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G qα/G 11α deficiency in dorsomedial hypothalamus leads to obesity resulting from decreased energy expenditure and impaired sympathetic nerve activity. Am J Physiol Endocrinol Metab 2021; 320:E270-E280. [PMID: 33166186 PMCID: PMC8260363 DOI: 10.1152/ajpendo.00059.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The G-protein subunits Gqα and G11α (Gq/11α) couple receptors to phospholipase C, leading to increased intracellular calcium. In this study we investigated the consequences of Gq/11α deficiency in the dorsomedial hypothalamus (DMH), a critical site for the control of energy homeostasis. Mice with DMH-specific deletion of Gq/11α (DMHGq/11KO) were generated by stereotaxic injection of adeno-associated virus (AAV)-Cre-green fluorescent protein (GFP) into the DMH of Gqαflox/flox:G11α-/- mice. Compared with control mice that received DMH injection of AAV-GFP, DMHGq/11KO mice developed obesity associated with reduced energy expenditure without significant changes in food intake or physical activity. DMHGq/11KO mice showed no defects in the ability of the melanocortin agonist melanotan II to acutely stimulate energy expenditure or to inhibit food intake. At room temperature (22°C), DMHGq/11KO mice showed reduced sympathetic nervous system activity in brown adipose tissue (BAT) and heart, accompanied with decreased basal BAT uncoupling protein 1 (Ucp1) gene expression and lower heart rates. These mice were cold intolerant when acutely exposed to cold (6°C for 5 h) and had decreased cold-stimulated BAT Ucp1 gene expression. DMHGq/11KO mice also failed to adapt to gradually declining ambient temperatures and to develop adipocyte browning in inguinal white adipose tissue although their BAT Ucp1 was proportionally stimulated. Consistent with impaired cold-induced thermogenesis, the onset of obesity in DMHGq/11KO mice was significantly delayed when housed under thermoneutral conditions (30°C). Thus our results show that Gqα and G11α in the DMH are required for the control of energy homeostasis by stimulating energy expenditure and thermoregulation.NEW & NOTEWORTHY This paper demonstrates that signaling within the dorsomedial hypothalamus via the G proteins Gqα and G11α, which couple cell surface receptors to the stimulation of phospholipase C, is critical for regulation of energy expenditure, thermoregulation by brown adipose tissue and the induction of white adipose tissue browning.
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2
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Abstract
BACKGROUND Although both Gαq- and Gα11-protein signaling are believed to be involved in the regulation of cardiac hypertrophy, their detailed contribution to myocardial function remains elusive. METHODS AND RESULTS We studied remodeling processes in healthy transgenic mice with genetically altered Gαq/Gα11-expression, in particular a global Gα11-knockout and a novel inducible cardiac specific Gαq-knockout, as well as a combined double knockout (dKO) mouse line. Echocardiography and telemetric ECG recordings revealed that compared with wild type mice, hearts of dKO mice showed an increased ejection fraction and a decreased heart rate, irrespective of age resulting in a maintained cardiac output. We attributed these findings to the lack of Gα11, which the absence was associated with a decreased afterload. Histological analysis of the extracellular matrix in the heart depicted a diminished presence of collagen in aging hearts of dKO mice compared to wild-type mice. The results of a transcriptome analysis on isolated ventricular cardiac myocytes revealed alterations of the activity of genes involved in the Gαq/Gα11-dependent regulation of the extracellular matrix, such as the matricellular protein Cyr61. CONCLUSIONS From our data we conclude that Gαq/Gα11 signaling pathways play a pivotal role in maintaining gene activity patterns. For the heart we revealed their importance in modulating the properties of the extracellular matrix, a mechanism that might be an important contributor and mechanistic basis for the development of pressure-overload induced cardiac hypertrophy.
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3
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Endocannabinoid-mediated modulation of Gq/11 protein-coupled receptor signaling-induced vasoconstriction and hypertension. Mol Cell Endocrinol 2015; 403:46-56. [PMID: 25595485 DOI: 10.1016/j.mce.2015.01.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 12/19/2014] [Accepted: 01/08/2015] [Indexed: 12/31/2022]
Abstract
Activation of G protein-coupled receptors (GPCRs) can induce vasoconstriction via calcium signal-mediated and Rho-dependent pathways. Earlier reports have shown that diacylglycerol produced during calcium signal generation can be converted to an endocannabinoid, 2-arachidonoylglycerol (2-AG). Our aim was to provide evidence that GPCR signaling-induced 2-AG production and activation of vascular type1 cannabinoid receptors (CB1R) is capable of reducing agonist-induced vasoconstriction and hypertension. Rat and mouse aortic rings were examined by myography. Vascular expression of CB1R was demonstrated with immunohistochemistry. Rat aortic vascular smooth muscle cells (VSMCs) were cultured for calcium measurements and 2-AG-determination. Inhibition or genetic loss of CB1Rs enhanced vasoconstriction induced by angiotensin II (AngII) or phenylephrine (Phe), but not by prostaglandin(PG)F2α. AngII-induced vasoconstriction was augmented by inhibition of diacylglycerol lipase (tetrahydrolipstatin) and was attenuated by inhibition of monoacylglycerol lipase (JZL184) suggesting a functionally relevant role for endogenously produced 2-AG. In Gαq/11-deficient mice vasoconstriction was absent to AngII or Phe, which activate Gq/11-coupled receptors, but was maintained in response to PGF2α. In VSMCs, AngII-stimulated 2-AG-formation was inhibited by tetrahydrolipstatin and potentiated by JZL184. CB1R inhibition increased the sustained phase of AngII-induced calcium signal. Pharmacological or genetic loss of CB1R function augmented AngII-induced blood pressure rise in mice. These data demonstrate that vasoconstrictor effect of GPCR agonists is attenuated via Gq/11-mediated vascular endocannabinoid formation. Agonist-induced endocannabinoid-mediated CB1R activation is a significant physiological modulator of vascular tone. Thus, the selective modulation of GPCR signaling-induced endocannabinoid release has a therapeutic potential in case of increased vascular tone and hypertension.
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MESH Headings
- Angiotensin II/pharmacology
- Animals
- Aorta/drug effects
- Arachidonic Acids/pharmacology
- Benzodioxoles/pharmacology
- Calcium/metabolism
- Calcium Signaling
- Dinoprost/pharmacology
- Endocannabinoids/pharmacology
- GTP-Binding Protein alpha Subunits, Gq-G11/deficiency
- GTP-Binding Protein alpha Subunits, Gq-G11/genetics
- Gene Expression Regulation
- Glycerides/pharmacology
- Hypertension/drug therapy
- Hypertension/genetics
- Hypertension/metabolism
- Hypertension/physiopathology
- Lactones/pharmacology
- Lipoprotein Lipase/antagonists & inhibitors
- Lipoprotein Lipase/genetics
- Lipoprotein Lipase/metabolism
- Male
- Mice
- Mice, Knockout
- Monoacylglycerol Lipases/antagonists & inhibitors
- Monoacylglycerol Lipases/genetics
- Monoacylglycerol Lipases/metabolism
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Orlistat
- Phenylephrine/pharmacology
- Piperidines/pharmacology
- Rats
- Rats, Wistar
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/genetics
- Receptor, Cannabinoid, CB1/metabolism
- Tissue Culture Techniques
- Vasoconstriction/drug effects
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Loss of gq/11 genes does not abolish melanopsin phototransduction. PLoS One 2014; 9:e98356. [PMID: 24870805 PMCID: PMC4037210 DOI: 10.1371/journal.pone.0098356] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 05/01/2014] [Indexed: 11/29/2022] Open
Abstract
In mammals, a subset of retinal ganglion cells (RGCs) expresses the photopigment melanopsin, which renders them intrinsically photosensitive (ipRGCs). These ipRGCs mediate various non-image-forming visual functions such as circadian photoentrainment and the pupillary light reflex (PLR). Melanopsin phototransduction begins with activation of a heterotrimeric G protein of unknown identity. Several studies of melanopsin phototransduction have implicated a G-protein of the Gq/11 family, which consists of Gna11, Gna14, Gnaq and Gna15, in melanopsin-evoked depolarization. However, the exact identity of the Gq/11 gene involved in this process has remained elusive. Additionally, whether Gq/11 G-proteins are necessary for melanopsin phototransduction in vivo has not yet been examined. We show here that the majority of ipRGCs express both Gna11 and Gna14, but neither Gnaq nor Gna15. Animals lacking the melanopsin protein have well-characterized deficits in the PLR and circadian behaviors, and we therefore examined these non-imaging forming visual functions in a variety of single and double mutants for Gq/11 family members. All Gq/11 mutant animals exhibited PLR and circadian behaviors indistinguishable from WT. In addition, we show persistence of ipRGC light-evoked responses in Gna11−/−; Gna14−/− retinas using multielectrode array recordings. These results demonstrate that Gq, G11, G14, or G15 alone or in combination are not necessary for melanopsin-based phototransduction, and suggest that ipRGCs may be able to utilize a Gq/11-independent phototransduction cascade in vivo.
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Pasteurella multocida toxin (PMT) upregulates CTGF which leads to mTORC1 activation in Swiss 3T3 cells. Cell Signal 2013; 25:1136-48. [PMID: 23415771 DOI: 10.1016/j.cellsig.2013.01.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 01/16/2013] [Accepted: 01/30/2013] [Indexed: 02/07/2023]
Abstract
Pasteurella multocida toxin (PMT) is a mitogenic protein that hijacks cellular signal transduction pathways via deamidation of heterotrimeric G proteins. We previously showed that rPMT activates mTOR signaling via a Gαq/11/PLCβ/PKC mediated pathway, leading in part to cell proliferation and migration. Herein, we show that mTOR and MAPK, but not membrane-associated tyrosine kinases, are activated in serum-starved 3T3 cells by an autocrine/paracrine substance(s) secreted into the conditioned medium following rPMT treatment. Surprisingly, this diffusible factor(s) is capable of activating mTOR and MAPK pathways even in MEF Gαq/11 double knockout cells. Microarray analysis identified connective tissue growth factor (CTGF) mRNA as the most upregulated gene in rPMT-treated serum-starved 3T3 cells relative to untreated cells. These results were further confirmed using RT-PCR and Western blot analyses. In accord with rPMT-induced mTOR activation, upregulation of CTGF protein was observed in WT MEF, but not in Gαq/11 double knockout MEF cells. Although CTGF expression is regulated by TGFβ, rPMT did not activate TGFβ pathway. In addition, MEK inhibitors U0126 or PD98059, but not mTOR specific inhibitors, rapamycin and Torin 1, inhibited rPMT-induced upregulation of CTGF. Importantly, CTGF overexpression in serum-starved 3T3 cells using adenovirus led to phosphorylation of ribosomal protein S6, a downstream target of mTOR. However, despite the ability of CTGF to activate the mTOR pathway, upregulation of CTGF alone could not induce morphological changes as those observed in rPMT-treated cells. Our findings reveal that CTGF plays an important role, but there are additional factors involved in the mitogenic action of PMT.
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6
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Abstract
Anaphylactic shock is a severe allergic reaction involving multiple organs including the bronchial and cardiovascular system. Most anaphylactic mediators, like platelet-activating factor (PAF), histamine, and others, act through G protein-coupled receptors, which are linked to the heterotrimeric G proteins G(q)/G(11), G(12)/G(13), and G(i). The role of downstream signaling pathways activated by anaphylactic mediators in defined organs during anaphylactic reactions is largely unknown. Using genetic mouse models that allow for the conditional abrogation of G(q)/G(11)- and G(12)/G(13)-mediated signaling pathways by inducible Cre/loxP-mediated mutagenesis in endothelial cells (ECs), we show that G(q)/G(11)-mediated signaling in ECs is required for the opening of the endothelial barrier and the stimulation of nitric oxide formation by various inflammatory mediators as well as by local anaphylaxis. The systemic effects of anaphylactic mediators like histamine and PAF, but not of bacterial lipopolysaccharide (LPS), are blunted in mice with endothelial G alpha(q)/G alpha(11) deficiency. Mice with endothelium-specific G alpha(q)/G alpha(11) deficiency, but not with G alpha(12)/G alpha(13) deficiency, are protected against the fatal consequences of passive and active systemic anaphylaxis. This identifies endothelial G(q)/G(11)-mediated signaling as a critical mediator of fatal systemic anaphylaxis and, hence, as a potential new target to prevent or treat anaphylactic reactions.
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7
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Thyrocyte-specific Gq/G11 deficiency impairs thyroid function and prevents goiter development. J Clin Invest 2007; 117:2399-407. [PMID: 17694176 PMCID: PMC1937498 DOI: 10.1172/jci30380] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Accepted: 05/29/2007] [Indexed: 11/17/2022] Open
Abstract
The function of the adult thyroid is regulated by thyroid-stimulating hormone (TSH), which acts through a G protein-coupled receptor. Overactivation of the TSH receptor results in hyperthyroidism and goiter. The Gs-mediated stimulation of adenylyl cyclase-dependent cAMP formation has been regarded as the principal intracellular signaling mechanism mediating the action of TSH. Here we show that the Gq/G11-mediated signaling pathway plays an unexpected and essential role in the regulation of thyroid function. Mice lacking the alpha subunits of Gq and G11 specifically in thyroid epithelial cells showed severely reduced iodine organification and thyroid hormone secretion in response to TSH, and many developed hypothyroidism within months after birth. In addition, thyrocyte-specific Galphaq/Galpha11-deficient mice lacked the normal proliferative thyroid response to TSH or goitrogenic diet, indicating an essential role of this pathway in the adaptive growth of the thyroid gland. Our data suggest that Gq/G11 and their downstream effectors are promising targets to interfere with increased thyroid function and growth.
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Role of G(q) protein in behavioral effects of the hallucinogenic drug 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane. Neuropharmacology 2007; 52:1671-7. [PMID: 17493641 PMCID: PMC1987710 DOI: 10.1016/j.neuropharm.2007.03.013] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2006] [Revised: 03/22/2007] [Accepted: 03/26/2007] [Indexed: 11/18/2022]
Abstract
Extensive evidence suggests that 5-HT2 receptors may play a role in mental disorders including schizophrenia. In addition, several studies indicate that G(q)-coupled 5-HT(2A) receptors are likely targets for the initiation of events leading to the hallucinogenic behavior elicited by lysergic acid diethylamide (LSD), (+/-)1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), and related drugs. However, 5-HT(2A) receptors couple to other G proteins in addition to G(q) protein. To evaluate the role of the G(q) signaling pathway in DOI-induced behaviors, we utilized two behavioral models of 5-HT(2A) receptor activation: induction of head-twitches by DOI, a common response to hallucinogenic drugs in rodents, and DOI elicited anxiolytic-like effects in the elevated plus maze. Experimental subjects were genetically modified mice [Galpha(q)(-/-)] in which the G(q) alpha gene was eliminated. Galpha(q)(-/-) mice exhibited a decrease in DOI-induced head-twitches, when compared to wild-type littermates. In addition, the DOI-induced increase in anxiolytic-like behavior was abolished in Galpha(q)(-/-) mice. These results, combined with our finding that DOI-induced FOS expression in the medial prefrontal cortex was also eliminated in Galpha(q)(-/-) mice, suggests a key role for G(q) protein in hallucinogenic drug effects.
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9
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G alpha(q)-coupled muscarinic acetylcholine receptors enhance nicotinic acetylcholine receptor signaling in Caenorhabditis elegans mating behavior. J Neurosci 2007; 27:1411-21. [PMID: 17287516 PMCID: PMC6673585 DOI: 10.1523/jneurosci.4320-06.2007] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 11/28/2006] [Accepted: 12/12/2006] [Indexed: 11/21/2022] Open
Abstract
In this study, we address why metabotropic and ionotropic cholinergic signaling pathways are used to facilitate motor behaviors. We demonstrate that a G alpha(q)-coupled muscarinic acetylcholine receptor (mAChR) signaling pathway enhances nicotinic acetylcholine receptor (nAChR) signaling to facilitate the insertion of the Caenorhabditis elegans male copulatory spicules into the hermaphrodite during mating. Previous studies showed that ACh (acetylcholine) activates nAChRs on the spicule protractor muscles to induce the attached spicules to extend from the tail. Using the mAChR agonist Oxo M (oxotremorine M), we identified a GAR-3(mAChR)-G alpha(q) pathway that promotes protractor muscle contraction by upregulating nAChR signaling before mating. GAR-3(mAChR) is expressed in the protractor muscles and in the spicule-associated SPC and PCB cholinergic neurons. However, ablation of these neurons or impairing cholinergic transmission reduces drug-induced spicule protraction, suggesting that drug-stimulated neurons directly activate muscle contraction. Behavioral analysis of gar-3 mutants indicates that, in wild-type males, GAR-3(mAChR) expression in the SPC and PCB neurons is required for the male to sustain rhythmic spicule muscle contractions during attempts to breach the vulva. We propose that the GAR-3(mAChR)/G alpha(q) pathway sensitizes the spicule neurons and muscles before and during mating so that the male can respond to hermaphrodite vulva efficiently.
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MESH Headings
- Acetylcholine/physiology
- Animals
- Animals, Genetically Modified
- Caenorhabditis elegans/genetics
- Caenorhabditis elegans/physiology
- Caenorhabditis elegans Proteins/drug effects
- Caenorhabditis elegans Proteins/genetics
- Caenorhabditis elegans Proteins/physiology
- Carrier Proteins/genetics
- Carrier Proteins/physiology
- Disorders of Sex Development
- GTP-Binding Protein alpha Subunits, Gq-G11/deficiency
- GTP-Binding Protein alpha Subunits, Gq-G11/genetics
- GTP-Binding Protein alpha Subunits, Gq-G11/physiology
- Genitalia/innervation
- Genitalia/physiology
- Isoenzymes/deficiency
- Isoenzymes/genetics
- Isoenzymes/physiology
- Levamisole/pharmacology
- Muscarinic Agonists/pharmacology
- Muscle Contraction/physiology
- Mutation, Missense
- Neurons/physiology
- Oxotremorine/pharmacology
- Periodicity
- Phospholipase C beta
- Potassium Channels/deficiency
- Potassium Channels/genetics
- Potassium Channels/physiology
- Receptors, Muscarinic/deficiency
- Receptors, Muscarinic/genetics
- Receptors, Muscarinic/physiology
- Receptors, Nicotinic/physiology
- Recombinant Fusion Proteins/physiology
- Ryanodine Receptor Calcium Release Channel/drug effects
- Sexual Behavior, Animal/physiology
- Signal Transduction/physiology
- Syntaxin 1/deficiency
- Syntaxin 1/genetics
- Syntaxin 1/physiology
- Type C Phospholipases/deficiency
- Type C Phospholipases/genetics
- Type C Phospholipases/physiology
- Vesicular Acetylcholine Transport Proteins/deficiency
- Vesicular Acetylcholine Transport Proteins/genetics
- Vesicular Acetylcholine Transport Proteins/physiology
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G protein-coupled receptor (GPCR) kinase 2 regulates agonist-independent Gq/11 signaling from the mouse cytomegalovirus GPCR M33. J Biol Chem 2006; 281:39796-805. [PMID: 17088245 PMCID: PMC2767100 DOI: 10.1074/jbc.m610026200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The mouse cytomegalovirus M33 protein is highly homologous to mammalian G protein-coupled receptors (GPCRs) yet functions in an agonist-independent manner to activate a number of classical GPCR signal transduction pathways. M33 is functionally similar to the human cytomegalovirus-encoded US28 GPCR in its ability to induce inositol phosphate accumulation, activate NF-kappaB, and promote smooth muscle cell migration. This ability to promote cellular migration suggests a role for viral GPCRs like M33 in viral dissemination in vivo, and accordingly, M33 is required for efficient murine cytomegalovirus replication in the mouse. Although previous studies have identified several M33-induced signaling pathways, little is known regarding the membrane-proximal events involved in signaling and regulation of this receptor. In this study, we used recombinant retroviruses to express M33 in wild-type and Galpha(q/11)(-/-) mouse embryonic fibroblasts and show that M33 couples directly to the G(q/11) signaling pathway to induce high levels of total inositol phosphates in an agonist-independent manner. Our data also show that GRK2 is a potent regulator of M33-induced G(q/11) signaling through its ability to phosphorylate M33 and sequester Galpha(q/11) proteins. Taken together, the results from this study provide the first genetic evidence of a viral GPCR coupling to a specific G protein signaling pathway as well as identify the first viral GPCR to be regulated specifically by both the catalytic activity of the GRK2 kinase domain and the Galpha(q/11) binding activity of the GRK2 RH domain.
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11
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Cardiac-specific overexpression of AT1 receptor mutant lacking G alpha q/G alpha i coupling causes hypertrophy and bradycardia in transgenic mice. J Clin Invest 2006; 115:3045-56. [PMID: 16276415 PMCID: PMC1265872 DOI: 10.1172/jci25330] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2005] [Accepted: 08/30/2005] [Indexed: 12/25/2022] Open
Abstract
Ang II type 1 (AT1) receptors activate both conventional heterotrimeric G protein-dependent and unconventional G protein-independent mechanisms. We investigated how these different mechanisms activated by AT1 receptors affect growth and death of cardiac myocytes in vivo. Transgenic mice with cardiac-specific overexpression of WT AT1 receptor (AT1-WT; Tg-WT mice) or an AT1 receptor second intracellular loop mutant (AT1-i2m; Tg-i2m mice) selectively activating G(alpha)q/G(alpha)i-independent mechanisms were studied. Tg-i2m mice developed more severe cardiac hypertrophy and bradycardia coupled with lower cardiac function than Tg-WT mice. In contrast, Tg-WT mice exhibited more severe fibrosis and apoptosis than Tg-i2m mice. Chronic Ang II infusion induced greater cardiac hypertrophy in Tg-i2m compared with Tg-WT mice whereas acute Ang II administration caused an increase in heart rate in Tg-WT but not in Tg-i2m mice. Membrane translocation of PKCepsilon, cytoplasmic translocation of G(alpha)q, and nuclear localization of phospho-ERKs were observed only in Tg-WT mice while activation of Src and cytoplasmic accumulation of phospho-ERKs were greater in Tg-i2m mice, consistent with the notion that G(alpha)q/G(alpha)i-independent mechanisms are activated in Tg-i2m mice. Cultured myocytes expressing AT1-i2m exhibited a left and upward shift of the Ang II dose-response curve of hypertrophy compared with those expressing AT1-WT. Thus, the AT1 receptor mediates downstream signaling mechanisms through G(alpha)q/G(alpha)i-dependent and -independent mechanisms, which induce hypertrophy with a distinct phenotype.
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MESH Headings
- Animals
- Apoptosis/genetics
- Bradycardia/genetics
- Bradycardia/metabolism
- Bradycardia/pathology
- Cells, Cultured
- Electrocardiography
- Extracellular Signal-Regulated MAP Kinases/metabolism
- Fibrosis/genetics
- Fibrosis/metabolism
- GTP-Binding Protein alpha Subunits, Gi-Go/deficiency
- GTP-Binding Protein alpha Subunits, Gi-Go/genetics
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- GTP-Binding Protein alpha Subunits, Gq-G11/deficiency
- GTP-Binding Protein alpha Subunits, Gq-G11/genetics
- GTP-Binding Protein alpha Subunits, Gq-G11/metabolism
- Hypertrophy, Left Ventricular/genetics
- Hypertrophy, Left Ventricular/metabolism
- Hypertrophy, Left Ventricular/pathology
- Mice
- Mice, Transgenic
- Mutation
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/pathology
- Phenotype
- Protein Kinase C-epsilon/metabolism
- Rats
- Rats, Wistar
- Receptor, Angiotensin, Type 1/deficiency
- Receptor, Angiotensin, Type 1/genetics
- Receptor, Angiotensin, Type 1/metabolism
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Characteristic defects in neural crest cell-specific Galphaq/Galpha11- and Galpha12/Galpha13-deficient mice. Dev Biol 2005; 282:174-82. [PMID: 15936338 DOI: 10.1016/j.ydbio.2005.03.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2004] [Revised: 02/08/2005] [Accepted: 03/08/2005] [Indexed: 10/25/2022]
Abstract
The endothelin/endothelin receptor system plays a critical role in the differentiation and terminal migration of particular neural crest cell subpopulations. Targeted deletion of the G-protein-coupled endothelin receptors ET(A) and ET(B) was shown to result in characteristic developmental defects of derivatives of cephalic and cardiac neural crest and of neural crest-derived melanocytes and enteric neurons, respectively. Since both endothelin receptors are coupled to G-proteins of the G(q)/G(11)- and G(12)/G(13)-families, we generated mouse lines lacking Galpha(q)/Galpha(11) or Galpha(12)/Galpha(13) in neural crest cells to study their roles in neural crest development. Mice lacking Galpha(q)/Galpha(11) in a neural crest cell-specific manner had craniofacial defects similar to those observed in mice lacking the ET(A) receptor or endothelin-1 (ET-1). However, in contrast to ET-1/ET(A) mutant animals, cardiac outflow tract morphology was intact. Surprisingly, neither Galpha(q)/Galpha(11)- nor Galpha(12)/Galpha(13)-deficient mice showed developmental defects seen in animals lacking either the ET(B) receptor or its ligand endothelin-3 (ET-3). Interestingly, Galpha(12)/Galpha(13) deficiency in neural crest cell-derived cardiac cells resulted in characteristic cardiac malformations. Our data show that G(q)/G(11)- but not G(12)/G(13)-mediated signaling processes mediate ET-1/ET(A)-dependent development of the cephalic neural crest. In contrast, ET-3/ET(B)-mediated development of neural crest-derived melanocytes and enteric neurons appears to involve G-proteins different from G(q)/G(11)/G(12)/G(13).
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13
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Resistance to volatile anesthetics by mutations enhancing excitatory neurotransmitter release in Caenorhabditis elegans. Genetics 2005; 168:831-43. [PMID: 15514057 PMCID: PMC1448830 DOI: 10.1534/genetics.104.030502] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The molecular mechanisms whereby volatile general anesthetics (VAs) disrupt behavior remain undefined. In Caenorhabditis elegans mutations in the gene unc-64, which encodes the presynaptic protein syntaxin 1A, produce large allele-specific differences in VA sensitivity. UNC-64 syntaxin normally functions to mediate fusion of neurotransmitter vesicles with the presynaptic membrane. The precise role of syntaxin in the VA mechanism is as yet unclear, but a variety of results suggests that a protein interacting with syntaxin to regulate neurotransmitter release is essential for VA action in C. elegans. To identify additional proteins that function with syntaxin to control neurotransmitter release and VA action, we screened for suppressors of the phenotypes produced by unc-64 reduction of function. Loss-of-function mutations in slo-1, which encodes a Ca(2+)-activated K+ channel, and in unc-43, which encodes CaM-kinase II, and a gain-of-function mutation in egl-30, which encodes Gqalpha, were isolated as syntaxin suppressors. The slo-1 and egl-30 mutations conferred resistance to VAs, but unc-43 mutations did not. The effects of slo-1 and egl-30 on VA sensitivity can be explained by their actions upstream or parallel to syntaxin to increase the level of excitatory neurotransmitter release. These results strengthen the link between transmitter release and VA action.
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14
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Anti-glycoprotein VI treatment severely compromises hemostasis in mice with reduced alpha2beta1 levels or concomitant aspirin therapy. Circulation 2004; 110:2946-51. [PMID: 15505105 DOI: 10.1161/01.cir.0000146341.63677.3c] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Platelet inhibition is a major strategy to prevent arterial thrombosis, but it is frequently associated with increased bleeding because of impaired primary hemostasis. The activating platelet collagen receptor, glycoprotein VI (GP VI), may serve as a powerful antithrombotic target because its inhibition or absence results in profound protection against arterial thrombosis but no major bleeding in mice. METHODS AND RESULTS Mice lacking (-/-) or expressing half-levels (+/-) of the other major platelet collagen receptor, integrin alpha2beta1, were injected with the anti-GP VI antibody JAQ1 and analyzed on day 5. Anti-GP VI treatment resulted in a marked hemostatic defect in alpha2-/- or alpha2+/- mice, as shown by dramatically prolonged tail bleeding times. Platelet adhesion to collagen was studied in an ex vivo whole-blood perfusion system under high shear conditions. Weak integrin activation by thromboxane A2 (TxA2) receptor stimulation restored defective adhesion of anti-GP VI-treated wild-type but not alpha2-/- or alpha2+/- platelets to collagen. This process required the simultaneous activation of the G(q) and G13 signaling pathways, as demonstrated by use of the respective knockout strains. Conversely, inhibition of TxA2 production by aspirin severely compromised hemostasis in anti-GP VI-treated or GP VI/Fc receptor gamma-chain-deficient but not control mice. CONCLUSIONS Anti-GP VI therapy may result in defective hemostasis in patients with reduced alpha2beta1 levels or concomitant aspirin therapy. These observations may have important implications for a potential use of anti-GP VI-based therapeutics in the prevention of cardiovascular disease.
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MESH Headings
- 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid/pharmacology
- Animals
- Antibodies, Monoclonal/administration & dosage
- Antibodies, Monoclonal/pharmacology
- Antibodies, Monoclonal/toxicity
- Aspirin/administration & dosage
- Aspirin/toxicity
- Bleeding Time
- Collagen/pharmacology
- Collagen/physiology
- Drug Evaluation, Preclinical
- Drug Synergism
- Fibrinolytic Agents/toxicity
- GTP-Binding Protein alpha Subunits, G12-G13/deficiency
- GTP-Binding Protein alpha Subunits, G12-G13/genetics
- GTP-Binding Protein alpha Subunits, G12-G13/physiology
- GTP-Binding Protein alpha Subunits, Gq-G11/deficiency
- GTP-Binding Protein alpha Subunits, Gq-G11/genetics
- GTP-Binding Protein alpha Subunits, Gq-G11/physiology
- Hemorrhage/chemically induced
- Hemorrhage/prevention & control
- Hemostasis/drug effects
- Hemostasis/physiology
- Integrin alpha2beta1/deficiency
- Integrin alpha2beta1/genetics
- Mice
- Mice, Knockout
- Platelet Activation/drug effects
- Platelet Activation/physiology
- Platelet Adhesiveness/drug effects
- Platelet Membrane Glycoproteins/antagonists & inhibitors
- Platelet Membrane Glycoproteins/deficiency
- Platelet Membrane Glycoproteins/physiology
- Receptors, Thromboxane A2, Prostaglandin H2/drug effects
- Receptors, Thromboxane A2, Prostaglandin H2/physiology
- Signal Transduction
- Thrombosis/prevention & control
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15
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Platelets and fibrin(ogen) increase metastatic potential by impeding natural killer cell-mediated elimination of tumor cells. Blood 2004; 105:178-85. [PMID: 15367435 DOI: 10.1182/blood-2004-06-2272] [Citation(s) in RCA: 690] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
To test the hypothesis that platelet activation contributes to tumor dissemination, we studied metastasis in mice lacking Galphaq, a G protein critical for platelet activation. Loss of platelet activation resulted in a profound diminution in both experimental and spontaneous metastases. Analyses of the distribution of radiolabeled tumor cells demonstrated that platelet function, like fibrinogen, significantly improved the survival of circulating tumor cells in the pulmonary vasculature. More detailed studies showed that the increase in metastatic success conferred by either platelets or fibrinogen was linked to natural killer cell function. Specifically, the pronounced reduction in tumor cell survival observed in fibrinogen- and Galphaq-deficient mice relative to control animals was eliminated by the immunologic or genetic depletion of natural killer cells. These studies establish an important link between hemostatic factors and innate immunity and indicate that one mechanism by which the platelet-fibrin(ogen) axis contributes to metastatic potential is by impeding natural killer cell elimination of tumor cells.
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16
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Heterotrimeric G proteins of the Gq/11 family are crucial for the induction of maternal behavior in mice. Mol Cell Biol 2004; 24:8048-54. [PMID: 15340067 PMCID: PMC515047 DOI: 10.1128/mcb.24.18.8048-8054.2004] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2004] [Revised: 04/24/2004] [Accepted: 06/17/2004] [Indexed: 11/20/2022] Open
Abstract
Heterotrimeric G proteins of the G(q/11) family transduce signals from a variety of neurotransmitter receptors and have therefore been implicated in several functions of the central nervous system. To investigate the potential role of G(q/11) signaling in behavior, we generated mice which lack the alpha-subunits of the two main members of the G(q/11) family, Galpha(q) and Galpha(11), selectively in the forebrain. We show here that forebrain Galpha(q/11)-deficient females do not display any maternal behavior such as nest building, pup retrieving, crouching, or nursing. However, olfaction, motor behavior and mammary gland function are normal in forebrain Galpha(q/11)-deficient females. We used c-fos immunohistochemistry to investigate pup-induced neuronal activation in different forebrain regions and found a significant reduction in the medial preoptic area, the bed nucleus of stria terminalis, and the lateral septum both in postpartum females and in virgin females after foster pup exposure. Pituitary function, especially prolactin release, was normal in forebrain Galpha(q/11)-deficient females, and activation of oxytocin receptor-positive neurons in the hypothalamus did not differ between genotypes. Our findings show that G(q/11) signaling is indispensable to the neuronal circuit that connects the perception of pup-related stimuli to the initiation of maternal behavior and that this defect cannot be attributed to either reduced systemic prolactin levels or impaired activation of oxytocin receptor-positive neurons of the hypothalamus.
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