1
|
Garcia-Marcos M. Heterotrimeric G protein signaling without GPCRs: The Gα-binding-and-activating (GBA) motif. J Biol Chem 2024; 300:105756. [PMID: 38364891 PMCID: PMC10943482 DOI: 10.1016/j.jbc.2024.105756] [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: 10/28/2023] [Revised: 01/30/2024] [Accepted: 02/02/2024] [Indexed: 02/18/2024] Open
Abstract
Heterotrimeric G proteins (Gαβγ) are molecular switches that relay signals from 7-transmembrane receptors located at the cell surface to the cytoplasm. The function of these receptors is so intimately linked to heterotrimeric G proteins that they are named G protein-coupled receptors (GPCRs), showcasing the interdependent nature of this archetypical receptor-transducer axis of transmembrane signaling in eukaryotes. It is generally assumed that activation of heterotrimeric G protein signaling occurs exclusively by the action of GPCRs, but this idea has been challenged by the discovery of alternative mechanisms by which G proteins can propagate signals in the cell. This review will focus on a general principle of G protein signaling that operates without the direct involvement of GPCRs. The mechanism of G protein signaling reviewed here is mediated by a class of G protein regulators defined by containing an evolutionarily conserved sequence named the Gα-binding-and-activating (GBA) motif. Using the best characterized proteins with a GBA motif as examples, Gα-interacting vesicle-associated protein (GIV)/Girdin and dishevelled-associating protein with a high frequency of leucine residues (DAPLE), this review will cover (i) the mechanisms by which extracellular cues not relayed by GPCRs promote the coupling of GBA motif-containing regulators with G proteins, (ii) the structural and molecular basis for how GBA motifs interact with Gα subunits to facilitate signaling, (iii) the relevance of this mechanism in different cellular and pathological processes, including cancer and birth defects, and (iv) strategies to manipulate GBA-G protein coupling for experimental therapeutics purposes, including the development of rationally engineered proteins and chemical probes.
Collapse
Affiliation(s)
- Mikel Garcia-Marcos
- Department of Biochemistry & Cell Biology, Chobanian & Avedisian School of Medicine, Boston University, Boston, Massachusetts, USA; Department of Biology, College of Arts & Sciences, Boston University, Boston, Massachusetts, USA.
| |
Collapse
|
2
|
Zhang H, Yu F, Qin F, Shao Y, Chong W, Guo Z, Liu X, Fu L, Gu F, Ma Y. Combination of cytoplasmic and nuclear girdin expression is an independent prognosis factor of breast cancer. FASEB J 2017; 32:2395-2410. [PMID: 29259035 DOI: 10.1096/fj.201700825rr] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Girdin is an actin-binding protein playing key roles in the development of various carcinomas. Although online tools have predicted nuclear localization of girdin with a high probability, convincing proof has rarely been provided until now. The purpose of this study was to discover girdin's precise subcellular distribution and the potential prognostic value corresponding to its localization. The subcellular distribution of girdin was detected in a human breast cancer cell line and in >800 samples of human breast tissue by clinical pathologic analysis. In this study, we discovered for the first time that girdin could attach to chromatin and interact with topoisomerase-IIα in nucleus. Cytoplasmic and nuclear girdin exhibited different roles in prognosis of breast cancer: cytoplasmic girdin expression was an independent prognostic factor for progression-free survival (PFS), whereas nuclear girdin expression was an independent prognostic factor for overall survival (OS). More important, combination cytoplasmic and nuclear girdin was an independent prognosis factor of both OS and PFS. In conclusion, our research results strongly recommend combination analysis of cytoplasmic and nuclear girdin for a precise prognostic prediction in breast cancer.-Zhang, H., Yu, F., Qin, F., Shao, Y., Chong, W., Guo, Z., Liu, X., Fu, L., Gu, F., Ma, Y. Combination of cytoplasmic and nuclear girdin expression is an independent prognosis factor of breast cancer.
Collapse
Affiliation(s)
- Huikun Zhang
- Department of Breast Cancer Pathology and Research Laboratory, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Feng Yu
- Department of Tumor Cell Biology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, China.,Tianjin's Clinical Research Center for Cancer, Tianjin, China.,Key Laboratory of Cancer Prevention and Therapy, Tianjin, China.,Key Laboratory of Breast Cancer Prevention and Therapy, Tianjin Medical University, Ministry of Education, Tianjin, China
| | - Fengxia Qin
- Department of Breast Cancer Pathology and Research Laboratory, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Ying Shao
- Department of Breast Cancer Pathology and Research Laboratory, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Wei Chong
- Department of Breast Cancer Pathology and Research Laboratory, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Zhifang Guo
- Department of Tumor Cell Biology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, China
| | - Xiaoli Liu
- Department of Tumor Cell Biology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, China
| | - Li Fu
- Department of Breast Cancer Pathology and Research Laboratory, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Feng Gu
- Department of Breast Cancer Pathology and Research Laboratory, Tianjin Medical University Cancer Institute and Hospital, Tianjin, China
| | - Yongjie Ma
- Department of Tumor Cell Biology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Tianjin, China.,Tianjin's Clinical Research Center for Cancer, Tianjin, China.,Key Laboratory of Cancer Prevention and Therapy, Tianjin, China.,Key Laboratory of Breast Cancer Prevention and Therapy, Tianjin Medical University, Ministry of Education, Tianjin, China
| |
Collapse
|
3
|
DiGiacomo V, de Opakua AI, Papakonstantinou MP, Nguyen LT, Merino N, Blanco-Canosa JB, Blanco FJ, Garcia-Marcos M. The Gαi-GIV binding interface is a druggable protein-protein interaction. Sci Rep 2017; 7:8575. [PMID: 28819150 PMCID: PMC5561080 DOI: 10.1038/s41598-017-08829-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 07/12/2017] [Indexed: 01/26/2023] Open
Abstract
Heterotrimeric G proteins are usually activated by the guanine-nucleotide exchange factor (GEF) activity of GPCRs. However, some non-receptor proteins are also GEFs. GIV (a.k.a Girdin) was the first non-receptor protein for which the GEF activity was ascribed to a well-defined protein sequence that directly binds Gαi. GIV expression promotes metastasis and disruption of its binding to Gαi blunts the pro-metastatic behavior of cancer cells. Although this suggests that inhibition of the Gαi-GIV interaction is a promising therapeutic strategy, protein-protein interactions (PPIs) are considered poorly "druggable" targets requiring case-by-case validation. Here, we set out to investigate whether Gαi-GIV is a druggable PPI. We tested a collection of >1,000 compounds on the Gαi-GIV PPI by in silico ligand screening and separately by a chemical high-throughput screening (HTS) assay. Two hits, ATA and NF023, obtained in both screens were confirmed in secondary HTS and low-throughput assays. The binding site of NF023, identified by NMR spectroscopy and biochemical assays, overlaps with the Gαi-GIV interface. Importantly, NF023 did not disrupt Gαi-Gβγ binding, indicating its specificity toward Gαi-GIV. This work establishes the Gαi-GIV PPI as a druggable target and sets the conceptual and technical framework for the discovery of novel inhibitors of this PPI.
Collapse
Affiliation(s)
- Vincent DiGiacomo
- Department of Biochemistry, Boston University School of Medicine, Boston, USA
| | | | | | - Lien T Nguyen
- Department of Biochemistry, Boston University School of Medicine, Boston, USA
| | | | - Juan B Blanco-Canosa
- Department of Chemistry and Molecular Pharmacology, IRB Barcelona, Barcelona, Spain
| | - Francisco J Blanco
- CIC-BioGune, Derio, Spain.,IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
| | - Mikel Garcia-Marcos
- Department of Biochemistry, Boston University School of Medicine, Boston, USA.
| |
Collapse
|
4
|
Dunkel Y, Diao K, Aznar N, Swanson L, Liu L, Zhu W, Mi XY, Ghosh P. Prognostic impact of total and tyrosine phosphorylated GIV/Girdin in breast cancers. FASEB J 2016; 30:3702-3713. [PMID: 27440794 DOI: 10.1096/fj.201600500] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 07/05/2016] [Indexed: 12/27/2022]
Abstract
Gα-interacting vesicle-associated protein (GIV, aka Girdin) is a guanine exchange factor (GEF) for the trimeric G protein Gαi and a bona fide metastasis-related gene that serves as a platform for amplification of tyrosine-based signals via G-protein intermediates. Here we present the first exploratory biomarker study conducted on a cohort of 187 patients with breast cancer to evaluate the prognostic role of total GIV (tGIV) and tyrosine phosphorylated GIV (pYGIV) across the various molecular subtypes. A Kaplan-Meier analysis of recurrence-free survival showed that the presence of tGIV, either cytoplasmic or nuclear, carried poor prognosis, but that nuclear tGIV had a greater prognostic impact (P = 0.007 in early and P = 0.0048 in late clinical stages). Activated pYGIV in the cytoplasm had the greatest prognostic impact in late clinical stages (P = 0.006). Furthermore, we found that the prognostic impacts of cytoplasmic pYGIV and nuclear tGIV were additive (hazard ratio 19.0548; P = 0.0002). Surprisingly, this additive effect of nuclear tGIV/cytoplasmic pYGIV was observed in human epidermal growth factor receptor 2-positive tumors (hazard ratio 16.918; P = 0.0005) but not in triple-negative breast cancers. In triple-negative breast cancers, tGIV and cytoplasmic pYGIV had no prognostic impact; however, membrane-association of pYGIV carried a poor prognosis (P = 0.026). Both tGIV and pYGIV showed no correlation with clinical stage, tumor size, pathologic type, lymph node involvement, and BRCA1/2 status. We conclude that immunocytochemical detection of pYGIV and tGIV can serve as an effective prognosticator. On the basis of the differential prognostic impact of tGIV/pYGIV within each molecular subtype, we propose a diagnostic algorithm. Further studies on larger cohorts are essential to rigorously assess the effectiveness and robustness of this algorithm in prognosticating outcome among patients with breast cancer.-Dunkel, Y., Diao, K., Aznar, N., Swanson, L., Liu, L., Zhu, W., Mi, X.-Y., Ghosh, P. Prognostic impact of total and tyrosine phosphorylated GIV/Girdin in breast cancers.
Collapse
Affiliation(s)
- Ying Dunkel
- Department of Medicine.,Department of Cell and Molecular Medicine
| | - Kexin Diao
- Department of Pathology, China Medical University, Shenyang, China
| | - Nicolas Aznar
- Department of Medicine.,Department of Cell and Molecular Medicine
| | - Lee Swanson
- Department of Medicine.,Department of Cell and Molecular Medicine
| | - Lawrence Liu
- Department of Medicine.,Department of Cell and Molecular Medicine
| | - Wenhong Zhu
- Division of Biomedical Informatics, University of California, San Diego, La Jolla, California, USA
| | - Xiao-Yi Mi
- Department of Pathology, China Medical University, Shenyang, China;
| | - Pradipta Ghosh
- Department of Medicine, .,Department of Cell and Molecular Medicine
| |
Collapse
|