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Luo H, Marron Fernandez de Velasco E, Wickman K. Neuronal G protein-gated K + channels. Am J Physiol Cell Physiol 2022; 323:C439-C460. [PMID: 35704701 PMCID: PMC9362898 DOI: 10.1152/ajpcell.00102.2022] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
G protein-gated inwardly rectifying K+ (GIRK/Kir3) channels exert a critical inhibitory influence on neurons. Neuronal GIRK channels mediate the G protein-dependent, direct/postsynaptic inhibitory effect of many neurotransmitters including γ-aminobutyric acid (GABA), serotonin, dopamine, adenosine, somatostatin, and enkephalin. In addition to their complex regulation by G proteins, neuronal GIRK channel activity is sensitive to PIP2, phosphorylation, regulator of G protein signaling (RGS) proteins, intracellular Na+ and Ca2+, and cholesterol. The application of genetic and viral manipulations in rodent models, together with recent progress in the development of GIRK channel modulators, has increased our understanding of the physiological and behavioral impact of neuronal GIRK channels. Work in rodent models has also revealed that neuronal GIRK channel activity is modified, transiently or persistently, by various stimuli including exposure drugs of abuse, changes in neuronal activity patterns, and aversive experience. A growing body of preclinical and clinical evidence suggests that dysregulation of GIRK channel activity contributes to neurological diseases and disorders. The primary goals of this review are to highlight fundamental principles of neuronal GIRK channel biology, mechanisms of GIRK channel regulation and plasticity, the nascent landscape of GIRK channel pharmacology, and the potential relevance of GIRK channels to the pathophysiology and treatment of neurological diseases and disorders.
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Affiliation(s)
- Haichang Luo
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States
| | | | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States
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2
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Taylor EL, Weaver SR, Lorang IM, Arnold KM, Bradley EW, Marron Fernandez de Velasco E, Wickman K, Westendorf JJ. GIRK3 deletion facilitates kappa opioid signaling in chondrocytes, delays vascularization and promotes bone lengthening in mice. Bone 2022; 159:116391. [PMID: 35314385 PMCID: PMC9035100 DOI: 10.1016/j.bone.2022.116391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Revised: 03/03/2022] [Accepted: 03/14/2022] [Indexed: 11/29/2022]
Abstract
Long bones are formed and repaired through the process of endochondral ossification. Activation of G protein-coupled receptor (GPCR) signaling pathways is crucial for skeletal development and long bone growth. G protein-gated inwardly-rectifying K+ (GIRK) channel genes are key functional components and effectors of GPCR signaling pathways in excitable cells of the heart and brain, but their roles in non-excitable cells that directly contribute to endochondral bone formation have not been studied. In this study, we analyzed skeletal phenotypes of Girk2-/-, Girk3-/- and Girk2/3-/- mice. Bones from 12-week-old Girk2-/- mice were normal in length, but femurs and tibiae from Girk3-/- and Girk2/3-/- mice were longer than age-matched controls at 12-weeks-old. Epiphyseal chondrocytes from 5-day-old Girk3-/- mice expressed higher levels of genes involved in collagen chain trimerization and collagen fibril assembly, lower levels of genes encoding VEGF receptors, and produced larger micromasses than wildtype chondrocytes in vitro. Girk3-/- chondrocytes were also more responsive to the kappa opioid receptor (KOR) ligand dynorphin, as evidenced by greater pCREB expression, greater cAMP and GAG production, and upregulation of Col2a1 and Sox9 transcripts. Imaging studies showed that Kdr (Vegfr2) and endomucin expression was dramatically reduced in bones from young Girk3-/- mice, supporting a role for delayed vasculogenesis and extended postnatal endochondral bone growth. Together these data indicate that GIRK3 controls several processes involved in bone lengthening.
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Affiliation(s)
- Earnest L Taylor
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, United States of America; Department of Cell Biology, University of North Carolina, NC, United States of America
| | - Samantha R Weaver
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, United States of America
| | - Ian M Lorang
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, United States of America; University of Washington School of Medicine, Seattle, WA, United States of America
| | - Katherine M Arnold
- Mayo Clinic Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN, United States of America
| | - Elizabeth W Bradley
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, United States of America; Department of Orthopedic Surgery, University of Minnesota, Minneapolis, MN, United States of America
| | | | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, United States of America
| | - Jennifer J Westendorf
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, United States of America; Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, United States of America.
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3
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Chandra M, Kendall AK, Jackson LP. Toward Understanding the Molecular Role of SNX27/Retromer in Human Health and Disease. Front Cell Dev Biol 2021; 9:642378. [PMID: 33937239 PMCID: PMC8083963 DOI: 10.3389/fcell.2021.642378] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 03/22/2021] [Indexed: 11/30/2022] Open
Abstract
Aberrations in membrane trafficking pathways have profound effects in cellular dynamics of cellular sorting processes and can drive severe physiological outcomes. Sorting nexin 27 (SNX27) is a metazoan-specific sorting nexin protein from the PX-FERM domain family and is required for endosomal recycling of many important transmembrane receptors. Multiple studies have shown SNX27-mediated recycling requires association with retromer, one of the best-known regulators of endosomal trafficking. SNX27/retromer downregulation is strongly linked to Down's Syndrome (DS) via glutamate receptor dysfunction and to Alzheimer's Disease (AD) through increased intracellular production of amyloid peptides from amyloid precursor protein (APP) breakdown. SNX27 is further linked to addiction via its role in potassium channel trafficking, and its over-expression is linked to tumorigenesis, cancer progression, and metastasis. Thus, the correct sorting of multiple receptors by SNX27/retromer is vital for normal cellular function to prevent human diseases. The role of SNX27 in regulating cargo recycling from endosomes to the cell surface is firmly established, but how SNX27 assembles with retromer to generate tubulovesicular carriers remains elusive. Whether SNX27/retromer may be a putative therapeutic target to prevent neurodegenerative disease is now an emerging area of study. This review will provide an update on our molecular understanding of endosomal trafficking events mediated by the SNX27/retromer complex on endosomes.
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Affiliation(s)
- Mintu Chandra
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States
- Center for Structural Biology, Vanderbilt University, Nashville, TN, United States
| | - Amy K. Kendall
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States
- Center for Structural Biology, Vanderbilt University, Nashville, TN, United States
| | - Lauren P. Jackson
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, United States
- Center for Structural Biology, Vanderbilt University, Nashville, TN, United States
- Department of Biochemistry, Vanderbilt University, Nashville, TN, United States
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4
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Parente DJ, Morris SM, McKinstry RC, Brandt T, Gabau E, Ruiz A, Shinawi M. Sorting nexin 27 (SNX27) variants associated with seizures, developmental delay, behavioral disturbance, and subcortical brain abnormalities. Clin Genet 2019; 97:437-446. [PMID: 31721175 DOI: 10.1111/cge.13675] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/30/2019] [Accepted: 11/01/2019] [Indexed: 11/27/2022]
Abstract
Sorting nexin 27 (SNX27) influences the composition of the cellular membrane via regulation of selective endosomal recycling. Molecular analysis indicates that SNX27 regulates numerous cellular processes through promiscuous interactions with its receptor cargos. SNX27 deficient (Snx27 -/- ) mice exhibit reduced embryonic survival, marked postnatal growth restriction and lethality. Haploinsufficient mice (Snx27 +/- ) show a less severe phenotype, with deficits in learning, memory, synaptic transmission and neuronal plasticity. One family previously reported with a homozygous SNX27 frameshift variant (c.515_516del;p.His172Argfs*6), exhibited infantile intractable myoclonic epilepsy, axial hypotonia, startle-like movements, cardiac septal defects, global developmental delay, failure to thrive, recurrent chest infections, persistent hypoxemia and early death secondary to respiratory failure. Here, we report two additional patients with compound heterozygous SNX27 variants, that are predicted to be damaging: (a) c.510C>G;p.Tyr170* and c.1295G>A;p.Cys432Tyr, and (b) c.782dupT;p.Leu262Profs*6 and c.989G>A;p.Arg330His. They exhibit global developmental delay, behavioral disturbance, epilepsy, some dysmorphic features and subcortical white matter abnormalities. In addition, possible connective tissue involvement was noted. Epilepsy, developmental delays and subcortical white matter abnormalities appear to be core features of SNX27-related disorders. We correlate the observed phenotype with available in vitro, in vivo and proteomic data and suggest additional possible molecular mediators of SNX27-related pathology.
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Affiliation(s)
- Daniel J Parente
- Department of Family Medicine, University of Kansas Medical Center, Kansas City, Kansas
| | - Stephanie M Morris
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri
| | - Robert C McKinstry
- Pediatric Radiology and Pediatric Neuroradiology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri
| | | | - Elisabeth Gabau
- Paediatric Unit, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí I3PT, Universitat Autònoma de Barcelona, Sabadell, Spain
| | - Anna Ruiz
- Genetics Laboratory, UDIAT-Centre Diagnòstic, Parc Taulí Hospital Universitari, Institut d'Investigació i Innovació Parc Taulí I3PT, Universitat Autònoma de Barcelona, Sabadell, Spain
| | - Marwan Shinawi
- Division of Genetics and Genomic Medicine, Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
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Zhang J, Li K, Zhang Y, Lu R, Wu S, Tang J, Xia Y, Sun J. Deletion of sorting nexin 27 suppresses proliferation in highly aggressive breast cancer MDA-MB-231 cells in vitro and in vivo. BMC Cancer 2019; 19:555. [PMID: 31182056 PMCID: PMC6558813 DOI: 10.1186/s12885-019-5769-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 05/29/2019] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Sorting Nexin 27 (SNX27) belongs to a family of sortin nexins and possesses a unique binding domain at the C-terminus which mediates protein-protein interaction in intracellular trafficking, membrane remodeling, organelle motility, and tight junctions. However, its role in cancer development, especially in vivo, remains largely unknown. METHODS We have generated a stable SNX27 knockdown clone in a highly aggressive breast cancer cell line MDA-MB-231 using an inducible lentiviral shRNA system. Cell migration and proliferation of SNX27 knockdown (KD) cells were compared with wild-type (WT) cells by MTT and wound healing assay, respectively. The differences in colony formation between SNX27-KD and WT cells were detected by soft agar culture and matrigel 3D culture. Furthermore, tumor growth was examined in a xenograft nude mouse model using SNX27-KD and WT MDA-MB-231 cells. The critical EMT (epithelial-mesenchymal transition) regulators were examined in vitro and in vivo. RESULTS The wound healing assay showed that SNX27 knockdown significantly decreased cell motility and proliferation. Colony formation in soft agar showed that the SNX27 knockdown cells formed significantly fewer and smaller colonies than the parental MDA-MB-231 cells. Western blots and immunostaining showed that knockdown of SNX27 led to increased expression of E-cadherin and β-catenin proteins, which facilitate adhesion formation and reverse EMT. EMT is a cellular program that allows polarized, immotile epithelial cells to convert to motile mesenchymal cells, promoting carcinoma invasion. The expression levels of Vimentin, the transcription factor of EMT, and tight junction protein Claudin-5, were significantly diminished in the SNX27 knockdown cells. The expression of PCNA, the cell proliferation marker, was increased in SNX27-KD cells transfected with E-cadherin siRNA. In a xenograft nude mouse model, we found that knockdown of SNX27 significantly inhibited tumor growth. The tumors from mice with SNX27-KD cells showed less proliferation compared to tumors from mice injected with wildtype cells. The increase in E-cadherin and β-catenin and decrease in Vimentin and Claudin-5 were observed in tumors of mice injected with SNX27-KD cells. CONCLUSIONS Our data have demonstrated that SNX27 plays a crucial role in tumor growth in vitro and in vivo.
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Affiliation(s)
- Jilei Zhang
- Division of Gastroenterology and Hepatology, Medicine, University of Illinois at Chicago, 840 S Wood Street, Room 704 CSB, MC716, Chicago, IL, 60612, USA
| | - Kendy Li
- Liberal Arts & Human Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
| | - Yongguo Zhang
- Division of Gastroenterology and Hepatology, Medicine, University of Illinois at Chicago, 840 S Wood Street, Room 704 CSB, MC716, Chicago, IL, 60612, USA
| | - Rong Lu
- Division of Gastroenterology and Hepatology, Medicine, University of Illinois at Chicago, 840 S Wood Street, Room 704 CSB, MC716, Chicago, IL, 60612, USA
| | - Shaoping Wu
- Department of Biochemistry, Rush University, Chicago, IL, USA
| | - Jingrong Tang
- Section of Inflammation and Cardiometabolic Diseases, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health, Bethesda, MD, USA
| | - Yinglin Xia
- Division of Gastroenterology and Hepatology, Medicine, University of Illinois at Chicago, 840 S Wood Street, Room 704 CSB, MC716, Chicago, IL, 60612, USA
| | - Jun Sun
- Division of Gastroenterology and Hepatology, Medicine, University of Illinois at Chicago, 840 S Wood Street, Room 704 CSB, MC716, Chicago, IL, 60612, USA.
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Kozell LB, Denmark DL, Walter NAR, Buck KJ. Distinct Roles for Two Chromosome 1 Loci in Ethanol Withdrawal, Consumption, and Conditioned Place Preference. Front Genet 2018; 9:323. [PMID: 30210527 PMCID: PMC6120100 DOI: 10.3389/fgene.2018.00323] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/30/2018] [Indexed: 11/18/2022] Open
Abstract
We previously identified a region on chromosome 1 that harbor quantitative trait loci (QTLs) with large effects on alcohol withdrawal risk using both chronic and acute models in mice. Here, using newly created and existing QTL interval-specific congenic (ISC) models, we report the first evidence that this region harbors two distinct alcohol withdrawal QTLs (Alcw11and Alcw12), which underlie 13% and 3–6%, respectively, of the genetic variance in alcohol withdrawal severity measured using the handling-induced convulsion. Our results also precisely localize Alcw11 and Alcw12 to discreet chromosome regions (syntenic with human 1q23.1–23.3) that encompass a limited number of genes with validated genotype-dependent transcript expression and/or non-synonymous sequence variation that may underlie QTL phenotypic effects. ISC analyses also implicate Alcw11and Alcw12 in withdrawal-induced anxiety-like behavior, representing the first evidence for their broader roles in alcohol withdrawal beyond convulsions; but detect no evidence for Alcw12 involvement in ethanol conditioned place preference (CPP) or consumption. Our data point to high-quality candidates for Alcw12, including genes involved in mitochondrial respiration, spatial buffering, and neural plasticity, and to Kcnj9 as a high-quality candidate for Alcw11. Our studies are the first to show, using two null mutant models on different genetic backgrounds, that Kcnj9−/− mice demonstrate significantly less severe alcohol withdrawal than wildtype littermates using acute and repeated exposure paradigms. We also demonstrate that Kcnj9−/− voluntarily consume significantly more alcohol (20%, two-bottle choice) than wildtype littermates. Taken together with evidence implicating Kcnj9 in ethanol CPP, our results support a broad role for this locus in ethanol reward and withdrawal phenotypes. In summary, our results demonstrate two distinct chromosome 1 QTLs that significantly affect risk for ethanol withdrawal, and point to their distinct unique roles in alcohol reward phenotypes.
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Affiliation(s)
- Laura B Kozell
- Department of Behavioral Neuroscience, Portland Veterans Affairs Medical Center and School of Medicine, Oregon Health and Science University, Portland, OR, United States
| | - Deaunne L Denmark
- Department of Behavioral Neuroscience, Portland Veterans Affairs Medical Center and School of Medicine, Oregon Health and Science University, Portland, OR, United States
| | - Nicole A R Walter
- Department of Behavioral Neuroscience, Portland Veterans Affairs Medical Center and School of Medicine, Oregon Health and Science University, Portland, OR, United States
| | - Kari J Buck
- Department of Behavioral Neuroscience, Portland Veterans Affairs Medical Center and School of Medicine, Oregon Health and Science University, Portland, OR, United States
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Seaman MNJ. Retromer and Its Role in Regulating Signaling at Endosomes. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2018; 57:137-149. [PMID: 30097774 DOI: 10.1007/978-3-319-96704-2_5] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The retromer complex is a key element of the endosomal protein sorting machinery being involved in trafficking of proteins from endosomes to the Golgi and also endosomes to the cell surface. There is now accumulating evidence that retromer also has a prominent role in regulating the activity of many diverse signaling proteins that traffic through endosomes and this activity has profound implications for the functioning of many different cell and tissue types from neuronal cells to cells of the immune system to specialized polarized epithelial cells of the retina. In this review, the protein composition of the retromer complex will be described along with many of the accessory factors that facilitate retromer-mediated endosomal protein sorting to detail how retromer activity contributes to the regulation of several distinct signaling pathways.
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Affiliation(s)
- Matthew N J Seaman
- Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/MRC Building, Addenbrookes Hospital, Cambridge, CB2 0XY, UK.
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Pavlos NJ, Friedman PA. GPCR Signaling and Trafficking: The Long and Short of It. Trends Endocrinol Metab 2017; 28:213-226. [PMID: 27889227 PMCID: PMC5326587 DOI: 10.1016/j.tem.2016.10.007] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 10/17/2016] [Accepted: 10/26/2016] [Indexed: 01/24/2023]
Abstract
Emerging findings disclose unexpected components of G protein-coupled receptor (GPCR) signaling and cell biology. Select GPCRs exhibit classical signaling, that is restricted to cell membranes, as well as newly described persistent signaling that depends on internalization of the GPCR bound to β-arrestins. Termination of non-canonical endosomal signaling requires intraluminal acidification and sophisticated protein trafficking machineries. Recent studies reveal the structural determinants of the trafficking chaperones. This review summarizes advances in GPCR signaling and trafficking with a focus on the parathyroid hormone receptor (PTHR) as a prototype, and on the actin-sorting nexin 27 (SNX27)-retromer tubule (ASRT) complex, an endosomal sorting hub responsible for recycling and preservation of cell surface receptors. The findings are integrated into a model of PTHR trafficking with implications for signal transduction, bone growth, and mineral ion metabolism.
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Affiliation(s)
- Nathan J Pavlos
- Cellular Orthopaedic Laboratory, School of Surgery, The University of Western Australia, Nedlands, WA 6009, Australia
| | - Peter A Friedman
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, Department of Structural Biology University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA.
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Rifkin RA, Moss SJ, Slesinger PA. G Protein-Gated Potassium Channels: A Link to Drug Addiction. Trends Pharmacol Sci 2017; 38:378-392. [PMID: 28188005 DOI: 10.1016/j.tips.2017.01.007] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 01/08/2017] [Accepted: 01/10/2017] [Indexed: 11/29/2022]
Abstract
G protein-gated inwardly rectifying potassium (GIRK) channels are regulators of neuronal excitability in the brain. Knockout mice lacking GIRK channels display altered behavioral responses to multiple addictive drugs, implicating GIRK channels in addictive behaviors. Here, we review the effects of GIRK subunit deletions on the behavioral response to psychostimulants, such as cocaine and methamphetamine. Additionally, exposure of mice to psychostimulants produces alterations in the surface expression of GIRK channels in multiple types of neurons within the reward system of the brain. Thus, we compare the subcellular mechanisms by which drug exposure appears to alter GIRK expression in multiple cell types and provide an outlook on future studies examining the role of GIRK channels in addiction. A greater understanding of how GIRK channels are regulated by addictive drugs may enable the development of therapies to prevent or treat drug abuse.
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Affiliation(s)
- Robert A Rifkin
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA; Medical Scientist Training Program, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA
| | - Stephen J Moss
- Dept of Neuroscience, Tufts University School of Medicine, Boston, MA 02155, USA; Dept of Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, UK
| | - Paul A Slesinger
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY 10029, USA.
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Rezania S, Kammerer S, Li C, Steinecker-Frohnwieser B, Gorischek A, DeVaney TTJ, Verheyen S, Passegger CA, Tabrizi-Wizsy NG, Hackl H, Platzer D, Zarnani AH, Malle E, Jahn SW, Bauernhofer T, Schreibmayer W. Overexpression of KCNJ3 gene splice variants affects vital parameters of the malignant breast cancer cell line MCF-7 in an opposing manner. BMC Cancer 2016; 16:628. [PMID: 27519272 PMCID: PMC4983040 DOI: 10.1186/s12885-016-2664-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Accepted: 08/03/2016] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Overexpression the KCNJ3, a gene that encodes subunit 1 of G-protein activated inwardly rectifying K(+) channel (GIRK1) in the primary tumor has been found to be associated with reduced survival times and increased lymph node metastasis in breast cancer patients. METHODS In order to survey possible tumorigenic properties of GIRK1 overexpression, a range of malignant mammary epithelial cells, based on the MCF-7 cell line that permanently overexpress different splice variants of the KCNJ3 gene (GIRK1a, GIRK1c, GIRK1d and as a control, eYFP) were produced. Subsequently, selected cardinal neoplasia associated cellular parameters were assessed and compared. RESULTS Adhesion to fibronectin coated surface as well as cell proliferation remained unaffected. Other vital parameters intimately linked to malignancy, i.e. wound healing, chemoinvasion, cellular velocities / motilities and angiogenesis were massively affected by GIRK1 overexpression. Overexpression of different GIRK1 splice variants exerted differential actions. While GIRK1a and GIRK1c overexpression reinforced the affected parameters towards malignancy, overexpression of GIRK1d resulted in the opposite. Single channel recording using the patch clamp technique revealed functional GIRK channels in the plasma membrane of MCF-7 cells albeit at very low frequency. DISCUSSION We conclude that GIRK1d acts as a dominant negative constituent of functional GIRK complexes present in the plasma membrane of MCF-7 cells, while overexpression of GIRK1a and GIRK1c augmented their activity. The core component responsible for the cancerogenic action of GIRK1 is apparently presented by a segment comprising aminoacids 235-402, that is present exclusively in GIRK1a and GIRK1c, but not GIRK1d (positions according to GIRK1a primary structure). CONCLUSIONS The current study provides insight into the cellular and molecular consequences of KCNJ3 overexpression in breast cancer cells and the mechanism upon clinical outcome in patients suffering from breast cancer.
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Affiliation(s)
- S. Rezania
- Institute of Biophysics, Molecular Physiology Group, Medical University of Graz, Harrachgasse 21/4, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
| | - S. Kammerer
- Institute of Biophysics, Molecular Physiology Group, Medical University of Graz, Harrachgasse 21/4, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
| | - C. Li
- Institute of Biophysics, Molecular Physiology Group, Medical University of Graz, Harrachgasse 21/4, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
| | - B. Steinecker-Frohnwieser
- Institute of Biophysics, Molecular Physiology Group, Medical University of Graz, Harrachgasse 21/4, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
- Present address: Institute of Human Genetics, Medical University of Graz, Graz, Austria
| | - A. Gorischek
- Institute of Biophysics, Molecular Physiology Group, Medical University of Graz, Harrachgasse 21/4, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
| | - T. T. J. DeVaney
- Institute of Biophysics, Molecular Physiology Group, Medical University of Graz, Harrachgasse 21/4, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
| | - S. Verheyen
- Institute of Biophysics, Molecular Physiology Group, Medical University of Graz, Harrachgasse 21/4, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
- Present address: Institute of Human Genetics, Medical University of Graz, Graz, Austria
| | - C. A. Passegger
- Institute of Pathophysiology and Immunology, SFL Chicken CAM Laboratory, Medical University of Graz, Graz, Austria
| | - N. Ghaffari Tabrizi-Wizsy
- Institute of Pathophysiology and Immunology, SFL Chicken CAM Laboratory, Medical University of Graz, Graz, Austria
| | - H. Hackl
- Division of Bioinformatics, Biocenter, Medical University of Innsbruck, Innsbruck, Austria
| | - D. Platzer
- Institute of Biophysics, Molecular Physiology Group, Medical University of Graz, Harrachgasse 21/4, Graz, Austria
| | - A. H. Zarnani
- Nanobiotechnology Research Center, Avicenna Research Institute, ACECR, Tehran, Iran
| | - E. Malle
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - S. W. Jahn
- Institute of Pathology, Medical University of Graz, Graz, Austria
| | - T. Bauernhofer
- Division of Oncology, Department of Internal Medicine, Medical University of Graz, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
| | - W. Schreibmayer
- Institute of Biophysics, Molecular Physiology Group, Medical University of Graz, Harrachgasse 21/4, Graz, Austria
- Research Unit on Ion Channels and Cancer Biology, Medical University of Graz, Graz, Austria
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11
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Tipps ME, Raybuck JD, Kozell LB, Lattal KM, Buck KJ. G Protein-Gated Inwardly Rectifying Potassium Channel Subunit 3 Knock-Out Mice Show Enhanced Ethanol Reward. Alcohol Clin Exp Res 2016; 40:857-64. [PMID: 27012303 PMCID: PMC4820358 DOI: 10.1111/acer.13012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 01/07/2016] [Indexed: 12/17/2022]
Abstract
BACKGROUND G protein-gated inwardly rectifying potassium (GIRK) channels contribute to the effects of a number of drugs of abuse, including ethanol. However, the roles of individual subunits in the rewarding effects of ethanol are poorly understood. METHODS We compare conditioned place preference (CPP) in GIRK3 subunit knock-out (GIRK3(-/-)), heterozygote (GIRK3(+/-)), and wild-type (WT) mice. In addition, the development of locomotor tolerance/sensitization and the effects of EtOH intoxication on associative learning (fear conditioning) are also assessed. RESULTS Our data show significant EtOH CPP in GIRK3(-/-) and GIRK3(+/-) mice, but not in the WT littermates. In addition, we demonstrate that these effects are not due to differences in EtOH metabolism, the development of EtOH tolerance/sensitivity, or associative learning abilities. While there were no consistent genotype differences in the fear conditioning assay, our data do show a selective sensitization of the impairing effects of EtOH intoxication on contextual learning, but no effect on cued learning. CONCLUSIONS These findings suggest that GIRK3 plays a role in EtOH reward. Furthermore, the selectivity of this effect suggests that GIRK channels could be an effective therapeutic target for the prevention and/or treatment of alcoholism.
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Affiliation(s)
- Megan E. Tipps
- Portland Alcohol Research Center; Portland VA Medical Center, 3710 SW US Veterans Hospital Rd., Bldg 104, Portland, OR 97239-3098, USA
- Department of Behavioral Neuroscience; Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Portland, OR 97239-3098, USA
| | - Jonathan D. Raybuck
- Department of Behavioral Neuroscience; Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Portland, OR 97239-3098, USA
| | - Laura B. Kozell
- Portland Alcohol Research Center; Portland VA Medical Center, 3710 SW US Veterans Hospital Rd., Bldg 104, Portland, OR 97239-3098, USA
- Department of Behavioral Neuroscience; Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Portland, OR 97239-3098, USA
| | - K. Matthew Lattal
- Department of Behavioral Neuroscience; Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Portland, OR 97239-3098, USA
| | - Kari J. Buck
- Portland Alcohol Research Center; Portland VA Medical Center, 3710 SW US Veterans Hospital Rd., Bldg 104, Portland, OR 97239-3098, USA
- Department of Behavioral Neuroscience; Oregon Health & Science University, 3181 SW Sam Jackson Park Rd., Portland, OR 97239-3098, USA
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12
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Ghai R, Tello-Lafoz M, Norwood SJ, Yang Z, Clairfeuille T, Teasdale RD, Mérida I, Collins BM. Phosphoinositide binding by the SNX27 FERM domain regulates its localization at the immune synapse of activated T-cells. J Cell Sci 2016; 128:553-65. [PMID: 25472716 DOI: 10.1242/jcs.158204] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Sorting nexin 27 (SNX27) controls the endosomal-to-cell-surface recycling of diverse transmembrane protein cargos. Crucial to this function is the recruitment of SNX27 to endosomes which is mediated by the binding of phosphatidylinositol-3-phosphate (PtdIns3P) by its phox homology (PX) domain. In T-cells, SNX27 localizes to the immunological synapse in an activation-dependent manner, but the molecular mechanisms underlying SNX27 translocation remain to be clarified. Here, we examined the phosphoinositide-lipid-binding capabilities of full-length SNX27, and discovered a new PtdInsP-binding site within the C-terminal 4.1, ezrin, radixin, moesin (FERM) domain. This binding site showed a clear preference for bi- and tri-phosphorylated phophoinositides, and the interaction was confirmed through biophysical, mutagenesis and modeling approaches. At the immunological synapse of activated T-cells, cell signaling regulates phosphoinositide dynamics, and we find that perturbing phosphoinositide binding by the SNX27 FERM domain alters the SNX27 distribution in both endosomal recycling compartments and PtdIns(3,4,5)P3-enriched domains of the plasma membrane during synapse formation. Our results suggest that SNX27 undergoes dynamic partitioning between different membrane domains during immunological synapse assembly, and underscore the contribution of unique lipid interactions for SNX27 orchestration of cargo trafficking.
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13
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Sorting nexin 27 interacts with Fzd7 and mediates Wnt signalling. Biosci Rep 2016; 36:e00296. [PMID: 26744382 PMCID: PMC4748333 DOI: 10.1042/bsr20150205] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 12/14/2015] [Indexed: 01/16/2023] Open
Abstract
This work found that sorting nexin 27 (SNX27) interacts with Frizzled receptors (Fzds) through PDZ domain interaction, which act as novel interacting partners for SNX27. Functional investigation of the interaction of SNX27 with Fzd7 revealed that SNX27 promotes the degradation of Fzd7, thus down-regulating Wnt signalling. SNX27 is the only sorting nexin (SNX) that contains a PDZ domain, which interacts with PDZ-binding motif of target proteins to regulate the trafficking of these proteins. We here showed that SNX27 interacts with Frizzled (Fzd) receptors via PDZ domain interaction. Immunofluorescence microscopy revealed that Fzd7 can be internalized and associate with SNX27-containing endosomal membrane. In addition, SNX27 enhances the endocytosis of Fzd7 and promotes the degradation of Fzd7. Further examination demonstrated that SNX27 inhibits the Wnt regulated transcription activity of TCF/LEF. Our results suggested that SNX27 interacts with Frizzled receptors to regulate the endocytosis and stability of Fzds, and consequently mediates canonical Wnt signalling.
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14
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Stiegler AL, Zhang R, Liu W, Boggon TJ. Structural determinants for binding of sorting nexin 17 (SNX17) to the cytoplasmic adaptor protein Krev interaction trapped 1 (KRIT1). J Biol Chem 2014; 289:25362-73. [PMID: 25059659 DOI: 10.1074/jbc.m114.584011] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Sorting nexin 17 (SNX17) is a member of the family of cytoplasmic sorting nexin adaptor proteins that regulate endosomal trafficking of cell surface proteins. SNX17 localizes to early endosomes where it directly binds NPX(Y/F) motifs in the cytoplasmic tails of its target receptors to mediate their rates of endocytic internalization, recycling, and/or degradation. SNX17 has also been implicated in mediating cell signaling and can interact with cytoplasmic proteins. KRIT1 (Krev interaction trapped 1), a cytoplasmic adaptor protein associated with cerebral cavernous malformations, has previously been shown to interact with SNX17. Here, we demonstrate that SNX17 indeed binds directly to KRIT1 and map the binding to the second Asn-Pro-Xaa-Tyr/Phe (NPX(Y/F)) motif in KRIT1. We further characterize the interaction as being mediated by the FERM domain of SNX17. We present the co-crystal structure of SNX17-FERM with the KRIT1-NPXF2 peptide to 3.0 Å resolution and demonstrate that the interaction is highly similar in structure and binding affinity to that between SNX17 and P-selectin. We verify the molecular details of the interaction by site-directed mutagenesis and pulldown assay and thereby confirm that the major binding site for SNX17 is confined to the NPXF2 motif in KRIT1. Taken together, our results verify a direct interaction between SNX17 and KRIT1 and classify KRIT1 as a SNX17 binding partner.
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Affiliation(s)
- Amy L Stiegler
- From the Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Rong Zhang
- From the Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Weizhi Liu
- From the Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520
| | - Titus J Boggon
- From the Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06520
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15
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Sorting nexin 27 regulation of G protein-gated inwardly rectifying K⁺ channels attenuates in vivo cocaine response. Neuron 2014; 82:659-69. [PMID: 24811384 DOI: 10.1016/j.neuron.2014.03.011] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/26/2014] [Indexed: 12/12/2022]
Abstract
The subcellular pathways that regulate G protein-gated inwardly rectifying potassium (GIRK or Kir3) channels are important for controlling the excitability of neurons. Sorting nexin 27 (SNX27) is a PDZ-containing protein known to bind GIRK2c/GIRK3 channels, but its function in vivo is poorly understood. Here, we investigated the role of SNX27 in regulating GIRK currents in dopamine (DA) neurons of the ventral tegmental area (VTA). Mice lacking SNX27 in DA neurons exhibited reduced GABABR-activated GIRK currents but had normal Ih currents and DA D2R-activated GIRK currents. Expression of GIRK2a, an SNX27-insensitive splice variant, restored GABABR-activated GIRK currents in SNX27-deficient DA neurons. Remarkably, mice with significantly reduced GABABR-activated GIRK currents in only DA neurons were hypersensitive to cocaine and could be restored to a normal locomotor response with GIRK2a expression. These results identify a pathway for regulating excitability of VTA DA neurons, highlighting SNX27 as a promising target for treating addiction.
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16
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Bodhinathan K, Slesinger PA. Alcohol modulation of G-protein-gated inwardly rectifying potassium channels: from binding to therapeutics. Front Physiol 2014; 5:76. [PMID: 24611054 PMCID: PMC3933770 DOI: 10.3389/fphys.2014.00076] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 02/07/2014] [Indexed: 12/27/2022] Open
Abstract
Alcohol (ethanol)-induced behaviors may arise from direct interaction of alcohol with discrete protein cavities within brain proteins. Recent structural and biochemical studies have provided new insights into the mechanism of alcohol-dependent activation of G protein-gated inwardly rectifying potassium (GIRK) channels, which regulate neuronal responses in the brain reward circuit. GIRK channels contain an alcohol binding pocket formed at the interface of two adjacent channel subunits. Here, we discuss the physiochemical properties of the alcohol pocket and the roles of G protein βγ subunits and membrane phospholipid PIP2 in regulating the alcohol response of GIRK channels. Some of the features of alcohol modulation of GIRK channels may be common to other alcohol-sensitive brain proteins. We discuss the possibility of alcohol-selective therapeutics that block alcohol access to the pocket. Understanding alcohol recognition and modulation of brain proteins is essential for development of therapeutics for alcohol abuse and addiction.
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Affiliation(s)
- Karthik Bodhinathan
- Structural Biology and Peptide Biology Laboratories, The Salk Institute for Biological Studies La Jolla, CA, USA
| | - Paul A Slesinger
- Structural Biology and Peptide Biology Laboratories, The Salk Institute for Biological Studies La Jolla, CA, USA ; Department of Neuroscience, Icahn School of Medicine at Mount Sinai New York, NY, USA
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17
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H-Ras forms dimers on membrane surfaces via a protein-protein interface. Proc Natl Acad Sci U S A 2014; 111:2996-3001. [PMID: 24516166 DOI: 10.1073/pnas.1321155111] [Citation(s) in RCA: 124] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The lipid-anchored small GTPase Ras is an important signaling node in mammalian cells. A number of observations suggest that Ras is laterally organized within the cell membrane, and this may play a regulatory role in its activation. Lipid anchors composed of palmitoyl and farnesyl moieties in H-, N-, and K-Ras are widely suspected to be responsible for guiding protein organization in membranes. Here, we report that H-Ras forms a dimer on membrane surfaces through a protein-protein binding interface. A Y64A point mutation in the switch II region, known to prevent Son of sevenless and PI3K effector interactions, abolishes dimer formation. This suggests that the switch II region, near the nucleotide binding cleft, is either part of, or allosterically coupled to, the dimer interface. By tethering H-Ras to bilayers via a membrane-miscible lipid tail, we show that dimer formation is mediated by protein interactions and does not require lipid anchor clustering. We quantitatively characterize H-Ras dimerization in supported membranes using a combination of fluorescence correlation spectroscopy, photon counting histogram analysis, time-resolved fluorescence anisotropy, single-molecule tracking, and step photobleaching analysis. The 2D dimerization Kd is measured to be ∼1 × 10(3) molecules/µm(2), and no higher-order oligomers were observed. Dimerization only occurs on the membrane surface; H-Ras is strictly monomeric at comparable densities in solution. Analysis of a number of H-Ras constructs, including key changes to the lipidation pattern of the hypervariable region, suggest that dimerization is a general property of native H-Ras on membrane surfaces.
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18
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Luján R, Marron Fernandez de Velasco E, Aguado C, Wickman K. New insights into the therapeutic potential of Girk channels. Trends Neurosci 2013; 37:20-9. [PMID: 24268819 DOI: 10.1016/j.tins.2013.10.006] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Revised: 10/24/2013] [Accepted: 10/25/2013] [Indexed: 01/01/2023]
Abstract
G protein-dependent signaling pathways control the activity of excitable cells of the nervous system and heart, and are the targets of neurotransmitters, clinically relevant drugs, and drugs of abuse. G protein-gated inwardly rectifying potassium (K(+)) (Girk/Kir3) channels are a key effector in inhibitory signaling pathways. Girk-dependent signaling contributes to nociception and analgesia, reward-related behavior, mood, cognition, and heart-rate regulation, and has been linked to epilepsy, Down syndrome, addiction, and arrhythmias. We discuss recent advances in our understanding of Girk channel structure, organization in signaling complexes, and plasticity, as well as progress on the development of subunit-selective Girk modulators. These findings offer new hope for the selective manipulation of Girk channels to treat a variety of debilitating afflictions.
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Affiliation(s)
- Rafael Luján
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain.
| | | | - Carolina Aguado
- Instituto de Investigación en Discapacidades Neurológicas (IDINE), Departamento de Ciencias Médicas, Facultad de Medicina, Universidad Castilla-La Mancha, Campus Biosanitario, C/Almansa 14, 02008 Albacete, Spain
| | - Kevin Wickman
- Department of Pharmacology, University of Minnesota, 321 Church Street South East, Minneapolis, MN 55455, USA.
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