1
|
Park Y, Matsumoto S, Ogata K, Ma B, Kanada R, Isaka Y, Arichi N, Liang X, Maki R, Kozasa T, Okuno Y, Ohno H, Ishihama Y, Toyoshima F. Receptor-independent regulation of Gα13 by alpha-1-antitrypsin C-terminal peptides. J Biol Chem 2025; 301:108136. [PMID: 39730062 PMCID: PMC11815680 DOI: 10.1016/j.jbc.2024.108136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2024] [Revised: 12/17/2024] [Accepted: 12/19/2024] [Indexed: 12/29/2024] Open
Abstract
Alpha-1-antitrypsin (AAT), a circulating serine protease inhibitor, is an acute inflammatory response protein with anti-inflammatory functions. The C-terminal peptides of AAT are found in various tissues and have been proposed as putative bioactive peptides with multiple functions, but its mechanism of action remains unclear. We previously reported that a mouse AAT C-terminal peptide of 35 amino acids (mAAT-C1-35) penetrates plasma membrane and associates guanine nucleotide-binding protein subunit alpha 13 (Gα13). Here, we show that mAAT-C1-35 binds directly to the guanosine diphosphate (GDP)-bound form of Gα13 through the N-terminal region (mAAT-C1-17), thereby facilitating the interaction of Gα13・GDP with its effector proteins. The minimal sequence (mAAT-C3-16) and essential amino acid residue (Phe11) of mAAT-C1-17 were identified as being necessary for this effect. A molecular dynamics simulation for the Gα13・GDP-mAAT-C1-17 complex model showed that binding of mAAT-C1-17 to the region surrounded by switch regions of Gα13 stabilizes the flexible switch II and III regions, thereby maintaining their active conformation. In addition, mAAT-C1-35 activates the Gα13 signaling pathway in cells where Phe11 is required. Our study reveals the structure-based mechanism of action of AAT-C peptides in the regulation of Gα13 and demonstrates that AAT-C peptides represent a biological peptide capable of activating G protein signals in a manner that is independent of G-protein-coupled receptors.
Collapse
Affiliation(s)
- Yonghak Park
- Department of Biosystems Science, Institute for Life and Medical Sciences, Kyoto University, Kyoto, Japan; Department of Mammalian and Regulatory Networks, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Shigeyuki Matsumoto
- Department of Biomedical Data Intelligence, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
| | - Kosuke Ogata
- Department of Molecular Systems BioAnalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Biao Ma
- HPC- and AI-driven Drug Development Platform Division, RIKEN Center for Computational Science, Kobe, Hyogo, Japan
| | - Ryo Kanada
- HPC- and AI-driven Drug Development Platform Division, RIKEN Center for Computational Science, Kobe, Hyogo, Japan
| | - Yuta Isaka
- HPC- and AI-driven Drug Development Platform Division, RIKEN Center for Computational Science, Kobe, Hyogo, Japan
| | - Norihito Arichi
- Department of Bioorganic Medicinal Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Xiaowen Liang
- Department of Biosystems Science, Institute for Life and Medical Sciences, Kyoto University, Kyoto, Japan; Department of Mammalian and Regulatory Networks, Graduate School of Biostudies, Kyoto University, Kyoto, Japan
| | - Ritsuko Maki
- Department of Biosystems Science, Institute for Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - Tohru Kozasa
- Department of Biochemistry, Yokohama University of Pharmacy, Yokohama, Japan
| | - Yasushi Okuno
- Department of Biomedical Data Intelligence, Graduate School of Medicine, Kyoto University, Kyoto, Japan; HPC- and AI-driven Drug Development Platform Division, RIKEN Center for Computational Science, Kobe, Hyogo, Japan
| | - Hiroaki Ohno
- Department of Bioorganic Medicinal Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Yasushi Ishihama
- Department of Molecular Systems BioAnalysis, Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan
| | - Fumiko Toyoshima
- Department of Biosystems Science, Institute for Life and Medical Sciences, Kyoto University, Kyoto, Japan; Department of Mammalian and Regulatory Networks, Graduate School of Biostudies, Kyoto University, Kyoto, Japan; Department of Homeostatic Medicine, Medical Research Laboratory, Institute of Integrated Research, Institute of Science Tokyo, Tokyo, Japan.
| |
Collapse
|
2
|
Lefevre TJ, Wei W, Mukhaleva E, Meda Venkata SP, Chandan NR, Abraham S, Li Y, Dessauer CW, Vaidehi N, Smrcka AV. Stabilization of interdomain interactions in G protein α subunits as a determinant of Gα i subtype signaling specificity. J Biol Chem 2024; 300:107211. [PMID: 38522511 PMCID: PMC11066577 DOI: 10.1016/j.jbc.2024.107211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 03/07/2024] [Accepted: 03/12/2024] [Indexed: 03/26/2024] Open
Abstract
Highly homologous members of the Gαi family, Gαi1-3, have distinct tissue distributions and physiological functions, yet their biochemical and functional properties are very similar. We recently identified PDZ-RhoGEF (PRG) as a novel Gαi1 effector that is poorly activated by Gαi2. In a proteomic proximity labeling screen we observed a strong preference for Gαi1 relative to Gαi2 with respect to engagement of a broad range of potential targets. We investigated the mechanistic basis for this selectivity using PRG as a representative target. Substitution of either the helical domain (HD) from Gαi1 into Gαi2 or substitution of a single amino acid, A230 in Gαi2 with the corresponding D in Gαi1, largely rescues PRG activation and interactions with other potential Gαi targets. Molecular dynamics simulations combined with Bayesian network models revealed that in the GTP bound state, separation at the HD-Ras-like domain (RLD) interface is more pronounced in Gαi2 than Gαi1. Mutation of A230 to D in Gαi2 stabilizes HD-RLD interactions via ionic interactions with R145 in the HD which in turn modify the conformation of Switch III. These data support a model where D229 in Gαi1 interacts with R144 and stabilizes a network of interactions between HD and RLD to promote protein target recognition. The corresponding A230 in Gαi2 is unable to stabilize this network leading to an overall lower efficacy with respect to target interactions. This study reveals distinct mechanistic properties that could underly differential biological and physiological consequences of activation of Gαi1 or Gαi2 by G protein-coupled receptors.
Collapse
Affiliation(s)
- Tyler J Lefevre
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA; Program in Chemical Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Wenyuan Wei
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, California, USA
| | - Elizaveta Mukhaleva
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, California, USA
| | | | - Naincy R Chandan
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA; Genentech, South San Francisco, California, USA
| | - Saji Abraham
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Yong Li
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, Texas, USA
| | - Carmen W Dessauer
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, Texas, USA
| | - Nagarajan Vaidehi
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, California, USA
| | - Alan V Smrcka
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, Michigan, USA.
| |
Collapse
|
3
|
Torres-Rodriguez MD, Lee SG, Roy Choudhury S, Paul R, Selvam B, Shukla D, Jez JM, Pandey S. Structure-function analysis of plant G-protein regulatory mechanisms identifies key Gα-RGS protein interactions. J Biol Chem 2024; 300:107252. [PMID: 38569936 PMCID: PMC11061236 DOI: 10.1016/j.jbc.2024.107252] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 03/20/2024] [Accepted: 03/28/2024] [Indexed: 04/05/2024] Open
Abstract
Heterotrimeric GTP-binding protein alpha subunit (Gα) and its cognate regulator of G-protein signaling (RGS) protein transduce signals in eukaryotes spanning protists, amoeba, animals, fungi, and plants. The core catalytic mechanisms of the GTPase activity of Gα and the interaction interface with RGS for the acceleration of GTP hydrolysis seem to be conserved across these groups; however, the RGS gene is under low selective pressure in plants, resulting in its frequent loss. Our current understanding of the structural basis of Gα:RGS regulation in plants has been shaped by Arabidopsis Gα, (AtGPA1), which has a cognate RGS protein. To gain a comprehensive understanding of this regulation beyond Arabidopsis, we obtained the x-ray crystal structures of Oryza sativa Gα, which has no RGS, and Selaginella moellendorffi (a lycophyte) Gα that has low sequence similarity with AtGPA1 but has an RGS. We show that the three-dimensional structure, protein-protein interaction with RGS, and the dynamic features of these Gα are similar to AtGPA1 and metazoan Gα. Molecular dynamic simulation of the Gα-RGS interaction identifies the contacts established by specific residues of the switch regions of GTP-bound Gα, crucial for this interaction, but finds no significant difference due to specific amino acid substitutions. Together, our data provide valuable insights into the regulatory mechanisms of plant G-proteins but do not support the hypothesis of adaptive co-evolution of Gα:RGS proteins in plants.
Collapse
Affiliation(s)
| | - Soon Goo Lee
- Department of Molecular & Cellular Biology, Kennesaw State University, Kennesaw, Georgia, USA
| | - Swarup Roy Choudhury
- Donald Danforth Plant Science Center, St Louis, Missouri, USA; Department of Biology, Indian Institute of Science Education and Research, Tirupati, India
| | - Rabindranath Paul
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Balaji Selvam
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Diwakar Shukla
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
| | - Joseph M Jez
- Department of Biology, Washington University in St Louis, St Louis, Missouri, USA
| | - Sona Pandey
- Donald Danforth Plant Science Center, St Louis, Missouri, USA.
| |
Collapse
|
4
|
Lefevre TJ, Wei W, Mukhaleva E, Venkata SPM, Chandan NR, Abraham S, Li Y, Dessauer CW, Vaidehi N, Smrcka AV. Stabilization of Interdomain Interactions in G protein α i Subunits Determines Gα i Subtype Signaling Specificity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.10.532072. [PMID: 37066214 PMCID: PMC10103935 DOI: 10.1101/2023.03.10.532072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Highly homologous members of the Gαi family, Gαi1-3, have distinct tissue distributions and physiological functions, yet the functional properties of these proteins with respect to GDP/GTP binding and regulation of adenylate cyclase are very similar. We recently identified PDZ-RhoGEF (PRG) as a novel Gαi1 effector, however, it is poorly activated by Gαi2. Here, in a proteomic proximity labeling screen we observed a strong preference for Gαi1 relative to Gαi2 with respect to engagement of a broad range of potential targets. We investigated the mechanistic basis for this selectivity using PRG as a representative target. Substitution of either the helical domain (HD) from Gαi1 into Gαi2 or substitution of a single amino acid, A230 in Gαi2 to the corresponding D in Gαi1, largely rescues PRG activation and interactions with other Gαi targets. Molecular dynamics simulations combined with Bayesian network models revealed that in the GTP bound state, dynamic separation at the HD-Ras-like domain (RLD) interface is prevalent in Gαi2 relative to Gαi1 and that mutation of A230s4h3.3 to D in Gαi2 stabilizes HD-RLD interactions through formation of an ionic interaction with R145HD.11 in the HD. These interactions in turn modify the conformation of Switch III. These data support a model where D229s4h3.3 in Gαi1 interacts with R144HD.11 stabilizes a network of interactions between HD and RLD to promote protein target recognition. The corresponding A230 in Gαi2 is unable to form the "ionic lock" to stabilize this network leading to an overall lower efficacy with respect to target interactions. This study reveals distinct mechanistic properties that could underly differential biological and physiological consequences of activation of Gαi1 or Gαi2 by GPCRs.
Collapse
Affiliation(s)
- Tyler J. Lefevre
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
- Program in Chemical Biology, University of Michigan, Ann Arbor, MI
| | - Wenyuan Wei
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, TX
| | - Elizaveta Mukhaleva
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, TX
| | | | - Naincy R. Chandan
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
- Genentech, South San Francisco, CA
| | - Saji Abraham
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
| | - Yong Li
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, TX
| | - Carmen W. Dessauer
- Department of Integrative Biology and Pharmacology McGovern Medical School, UTHealth, Houston, TX
| | - Nagarajan Vaidehi
- Department of Computational and Quantitative Medicine, Beckman Research Institute of the City of Hope, Duarte, CA
| | - Alan V. Smrcka
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI
| |
Collapse
|
5
|
Interaction kinetics between p115-RhoGEF and Gα 13 are determined by unique molecular interactions affecting agonist sensitivity. Commun Biol 2022; 5:1287. [PMID: 36434027 PMCID: PMC9700851 DOI: 10.1038/s42003-022-04224-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 11/04/2022] [Indexed: 11/27/2022] Open
Abstract
The three RH-RhoGEFs (Guanine nucleotide exchange factors) p115-RhoGEF, LARG (leukemia-associated RhoGEF) and PDZ-RhoGEF link G-protein coupled receptors (GPCRs) with RhoA signaling through activation of Gα12/13. In order to find functional differences in signaling between the different RH-RhoGEFs we examined their interaction with Gα13 in high spatial and temporal resolution, utilizing a FRET-based single cell assay. We found that p115-RhoGEF interacts significantly shorter with Gα13 than LARG and PDZ-RhoGEF, while narrowing the structural basis for these differences down to a single amino acid in the rgRGS domain of p115-RhoGEF. The mutation of this amino acid led to an increased interaction time with Gα13 and an enhanced agonist sensitivity, comparable to LARG, while mutating the corresponding amino acid in Gα13 the same effect could be achieved. While the rgRGS domains of RH-RhoGEFs showed GAP (GTPase-activating protein) activity towards Gα13 in vitro, our approach suggests higher GAP activity of p115-RhoGEF in intact cells.
Collapse
|
6
|
Stecky RC, Quick CR, Fleming TL, Mull ML, Vinson VK, Whitley MS, Dover EN, Meigs TE. Divergent C-terminal motifs in Gα12 and Gα13 provide distinct mechanisms of effector binding and SRF activation. Cell Signal 2020; 72:109653. [PMID: 32330601 DOI: 10.1016/j.cellsig.2020.109653] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 04/19/2020] [Accepted: 04/19/2020] [Indexed: 11/18/2022]
Abstract
The G12/13 subfamily of heterotrimeric guanine nucleotide binding proteins comprises the α subunits Gα12 and Gα13, which transduce signals for cell growth, cytoskeletal rearrangements, and oncogenic transformation. In an increasing range of cancers, overexpressed Gα12 or Gα13 are implicated in aberrant cell proliferation and/or metastatic invasion. Although Gα12 and Gα13 bind non-redundant sets of effector proteins and participate in unique signalling pathways, the structural features responsible for functional differences between these α subunits are largely unknown. Invertebrates encode a single G12/13 homolog that participates in cytoskeletal changes yet appears to lack signalling to SRF (serum response factor), a transcriptional activator stimulated by mammalian Gα12 and Gα13 to promote growth and tumorigenesis. Our previous studies identified an evolutionarily divergent region in Gα12 for which replacement by homologous sequence from Drosophila melanogaster abolished SRF signalling, whereas the same invertebrate substitution was fully tolerated in Gα13 [Montgomery et al. (2014) Mol. Pharmacol. 85: 586]. These findings prompted our current approach of evolution-guided mutagenesis to identify fine structural features of Gα12 and Gα13 that underlie their respective SRF activation mechanisms. Our results identified two motifs flanking the α4 helix that play a key role in Gα12 signalling to SRF. We found the region encompassing these motifs to provide an interacting surface for multiple Gα12-specific target proteins that fail to bind Gα13. Adjacent to this divergent region, a highly-conserved domain was vital for SRF activation by both Gα12 and Gα13. However, dissection of this domain using invertebrate substitutions revealed different signalling mechanisms in these α subunits and identified Gα13-specific determinants of binding Rho-specific guanine nucleotide exchange factors. Furthermore, invertebrate substitutions in the C-terminal, α5 helical region were selectively disruptive to Gα12 signalling. Taken together, our results identify key structural features near the C-terminus that evolved after the divergence of Gα12 and Gα13, and should aid the development of agents to selectively manipulate signalling by individual α subunits of the G12/13 subfamily.
Collapse
Affiliation(s)
- Rebecca C Stecky
- Department of Biology, University of North Carolina Asheville, One University Heights, Asheville, NC 28804, United States of America
| | - Courtney R Quick
- Department of Biology, University of North Carolina Asheville, One University Heights, Asheville, NC 28804, United States of America
| | - Todd L Fleming
- Department of Biology, University of North Carolina Asheville, One University Heights, Asheville, NC 28804, United States of America
| | - Makenzy L Mull
- Department of Biology, University of North Carolina Asheville, One University Heights, Asheville, NC 28804, United States of America
| | - Vanessa K Vinson
- Department of Biology, University of North Carolina Asheville, One University Heights, Asheville, NC 28804, United States of America
| | - Megan S Whitley
- Department of Biology, University of North Carolina Asheville, One University Heights, Asheville, NC 28804, United States of America
| | - E Nicole Dover
- Department of Biology, University of North Carolina Asheville, One University Heights, Asheville, NC 28804, United States of America
| | - Thomas E Meigs
- Department of Biology, University of North Carolina Asheville, One University Heights, Asheville, NC 28804, United States of America.
| |
Collapse
|
7
|
Abstract
AKAP-Lbc is a Rho-activating guanine nucleotide exchange factor (RhoGEF) important in heart development and pro-fibrotic signaling in cardiomyocytes. Heterotrimeric G proteins of the G12/13 subfamily, comprising Gα12 and Gα13, are well characterized as stimulating a specialized group of RhoGEFs through interaction with their RGS-homology (RH) domain. Despite lacking an RH domain, AKAP-Lbc is bound by Gα12 through an unknown mechanism to activate Rho signaling. We identified a Gα12-binding region near the C-terminus of AKAP-Lbc, closely homologous to a region of p114RhoGEF that we also discovered to interact with Gα12. This binding mechanism is distinct from the well-studied interface between RH-RhoGEFs and G12/13 α subunits, as demonstrated by Gα12 mutants selectively impaired in binding either this AKAP-Lbc/p114RhoGEF region or RH-RhoGEFs. AKAP-Lbc and p114RhoGEF showed high specificity for binding Gα12 in comparison to Gα13, and experiments using chimeric G12/13 α subunits mapped determinants of this selectivity to the N-terminal region of Gα12. In cultured cells expressing constitutively GDP-bound Gα12 or Gα13, the Gα12 construct was more potent in exerting a dominant-negative effect on serum-mediated signaling to p114RhoGEF, demonstrating coupling of these signaling proteins in a cellular pathway. In addition, charge-reversal of conserved residues in AKAP-Lbc and p114RhoGEF disrupted Gα12 binding for both proteins, suggesting they harbor a common structural mechanism for interaction with this α subunit. Our results provide the first evidence of p114RhoGEF as a Gα12 signaling effector, and define a novel region conserved between AKAP-Lbc and p114RhoGEF that allows Gα12 signaling input to these non-RH RhoGEFs.
Collapse
|
8
|
Masià-Balagué M, Izquierdo I, Garrido G, Cordomí A, Pérez-Benito L, Miller NLG, Schlaepfer DD, Gigoux V, Aragay AM. Gastrin-stimulated Gα13 Activation of Rgnef Protein (ArhGEF28) in DLD-1 Colon Carcinoma Cells. J Biol Chem 2015; 290:15197-209. [PMID: 25922072 PMCID: PMC4463461 DOI: 10.1074/jbc.m114.628164] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2014] [Revised: 04/27/2015] [Indexed: 12/15/2022] Open
Abstract
The guanine nucleotide exchange factor Rgnef (also known as ArhGEF28 or p190RhoGEF) promotes colon carcinoma cell motility and tumor progression via interaction with focal adhesion kinase (FAK). Mechanisms of Rgnef activation downstream of integrin or G protein-coupled receptors remain undefined. In the absence of a recognized G protein signaling homology domain in Rgnef, no proximal linkage to G proteins was known. Utilizing multiple methods, we have identified Rgnef as a new effector for Gα13 downstream of gastrin and the type 2 cholecystokinin receptor. In DLD-1 colon carcinoma cells depleted of Gα13, gastrin-induced FAK Tyr(P)-397 and paxillin Tyr(P)-31 phosphorylation were reduced. RhoA GTP binding and promoter activity were increased by Rgnef in combination with active Gα13. Rgnef co-immunoprecipitated with activated Gα13Q226L but not Gα12Q229L. The Rgnef C-terminal (CT, 1279-1582) region was sufficient for co-immunoprecipitation, and Rgnef-CT exogenous expression prevented Gα13-stimulated SRE activity. A domain at the C terminus of the protein close to the FAK binding domain is necessary to bind to Gα13. Point mutations of Rgnef-CT residues disrupt association with active Gα13 but not Gαq. These results show that Rgnef functions as an effector of Gα13 signaling and that this linkage may mediate FAK activation in DLD-1 colon carcinoma cells.
Collapse
Affiliation(s)
- Miriam Masià-Balagué
- From the Molecular Biology Institute of Barcelona, Spanish National Research Council (CSIC), 08028 Barcelona, Spain
| | - Ismael Izquierdo
- From the Molecular Biology Institute of Barcelona, Spanish National Research Council (CSIC), 08028 Barcelona, Spain
| | - Georgina Garrido
- From the Molecular Biology Institute of Barcelona, Spanish National Research Council (CSIC), 08028 Barcelona, Spain
| | - Arnau Cordomí
- the Departament de Pediatria, Unitat de Bioestadística, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain
| | - Laura Pérez-Benito
- the Departament de Pediatria, Unitat de Bioestadística, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain
| | - Nichol L G Miller
- the Université Paul Sabatier Réceptologie et Ciblage Thérapeutique en Cancérologie, INSERM, Toulouse, France, and
| | - David D Schlaepfer
- the Université Paul Sabatier Réceptologie et Ciblage Thérapeutique en Cancérologie, INSERM, Toulouse, France, and
| | - Véronique Gigoux
- the Moores Cancer Center, University of California at San Diego, La Jolla, California 92093
| | - Anna M Aragay
- From the Molecular Biology Institute of Barcelona, Spanish National Research Council (CSIC), 08028 Barcelona, Spain,
| |
Collapse
|
9
|
Montgomery ER, Temple BRS, Peters KA, Tolbert CE, Booker BK, Martin JW, Hamilton TP, Tagliatela AC, Smolski WC, Rogers SL, Jones AM, Meigs TE. Gα12 structural determinants of Hsp90 interaction are necessary for serum response element-mediated transcriptional activation. Mol Pharmacol 2014; 85:586-97. [PMID: 24435554 PMCID: PMC3965892 DOI: 10.1124/mol.113.088443] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 01/16/2014] [Indexed: 12/31/2022] Open
Abstract
The G12/13 class of heterotrimeric G proteins, comprising the α-subunits Gα12 and Gα13, regulates multiple aspects of cellular behavior, including proliferation and cytoskeletal rearrangements. Although guanine nucleotide exchange factors for the monomeric G protein Rho (RhoGEFs) are well characterized as effectors of this G protein class, a variety of other downstream targets has been reported. To identify Gα12 determinants that mediate specific protein interactions, we used a structural and evolutionary comparison between the G12/13, Gs, Gi, and Gq classes to identify "class-distinctive" residues in Gα12 and Gα13. Mutation of these residues in Gα12 to their deduced ancestral forms revealed a subset necessary for activation of serum response element (SRE)-mediated transcription, a G12/13-stimulated pathway implicated in cell proliferative signaling. Unexpectedly, this subset of Gα12 mutants showed impaired binding to heat-shock protein 90 (Hsp90) while retaining binding to RhoGEFs. Corresponding mutants of Gα13 exhibited robust SRE activation, suggesting a Gα12-specific mechanism, and inhibition of Hsp90 by geldanamycin or small interfering RNA-mediated lowering of Hsp90 levels resulted in greater downregulation of Gα12 than Gα13 signaling in SRE activation experiments. Furthermore, the Drosophila G12/13 homolog Concertina was unable to signal to SRE in mammalian cells, and Gα12:Concertina chimeras revealed Gα12-specific determinants of SRE activation within the switch regions and a C-terminal region. These findings identify Gα12 determinants of SRE activation, implicate Gα12:Hsp90 interaction in this signaling mechanism, and illuminate structural features that arose during evolution of Gα12 and Gα13 to allow bifurcated mechanisms of signaling to a common cell proliferative pathway.
Collapse
Affiliation(s)
- Ellyn R Montgomery
- Department of Biology, University of North Carolina at Asheville, Asheville, North Carolina (E.R.M., B.K.B., J.W.M., T.P.H., A.C.T., W.C.S., T.E.M.); Departments of Biology (K.A.P., S.L.R., A.M.J.), Biochemistry and Biophysics (B.R.S.T.), Cell Biology and Physiology (C.E.T.), and Pharmacology (A.M.J.), R. L. Juliano Structural Bioinformatics Core Facility (B.R.S.T.), and Carolina Center for Genome Sciences (S.L.R.), University of North Carolina, and the Lineberger Comprehensive Cancer Center, (S.L.R., T.E.M.), Chapel Hill, North Carolina
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Chow CR, Suzuki N, Kawamura T, Hamakubo T, Kozasa T. Modification of p115RhoGEF Ser(330) regulates its RhoGEF activity. Cell Signal 2013; 25:2085-92. [PMID: 23816534 PMCID: PMC4076829 DOI: 10.1016/j.cellsig.2013.06.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 06/14/2013] [Accepted: 06/18/2013] [Indexed: 01/04/2023]
Abstract
p115RhoGEF is a member of a family of Rho-specific guanine nucleotide exchange factors that also contains a regulator of G protein signaling homology domain (RH-RhoGEFs) that serves as a link between Gα13 signaling and RhoA activation. While the mechanism of regulation of p115RhoGEF by Gα13 is becoming well-known, the role of other regulatory mechanisms, such as post-translational modification or autoinhibition, in mediating p115RhoGEF activity is less well-characterized. Here, putative phosphorylation sites on p115RhoGEF are identified and characterized. Mutation of Ser(330) leads to a decrease in serum response element-mediated transcription as well as decreased activation by Gα13 in vitro. Additionally, this study provides the first report of the binding kinetics between full-length p115RhoGEF and RhoA in its various nucleotide states and examines the binding kinetics of phospho-mutant p115RhoGEF to RhoA. These data, together with other recent reports on regulatory mechanisms of p115RhoGEF, suggest that this putative phosphorylation site serves as a means for initiation or relief of autoinhibition of p115RhoGEF, providing further insight into the regulation of its activity.
Collapse
Affiliation(s)
- Christina R. Chow
- Department of Pharmacology, University of Illinois at Chicago, 835 S. Wolcott Avenue Room E403 (m/c 868), Chicago, Illinois 60612, USA
- Laboratory for Systems Biology and Medicine, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Nobuchika Suzuki
- Laboratory for Systems Biology and Medicine, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Takeshi Kawamura
- Laboratory for Systems Biology and Medicine, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Takao Hamakubo
- Department of Quantitative Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Tohru Kozasa
- Department of Pharmacology, University of Illinois at Chicago, 835 S. Wolcott Avenue Room E403 (m/c 868), Chicago, Illinois 60612, USA
- Laboratory for Systems Biology and Medicine, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| |
Collapse
|
11
|
Baltoumas FA, Theodoropoulou MC, Hamodrakas SJ. Interactions of the α-subunits of heterotrimeric G-proteins with GPCRs, effectors and RGS proteins: A critical review and analysis of interacting surfaces, conformational shifts, structural diversity and electrostatic potentials. J Struct Biol 2013; 182:209-18. [DOI: 10.1016/j.jsb.2013.03.004] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Revised: 03/06/2013] [Accepted: 03/11/2013] [Indexed: 01/05/2023]
|
12
|
Ritchie BJ, Smolski WC, Montgomery ER, Fisher ES, Choi TY, Olson CM, Foster LA, Meigs TE. Determinants at the N- and C-termini of Gα12 required for activation of Rho-mediated signaling. J Mol Signal 2013; 8:3. [PMID: 23531275 PMCID: PMC3636079 DOI: 10.1186/1750-2187-8-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 03/17/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Heterotrimeric guanine nucleotide binding proteins of the G12/13 subfamily, which includes the α-subunits Gα12 and Gα13, stimulate the monomeric G protein RhoA through interaction with a distinct subset of Rho-specific guanine nucleotide exchange factors (RhoGEFs). The structural features that mediate interaction between Gα13 and RhoGEFs have been examined in crystallographic studies of the purified complex, whereas a Gα12:RhoGEF complex has not been reported. Several signaling responses and effector interactions appear unique to Gα12 or Gα13, despite their similarity in amino acid sequence. METHODS To comprehensively examine Gα12 for regions involved in RhoGEF interaction, we screened a panel of Gα12 cassette substitution mutants for binding to leukemia-associated RhoGEF (LARG) and for activation of serum response element mediated transcription. RESULTS We identified several cassette substitutions that disrupt Gα12 binding to LARG and the related p115RhoGEF. These Gα12 mutants also were impaired in activating serum response element mediated signaling, a Rho-dependent response. Most of these mutants matched corresponding regions of Gα13 reported to contact p115RhoGEF, but unexpectedly, several RhoGEF-uncoupling mutations were found within the N- and C-terminal regions of Gα12. Trypsin protection assays revealed several mutants in these regions as retaining conformational activation. In addition, charge substitutions near the Gα12 N-terminus selectively disrupted binding to LARG but not p115RhoGEF. CONCLUSIONS Several structural aspects of the Gα12:RhoGEF interface differ from the reported Gα13:RhoGEF complex, particularly determinants within the C-terminal α5 helix and structurally uncharacterized N-terminus of Gα12. Furthermore, key residues at the Gα12 N-terminus may confer selectivity for LARG as a downstream effector.
Collapse
Affiliation(s)
- Benjamin J Ritchie
- Department of Biology, University of North Carolina at Asheville, One University Heights, Asheville, NC 28804, USA.
| | | | | | | | | | | | | | | |
Collapse
|
13
|
The zinc-binding region of IL-2 inducible T cell kinase (Itk) is required for interaction with Gα13 and activation of serum response factor. Int J Biochem Cell Biol 2013; 45:1074-82. [PMID: 23454662 DOI: 10.1016/j.biocel.2013.02.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2012] [Revised: 02/04/2013] [Accepted: 02/18/2013] [Indexed: 11/20/2022]
Abstract
Tec family kinases play critical roles in the activation of immune cells. In particular, Itk is important for the activation of T cells via the T cell Receptor (TcR), however, molecules that cooperate with Itk to activate downstream targets remain little explored. Here we show that Itk interacts with the heterotrimeric G-protein α subunit Gα13 during TcR triggering. This interaction requires membrane localization of both partners, and is partially dependent on GDP- and GTP-bound states of Gα13. Furthermore, we find that Itk interacts with Gα13 via the zinc binding regions within its Tec homology domain. The interaction between Itk and Gα13 also results in tyrosine phosphorylation of Gα13, however this is not required for the interaction. Itk enhances Gα13 mediated activation of serum response factor (SRF) transcriptional activity dependent on its ability to interact with Gα13, but its kinase activity is not required to enhance SRF activity. These data reveal a new pathway regulated by Itk in cells, and suggest cross talk between Itk and G-protein signaling downstream of the TcR.
Collapse
|
14
|
Abstract
Spatio-temporal control of RhoA GTPase is critical for regulation of cell migration, attachment to extracellular matrix, and cell-cell adhesions. Activation of RhoA is mediated by guanine nucleotide exchange factors (GEFs), a diverse family of enzymes that are controlled by multiple signaling pathways regulating actin cytoskeleton and cell migration. GEFs can be regulated by different mechanisms. Growing evidence demonstrates that phosphorylation serves as one of the predominant signals controlling activity, interactions, and localization of RhoGEFs. It acts as a positive and a negative regulator, and allows for regulation of RhoGEFs by multiple signaling cascades. Although there are common trends in phosphorylation-mediated regulation of some RhoGEF homologs, the majority of GEFs utilize distinct mechanisms that are dictated by their unique structure and interaction networks. This diversity enables multiple signaling pathways to use different RhoGEFs for regulation of a single central-RhoA. Here, we review current examples of phosphorylation-mediated regulation of GEFs for RhoA and its role in cell migration, discuss mechanisms, and provide insights into potential future directions.
Collapse
Affiliation(s)
- Maulik Patel
- Department of Pharmacology; University of Illinois at Chicago; Chicago, IL USA
| | - Andrei V Karginov
- Department of Pharmacology; University of Illinois at Chicago; Chicago, IL USA
| |
Collapse
|
15
|
Dohlman HG, Jones JC. Signal activation and inactivation by the Gα helical domain: a long-neglected partner in G protein signaling. Sci Signal 2012; 5:re2. [PMID: 22649098 DOI: 10.1126/scisignal.2003013] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Heterotrimeric guanine nucleotide-binding proteins (G proteins) are positioned at the top of many signal transduction pathways. The G protein α subunit is composed of two domains, one that resembles Ras and another that is composed entirely of α helices. Historically most attention has focused on the Ras-like domain, but emerging evidence reveals that the helical domain is an active participant in G protein signaling.
Collapse
Affiliation(s)
- Henrik G Dohlman
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | | |
Collapse
|
16
|
Kozasa T, Hajicek N, Chow CR, Suzuki N. Signalling mechanisms of RhoGTPase regulation by the heterotrimeric G proteins G12 and G13. J Biochem 2011; 150:357-69. [PMID: 21873336 DOI: 10.1093/jb/mvr105] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
G protein-mediated signal transduction can transduce signals from a large variety of extracellular stimuli into cells and is the most widely used mechanism for cell communication at the membrane. The RhoGTPase family has been well established as key regulators of cell growth, differentiation and cell shape changes. Among G protein-mediated signal transduction, G12/13-mediated signalling is one mechanism to regulate RhoGTPase activity in response to extracellular stimuli. The alpha subunits of G12 or G13 have been shown to interact with members of the RH domain containing guanine nucleotide exchange factors for Rho (RH-RhoGEF) family of proteins to directly connect G protein-mediated signalling and RhoGTPase signalling. The G12/13-RH-RhoGEF signalling mechanism is well conserved over species and is involved in critical steps for cell physiology and disease conditions, including embryonic development, oncogenesis and cancer metastasis. In this review, we will summarize current progress on this important signalling mechanism.
Collapse
Affiliation(s)
- Tohru Kozasa
- Laboratory of Systems Biology and Medicine, Research Center for Advanced Science and Technology, University of Tokyo, Tokyo 153-8904, Japan.
| | | | | | | |
Collapse
|
17
|
Aittaleb M, Nishimura A, Linder ME, Tesmer JJG. Plasma membrane association of p63 Rho guanine nucleotide exchange factor (p63RhoGEF) is mediated by palmitoylation and is required for basal activity in cells. J Biol Chem 2011; 286:34448-56. [PMID: 21832057 DOI: 10.1074/jbc.m111.273342] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activation of G protein-coupled receptors at the cell surface leads to the activation or inhibition of intracellular effector enzymes, which include various Rho guanine nucleotide exchange factors (RhoGEFs). RhoGEFs activate small molecular weight GTPases at the plasma membrane (PM). Many of the known G protein-coupled receptor-regulated RhoGEFs are found in the cytoplasm of unstimulated cells, and PM recruitment is a critical aspect of their regulation. In contrast, p63RhoGEF, a Gα(q)-regulated RhoGEF, appears to be constitutively localized to the PM. The objective of this study was to determine the molecular basis for the localization of p63RhoGEF and the impact of its subcellular localization on its regulation by Gα(q). Herein, we show that the pleckstrin homology domain of p63RhoGEF is not involved in its PM targeting. Instead, a conserved string of cysteines (Cys-23/25/26) at the N terminus of the enzyme is palmitoylated and required for membrane localization and full basal activity in cells. Conversion of these residues to serine relocates p63RhoGEF from the PM to the cytoplasm, diminishes its basal activity, and eliminates palmitoylation. The activity of palmitoylation-deficient p63RhoGEF can be rescued by targeting to the PM by fusion with tandem phospholipase C-δ1 pleckstrin homology domains or by co-expression with wild-type Gα(q) but not with palmitoylation-deficient Gα(q). Our data suggest that p63RhoGEF is regulated chiefly through allosteric control by Gα(q), as opposed to other known Gα-regulated RhoGEFs, which are instead sequestered in the cytoplasm, perhaps because of their high basal activity.
Collapse
Affiliation(s)
- Mohamed Aittaleb
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109-2216, USA
| | | | | | | |
Collapse
|