulated by Gqα protein-coupled receptor (GPCR) agonists such as angiotensin II, phenylephrine, and others. Diacylglycerol functions as a potent activator of protein kinase C (PKC) and is catalyzed by diacylglycerol kinase (DGK) to form phosphatidic acid and inactivated. However, the functional roles of DGK have not been previously examined in the heart. We hypothesized that DGK might prevent GPCR agonist-induced activation of diacylglycerol downstream signaling cascades and subsequent cardiac hypertrophy.
Methods and Results—
To test this hypothesis, we generated transgenic (DGKζ-TG) mice with cardiac-specific overexpression of DGKζ. There were no differences in heart size and heart weight between DGKζ-TG and wild-type littermate mice. The left ventricular function was normal in DGKζ-TG mice. Continuous administration of subpressor doses of angiotensin II and phenylephrine caused PKC translocation, gene induction of atrial natriuretic factor, and subsequent cardiac hypertrophy in WT mice. However, in DGKζ-TG mice, neither translocation of PKC nor upregulation of atrial natriuretic factor gene expression was observed after angiotensin II and phenylephrine infusion. Furthermore, in DGKζ-TG mice, angiotensin II and phenylephrine failed to increase cross-sectional cardiomyocyte areas and heart to body weight ratios. Phenylephrine-induced increases in myocardial diacylglycerol levels were completely blocked in DGKζ-TG mouse hearts, suggesting that DGKζ regulated PKC activity by controlling cellular diacylglycerol levels.
Conclusions—
These results demonstrated the first evidence that DGKζ negatively regulated the hypertrophic signaling cascade and resultant cardiac hypertrophy in response to GPCR agonists without detectable adverse effects in in vivo hearts.
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Affiliation(s)
- Takanori Arimoto
- First Department of Internal Medicine, Yamagata University School of Medicine, Yamagata, Japan
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36
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Liu AMF, Wong YH. Activation of Nuclear Factor κB by Somatostatin Type 2 Receptor in Pancreatic Acinar AR42J Cells Involves Gα14 and Multiple Signaling Components. J Biol Chem 2005; 280:34617-25. [PMID: 16115892 DOI: 10.1074/jbc.m504264200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Medications targeting the somatostatin type 2 receptor (SSTR2) have been employed for pancreatic inflammations and cancers, possibly via the regulation of the transcription factor nuclear factor kappaB (NFkappaB). Here we demonstrate that in tumoral pancreatic acinar AR42J cells, activation of SSTR2 leads to stimulation of the inhibitor kappaB kinase (IKK)/NFkappaB signaling cascade via pertussis toxin-insensitive G proteins in a time- and dose-dependent manner. The inability of G(q/11) and G(12/13) proteins to activate IKK/NFkappaB by SSTR2 in transfected human embryonic kidney 293 cells and the lack of Galpha(16) in AR42J cells suggested a possible role of Galpha(14) in mediating SSTR2-induced responses. This regulatory role of Galpha(14) was further confirmed by the activation of IKK and NFkappaB in human embryonic kidney 293 cells expressing SSTR2 and Galpha(14) upon induction. The stimulatory effect of Gbeta(1)gamma(2) and the abrogation by overexpressing transducin confirmed the participation of Gbetagamma in SSTR2-mediated IKK/NFkappaB activation. By the application of specific inhibitors and dominant negative mutants, phospholipase Cbeta, protein kinase C, and calmodulin-dependent kinase II were shown to be involved in SSTR2-induced responses. Inhibition of c-Src and numerous intermediates, including Ras, Raf-1 kinase, MEK1/2, along with the extracellular signal-regulated kinase cascade attenuated somatostatin-mediated IKK/NFkappaB activation. Although c-Jun N-terminal kinase and p38 mitogen-activated protein kinase (MAPK) were also stimulated by SSTR2, suppression of these two MAPKs was ineffective in altering the somatostatin-mediated responses. Similar results were also obtained using AR42J cells. These data suggest that activation of the IKK/NFkappaB signaling cascade by SSTR2 requires a complicated network consisting of Galpha(14) and multiple intermediates.
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Affiliation(s)
- Andrew M F Liu
- Department of Biochemistry, Molecular Neuroscience Center, and Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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37
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Kostenis E, Waelbroeck M, Milligan G. Techniques: promiscuous Galpha proteins in basic research and drug discovery. Trends Pharmacol Sci 2005; 26:595-602. [PMID: 16183138 DOI: 10.1016/j.tips.2005.09.007] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2005] [Revised: 08/01/2005] [Accepted: 09/12/2005] [Indexed: 10/25/2022]
Abstract
Assay technologies that measure the activation of heterotrimeric (alphabetagamma) G proteins by G-protein-coupled receptors (GPCRs) are well established within the pharmaceutical industry, either for pharmacological characterization or for the identification of natural or surrogate receptor ligands. Despite recent evidence indicating that GPCR-linked signalling events might not be mediated exclusively by G proteins, G-protein activation remains a common benchmark for assessing GPCR family members. Thus, assay systems that translate ligand-mediated modulation of GPCRs into G-protein-dependent intracellular responses still represent key components of both basic research and the drug discovery process. In this article, the current knowledge and recent progress of integrating Galpha subunits into assay systems for GPCR drug discovery will be reviewed. Emphasis is given to novel promiscuous and chimeric Galpha proteins. Because of their ability to interact with a wide range of GPCRs, such novel G proteins are likely to be incorporated rapidly into drug discovery programmes.
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Affiliation(s)
- Evi Kostenis
- 7TM Pharma A/S, 3 Fremtidsvej, 2970 Hoersholm, Denmark.
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38
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Brem RB, Storey JD, Whittle J, Kruglyak L. Genetic interactions between polymorphisms that affect gene expression in yeast. Nature 2005; 436:701-3. [PMID: 16079846 PMCID: PMC1409747 DOI: 10.1038/nature03865] [Citation(s) in RCA: 258] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2005] [Accepted: 06/02/2005] [Indexed: 11/08/2022]
Abstract
Interactions between polymorphisms at different quantitative trait loci (QTLs) are thought to contribute to the genetics of many traits, and can markedly affect the power of genetic studies to detect QTLs. Interacting loci have been identified in many organisms. However, the prevalence of interactions, and the nucleotide changes underlying them, are largely unknown. Here we search for naturally occurring genetic interactions in a large set of quantitative phenotypes--the levels of all transcripts in a cross between two strains of Saccharomyces cerevisiae. For each transcript, we searched for secondary loci interacting with primary QTLs detected by their individual effects. Such locus pairs were estimated to be involved in the inheritance of 57% of transcripts; statistically significant pairs were identified for 225 transcripts. Among these, 67% of secondary loci had individual effects too small to be significant in a genome-wide scan. Engineered polymorphisms in isogenic strains confirmed an interaction between the mating-type locus MAT and the pheromone response gene GPA1. Our results indicate that genetic interactions are widespread in the genetics of transcript levels, and that many QTLs will be missed by single-locus tests but can be detected by two-stage tests that allow for interactions.
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MESH Headings
- Crosses, Genetic
- GTP-Binding Protein alpha Subunits/genetics
- GTP-Binding Protein alpha Subunits/metabolism
- GTP-Binding Protein alpha Subunits, Gq-G11
- Gene Expression Regulation, Fungal/genetics
- Genes, Fungal/genetics
- Genes, Mating Type, Fungal
- Genome, Fungal
- Haploidy
- Mutation/genetics
- Pheromones/pharmacology
- Polymorphism, Genetic/genetics
- Quantitative Trait Loci/genetics
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Saccharomyces cerevisiae/drug effects
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/physiology
- Saccharomyces cerevisiae Proteins/genetics
- Saccharomyces cerevisiae Proteins/metabolism
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Affiliation(s)
- Rachel B Brem
- Program in Computational Biology, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N, M2-B876, Seattle, Washington 98109, USA.
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39
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Kaplan-Albuquerque N, Bogaert YE, Van Putten V, Weiser-Evans MC, Nemenoff RA. Patterns of gene expression differentially regulated by platelet-derived growth factor and hypertrophic stimuli in vascular smooth muscle cells: markers for phenotypic modulation and response to injury. J Biol Chem 2005; 280:19966-76. [PMID: 15774477 DOI: 10.1074/jbc.m500917200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
In vascular smooth muscle cells (VSMC), platelet-derived growth factor (PDGF) suppresses expression of multiple smooth muscle contractile proteins, useful markers of differentiation. Conversely, hypertrophic agents induce expression of these genes. The goal of this study was to employ genomic approaches to identify classes of genes differentially regulated by PDGF and hypertrophic stimuli. Changes in gene expression were determined using Affymetrix RAE-230 GeneChips in rat aortic VSMC stimulated with PDGF. For comparison with a model hypertrophic stimulus, a microarray was performed with VSMC stably expressing constitutively active Galpha(16), which strongly induces smooth muscle marker expression. We identified 75 genes whose expression was increased by exposure to PDGF and decreased by expression of Galpha(16) and 97 genes whose expression was decreased by PDGF and increased by Galpha(16). These genes included many smooth muscle-specific proteins; several extracellular matrix, cytoskeletal, and chemotaxis-related proteins; cell signaling molecules; and transcription factors. Changes in gene expression for many of these were confirmed by PCR or immunoblotting. The contribution of signaling pathways activated by PDGF to the gene expression profile was examined in VSMC stably expressing gain-of-function H-Ras or myristoylated Akt. Among the genes that were confirmed to be differentially regulated were CCAAT/enhancer-binding protein delta, versican, and nexilin. All of these genes also had altered expression in injured aortas, consistent with a role for PDGF in the response of injured VSMC. These data indicate that genes that are differentially regulated by PDGF and hypertrophic stimuli may represent families of genes and potentially be biomarkers for vascular injury.
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MESH Headings
- Animals
- Cell Size
- Cells, Cultured
- GTP-Binding Protein alpha Subunits, Gq-G11
- Gene Expression Profiling
- Gene Expression Regulation/drug effects
- Genetic Markers
- Heterotrimeric GTP-Binding Proteins/genetics
- Heterotrimeric GTP-Binding Proteins/metabolism
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/injuries
- Muscle, Smooth, Vascular/metabolism
- Oligonucleotide Array Sequence Analysis
- Phenotype
- Platelet-Derived Growth Factor/pharmacology
- Rats
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Transfection
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40
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Pukkila-Worley R, Gerrald QD, Kraus PR, Boily MJ, Davis MJ, Giles SS, Cox GM, Heitman J, Alspaugh JA. Transcriptional network of multiple capsule and melanin genes governed by the Cryptococcus neoformans cyclic AMP cascade. Eukaryot Cell 2005; 4:190-201. [PMID: 15643074 PMCID: PMC544166 DOI: 10.1128/ec.4.1.190-201.2005] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Accepted: 10/13/2004] [Indexed: 11/20/2022]
Abstract
Cryptococcus neoformans is an opportunistic human fungal pathogen that elaborates several virulence attributes, including a polysaccharide capsule and melanin pigments. A conserved Galpha protein/cyclic AMP (cAMP) pathway controls melanin and capsule production. To identify targets of this pathway, we used an expression profiling approach to define genes that are transcriptionally regulated by the Galpha protein Gpa1. This approach revealed that Gpa1 transcriptionally regulates multiple genes involved in capsule assembly and identified two additional genes with a marked dependence on Gpa1 for transcription. The first is the LAC1 gene, encoding the laccase enzyme that catalyzes a rate-limiting step in diphenol oxidation and melanin production. The second gene identified (LAC2) is adjacent to the LAC1 gene and encodes a second laccase that shares 75% nucleotide identity with LAC1. Similar to the LAC1 gene, LAC2 is induced in response to glucose deprivation. However, LAC2 basal transcript levels are much lower than those for LAC1. Accordingly, a lac2 mutation results in only a modest delay in melanin formation. LAC2 overexpression suppresses the melanin defects of gpa1 and lac1 mutants and partially restores virulence of these strains. These studies provide mechanistic insights into the regulation of capsule and melanin production by the C. neoformans cAMP pathway and demonstrate that multiple laccases contribute to C. neoformans melanin production and pathogenesis.
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Affiliation(s)
- Read Pukkila-Worley
- Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
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41
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Kotevic I, Kirschner KM, Porzig H, Baltensperger K. Constitutive interaction of the P2Y2 receptor with the hematopoietic cell-specific G protein G(alpha16) and evidence for receptor oligomers. Cell Signal 2004; 17:869-80. [PMID: 15763429 DOI: 10.1016/j.cellsig.2004.11.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2004] [Revised: 11/03/2004] [Accepted: 11/03/2004] [Indexed: 11/16/2022]
Abstract
Hematopoietic cells uniquely express G(alpha16), a G protein alpha-subunit of the G(q)-type. G(alpha16) is obligatory for P2Y2 receptor-dependent Ca2+-mobilization in human erythroleukemia cells and induces hematopoietic cell differentiation. We tested whether P2Y2 receptors physically interact with G(alpha16). Receptor and G protein were fused to cyan (CFP) and yellow (YFP) variants of the green fluorescent protein (GFP), respectively. When expressed in K562 leukemia cells, the fusion proteins were capable of triggering a Ca2+-signal upon receptor stimulation, demonstrating their functional integrity. In fluorescence resonance energy transfer (FRET) measurements using confocal microscopy, a strong FRET signal from the plasma membrane region of fixed, resting cells was detected when the receptor was co-expressed with the G protein as the FRET acceptor, as well as when the CFP-tagged receptor was co-expressed with receptor fused to YFP. We conclude that, under resting conditions, G(alpha16) and P2Y2 receptors form constitutive complexes, and that the P2Y2 receptor is present as an oligomer.
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Affiliation(s)
- Ivana Kotevic
- Institute of Pharmacology, University of Bern, Friedbühlstrasse 49, 3010 Bern, Switzerland
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42
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Liu AMF, Wong YH. G16-mediated activation of nuclear factor kappaB by the adenosine A1 receptor involves c-Src, protein kinase C, and ERK signaling. J Biol Chem 2004; 279:53196-204. [PMID: 15485865 DOI: 10.1074/jbc.m410196200] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The G(i)-linked adenosine A1 receptor has been shown to mediate anti-inflammatory actions, possibly via modulation of the transcription factor nuclear factor-kappaB (NFkappaB). Here we demonstrate that an adenosine A1 agonist, N(6)-cyclohexyladenosine (CHA), activated IKKalpha/beta phosphorylation through PTX-insensitive G proteins in human lymphoblastoma Reh cells. To delineate the mechanism of action, different PTX-insensitive G proteins were expressed in human embryonic kidney 293 cells. Only Galpha(16) supported the CHA-induced IKK phosphorylation and NFkappaB-driven luciferase activity in time-dependent, dose-dependent, and PTX-insensitive manners. Gbetagamma subunits also modulated IKK/NFkappaB, as indicated by the stimulatory actions of Gbeta(1)gamma(2) and the abrogation of CHA-induced response by transducin. The participation of phospholipase Cbeta, protein kinase C, and calmodulin-dependent kinase II in CHA-induced IKK/NFkappaB activation were demonstrated by employing specific inhibitors and dominant-negative mutants. Inhibition of c-Src and numerous intermediates along the extracellular signal-regulated (ERK) kinase cascade including Ras, Raf-1 kinase, and MEK1/2 abolished the CHA-induced IKK/NFkappaB activation. Although c-Jun N-terminal kinase and p38 MAPK were also activated by CHA, they were not required for the IKK/NFkappaB regulation. Similar results were obtained using Reh cells. These data suggest that the G(16)-mediated activation of IKK/NFkappaB by CHA required a complex signaling network composed of multiple intermediates.
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Affiliation(s)
- Andrew M F Liu
- Department of Biochemistry, Molecular Neuroscience Center, and Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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Lo RKH, Wong YH. Signal transducer and activator of transcription 3 activation by the delta-opioid receptor via Galpha14 involves multiple intermediates. Mol Pharmacol 2004; 65:1427-39. [PMID: 15155836 DOI: 10.1124/mol.65.6.1427] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The hematopoietic-specific Galpha14 links a variety of G protein-coupled receptors to phospholipase Cbeta (PLCbeta) stimulation. Recent studies reveal that several Galpha subunits are capable of activating signal transducer and activator of transcription (STAT) proteins. In the present study, we investigated the mechanism by which Galpha14 mediates receptor-induced stimulation of STAT3. In human embryonic kidney 293 cells, coexpression of Galpha14 with delta-opioid receptor supported [D-Pen2, D-Pen5]enkephalin (DPDPE)-induced STAT3 phosphorylations at both Tyr705 and Ser727 in a pertussis toxin-insensitive manner. The constitutively active Galpha4QL mutant also induced STAT3 phosphorylations at these sites and promoted STAT3-dependent luciferase activity. Requirements for PLCbeta, protein kinase C (PKC), and calmodulin-dependent kinase II (CaMKII) in Galpha14QL-induced STAT3 activation were demonstrated by their respective inhibitors as well as by coexpression of their dominant-negative mutants. Inhibition of c-Src and Janus kinase 2 and 3 activities abolished STAT3 activation induced by Galpha14QL, but no physical association between Galpha14QL and c-Src could be detected by coimmunoprecipitation. Various intermediates along the extracellular signal-regulated kinase signaling cascade were apparently required for Galpha14QL-induced STAT3 activation; they included Ras/Rac1, Raf-1, and mitogen-activated protein kinase kinase-1/2. In contrast, functional blockade of c-Jun N-terminal kinase, p38 mitogen-activated protein kinase, and phosphatidylinositol-3 kinase had no effect on Galpha14QL-induced responses. PLCbeta, PKC, and CaMKII were shown to be involved in Galpha14QL-mediated c-Src phosphorylation. Similar results were obtained with human erythro-leukemia cells upon DPDPE treatment. These results demonstrate for the first time that Galpha14 activation can lead to STAT3 stimulation via a complex signaling network involving multiple intermediates.
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Affiliation(s)
- Rico K H Lo
- Department of Biochemistry, Molecular Neuroscience Center, and Biotechnology Research Institute, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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44
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Wu YL, Hooks SB, Harden TK, Dohlman HG. Dominant-negative inhibition of pheromone receptor signaling by a single point mutation in the G protein alpha subunit. J Biol Chem 2004; 279:35287-97. [PMID: 15197187 DOI: 10.1074/jbc.m404896200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In yeast, two different constitutive mutants of the G protein alpha subunit have been reported. Gpa1(Q323L) cannot hydrolyze GTP and permanently activates the pheromone response pathway. Gpa1(N388D) was also proposed to lack GTPase activity, yet it has an inhibitory effect on pheromone responsiveness. We have characterized this inhibitory mutant (designated Galpha(ND)) and found that it binds GTP, interacts with G protein betagamma subunits, and exhibits full GTPase activity in vitro. Although pheromone leads to dissociation of the receptor from wild-type G protein, the same treatment promotes stable association of the receptor with Galpha(ND). We conclude that agonist binding to the receptor promotes the formation of a nondissociable complex with Galpha(ND), and in this manner prevents activation of the endogenous wild-type G protein. Dominant-negative mutants may be useful in matching specific receptors and their cognate G proteins and in determining mechanisms of G protein signaling specificity.
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Affiliation(s)
- Yuh-Lin Wu
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill 27599-7260, USA
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Suga H, Takeda S, Haga T, Okamura M, Takao K, Tatemoto K. Stimulation of Increases in Intracellular Calcium and Prostaglandin E2 Generation in Chinese Hamster Ovary Cells Expressing Receptor-G 16 Fusion Proteins. J Biochem 2004; 135:605-13. [PMID: 15173199 DOI: 10.1093/jb/mvh058] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We examined whether fusion proteins of G protein-coupled receptors with the alpha subunit of G(16) (Galpha(16)) could activate downstream signals. We expressed fusion proteins of G(i)-coupled receptors, i.e. CX(3)C chemokine receptor 1 (CX(3)CR1) and M(2) receptor, in Chinese hamster ovary cells. An agonist for CX(3)CR1 induced greater increases in intracellular Ca(2+) and prostaglandin E(2) generation in cells expressing CX(3)CR1-Galpha(16) fusion protein than in cells expressing CX(3)CR1 alone or both CX(3)CR1 and Galpha(16) separately. Similarly, agonist-induced prostaglandin E(2) generation was greater in cells expressing M(2)-Galpha(16) fusion protein than ones expressing M(2) alone or both M(2) and Galpha(16) separately. In cells expressing fusion proteins with Galpha(16) of G(q)-coupled receptors, i.e. urotensin II receptor and M(1) receptor, the relevant agonists induced similar increases in intracellular Ca(2+) and prostaglandin E(2) generation as in ones expressing the receptor alone. In cells expressing urotensin II receptor-Galpha(16) fusion protein, prostaglandin E(2) generation exhibited a lower EC(50) value than the intracellular Ca(2+) increase. These results indicate that agonist-stimulated receptor-Galpha(16) fusion proteins are coupled to downstream signaling pathways, and suggest that receptor-Galpha(16) fusion proteins may be useful for screening for ligands of orphan G protein-coupled receptors and G(i)-coupled receptors.
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Affiliation(s)
- Hinako Suga
- Department of Neurochemistry, Graduate School of Medicine, the University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033.
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Roginskaya M, Connelly SM, Kim KS, Patel D, Dumont ME. Effects of mutations in the N terminal region of the yeast G protein α-subunit Gpa1p on signaling by pheromone receptors. Mol Genet Genomics 2004; 271:237-48. [PMID: 14767760 DOI: 10.1007/s00438-004-0975-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2003] [Accepted: 12/07/2003] [Indexed: 11/26/2022]
Abstract
The sites and modes of interaction between G protein-coupled receptors and their cognate heterotrimeric G proteins remain poorly defined. The C-terminus of the Galpha subunit is the best established site of contact of G proteins with receptors, but structural analyses and crosslinking studies suggest the possibility of interactions at the N-terminus of Galpha as well. We screened for mutations in the N-terminal region of the Galpha subunit encoded by the yeast GPA1 gene that specifically affect the ability of the G protein to be activated by the yeast alpha-mating factor receptor. The screen led to identification of substitutions of glutamine or proline for Leu18 of Gpa1p that reduce the response to the pheromones alpha-factor and a-factor without affecting cellular levels of the subunit or its ability to interact with beta and gamma subunits. The mutations do not appear to affect the intrinsic ability of the G protein to be converted to the activated state. The low yield of different mutations with this phenotype indicates either that the N-terminal segment of the yeast Galpha subunit does not undergo extensive interactions with the alpha-factor receptor, or that this region can not be altered without detrimental effects upon the formation of G protein trimers.
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Affiliation(s)
- M Roginskaya
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, PO Box 712, Rochester, NY 14642, USA
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Abstract
Regulators of G-protein Signalling (RGS) regulate the functional lifetime of G-Protein Coupled Receptor (GPCR)-activated heterotrimeric G-protein by serving as GTPase Accelerating Proteins (GAPs) for the G(alpha) subunit. A number of mammalian RGSs can functionally replace the yeast RGS containing SST2 gene and inhibit GPCR signalling. Using yeast strains harbouring a G(betagamma)-responsive FUS1-LacZ reporter gene, we demonstrate that heterologously expressed mammalian RGS1 also serves to decrease basal signalling in the absence of agonist. Although this effect was dependent on the expression of a GPA1-encoded functional G(alpha) protein, the GPCR itself was nevertheless not required. Using the GAL1 inducible promoter to express RGS1, we further demonstrate that in addition to serving as a GAP for Gpa1p in yeast, RGS1 is a dosage-dependent inhibitor of growth. This effect is specific to RGS1 since growth is not altered in cells expressing either mammalian RGS2 or RGS5. We further demonstrate that neither of the two yeast G(alpha) proteins is responsible for mediating this growth inhibitory effect of RGS1. Taken together, our results indicate that RGS1 can function in both G-protein-dependent and -independent manners in yeast.
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Affiliation(s)
- Xiao Yu Li
- Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
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Hazari A, Lowes V, Chan JHP, Wong CSS, Ho MKC, Wong YH. Replacement of the α5 helix of Gα16 with Gαs-specific sequences enhances promiscuity of Gα16 toward Gs-coupled receptors. Cell Signal 2004; 16:51-62. [PMID: 14607275 DOI: 10.1016/s0898-6568(03)00097-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
G(16) can couple indiscriminately to a large number of G protein-coupled receptors (GPCRs), making it a prime candidate as a universal adaptor for GPCRs. In order to increase the promiscuity of Galpha(16), three chimeras incorporating increasing lengths of G(s)-specific residues (25, 44 or 81 residues) into the C-terminus of Galpha(16) were constructed and named 16s25, 16s44 and 16s81, respectively. The chimeras were examined for their ability to mediate receptor-induced stimulation of phospholipase C (PLC) and Ca(2+) mobilization. 16s25 was more effective than 16s44 and 16s81 at coupling to G(s)-linked receptors. 16s25 coupled productively to 10 different G(s)-coupled receptors examined and, for 50% of these receptors, 16s25-mediated PLC activities were higher than those mediated via Galpha(16). Similar results were observed for agonist-induced Ca(2+) mobilizations. These results show that incorporating the alpha5 helix of Galpha(s) into Galpha(16) can increase the promiscuity of 16s25 towards G(s)-coupled receptors.
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MESH Headings
- Animals
- Base Sequence/genetics
- COS Cells
- Calcium/metabolism
- Calcium Signaling/physiology
- GTP-Binding Protein alpha Subunits/genetics
- GTP-Binding Protein alpha Subunits/metabolism
- GTP-Binding Protein alpha Subunits, Gq-G11
- GTP-Binding Protein alpha Subunits, Gs/genetics
- GTP-Binding Protein alpha Subunits, Gs/metabolism
- Heterotrimeric GTP-Binding Proteins/genetics
- Heterotrimeric GTP-Binding Proteins/metabolism
- Protein Structure, Secondary/genetics
- Protein Structure, Tertiary/genetics
- Receptors, Adrenergic, beta/genetics
- Receptors, Adrenergic, beta/metabolism
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Signal Transduction/genetics
- Type C Phospholipases/metabolism
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Affiliation(s)
- Anjali Hazari
- Department of Biochemistry, the Biotechnology Research Institute, and the Molecular Neuroscience Center, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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Qiu J, Bosch MA, Tobias SC, Grandy DK, Scanlan TS, Ronnekleiv OK, Kelly MJ. Rapid signaling of estrogen in hypothalamic neurons involves a novel G-protein-coupled estrogen receptor that activates protein kinase C. J Neurosci 2003; 23:9529-40. [PMID: 14573532 PMCID: PMC6740471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/27/2023] Open
Abstract
Classically, 17beta-estradiol (E2) is thought to control homeostatic functions such as reproduction, stress responses, feeding, sleep cycles, temperature regulation, and motivated behaviors through transcriptional events. Although it is increasingly evident that E2 can also rapidly activate kinase pathways to have multiple downstream actions in CNS neurons, the receptor(s) and the signal transduction pathways involved have not been identified. We discovered that E2 can alter mu-opioid and GABA neurotransmission rapidly through nontranscriptional events in hypothalamic GABA, proopiomelanocortin (POMC), and dopamine neurons. Therefore, we examined the effects of E2 in these neurons using whole-cell recording techniques in ovariectomized female guinea pigs. E2 reduced rapidly the potency of the GABAB receptor agonist baclofen to activate G-protein-coupled, inwardly rectifying K+ channels in hypothalamic neurons. These effects were mimicked by the membrane impermeant E2-BSA and selective estrogen receptor modulators, including a new diphenylacrylamide compound, STX, that does not bind to intracellular estrogen receptors alpha or beta, suggesting that E2 acts through a unique membrane receptor. We characterized the coupling of this estrogen receptor to a Galpha(q)-mediated activation of phospholipase C, leading to the upregulation of protein kinase Cdelta and protein kinase A activity in these neurons. Moreover, using single-cell reverse transcription-PCR, we identified the critical transcripts, PKCdelta and its downstream target adenylyl cyclase VII, for rapid, novel signaling of E2 in GABA, POMC, and dopamine neurons. Therefore, this unique Gq-coupled estrogen receptor may be involved in rapid signaling in hypothalamic neurons that are critical for normal homeostatic functions.
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Affiliation(s)
- Jian Qiu
- Department of Physiology and Pharmacology, Oregon Health and Science University, Portland, Oregon 97239-3098, USA
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50
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Abstract
The hematopoietic-specific Galpha16 protein has recently been shown to mediate receptor-induced activation of the signal transducer and activator of transcription 3 (STAT3). In the present study, we have delineated the mechanism by which Galpha16 stimulates STAT3 in human embryonic kidney 293 cells. A constitutively active Galpha16 mutant, Galpha16QL, stimulated STAT3-dependent luciferase activity as well as the phosphorylation of STAT3 at both Tyr705 and Ser727. Galpha16QL-induced STAT3 activation was enhanced by overexpression of extracellular signal-regulated kinase 1 (ERK1), but was inhibited by U0126, a Raf-1 inhibitor, and coexpression of the dominant negative mutants of Ras and Rac1. Inhibition of phospholipase Cbeta, protein kinase C, and calmodulin-dependent kinase II by their respective inhibitors also suppressed Galpha16QL-induced STAT3 activation. The involvement of tyrosine kinases such as c-Src and Janus kinase 2 and 3 (JAK2 and JAK3) in Galpha16QL-induced activation of STAT3 was illustrated by the combined use of selective inhibitors and dominant negative mutants. In contrast, c-Jun N-terminal kinase, p38 MAPK, RhoA, Cdc42, phosphatidylinositol 3-kinase, and the epidermal growth factor receptor did not appear to be required. Similar observations were obtained with human erythroleukemia cells, where STAT3 phosphorylation was stimulated by C5a in a PTX-insensitive manner. Collectively, these results highlight the important regulatory roles of the Ras/Raf/MEK/ERK and c-Src/JAK pathways on the stimulation of STAT3 by activated Galpha16. Demonstration of the involvement of different kinases in Galpha16QL-induced STAT3 activation supports the involvement of multiple signaling pathways in the regulation of transcription by G proteins.
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Affiliation(s)
- Rico K H Lo
- Department of Biochemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
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