1
|
Saleh MA, Shaaban AA, Talaat IM, Elmougy A, Adra SF, Ahmad F, Qaisar R, Elmoselhi AB, Abu-Gharbieh E, El-Huneidi W, Eladl MA, Shehatou G, Kafl HE. RhoA/ROCK inhibition attenuates endothelin-1-induced elevated glomerular permeability to albumin, inflammation, and fibrosis. Life Sci 2023; 323:121687. [PMID: 37030613 DOI: 10.1016/j.lfs.2023.121687] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 03/25/2023] [Accepted: 04/05/2023] [Indexed: 04/10/2023]
Abstract
Endothelin-1 (ET-1) contributes to the development of kidney diseases. However, the underlying molecular mechanism is largely undefined. Here we sought to investigate the potential role of ET-1 receptors, ETA and ETB in the regulation of increased glomerular permeability and underlying signaling pathways post-ET-1 infusion. Male Sprague-Dawley rats were infused with ET-1 (2 pmol/kg per minute, i.v.) for four weeks, and the effect on glomerular permeability to albumin (Palb) and albuminuria was measured. The selective ROCK-1/2 inhibitor, Y-27632, was administered to a separate group of rats to determine its effect on ET-1-induced Palb and albuminuria. The role of ETA and ETB receptors in regulating RhoA/ROCK activity was determined by incubating isolated glomeruli from normal rats with ET-1 and with selective ETA and ETB receptor antagonists. ET-1 infusion for four weeks significantly elevated Palb and albuminuria. Y-27632 significantly reduced the elevation of Palb and albuminuria. The activities of both RhoA and ROCK-1/2 were increased by ET-1 infusion. Selective ETB receptor antagonism had no effect on the elevated activity of both RhoA and ROCK-1/2 enzymes. Selective ETA receptor and combined ETA/ETB receptors blockade restored the activity of RhoA and ROCK-1/2 to normal levels. In addition, chronic ET-1 infusion increased the levels of glomerular inflammatory and fibrotic markers. These effects were all attenuated in rats following ROCK-1/2 inhibition. These observations suggest that ET-1 contributes to increased albuminuria, inflammation, and fibrosis by modulating the activity of the ETA-RhoA/ROCK-1/2 pathway. Selective ETA receptor blockade may represent a potential therapeutic strategy to limit glomerular injury and albuminuria in kidney disease.
Collapse
Affiliation(s)
- Mohamed A Saleh
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates; Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; Department of Pharmacology and Toxicology, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt.
| | - Ahmed A Shaaban
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt; Department of Pharmacology and Biochemistry, Faculty of Pharmacy, Delta University for Science and Technology, Gamasa City 35712, Egypt
| | - Iman M Talaat
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates; Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; Pathology Department, Faculty of Medicine, Alexandria University, Alexandria 21526, Egypt
| | - Atef Elmougy
- Pediatric Nephrology Unit, Mansoura University Children's Hospital, Mansoura University, Mansoura 35516, Egypt
| | - Saryia F Adra
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates
| | - Firdos Ahmad
- Department of Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates; Department of Biomedical Sciences, College of Health Sciences, Abu Dhabi University, Abu Dhabi 59911, United Arab Emirates
| | - Rizwan Qaisar
- Department of Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates
| | - Adel B Elmoselhi
- Department of Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates
| | - Eman Abu-Gharbieh
- Department of Clinical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates; Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates
| | - Waseem El-Huneidi
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah 27272, United Arab Emirates; Department of Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates
| | - Mohamed A Eladl
- Department of Basic Medical Sciences, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates
| | - George Shehatou
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt; Department of Pharmacology and Biochemistry, Faculty of Pharmacy, Delta University for Science and Technology, Gamasa City 35712, Egypt
| | - Hoda E Kafl
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Mansoura University, Mansoura 35516, Egypt
| |
Collapse
|
2
|
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: 0.5] [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
|
3
|
Barta T, Tosaki A, Haines D, Balla G, Lekli I, Tosaki A. Endothelin-1-induced hypertrophic alterations and heme oxygenase-1 expression in cardiomyoblasts are counteracted by beta estradiol: in vitro and in vivo studies. Naunyn Schmiedebergs Arch Pharmacol 2018; 391:371-383. [PMID: 29354880 PMCID: PMC5851684 DOI: 10.1007/s00210-018-1462-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Accepted: 01/03/2018] [Indexed: 12/31/2022]
Abstract
Endothelin-1 (ET-1), a potent vasoconstrictor normally active in maintaining vascular tone, may mediate significant pathogenic effects, contributing to several serious diseases when aberrantly expressed or regulated. The present study evaluates the capacity of ET-1 to affect endothelin-1-associated hypertrophic activity and decreased expression of heme oxygenase-1 by H9c2 rat cardiomyoblasts in vitro, corresponding to in vivo processes underlying cardiovascular diseases (CVDs). Beta estradiol (β-E) is tested for its capacity to alter the effects of ET-1. H9c2 cells, cultured 48 h, were stimulated with 100-10,000 nM of ET-1 and evaluated for changes in cell size, cell viability, and expression of the cytoprotective heat shock protein heme oxygenase-1 (HO-1), with 200 nM of β-E included in selected cultures to evaluate its effect on ET-1-mediated changes. The application of 100 to 10,000 nM of ET-1 resulted in a significant increase in average cell size and decreases in both cell viability and HO-1 protein content (p < 0.05). Moreover, 200 nM of β-E was observed to significantly counteract these effects by cardiomyoblasts stimulated with 1000 nM of ET-1 (p < 0.05). Sprague-Dawley rats treated intravenously with 1000 ng/kg of ET-1 demonstrated reduced HO-1 expression in peripheral blood and left ventricular tissue, which was counteracted by injection of 200 ng/kg β-E-demonstrating a possible correspondence between in vitro and in vivo effects. An outcome of particular value for clinical use of β-E, in the management of cardiac hypertrophy, is the observed capacity of the drug to abate ET-1-mediated suppression of HO-1 expression. It has been previously demonstrated that HO-1 inducers exhibit potent cardioprotective properties, thus offering the promise of combining them with β-E, allowing lower effective dosage of the drug and concomitantly lower adverse side effects associated with its clinical use. Major findings of this investigation are that pretreatment of cardiomyoblasts with β-E inhibited their hypertrophic response to ET-1 and counteracts the decrease of cell viability. These effects were associated with a restoration of HO-1 protein expression in both under in vitro and in vivo conditions.
Collapse
Affiliation(s)
- Tunde Barta
- Department of Pharmacology, Faculty of Pharmacy, University of Debrecen, Nagyerdei krt., 98, Debrecen, 4032, Hungary
| | - Agnes Tosaki
- Department of Pharmacology, Faculty of Pharmacy, University of Debrecen, Nagyerdei krt., 98, Debrecen, 4032, Hungary
| | - David Haines
- Department of Pharmacology, Faculty of Pharmacy, University of Debrecen, Nagyerdei krt., 98, Debrecen, 4032, Hungary
| | - Gyorgy Balla
- Department of Pediatrics, Medical and Health Science Center, University of Debrecen, Debrecen, Hungary.,Hemostasis, Thrombosis and Vascular Biology Research Group, Hungarian Academy of Sciences, Debrecen, Hungary
| | - Istvan Lekli
- Department of Pharmacology, Faculty of Pharmacy, University of Debrecen, Nagyerdei krt., 98, Debrecen, 4032, Hungary
| | - Arpad Tosaki
- Department of Pharmacology, Faculty of Pharmacy, University of Debrecen, Nagyerdei krt., 98, Debrecen, 4032, Hungary.
| |
Collapse
|
4
|
Fazzini A, D’Antongiovanni V, Giusti L, Da Valle Y, Ciregia F, Piano I, Caputo A, D’Ursi AM, Gargini C, Lucacchini A, Mazzoni MR. Altered protease-activated receptor-1 expression and signaling in a malignant pleural mesothelioma cell line, NCI-H28, with homozygous deletion of the β-catenin gene. PLoS One 2014; 9:e111550. [PMID: 25364818 PMCID: PMC4218765 DOI: 10.1371/journal.pone.0111550] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 09/29/2014] [Indexed: 01/13/2023] Open
Abstract
Protease activated receptors (PARs) are G-protein coupled receptors that are activated by an unique proteolytic mechanism. These receptors play crucial roles in hemostasis and thrombosis but also in inflammation and vascular development. PARs have also been implicated in tumor progression, invasion and metastasis. In this study, we investigated expression and signaling of PAR1 in nonmalignant pleural mesothelial (Met-5A) and malignant pleural mesothelioma (NCI-H28) cells. We found that the expression level of PAR1 was markedly higher in NCI-H28 cells compared to Met-5A and human primary mesothelial cells. Other three malignant pleural mesothelioma cell lines, i.e. REN, Ist-Mes2, and Mero-14, did not show any significant PAR1 over-expression compared to Met-5A cell line. Thrombin and PAR1 activating peptides enhanced Met-5A and NCI-H28 cell proliferation but in NCI-H28 cells higher thrombin concentrations were required to obtain the same proliferation increase. Similarly, thrombin caused extracellular signal-regulated kinase 1/2 activation in both cell lines but NCI-H28 cells responded at higher agonist concentrations. We also determined that PAR1 signaling through Gq and G12/13 proteins is severely altered in NCI-H28 cells compared to Met-5A cells. On the contrary, PAR1 signaling through Gi proteins was persistently maintained in NCI-H28 cells. Furthermore, we demonstrated a reduction of cell surface PAR1 expression in NCI-H28 and malignant pleural mesothelioma REN cells. Thus, our results provide evidences for dysfunctional PAR1 signaling in NCI-H28 cells together with reduced plasma membrane localization. The role of PAR1 in mesothelioma progression is just emerging and our observations can promote further investigations focused on this G-protein coupled receptor.
Collapse
Affiliation(s)
| | | | - Laura Giusti
- Department of Pharmacy, University of Pisa, Pisa, Italy
| | | | | | - Ilaria Piano
- Department of Pharmacy, University of Pisa, Pisa, Italy
| | | | | | | | | | | |
Collapse
|
5
|
Spindler MJ, Burmeister BT, Huang Y, Hsiao EC, Salomonis N, Scott MJ, Srivastava D, Carnegie GK, Conklin BR. AKAP13 Rho-GEF and PKD-binding domain deficient mice develop normally but have an abnormal response to β-adrenergic-induced cardiac hypertrophy. PLoS One 2013; 8:e62705. [PMID: 23658642 PMCID: PMC3637253 DOI: 10.1371/journal.pone.0062705] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Accepted: 03/28/2013] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND A-kinase anchoring proteins (AKAPs) are scaffolding molecules that coordinate and integrate G-protein signaling events to regulate development, physiology, and disease. One family member, AKAP13, encodes for multiple protein isoforms that contain binding sites for protein kinase A (PKA) and D (PKD) and an active Rho-guanine nucleotide exchange factor (Rho-GEF) domain. In mice, AKAP13 is required for development as null embryos die by embryonic day 10.5 with cardiovascular phenotypes. Additionally, the AKAP13 Rho-GEF and PKD-binding domains mediate cardiomyocyte hypertrophy in cell culture. However, the requirements for the Rho-GEF and PKD-binding domains during development and cardiac hypertrophy are unknown. METHODOLOGY/PRINCIPAL FINDINGS To determine if these AKAP13 protein domains are required for development, we used gene-trap events to create mutant mice that lacked the Rho-GEF and/or the protein kinase D-binding domains. Surprisingly, heterozygous matings produced mutant mice at Mendelian ratios that had normal viability and fertility. The adult mutant mice also had normal cardiac structure and electrocardiograms. To determine the role of these domains during β-adrenergic-induced cardiac hypertrophy, we stressed the mice with isoproterenol. We found that heart size was increased similarly in mice lacking the Rho-GEF and PKD-binding domains and wild-type controls. However, the mutant hearts had abnormal cardiac contractility as measured by fractional shortening and ejection fraction. CONCLUSIONS These results indicate that the Rho-GEF and PKD-binding domains of AKAP13 are not required for mouse development, normal cardiac architecture, or β-adrenergic-induced cardiac hypertrophic remodeling. However, these domains regulate aspects of β-adrenergic-induced cardiac hypertrophy.
Collapse
Affiliation(s)
- Matthew J Spindler
- Gladstone Institute of Cardiovascular Disease, San Francisco, California, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Moey M, Rajapurohitam V, Zeidan A, Karmazyn M. Ginseng (Panax quinquefolius) attenuates leptin-induced cardiac hypertrophy through inhibition of p115Rho guanine nucleotide exchange factor-RhoA/Rho-associated, coiled-coil containing protein kinase-dependent mitogen-activated protein kinase pathway activation. J Pharmacol Exp Ther 2011; 339:746-56. [PMID: 21875949 DOI: 10.1124/jpet.111.182600] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Leptin is a 16-kDa peptide primarily derived from white adipocytes and is typically elevated in plasma of obese individuals. Although leptin plays a critical role in appetite regulation, leptin receptors have been identified in numerous tissues including the heart and have been shown to directly mediate cardiac hypertrophy through RhoA/ROCK (Ras homolog gene family, member A/Rho-associated, coiled-coil containing protein kinase)-dependent p38 mitogen-activated protein kinase (MAPK) activation; however, the basis for RhoA stimulation is unknown. Rho guanine nucleotide exchange factors (GEFs) catalyze the exchange of GDP for GTP resulting in Rho activation and may be the potential upstream factors mediating leptin-induced RhoA activation and therefore a potential target for inhibition. We investigated the effects of North American ginseng (Panax quinquefolius), reported to reduce cardiac hypertrophy, on RhoA/ROCK and MAPK activation in ventricular cardiomyocytes exposed to leptin (50 ng/ml) and the possible role of p115RhoGEF and p63RhoGEF in these responses. Leptin produced a robust hypertrophic response that was associated with RhoA/ROCK activation resulting in a significant increase in cofilin-2 phosphorylation and actin polymerization, the latter evidenced by a reduction in the G/F actin ratio. These effects were prevented by ginseng (10 μg/ml). The stimulation of RhoA/ROCK by leptin was associated with significantly increased p115RhoGEF gene and protein expression and exchange activity, all of which were completely prevented by ginseng. The ability of ginseng to prevent leptin-induced activation of RhoA/ROCK was further associated with diminished p38 MAPK activation and nuclear translocation. These results demonstrate a potent inhibitory effect of ginseng against leptin-induced cardiac hypertrophy, an effect associated with prevention of p115RhoGEF-RhoA/ROCK-dependent p38 MAPK activation.
Collapse
Affiliation(s)
- Melissa Moey
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, Ontario, Canada N6A 5C1
| | | | | | | |
Collapse
|
7
|
Xiaolu D, Jing P, Fang H, Lifen Y, Liwen W, Ciliu Z, Fei Y. Role of p115RhoGEF in lipopolysaccharide-induced mouse brain microvascular endothelial barrier dysfunction. Brain Res 2011; 1387:1-7. [PMID: 21354111 DOI: 10.1016/j.brainres.2011.02.059] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2010] [Revised: 02/15/2011] [Accepted: 02/18/2011] [Indexed: 12/24/2022]
Abstract
BACKGROUND In endothelial cells, exposure to lipopolysaccharide (LPS) results in barrier dysfunction through a complex signaling mechanism. The RhoA/Rho-kinase pathway plays a significant role in endothelial cell permeability. p115RhoGEF, a specific guanine nucleotide exchange factors (GEFs) activates RhoA, triggering RhoA-dependent cytoskeletal remodeling. However, little is known about the role of p115RhoGEF in LPS-induced brain endothelial barrier breakdown. We hypothesized that suppression of p115RhoGEF may inhibit activation of RhoA and prevent LPS-induced brain microvascular endothelial cell hyperpermeability. METHODS The cultured monolayer of bEnd.3 cells, an immortalized mouse brain endothelial cell line, was used in this study. bEnd.3 cells were pretreated with specific siRNA to knockdown p115RhoGEF or C3 transferase to inhibit RhoA activity, and then incubated with LPS (5μg/ml). The degree of RhoA activation was determined by a Rhotekin-based pull-down assay, and expression of p115RhoGEF, zonula occludens-1 (ZO-1), occludin and claudin-5 proteins were detected by Western blot analysis. The barrier function was measured by transendothelial electrical resistance (TEER). F-actin cytoskeleton was visualized by Rhodamine-phalloidin staining. RESULTS The expression level of p115RhoGEF protein was significantly increased in LPS-treated bEnd.3 cells. The activity of RhoA was enhanced after LPS stimulation and pretreatment with p115RhoGEF siRNA or exoenzyme C3 transferase reduced RhoA activation significantly as shown by the pull-down assay. Furthermore, depletion of p115RhoGEF partially prevented the LPS-induced decrease in TEER, stress fiber formation and tight junction proteins degradation. CONCLUSIONS These results suggest that p115RhoGEF is important for LPS signaling to RhoA and LPS-induced endothelial barrier dysfunction, providing new insight into the function of RhoGEFs in inflammation.
Collapse
Affiliation(s)
- Deng Xiaolu
- Department of Pediatrics, Xiangya Hospital, Central South University, Changsha 410008, China
| | | | | | | | | | | | | |
Collapse
|
8
|
Zizer E, Beilke S, Bäuerle T, Schilling K, Möhnle U, Adler G, Fischer KD, Wagner M. Loss of Lsc/p115 protein leads to neuronal hypoplasia in the esophagus and an achalasia-like phenotype in mice. Gastroenterology 2010; 139:1344-54. [PMID: 20600037 DOI: 10.1053/j.gastro.2010.06.041] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Revised: 05/21/2010] [Accepted: 06/10/2010] [Indexed: 12/30/2022]
Abstract
BACKGROUND & AIMS Lsc/p115 originally was described as hematopoietic Ras homologous protein guanine exchange factor (Rho-GEF) regulating leukocyte migration, adhesion, and marginal zone B-cell homeostasis. Here we investigate the expression pattern of lsc/p115 in the gastrointestinal tract and the consequences of lsc/p115 deficiency in lsc/p115-knockout mice. METHODS The phenotype of lsc/p115-deficient mice was analyzed in vivo with small-animal computed tomography scans and esophageal manometry. The morphology and myenteric plexus were evaluated with immunohistochemistry, morphometry, Western blot analyses, and quantitative reverse-transcription polymerase chain reaction. RESULTS lsc/p115 is expressed in the gastrointestinal tract, sparing the segment of the small intestine. Immunohistochemical staining detects lsc/p115 in the muscle layer and the glial fibrillary acidic protein-positive glia in the esophagus. Esophageal manometry uncovers a severe motor dysfunction in lsc/p115-deficient mice. This achalasia-like phenotype is characterized by disturbed peristalsis, hypertension of the lower esophageal sphincter, and impaired relaxation of the lower esophageal sphincter. Lsc/p115-deficient mice develop a progressive dilatation of the esophagus and decrease of the muscle layer. The muscle cell differentiation is not altered in lsc/p115-deficient mice. However, the density of inhibitory and excitatory neurons and glia cells in the myenteric plexus and the muscle layer are reduced in morphometric analyses. This reduced number of glia cells is accompanied by reduced expression of the neurotrophic nerve growth factor. CONCLUSIONS lsc/p115 deficiency results in impaired neuronal innervation and in motor dysfunction recapitulating several aspects of esophageal achalasia. Reduced expression of nerve growth factor and a reduced number of glia cells most likely contribute to this phenotype.
Collapse
Affiliation(s)
- Eugen Zizer
- Department of Internal Medicine I, Center of Internal Medicine, University Ulm, Ulm, Germany
| | | | | | | | | | | | | | | |
Collapse
|
9
|
Prager-Khoutorsky M, Bourque CW. Osmosensation in vasopressin neurons: changing actin density to optimize function. Trends Neurosci 2009; 33:76-83. [PMID: 19963290 DOI: 10.1016/j.tins.2009.11.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Revised: 10/31/2009] [Accepted: 11/13/2009] [Indexed: 11/19/2022]
Abstract
The proportional relation between circulating vasopressin concentration and plasma osmolality is fundamental for body fluid homeostasis. Although changes in the sensitivity of this relation are associated with pathophysiological conditions, central mechanisms modulating osmoregulatory gain are unknown. Here, we review recent data that sheds important light on this process. The cell autonomous osmosensitivity of vasopressin neurons depends on cation channels comprising a variant of the transient receptor potential vanilloid 1 (TRPV1) channel. Hyperosmotic activation is mediated by a mechanical process where sensitivity increases in proportion with actin filament density. Moreover, angiotensin II amplifies osmotic activation by a rapid stimulation of actin polymerization, suggesting that neurotransmitter-induced changes in cytoskeletal organization in osmosensory neurons can mediate central changes in osmoregulatory gain.
Collapse
Affiliation(s)
- Masha Prager-Khoutorsky
- Center for Research in Neuroscience, Research Institute of the McGill University Health Center, Montreal General Hospital, 1650 Cedar Avenue, Montreal, Canada
| | | |
Collapse
|
10
|
Abstract
G protein-coupled receptors (GPCRs) represent a large family of seven transmembrane receptors, which communicate extracellular signals into the cellular lumen. The human genome contains 720-800 GPCRs, and their diverse signal characteristics are determined by their specific tissue and subcellular expression profiles, as well as their coupling profile to the various G protein families (G(s), G(i), G(q), G(12)). The G protein coupling pattern links GPCR activation to the specific downstream effector pathways. G(12/13) signalling of GPCRs has been studied only recently in more detail, and involves activation of RhoGTPase nucleotide exchange factors (RhoGEFs). Four mammalian RhoGEFs regulated by G(12/13) proteins are known: p115-RhoGEF, PSD-95/Disc-large/ZO-1 homology-RhoGEF, leukemia-associated RhoGEF and lymphoid blast crisis-RhoGEF. These link GPCRs to activation of the small monomeric GTPase RhoA, and other downstream effectors. Misregulated G(12/13) signalling is involved in multiple pathophysiological conditions such as cancer, cardiovascular diseases, arterial and pulmonary hypertension, and bronchial asthma. Specific targeting of G(12/13) signalling-related diseases of GPCRs hence provides novel therapeutic approaches. Assays to quantitatively measure GPCR-mediated activation of G(12/13) are only emerging, and are required to understand the G(12/13)-linked pharmacology. The review gives an overview of G(12/13) signalling of GPCRs with a focus on RhoGEF proteins as the immediate mediators of G(12/13) activation.
Collapse
Affiliation(s)
- Sandra Siehler
- Novartis Institutes for BioMedical Research Basel, Center for Proteomic Chemistry, Novartis Pharma AG, Basel, Switzerland.
| |
Collapse
|