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Martín-Aragón Baudel M, Hong J, Hell JW, Nieves-Cintrón M, Navedo MF. Mechanisms of Vascular Ca V1.2 Channel Regulation During Diabetic Hyperglycemia. Handb Exp Pharmacol 2023; 279:41-58. [PMID: 36598607 DOI: 10.1007/164_2022_628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Diabetes is a leading cause of disability and mortality worldwide. A major underlying factor in diabetes is the excessive glucose levels in the bloodstream (e.g., hyperglycemia). Vascular complications directly result from this metabolic abnormality, leading to disabling and life-threatening conditions. Dysfunction of vascular smooth muscle cells is a well-recognized factor mediating vascular complications during diabetic hyperglycemia. The function of vascular smooth muscle cells is exquisitely controlled by different ion channels. Among the ion channels, the L-type CaV1.2 channel plays a key role as it is the main Ca2+ entry pathway regulating vascular smooth muscle contractile state. The activity of CaV1.2 channels in vascular smooth muscle is altered by diabetic hyperglycemia, which may contribute to vascular complications. In this chapter, we summarize the current understanding of the regulation of CaV1.2 channels in vascular smooth muscle by different signaling pathways. We place special attention on the regulation of CaV1.2 channel activity in vascular smooth muscle by a newly uncovered AKAP5/P2Y11/AC5/PKA/CaV1.2 axis that is engaged during diabetic hyperglycemia. We further describe the pathophysiological implications of activation of this axis as it relates to myogenic tone and vascular reactivity and propose that this complex may be targeted for developing therapies to treat diabetic vascular complications.
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Affiliation(s)
| | - Junyoung Hong
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | - Johannes W Hell
- Department of Pharmacology, University of California Davis, Davis, CA, USA
| | | | - Manuel F Navedo
- Department of Pharmacology, University of California Davis, Davis, CA, USA.
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2
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Hu XQ, Zhang L. Oxidative Regulation of Vascular Ca v1.2 Channels Triggers Vascular Dysfunction in Hypertension-Related Disorders. Antioxidants (Basel) 2022; 11:antiox11122432. [PMID: 36552639 PMCID: PMC9774363 DOI: 10.3390/antiox11122432] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 11/28/2022] [Accepted: 12/06/2022] [Indexed: 12/13/2022] Open
Abstract
Blood pressure is determined by cardiac output and peripheral vascular resistance. The L-type voltage-gated Ca2+ (Cav1.2) channel in small arteries and arterioles plays an essential role in regulating Ca2+ influx, vascular resistance, and blood pressure. Hypertension and preeclampsia are characterized by high blood pressure. In addition, diabetes has a high prevalence of hypertension. The etiology of these disorders remains elusive, involving the complex interplay of environmental and genetic factors. Common to these disorders are oxidative stress and vascular dysfunction. Reactive oxygen species (ROS) derived from NADPH oxidases (NOXs) and mitochondria are primary sources of vascular oxidative stress, whereas dysfunction of the Cav1.2 channel confers increased vascular resistance in hypertension. This review will discuss the importance of ROS derived from NOXs and mitochondria in regulating vascular Cav1.2 and potential roles of ROS-mediated Cav1.2 dysfunction in aberrant vascular function in hypertension, diabetes, and preeclampsia.
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Cilleros-Mañé V, Just-Borràs L, Polishchuk A, Durán M, Tomàs M, Garcia N, Tomàs JM, Lanuza MA. M 1 and M 2 mAChRs activate PDK1 and regulate PKC βI and ε and the exocytotic apparatus at the NMJ. FASEB J 2021; 35:e21724. [PMID: 34133802 DOI: 10.1096/fj.202002213r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 05/07/2021] [Accepted: 05/24/2021] [Indexed: 01/14/2023]
Abstract
Neuromuscular junctions (NMJ) regulate cholinergic exocytosis through the M1 and M2 muscarinic acetylcholine autoreceptors (mAChR), involving the crosstalk between receptors and downstream pathways. Protein kinase C (PKC) regulates neurotransmission but how it associates with the mAChRs remains unknown. Here, we investigate whether mAChRs recruit the classical PKCβI and the novel PKCε isoforms and modulate their priming by PDK1, translocation and activity on neurosecretion targets. We show that each M1 and M2 mAChR activates the master kinase PDK1 and promotes a particular priming of the presynaptic PKCβI and ε isoforms. M1 recruits both primed-PKCs to the membrane and promotes Munc18-1, SNAP-25, and MARCKS phosphorylation. In contrast, M2 downregulates PKCε through a PKA-dependent pathway, which inhibits Munc18-1 synthesis and PKC phosphorylation. In summary, our results discover a co-dependent balance between muscarinic autoreceptors which orchestrates the presynaptic PKC and their action on ACh release SNARE-SM mechanism. Altogether, this molecular signaling explains previous functional studies at the NMJ and guide toward potential therapeutic targets.
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Affiliation(s)
- V Cilleros-Mañé
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Facultat de Medicina i Ciències de la Salut, Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - L Just-Borràs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Facultat de Medicina i Ciències de la Salut, Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - A Polishchuk
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Facultat de Medicina i Ciències de la Salut, Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - M Durán
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Facultat de Medicina i Ciències de la Salut, Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - M Tomàs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Facultat de Medicina i Ciències de la Salut, Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - N Garcia
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Facultat de Medicina i Ciències de la Salut, Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - J M Tomàs
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Facultat de Medicina i Ciències de la Salut, Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
| | - M A Lanuza
- Unitat d'Histologia i Neurobiologia (UHNEUROB), Facultat de Medicina i Ciències de la Salut, Departament de Ciències Mèdiques Bàsiques, Universitat Rovira i Virgili, Reus, Spain
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4
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Tsai CY, Dai KY, Fang C, Wu JCC, Chan SHH. PTEN/FLJ10540/PI3K/Akt cascade in experimental brain stem death: A newfound role for a classical tumorigenic signaling pathway. Biochem Pharmacol 2018; 155:207-212. [PMID: 30008438 DOI: 10.1016/j.bcp.2018.07.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 07/01/2018] [Indexed: 12/28/2022]
Abstract
Despite great advances in contemporary medicine, brain death still remains enigmatic and its cellular and molecular mechanisms unsettled. This review summarizes recent findings that substantiate the notion that PTEN/FLJ10540/PI3K/Akt cascade, the classical tumorigenic signaling pathway, is actively engaged in experimental brain stem death. These results were based on a clinically relevant animal model that employs the pesticide mevinphos as the experimental insult in Sprague-Dawley rats to mimic brain stem death in patients died of organophosphate poisoning. The neural substrate investigated is the rostral ventrolateral medulla (RVLM), a brain stem site classically known to maintain arterial pressure (AP) and is established to be the origin of a "life-and-death" signal detected from AP, which reflects brain stem cardiovascular dysregulation that precedes death. Activation of PI3K/Akt signaling pathway in the RVLM upregulates the nuclear factor-κB/nitric oxide synthase II/peroxynitrite cascade, resulting in impairment of brain stem cardiovascular regulation that leads to the loss of the "life-and-death" signal in experimental brain stem death. This process is reinforced by FLJ10540, a PI3K-association protein; and is counteracted by PTEN, a negative regulator of PI3K/Akt signaling. The concept that a classical signaling pathway in tumorigenesis is also an active player in cardiovascular dysregulation in brain stem death provides new ramifications for translational medicine. It promulgates the concept that rather than focusing on a particular disease condition, a new vista for future therapeutic strategy against both fatal eventualities should target at this common cellular cascade.
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Affiliation(s)
- Ching-Yi Tsai
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan, Republic of China.
| | - Kuang-Yu Dai
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan, Republic of China
| | - Chi Fang
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan, Republic of China
| | - Jacqueline C C Wu
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan, Republic of China
| | - Samuel H H Chan
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung 83301, Taiwan, Republic of China.
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Matsuoka H, Inoue M. Molecular mechanism for muscarinic M 1 receptor-mediated endocytosis of TWIK-related acid-sensitive K + 1 channels in rat adrenal medullary cells. J Physiol 2017; 595:6851-6867. [PMID: 28944482 DOI: 10.1113/jp275039] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 09/15/2017] [Indexed: 01/25/2023] Open
Abstract
KEY POINTS The muscarinic acetylcholine receptor (mAChR)-mediated increase in excitability in rat adrenal medullary cells is at least in part due to inhibition of TWIK (tandem of P domains in a weak inwardly rectifying K+ channel)-related acid-sensitive K+ (TASK)1 channels. In this study we focused on the molecular mechanism of mAChR-mediated inhibition of TASK1 channels. Exposure to muscarine resulted in a clathrin-dependent endocytosis of TASK1 channels following activation of the muscarinic M1 receptor (M1 R). This muscarinic signal for the endocytosis was mediated in sequence by phospholipase C (PLC), protein kinase C (PKC), and then the non-receptor tyrosine kinase Src with the consequent tyrosine phosphorylation of TASK1. The present results establish that TASK1 channels are tyrosine phosphorylated and internalized in a clathrin-dependent manner in response to M1 R stimulation and this translocation is at least in part responsible for muscarinic inhibition of TASK1 channels in rat AM cells. ABSTRACT Activation of muscarinic receptor (mAChR) in rat adrenal medullary (AM) cells induces depolarization through the inhibition of TWIK-related acid-sensitive K+ (TASK)1 channels. Here, pharmacological and immunological approaches were used to elucidate the molecular mechanism for this mAChR-mediated inhibition. TASK1-like immunoreactive (IR) material was mainly located at the cell periphery in dissociated rat AM cells, and its majority was internalized in response to muscarine. The muscarine-induced inward current and translocation of TASK1 were suppressed by dynasore, a dynamin inhibitor. The muscarinic translocation was suppressed by MT7, a specific M1 antagonist, and the dose-response curves for muscarinic agonist-induced translocation were similar to those for the muscarinic inhibition of TASK1 currents. The muscarine-induced inward current and/or translocation of TASK1 were suppressed by inhibitors for phospholipase C (PLC), protein kinase C (PKC), and/or Src. TASK1 channels in AM cells and PC12 cells were transiently associated with Src and were tyrosine phosphorylated in response to muscarinic stimulation. After internalization, TASK1 channels were quickly dephosphorylated even while they remained in the cytoplasm. The cytoplasmic TASK1-like IR material quickly recycled back to the cell periphery after muscarine stimulation for 0.5 min, but not 10 min. We conclude that M1 R stimulation results in internalization of TASK1 channels through the PLC-PKC-Src pathway with the consequent phosphorylation of tyrosine and that this M1 R-mediated internalization is at least in part responsible for muscarinic inhibition of TASK1 channels in rat AM cells.
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Affiliation(s)
- Hidetada Matsuoka
- Department of Cell and Systems Physiology, University of Occupational and Environmental Health School of Medicine, Kitakyushu, 807-8555, Japan
| | - Masumi Inoue
- Department of Cell and Systems Physiology, University of Occupational and Environmental Health School of Medicine, Kitakyushu, 807-8555, Japan
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Leist M, Rinné S, Datunashvili M, Aissaoui A, Pape HC, Decher N, Meuth SG, Budde T. Acetylcholine-dependent upregulation of TASK-1 channels in thalamic interneurons by a smooth muscle-like signalling pathway. J Physiol 2017; 595:5875-5893. [PMID: 28714121 DOI: 10.1113/jp274527] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 07/10/2017] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS The ascending brainstem transmitter acetylcholine depolarizes thalamocortical relay neurons while it induces hyperpolarization in local circuit inhibitory interneurons. Sustained K+ currents are modulated in thalamic neurons to control their activity modes; for the interneurons the molecular nature of the underlying ion channels is as yet unknown. Activation of TASK-1 K+ channels results in hyperpolarization of interneurons and suppression of their action potential firing. The modulation cascade involves a non-receptor tyrosine kinase, c-Src. The present study identifies a novel pathway for the activation of TASK-1 channels in CNS neurons that resembles cholinergic signalling and TASK-1 current modulation during hypoxia in smooth muscle cells. ABSTRACT The dorsal part of the lateral geniculate nucleus (dLGN) is the main thalamic site for state-dependent transmission of visual information. Non-retinal inputs from the ascending arousal system and inhibition provided by γ-aminobutyric acid (GABA)ergic local circuit interneurons (INs) control neuronal activity within the dLGN. In particular, acetylcholine (ACh) depolarizes thalamocortical relay neurons by inhibiting two-pore domain potassium (K2P ) channels. Conversely, ACh also hyperpolarizes INs via an as-yet-unknown mechanism. By using whole cell patch-clamp recordings in brain slices and appropriate pharmacological tools we here report that stimulation of type 2 muscarinic ACh receptors induces IN hyperpolarization by recruiting the G-protein βγ subunit (Gβγ), class-1A phosphatidylinositol-4,5-bisphosphate 3-kinase, and cellular and sarcoma (c-Src) tyrosine kinase, leading to activation of two-pore domain weakly inwardly rectifying K+ channel (TWIK)-related acid-sensitive K+ (TASK)-1 channels. The latter was confirmed by the use of TASK-1-deficient mice. Furthermore inhibition of phospholipase Cβ as well as an increase in the intracellular level of phosphatidylinositol-3,4,5-trisphosphate facilitated the muscarinic effect. Our results have uncovered a previously unknown role of c-Src tyrosine kinase in regulating IN function in the brain and identified a novel mechanism by which TASK-1 channels are activated in neurons.
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Affiliation(s)
- Michael Leist
- Institut für Physiologie I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, D-48149, Münster, Germany
| | - Susanne Rinné
- Institut für Physiologie und Pathophysiologie, AG Vegetative Physiologie, Philipps-Universität, Deutschhausstraße 1-2, D-35037, Marburg, Germany
| | - Maia Datunashvili
- Institut für Physiologie I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, D-48149, Münster, Germany
| | - Ania Aissaoui
- Institut für Physiologie I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, D-48149, Münster, Germany
| | - Hans-Christian Pape
- Institut für Physiologie I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, D-48149, Münster, Germany
| | - Niels Decher
- Institut für Physiologie und Pathophysiologie, AG Vegetative Physiologie, Philipps-Universität, Deutschhausstraße 1-2, D-35037, Marburg, Germany
| | - Sven G Meuth
- Department of Neurology, Westfälische Wilhelms-Universität, Albert-Schweitzer-Campus 1, D-48149, Münster, Germany
| | - Thomas Budde
- Institut für Physiologie I, Westfälische Wilhelms-Universität, Robert-Koch-Str. 27a, D-48149, Münster, Germany
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7
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Tykocki NR, Boerman EM, Jackson WF. Smooth Muscle Ion Channels and Regulation of Vascular Tone in Resistance Arteries and Arterioles. Compr Physiol 2017; 7:485-581. [PMID: 28333380 DOI: 10.1002/cphy.c160011] [Citation(s) in RCA: 222] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Vascular tone of resistance arteries and arterioles determines peripheral vascular resistance, contributing to the regulation of blood pressure and blood flow to, and within the body's tissues and organs. Ion channels in the plasma membrane and endoplasmic reticulum of vascular smooth muscle cells (SMCs) in these blood vessels importantly contribute to the regulation of intracellular Ca2+ concentration, the primary determinant of SMC contractile activity and vascular tone. Ion channels provide the main source of activator Ca2+ that determines vascular tone, and strongly contribute to setting and regulating membrane potential, which, in turn, regulates the open-state-probability of voltage gated Ca2+ channels (VGCCs), the primary source of Ca2+ in resistance artery and arteriolar SMCs. Ion channel function is also modulated by vasoconstrictors and vasodilators, contributing to all aspects of the regulation of vascular tone. This review will focus on the physiology of VGCCs, voltage-gated K+ (KV) channels, large-conductance Ca2+-activated K+ (BKCa) channels, strong-inward-rectifier K+ (KIR) channels, ATP-sensitive K+ (KATP) channels, ryanodine receptors (RyRs), inositol 1,4,5-trisphosphate receptors (IP3Rs), and a variety of transient receptor potential (TRP) channels that contribute to pressure-induced myogenic tone in resistance arteries and arterioles, the modulation of the function of these ion channels by vasoconstrictors and vasodilators, their role in the functional regulation of tissue blood flow and their dysfunction in diseases such as hypertension, obesity, and diabetes. © 2017 American Physiological Society. Compr Physiol 7:485-581, 2017.
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Affiliation(s)
- Nathan R Tykocki
- Department of Pharmacology, University of Vermont, Burlington, Vermont, USA
| | - Erika M Boerman
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri, USA
| | - William F Jackson
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan, USA
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Zhu Z, Tang J, Zhou X, Xiang S, Zhu X, Li N, Shi R, Zhong Y, Zhang L, Sun M, Xu Z. Roles of ion channels in regulation of acetylcholine-mediated vasoconstrictions in umbilical cords of rabbit/rats. Reprod Toxicol 2016; 65:95-103. [PMID: 27421582 DOI: 10.1016/j.reprotox.2016.07.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 05/31/2016] [Accepted: 07/08/2016] [Indexed: 12/25/2022]
Abstract
We recently demonstrated that acetylcholine (ACh) produced reliable vasoconstrictions in the umbilical cords. This study investigated the possible mechanisms with different antagonists. ACh-mediated vasoconstrictions were decreased by voltage-operated calcium (Ca2+) channels antagonist nifedipine or inositol-1,4,5-trisphosphate-mediated Ca2+ release antagonist 2-aminoethyl diphenylborinate, indicating that both extracellular and intracellular calcium modulated the ACh-stimulated umbilical contraction. Intracellular Ca2+ concentrations were increased simultaneously with vasoconstrictions by ACh in the umbilical vessels. Inhibiting large-conductance calcium-dependent potassium (BK) channels enhanced ACh-mediated contraction, whereas inhibiting voltage dependent potassium (K+), inward rectifier K+ and ATP-sensitive K+ channels had no effects. Incubation with specific K+ channel inhibitors showed that ACh suppressed BK currents rather than 4-aminopyridine-sensitive K+ channels currents. The results suggested that blood vessels in umbilical cords had special characteristics in response to cholinergic signals. ACh-stimulated umbilical vasoconstrictions were mediated via muscarinic receptor subtype 1/3-protein kinase C/cyclooxygenase-BK channel pathways.
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Affiliation(s)
- Zhoufeng Zhu
- Institute for Fetology, the First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Jiaqi Tang
- Institute for Fetology, the First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Xiuwen Zhou
- Institute for Fetology, the First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Sharon Xiang
- Institute for Fetology, the First Affiliated Hospital of Soochow University, Suzhou 215006, China; Center for Perinatal Biology, Loma Linda University, Loma Linda, CA, USA
| | - Xiaolin Zhu
- Institute for Fetology, the First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Na Li
- Institute for Fetology, the First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Ruixiu Shi
- Institute for Fetology, the First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Yuan Zhong
- Institute for Fetology, the First Affiliated Hospital of Soochow University, Suzhou 215006, China
| | - Lubo Zhang
- Center for Perinatal Biology, Loma Linda University, Loma Linda, CA, USA
| | - Miao Sun
- Institute for Fetology, the First Affiliated Hospital of Soochow University, Suzhou 215006, China.
| | - Zhice Xu
- Institute for Fetology, the First Affiliated Hospital of Soochow University, Suzhou 215006, China; Center for Perinatal Biology, Loma Linda University, Loma Linda, CA, USA.
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9
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Zhang Y, Ying J, Jiang D, Chang Z, Li H, Zhang G, Gong S, Jiang X, Tao J. Urotensin-II receptor stimulation of cardiac L-type Ca2+ channels requires the βγ subunits of Gi/o-protein and phosphatidylinositol 3-kinase-dependent protein kinase C β1 isoform. J Biol Chem 2015; 290:8644-55. [PMID: 25678708 DOI: 10.1074/jbc.m114.615021] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Recent studies have demonstrated that urotensin-II (U-II) plays important roles in cardiovascular actions including cardiac positive inotropic effects and increasing cardiac output. However, the mechanisms underlying these effects of U-II in cardiomyocytes still remain unknown. We show by electrophysiological studies that U-II dose-dependently potentiates L-type Ca(2+) currents (ICa,L) in adult rat ventricular myocytes. This effect was U-II receptor (U-IIR)-dependent and was associated with a depolarizing shift in the voltage dependence of inactivation. Intracellular application of guanosine-5'-O-(2-thiodiphosphate) and pertussis toxin pretreatment both abolished the stimulatory effects of U-II. Dialysis of cells with the QEHA peptide, but not scrambled peptide SKEE, blocked the U-II-induced response. The phosphatidylinositol 3-kinase (PI3K) inhibitor wortmannin as well as the class I PI3K antagonist CH132799 blocked the U-II-induced ICa,L response. Protein kinase C antagonists calphostin C and chelerythrine chloride as well as dialysis of cells with 1,2bis(2aminophenoxy)ethaneN,N,N',N'-tetraacetic acid abolished the U-II-induced responses, whereas PKCα inhibition or PKA blockade had no effect. Exposure of ventricular myocytes to U-II markedly increased membrane PKCβ1 expression, whereas inhibition of PKCβ1 pharmacologically or by shRNA targeting abolished the U-II-induced ICa,L response. Functionally, we observed a significant increase in the amplitude of sarcomere shortening induced by U-II; blockade of U-IIR as well as PKCβ inhibition abolished this effect, whereas Bay K8644 mimicked the U-II response. Taken together, our results indicate that U-II potentiates ICa,L through the βγ subunits of Gi/o-protein and downstream activation of the class I PI3K-dependent PKCβ1 isoform. This occurred via the activation of U-IIR and contributes to the positive inotropic effect on cardiomyocytes.
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Affiliation(s)
- Yuan Zhang
- From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China, Department of Geriatrics and Institute of Neuroscience, the Second Affiliated Hospital of Soochow University, Suzhou 215004, China
| | - Jiaoqian Ying
- From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China, Department of Emergency Medicine, China-Japan Friendship Hospital, Beijing 100029, China
| | - Dongsheng Jiang
- From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China, Department of Dermatology and Allergic Diseases, University of Ulm, Ulm 89081, Germany, and
| | - Zhigang Chang
- From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China
| | - Hua Li
- From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China, National Shanghai Center for New Drug Safety Evaluation and Research, Shanghai 201203, China
| | - Guoqiang Zhang
- Department of Emergency Medicine, China-Japan Friendship Hospital, Beijing 100029, China
| | - Shan Gong
- From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China
| | - Xinghong Jiang
- From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China
| | - Jin Tao
- From the Department of Physiology and Neurobiology, Medical College of Soochow University, Suzhou 215123, China,
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10
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Son I, Shin HJ, Ryu JH, Kim HK, Do SH, Zuo Z. Progesterone increases the activity of glutamate transporter type 3 expressed in Xenopus oocytes. Eur J Pharmacol 2013; 715:414-9. [PMID: 23602688 DOI: 10.1016/j.ejphar.2013.03.053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Revised: 03/25/2013] [Accepted: 03/28/2013] [Indexed: 11/15/2022]
Abstract
Progesterone is an important sex hormone for pregnancy and also has neuroprotective and anticonvulsant effects. It is well-known that full-term parturients become more susceptible to volatile anesthetics. Glutamate transporters are important for preventing neurotoxicity and anesthetic action in the central nervous system. We investigated the effects of progesterone on the activity of glutamate transporter type 3 (EAAT3), the major neuronal EAAT. EAAT3 was expressed in Xenopus laevis oocytes by injecting its mRNA. Oocytes were incubated with diluted progesterone for 72 h. Two-electrode voltage clamping was used to measure membrane currents before, during, and after applying 30 μML-glutamate. Progesterone (1-100 nM) significantly increased EAAT3 activity in a dose-dependent manner. Our kinetic study showed that the Vmax was increased in the progesterone group compared with that in the control group (2.7 ± 0.2 vs. 3.6 ± 0.2μC for control group vs. progesterone group; n=18-23; P<0.05), however, Km was unaltered (46.7 ± 10.2μM vs. 55.9 ± 10.5μM for control group vs. progesterone group; n=18-23; P>0.05). Phorbol-12-myristate-13-acetate, a protein kinase C (PKC) activator, did not change progesterone-enhanced EAAT3 activity. Inhibitors of PKC or phosphatidylinositol 3-kinase (PI3K) abolished the progesterone-induced increases in EAAT3 activity. Our results suggest that progesterone enhances EAAT3 activity and that PKC and PI3K are involved in mediating these effects. These effects of progesterone may contribute to its anticonvulsant and anesthesia-related properties.
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Affiliation(s)
- Ilsoon Son
- Department of Anesthesiology & Pain Medicine, Konkuk University School of Medicine, Seoul, South Korea
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11
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Gulia J, Navedo MF, Gui P, Chao JT, Mercado JL, Santana LF, Davis MJ. Regulation of L-type calcium channel sparklet activity by c-Src and PKC-α. Am J Physiol Cell Physiol 2013; 305:C568-77. [PMID: 23804206 DOI: 10.1152/ajpcell.00381.2011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The activity of persistent Ca²⁺ sparklets, which are characterized by longer and more frequent channel open events than low-activity sparklets, contributes substantially to steady-state Ca²⁺ entry under physiological conditions. Here, we addressed two questions related to the regulation of Ca²⁺ sparklets by PKC-α and c-Src, both of which increase whole cell Cav1.2 current: 1) Does c-Src activation enhance persistent Ca²⁺ sparklet activity? 2) Does PKC-α activate c-Src to produce persistent Ca²⁺ sparklets? With the use of total internal reflection fluorescence microscopy, Ca²⁺ sparklets were recorded from voltage-clamped tsA-201 cells coexpressing wild-type (WT) or mutant Cav1.2c (the neuronal isoform of Cav1.2) constructs ± active or inactive PKC-α/c-Src. Cells expressing Cav1.2c exhibited both low-activity and persistent Ca²⁺ sparklets. Persistent Ca²⁺ sparklet activity was significantly reduced by acute application of the c-Src inhibitor PP2 or coexpression of kinase-dead c-Src. Cav1.2c constructs mutated at one of two COOH-terminal residues (Y²¹²²F and Y²¹³⁹F) were used to test the effect of blocking putative phosphorylation sites for c-Src. Expression of Y²¹²²F but not Y²¹³⁹F Cav1.2c abrogated the potentiating effect of c-Src on Ca²⁺ sparklet activity. We could not detect a significant change in persistent Ca²⁺ sparklet activity or density in cells coexpressing Cav1.2c + PKC-α, regardless of whether WT or Y²¹²²F Cav1.2c was used, or after PP2 application, suggesting that PKC-α does not act upstream of c-Src to produce persistent Ca²⁺ sparklets. However, our results indicate that persistent Ca²⁺ sparklet activity is promoted by the action of c-Src on residue Y²¹²² of the Cav1.2c COOH terminus.
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Affiliation(s)
- Jyoti Gulia
- Department of Biological Engineering University of Missouri, Columbia, Missouri, USA
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Weiss S, Keren-Raifman T, Oz S, Ben Mocha A, Haase H, Dascal N. Modulation of distinct isoforms of L-type calcium channels by G(q)-coupled receptors in Xenopus oocytes: antagonistic effects of Gβγ and protein kinase C. Channels (Austin) 2012; 6:426-37. [PMID: 22990911 DOI: 10.4161/chan.22016] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
L-type voltage dependent Ca(2+) channels (L-VDCCs; Ca(v)1.2) are crucial in cardiovascular physiology. In heart and smooth muscle, hormones and transmitters operating via G(q) enhance L-VDCC currents via essential protein kinase C (PKC) involvement. Heterologous reconstitution studies in Xenopus oocytes suggested that PKC and G(q)-coupled receptors increased L-VDCC currents only in cardiac long N-terminus (NT) isoforms of α(1C), whereas known smooth muscle short-NT isoforms were inhibited by PKC and G(q) activators. We report a novel regulation of the long-NT α(1C) isoform by Gβγ. Gβγ inhibited whereas a Gβγ scavenger protein augmented the G(q)--but not phorbol ester-mediated enhancement of channel activity, suggesting that Gβγ acts upstream from PKC. In vitro binding experiments reveal binding of both Gβγ and PKC to α(1C)-NT. However, PKC modulation was not altered by mutations of multiple potential phosphorylation sites in the NT, and was attenuated by a mutation of C-terminally located serine S1928. The insertion of exon 9a in intracellular loop 1 rendered the short-NT α(1C) sensitive to PKC stimulation and to Gβγ scavenging. Our results suggest a complex antagonistic interplay between G(q)-activated PKC and Gβγ in regulation of L-VDCC, in which multiple cytosolic segments of α(1C) are involved.
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Affiliation(s)
- Sharon Weiss
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
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Wenzel D, Koch M, Matthey M, Heinemann JC, Fleischmann BK. Identification of a Novel Vasoconstrictor Peptide Specific for the Systemic Circulation. Hypertension 2012; 59:1256-62. [DOI: 10.1161/hypertensionaha.111.188367] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Daniela Wenzel
- From the Institute of Physiology I (D.W., M.M., J.C.H., B.K.F.), University of Bonn, Bonn, Germany; Institute for Oral and Musculo-skeletal Biology (M.K.), Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany
| | - Manuel Koch
- From the Institute of Physiology I (D.W., M.M., J.C.H., B.K.F.), University of Bonn, Bonn, Germany; Institute for Oral and Musculo-skeletal Biology (M.K.), Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany
| | - Michaela Matthey
- From the Institute of Physiology I (D.W., M.M., J.C.H., B.K.F.), University of Bonn, Bonn, Germany; Institute for Oral and Musculo-skeletal Biology (M.K.), Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany
| | - Jan C. Heinemann
- From the Institute of Physiology I (D.W., M.M., J.C.H., B.K.F.), University of Bonn, Bonn, Germany; Institute for Oral and Musculo-skeletal Biology (M.K.), Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany
| | - Bernd K. Fleischmann
- From the Institute of Physiology I (D.W., M.M., J.C.H., B.K.F.), University of Bonn, Bonn, Germany; Institute for Oral and Musculo-skeletal Biology (M.K.), Center for Biochemistry, Medical Faculty, University of Cologne, Cologne, Germany
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Matsumoto Y, Miyazato M, Yokoyama H, Kita M, Hirao Y, Chancellor MB, Yoshimura N. Role of M2 and M3 muscarinic acetylcholine receptor subtypes in activation of bladder afferent pathways in spinal cord injured rats. Urology 2012; 79:1184.e15-20. [PMID: 22386753 DOI: 10.1016/j.urology.2012.01.022] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Revised: 01/14/2012] [Accepted: 01/14/2012] [Indexed: 01/07/2023]
Abstract
OBJECTIVE To evaluate the role of M2 and M3 muscarinic acetylcholine receptor (mAChR) subtypes in the activation of bladder afferent pathways in rats with chronic spinal cord injury (SCI). METHODS Adult female Sprague-Dawley rats were spinalized at the T9 level. Continuous cystometry was performed under awake conditions 2 or 4 weeks after SCI. The effects of intravesical administration of an mAChR agonist (oxotremorine-methiodide), a nonselective antagonist (atropine), an M2-selective antagonist (methoctramine), and an M3-selective antagonist (darifenacin) were examined. After cystometry, the bladder was removed and separated into the mucosa and detrusor, and the M2 and M3 mAChR mRNA expression in the mucosa was determined using real-time quantitative polymerase chain reaction. RESULTS At 2 and 4 weeks after SCI, intravesical administration of a nonselective mAChR agonist (25 μM oxotremorine-methiodide) increased the area under the curve of nonvoiding contractions, although the intercontraction interval of voiding contractions and maximal voiding pressure did not change. This effect was blocked by atropine and methoctramine (10 μM) but not by darifenacin (50 μM). However, mAChR antagonists alone (10-50 μM) had no effect on cystometric parameters. M2 mAChR mRNA expression was increased in the mucosa of SCI rats compared with that in normal rats. CONCLUSION Our results suggest that the M2 mAChR subtype plays an important role in bladder afferent activation that enhances detrusor overactivity in SCI rats. However, because mAChR antagonists alone did not affect any cystometric parameters, the muscarinic mechanism controlling bladder afferent activity might not be involved in the emergence of detrusor overactivity in SCI.
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Affiliation(s)
- Yoshihiro Matsumoto
- Department of Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA
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15
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Chao JT, Gui P, Zamponi GW, Davis GE, Davis MJ. Spatial association of the Cav1.2 calcium channel with α5β1-integrin. Am J Physiol Cell Physiol 2010; 300:C477-89. [PMID: 21178109 DOI: 10.1152/ajpcell.00171.2010] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Engagement of α(5)β(1)-integrin by fibronectin (FN) acutely enhances Cav1.2 channel (Ca(L)) current in rat arteriolar smooth muscle and human embryonic kidney cells (HEK293-T) expressing Ca(L). Using coimmunoprecipitation strategies, we show that coassociation of Ca(L) with α(5)- or β(1)-integrin in HEK293-T cells is specific and depends on cell adhesion to FN. In rat arteriolar smooth muscle, coassociations between Ca(L) and α(5)β(1)-integrin and between Ca(L) and phosphorylated c-Src are also revealed and enhanced by FN treatment. Using site-directed mutagenesis of Ca(L) heterologously expressed in HEK293-T cells, we identified two regions of Ca(L) required for these interactions: 1) COOH-terminal residues Ser(1901) and Tyr(2122), known to be phosphorylated by protein kinase A (PKA) and c-Src, respectively; and 2) two proline-rich domains (PRDs) near the middle of the COOH terminus. Immunofluorescence confocal imaging revealed a moderate degree of wild-type Ca(L) colocalization with β(1)-integrin on the plasma membrane. Collectively, our results strongly suggest that 1) upon ligation by FN, Ca(L) associates with α(5)β(1)-integrin in a macromolecular complex including PKA, c-Src, and potentially other protein kinases; 2) phosphorylation of Ca(L) at Y(2122) and/or S(1901) is required for association of Ca(L) with α(5)β(1)-integrin; and 3) c-Src, via binding to PRDs that reside in the II-III linker region and/or the COOH terminus of Ca(L), mediates current potentiation following α(5)β(1)-integrin engagement. These findings provide new evidence for how interactions between α(5)β(1)-integrin and FN can modulate Ca(L) entry and consequently alter the physiological function of multiple types of excitable cells.
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Affiliation(s)
- Jun-Tzu Chao
- Dept. of Medical Pharmacology and Physiology, M451 Med. Sci. Bldg., Univ. of Missouri, Columbia, 1 Hospital Dr., Columbia, MO 65211, USA
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Wan X, Dennis AT, Obejero-Paz C, Overholt JL, Heredia-Moya J, Kirk KL, Ficker E. Oxidative inactivation of the lipid phosphatase phosphatase and tensin homolog on chromosome ten (PTEN) as a novel mechanism of acquired long QT syndrome. J Biol Chem 2010; 286:2843-52. [PMID: 21097842 DOI: 10.1074/jbc.m110.125526] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The most common cause of cardiac side effects of pharmaco-therapy is acquired long QT syndrome, which is characterized by abnormal cardiac repolarization and most often caused by direct blockade of the cardiac potassium channel human ether a-go-go-related gene (hERG). However, little is known about therapeutic compounds that target ion channels other than hERG. We have discovered that arsenic trioxide (As(2)O(3)), a very potent antineoplastic compound for the treatment of acute promyelocytic leukemia, is proarrhythmic via two separate mechanisms: a well characterized inhibition of hERG/I(Kr) trafficking and a poorly understood increase of cardiac calcium currents. We have analyzed the latter mechanism in the present study using biochemical and electrophysiological methods. We find that oxidative inactivation of the lipid phosphatase PTEN by As(2)O(3) enhances cardiac calcium currents in the therapeutic concentration range via a PI3Kα-dependent increase in phosphatidylinositol 3,4,5-triphosphate (PIP(3)) production. In guinea pig ventricular myocytes, even a modest reduction in PTEN activity is sufficient to increase cellular PIP(3) levels. Under control conditions, PIP(3) levels are kept low by PTEN and do not affect calcium current amplitudes. Based on pharmacological experiments and intracellular infusion of PIP(3), we propose that in guinea pig ventricular myocytes, PIP(3) regulates calcium currents independently of the protein kinase Akt along a pathway that includes a secondary oxidation-sensitive target. Overall, our report describes a novel form of acquired long QT syndrome where the target modified by As(2)O(3) is an intracellular signaling cascade.
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Affiliation(s)
- Xiaoping Wan
- Rammelkamp Center for Education and Research, MetroHealth Campus, Case Western Reserve University, Cleveland, Ohio 44109, USA
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Activation of neuromedin U type 1 receptor inhibits L-type Ca2+ channel currents via phosphatidylinositol 3-kinase-dependent protein kinase C epsilon pathway in mouse hippocampal neurons. Cell Signal 2010; 22:1660-8. [PMID: 20599609 DOI: 10.1016/j.cellsig.2010.06.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2010] [Revised: 06/10/2010] [Accepted: 06/21/2010] [Indexed: 11/24/2022]
Abstract
Neuromedin U (NMU) plays very important roles in the central nervous system. However, to date, any role of NMU in hippocampal neurons and the relevant mechanisms still remain unknown. In the present study, we report that NMU selectively inhibits L-type high-voltage-gated Ca(2+) channels (HVGCC) in mouse hippocampal neurons, in which NMU type 1 receptor (NMUR1), but not NMUR2, is endogenously expressed. In wild type mice, NMU (0.1 microM) reversibly inhibited HVGCC barium currents (I(Ba)) by approximately 28%, while in NMUR1(-/-) mice NMU had no significant effects. Intracellular infusion of GDP-beta-S or a selective antibody raised against the G(o)alpha, as well as pretreatment of the neurons with pertussis toxin, blocked the inhibitory effects of NMU, indicating the involvement of G(o)-protein. This NMUR1-mediated effect did not display the characteristics of a direct interaction between G-protein betagamma subunit (G(betagamma)) and L-type HVGCC, but was abolished by dialyzing cells with QEHA peptide or an antibody to the G(beta). The classical and novel protein kinase C (PKC) antagonist calphostin C, as well as phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002, abolished NMU responses, whereas the classical PKC antagonist Gö6976 had no such effects. Cells dialyzed with a PKC epsilon isoform (PKCepsilon) specific inhibitor peptide, GAVSLLPT, abolished NMU responses. In contrast, in cells dialyzed with an inactive PKCepsilon control scramble peptide, LSGTLPAV, no significant effects were observed. In summary, these results suggest that NMU inhibits L-type HVGCC via activation of NMUR1 and downstream G(betagamma), PI3K, and a novel PKCepsilon signaling pathway.
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Huster M, Frei E, Hofmann F, Wegener JW. A complex of Ca(V)1.2/PKC is involved in muscarinic signaling in smooth muscle. FASEB J 2010; 24:2651-9. [PMID: 20371628 DOI: 10.1096/fj.09-149856] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Here we present functional and biochemical evidence for a Ca(2+) channel (Ca(V)1.2)/protein kinase C (PKC) signaling complex being a key player in muscarinic regulation of urinary bladder smooth muscle. Muscarinic stimulation induced Ca(2+) signals and concomitant contractions in detrusor muscle from mice that were dependent on functional Ca(2+) channels. These signals were still present in muscles being depolarized by 85 mM extracellular K(+). Muscarinic-induced contractions were reduced by a PKC inhibitor [bisindolylmaleimide I (BIM-I)] and a phospholipase D (PLD) inhibitor (1-butanol). A phorbol ester (PDBu) enlarged muscarinic-induced Ca(2+) signals and contractions. The effects of BIM-I and PDBu were inhibited by isradipine and/or absent in muscles from Ca(V)1.2-deficient mice. Both carbachol and PDBu increased Ca(V)1.2 channel currents in isolated bladder myocytes. Blue native-PAGE electrophoresis revealed that Ca(V)1.2, PKC, and PLD are closely associated in muscles being previously stimulated by carbachol. Immunoprecipitation using anti-Ca(V)1.2 followed by Western blotting demonstrated that Ca(V)1.2 and PKC are coupled in stimulated muscles from wild-type mice. Autoradiography on immunoprecipitates showed that Ca(V)1.2 is a substrate for PKC-mediated phosphorylation. These findings suggest that a signaling complex consisting of Ca(V)1.2, PKC, and, probably, PLD controls muscarinic-mediated phasic contraction of urinary bladder smooth muscle.
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Affiliation(s)
- Maria Huster
- Institut für Pharmakologie und Toxikologie, TU München, Biedersteiner Str. 29, 80802 Munich, Germany
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Differential roles of M2 and M3 muscarinic receptor subtypes in modulation of bladder afferent activity in rats. Urology 2010; 75:862-7. [PMID: 20156651 DOI: 10.1016/j.urology.2009.12.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Revised: 12/06/2009] [Accepted: 12/15/2009] [Indexed: 11/23/2022]
Abstract
OBJECTIVES To investigate the effects of various muscarinic acetylcholine receptor (mAChR) antagonists, including selective M2 and M3 mAChR antagonists, on bladder overactivity. It has been proposed that the urothelium modulates the activity of bladder afferent pathways. However, the differential roles of mAChR subtypes in local bladder afferent activation remain unclear. METHODS Cystometry was performed in urethane-anesthetized female rats. We examined the effects of intravesical administration of antimuscarinic agents (nonselective mAChR antagonists: atropine sulfate, tolterodine tartrate, and propiverine hydrochloride; M2-selective antagonists: dimethindene maleate and methoctramine hemihydrate; M3-selective antagonists: darifenacin hydrobromide and 4-DAMP) on bladder overactivity induced by oxotremorine-M (oxo-M; nonselective mAChR agonist). RESULTS Intravesical administration of oxo-M (200 microM) elicited bladder overactivity as evidenced by decreased intercontraction interval, bladder capacity, and pressure threshold. These effects were blocked by intravesical administration of nonselective or M2-selective antagonists (30-60 microM), whereas M3-selective antagonists (150 microM) did not suppress the overactivity. When instilled intravesically by itself, none of the antimuscarinic agents (nonselective, M2-selective or M3-selective antagonists) affected any cystometric parameters. CONCLUSIONS The M2 mAChR subtype plays an important role in the local cholinergic modulation of bladder afferent activity that contributes to bladder overactivity in normal rats. Therefore, it is expected that antimuscarinic agents that have antagonistic activity against M2 mAChR can be more beneficial for the treatment of patients with overactive bladder if enhanced acetylcholine mechanisms are involved in pathogenesis of overactive bladder.
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Zhang HM, Chen SR, Cai YQ, Richardson TE, Driver LC, Lopez-Berestein G, Pan HL. Signaling mechanisms mediating muscarinic enhancement of GABAergic synaptic transmission in the spinal cord. Neuroscience 2008; 158:1577-88. [PMID: 19110040 DOI: 10.1016/j.neuroscience.2008.11.039] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2008] [Revised: 11/14/2008] [Accepted: 11/22/2008] [Indexed: 11/30/2022]
Abstract
Activation of muscarinic acetylcholine receptors (mAChRs) inhibits spinal nociceptive transmission by potentiation of GABAergic tone through M(2), M(3), and M(4) subtypes. To study the signaling mechanisms involved in this unique mAChR action, GABAergic spontaneous inhibitory postsynaptic currents (sIPSCs) of lamina II neurons were recorded using whole-cell patch clamp techniques in rat spinal cord slices. The mAChR agonist oxotremorine-M caused a profound increase in the frequency of GABAergic sIPSCs, which was abolished in the Ca(2+)-free solution. Inhibition of voltage-gated Ca(2+) channels with Cd(2+) and Ni(2+) largely reduced the effect of oxotremorine-M on sIPSCs. Blocking nonselective cation channels (NSCCs) with SKF96365 or 2-APB also largely attenuated the effect of oxotremorine-M. However, the KCNQ channel blocker XE991 and the adenylyl cyclase inhibitor MDL12330A had no significant effect on oxotremorine-M-induced increases in sIPSCs. Furthermore, the phosphoinositide-3-kinase (PI3K) inhibitor wortmannin or LY294002 significantly reduced the potentiating effect of oxotremorine-M on sIPSCs. In the spinal cord in which the M(3) subtype was specifically knocked down by intrathecal small interfering RNA (siRNA) treatment, SKF96365 and wortmannin still significantly attenuated the effect of oxotremorine-M. In contrast, SKF96365 and wortmannin both failed to alter the effect of oxotremorine-M on sIPSCs when the M(2)/M(4) mAChRs were blocked. Therefore, our study provides new evidence that activation of mAChRs increases synaptic GABA release through Ca(2+) influx and voltage-gated Ca(2+) channels. The PI3K-NSCC signaling cascade is primarily involved in the excitation of GABAergic interneurons by the M(2)/M(4) mAChRs in the spinal dorsal horn.
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Affiliation(s)
- H-M Zhang
- Department of Anesthesiology and Pain Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
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Fritz N, Dabertrand F, Mironneau J, Macrez N, Morel JL. Acetylcholine evokes an InsP3R1-dependent transient Ca2+ signal in rat duodenum myocytes. Can J Physiol Pharmacol 2008; 86:626-32. [PMID: 18758512 DOI: 10.1139/y08-067] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
In smooth muscle myocytes, agonist-activated release of calcium ions (Ca2+) stored in the sarcoplasmic reticulum (SR) occurs via different but overlapping transduction pathways. Hence, to fully study how SR Ca2+ channels are activated, the simultaneous activation of different Ca2+ signals should be separated. In rat duodenum myocytes, we have previously characterized that acetylcholine (ACh) induces Ca2+ oscillations by binding to its M2 muscarinic receptor and activating the ryanodine receptor subtype 2. Here, we show that ACh simultaneously evokes a Ca2+ signal dependent on activation of inositol 1,4,5-trisphosphate (InsP3) receptor subtype 1. A pharmacologic approach, the use of antisense oligonucleotides directed against InsP3R1, and the expression of a specific biosensor derived from green-fluorescent protein coupled to the pleckstrin homology domain of phospholipase C, suggested that the InsP3R1-dependent Ca2+ signal is transient and due to a transient synthesis of InsP3 via M3 muscarinic receptor. Moreover, we suggest that both M2 and M3 signalling pathways are modulating phosphatidylinositol 4,5-bisphosphate and InsP3 concentration, thus describing closely interacting pathways activated by ACh in duodenum myocytes.
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Affiliation(s)
- Nicolas Fritz
- Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
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22
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Liu Y, Chen X. Cholinergic excitation of dopaminergic cells depends on sequential activation of protein kinase C and the L-type calcium channel in ventral tegmental area slices. Brain Res 2008; 1245:41-51. [PMID: 18929546 DOI: 10.1016/j.brainres.2008.09.062] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Accepted: 09/22/2008] [Indexed: 10/21/2022]
Abstract
Dopaminergic projections from the ventral tegmental area (VTA) constitute the mesolimbocortical system that underlies addiction and psychosis primarily as the result of increased dopaminergic transmission. Dopaminergic neurons in the VTA receive glutamatergic and cholinergic innervations that regulate their firing activities. Both transmitter systems can activate protein kinase C (PKC) by increasing intracellular calcium and lipid second messengers, however, whether PKC mediates increased firing following glutamatergic and cholinergic activation remains unknown. This paper examined the effects of acute PKC inhibition on firing responses to carbachol, NMDA or AMPA using patch clamp recordings from brain slices. The three ligands all induced a reversible increase in firing, however, only carbachol-induced increase in firing was attenuated by the PKC inhibitors chelerythrine or GF 109203X. The L-type calcium channel blocker nifedipine partially blocked carbachol-induced excitation similar to PKC inhibitors. PKC inhibition and L-type channel blockade did not significantly alter NMDA- or AMPA-induced excitation. Concurrent blockade of PKC and L-type channels with chelerythrine and nifedipine did not additively suppress carbachol-induced excitation indicating they were sequential events in the same signaling pathway. Furthermore, preincubation with the PKC inhibitor GF 109203X reduced the carbachol-induced increase in nifedipine-sensitive high-voltage gated calcium currents. These results indicate that cholinergic activation enhances PKC activity, which in turn facilitates L-type channel opening to excite dopaminergic cells, a finding that is in line with reports of increased PKC in the VTA in animals displaying addictive behavior.
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Affiliation(s)
- Yudan Liu
- Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada A1B3V6
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Salgado H, Bellay T, Nichols JA, Bose M, Martinolich L, Perrotti L, Atzori M. Muscarinic M2 and M1 receptors reduce GABA release by Ca2+ channel modulation through activation of PI3K/Ca2+ -independent and PLC/Ca2+ -dependent PKC. J Neurophysiol 2007; 98:952-65. [PMID: 17581851 DOI: 10.1152/jn.00060.2007] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We measured pharmacologically isolated GABAergic currents from layer II/III neurons of the rat auditory cortex using patch-clamp recording. Activation of muscarinic receptors by muscarine (1 microM) or oxotremorine (10 microM) decreased the amplitude of electrically evoked inhibitory postsynaptic currents to about one third of their control value. Neither miniature nor exogenously evoked GABAergic currents were altered by the presence of muscarinic agonists, indicating that the effect was spike-dependent and not mediated postsynaptically. The presence of the N- or P/Q-type Ca(2+) channel blockers omega-conotoxin GVIA (1 microM) or omega-AgaTx TK (200 nM) greatly blocked the muscarinic effect, suggesting that Ca(2+)-channels were target of the muscarinic modulation. The presence of the muscarinic M(2) receptor (M(2)R) antagonists methoctramine (5 muM) or AF-DX 116 (1 microM) blocked most of the muscarinic evoked inhibitory postsynaptic current (eIPSC) reduction, indicating that M(2)Rs were responsible for the effect, whereas the remaining component of the depression displayed M(1)R-like sensitivity. Tissue preincubation with the specific blockers of phosphatidyl-inositol-3-kinase (PI(3)K) wortmannin (200 nM), LY294002 (1 microM), or with the Ca(2+)-dependent PKC inhibitor Gö 6976 (200 nM) greatly impaired the muscarinic decrease of the eIPSC amplitude, whereas the remaining component was sensitive to preincubation in the phospholipase C blocker U73122 (10 microM). We conclude that acetylcholine release enhances the excitability of the auditory cortex by decreasing the release of GABA by inhibiting axonal V-dependent Ca(2+) channels, mostly through activation of presynaptic M(2)Rs/PI(3)K/Ca(2+)-independent PKC pathway and-to a smaller extent-by the activation of M(1)/PLC/Ca(2+)-dependent PKC.
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Affiliation(s)
- H Salgado
- Laboratory of Synaptic and Cell Physiology, School of Behavioral and Brain Sciences, The University of Texas at Dallas, Richardson Texas 75080, USA
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Cobine CA, Callaghan BP, Keef KD. Role of L-type calcium channels and PKC in active tone development in rabbit coronary artery. Am J Physiol Heart Circ Physiol 2007; 292:H3079-88. [PMID: 17277031 DOI: 10.1152/ajpheart.01261.2006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The present study investigated active tone development in isolated ring segments of rabbit epicardial coronary artery. Endothelium-denuded (E-) or endothelium-intact (E+) vessels treated with the NO synthase inhibitor N(omega)-nitro-L-arginine (100 microM) developed active tone, which was enhanced by stretch and reversed by the NO donor sodium nitroprusside (SNP; IC(50)=9 nM). Nifedipine abolished active tone and the contractile response to phorbol dibutyrate (PDBu; 10 nM) with the same potency (IC(50)=8 nM), whereas 300 nM PDBu responses were only partially blocked by nifedipine. The classical and novel PKC inhibitors GF-109203X (IC(50)=1-2 microM) and chelerythrine (IC(50)=4-5 microM) and the classical PKC inhibitor Gö-6976 (IC(50)=0.3-0.4 microM) blocked both active tone and 10 nM PDBu responses with similar potency. Active tone development was associated with depolarization of membrane potential (E(m)) and a shift to the left of the E(m)-vs.-contraction relationship determined by varying extracellular potassium. The depolarization and leftward shift were reversed by either chelerythrine (10 microM) or SNP (30 nM). PDBu (100-300 nM) increased peak L-type calcium channel (Ca(v)) currents in isolated coronary myocytes, and this effect was reversed by chelerythrine (1 microM) or Gö-6976 (200 nM). SNP (500 nM) reduced Ca(v) currents only in the presence of the PKA blocker 8-bromo-2'-O-monobutyryl-cAMPS, Rp isomer (10 microM). In conclusion, active tone development in coronary artery is suppressed by basal NO release and is dependent on both enhanced Ca(v) activity and classical PKC activity. Both E(m)-dependent and -independent processes contribute to contraction. Our results suggest that one E(m)-independent process is direct enhancement of Ca(v) current by PKC.
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Affiliation(s)
- Caroline A Cobine
- Department of Physiology and Cell Biology, University of Nevada, Reno, Anderson Medical Science Bldg. MS 352, Reno, Nevada 89557, USA
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25
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Wellman GC. Ion channels and calcium signaling in cerebral arteries following subarachnoid hemorrhage. Neurol Res 2007; 28:690-702. [PMID: 17164032 DOI: 10.1179/016164106x151972] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Entry of Ca(2+) through voltage-dependent calcium channels (VDCCs) is critical to the regulation of intracellular free calcium concentration ([Ca(2+)](i)) in vascular smooth muscle and thus the control of cerebral artery diameter. Increased VDCC activity in cerebral artery myocytes may contribute to decreased cerebral blood flow and the accompanying neurological deficits associated with subarachnoid hemorrhage (SAH). This review will focus on the impact of SAH on VDCCs and K(+)-selective ion channels, two important classes of ion channels located in the plasma membrane of cerebral artery myocytes. SAH may act through a variety of direct and indirect mechanisms to increase the activity of VDCCs promoting cerebral artery constriction and reduced cerebral blood flow. Further, SAH may lead to suppression of K(+) channel activity to cause membrane potential depolarization to enhance VDCC activity. The ability of VDCC blockers or K(+) channel activators to alleviate SAH-induced vasospasm will also be examined.
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Affiliation(s)
- George C Wellman
- Department of Pharmacology, University of Vermont College of Medicine, Burlington, VT 05405-0068, USA.
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26
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Levi R, Seyedi N, Schaefer U, Estephan R, Mackins CJ, Tyler E, Silver RB. Histamine H3-receptor signaling in cardiac sympathetic nerves: Identification of a novel MAPK-PLA2-COX-PGE2-EP3R pathway. Biochem Pharmacol 2007; 73:1146-56. [PMID: 17266940 PMCID: PMC1893009 DOI: 10.1016/j.bcp.2007.01.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Revised: 12/12/2006] [Accepted: 01/03/2007] [Indexed: 01/08/2023]
Abstract
We hypothesized that the histamine H(3)-receptor (H(3)R)-mediated attenuation of norepinephrine (NE) exocytosis from cardiac sympathetic nerves results not only from a Galpha(i)-mediated inhibition of the adenylyl cyclase-cAMP-PKA pathway, but also from a Gbetagamma(i)-mediated activation of the MAPK-PLA(2) cascade, culminating in the formation of an arachidonate metabolite with anti-exocytotic characteristics (e.g., PGE(2)). We report that in Langendorff-perfused guinea-pig hearts and isolated sympathetic nerve endings (cardiac synaptosomes), H(3)R-mediated attenuation of K(+)-induced NE exocytosis was prevented by MAPK and PLA(2) inhibitors, and by cyclooxygenase and EP(3)-receptor (EP(3)R) antagonists. Moreover, H(3)R activation resulted in MAPK phosphorylation in H(3)R-transfected SH-SY5Y neuroblastoma cells, and in PLA(2) activation and PGE(2) production in cardiac synaptosomes; H(3)R-induced MAPK phosphorylation was prevented by an anti-betagamma peptide. Synergism between H(3)R and EP(3)R agonists (i.e., imetit and sulprostone, respectively) suggested that PGE(2) may be a downstream effector of the anti-exocytotic effect of H(3)R activation. Furthermore, the anti-exocytotic effect of imetit and sulprostone was potentiated by the N-type Ca(2+)-channel antagonist omega-conotoxin GVIA, and prevented by an anti-Gbetagamma peptide. Our findings imply that an EP(3)R Gbetagamma(i)-induced decrease in Ca(2+) influx through N-type Ca(2+)-channels is involved in the PGE(2)/EP(3)R-mediated attenuation of NE exocytosis elicited by H(3)R activation. Conceivably, activation of the Gbetagamma(i) subunit of H(3)R and EP(3)R may also inhibit Ca(2+) entry directly, independent of MAPK intervention. As heart failure, myocardial ischemia and arrhythmic dysfunction are associated with excessive local NE release, attenuation of NE release by H(3)R activation is cardioprotective. Accordingly, this novel H(3)R signaling pathway may ultimately bear therapeutic significance in hyper-adrenergic states.
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Affiliation(s)
- Roberto Levi
- Department of Pharmacology, Weill Medical College of Cornell University, New York, NY 10021, USA.
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27
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Callaghan B, Zhong J, Keef KD. Signaling pathway underlying stimulation of L-type Ca2+ channels in rabbit portal vein myocytes by recombinant Gbetagamma subunits. Am J Physiol Heart Circ Physiol 2006; 291:H2541-6. [PMID: 16877561 DOI: 10.1152/ajpheart.00420.2006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In previous studies, we (Callaghan B, Koh SD, and Keef KD, Circ Res 94: 626-633, 2004) have shown that voltage-dependent L-type Ca(2+) channels (Cav) in portal vein myocytes are enhanced when muscarinic M2 receptors are activated with ACh. Current stimulation was coupled to the G protein subunit Gbetagamma along with the downstream mediators phosphatidylinositol-3-kinase (PI3K), protein kinase C (PKC), and c-Src. The present study was designed to determine whether the same second messenger pathway could be identified when exogenous recombinant Gbetagamma subunits are introduced into cells. Smooth muscle myocytes were freshly isolated from rabbit portal vein, and Cav currents were recorded by using the patch-clamp technique. Dialysis of cells with recombinant Gbetagamma (50 nM) significantly increased Cav currents (141%). Nifedipine (1 microM) reduced both control and stimulated currents by approximately 90%. The enhancement of current by Gbetagamma was equivalent to that produced by ACh (142%), whereas the PKC activator phorbol 12,13-dibutyrate (PdBu) gave rise to greater current stimulation (192%). Current stimulation with Gbetagamma, ACh, and PdBu were not associated with changes in the voltage dependence of activation or inactivation. The PI3K inhibitor LY-294002 (20 microM) reduced peak currents by 32% in cells dialyzed with Gbetagamma, whereas the inactive analog LY-303511 resulted in a small but significant reduction in current (12%). The c-Src inhibitor PP2 (1 microM) also significantly reduced currents (34%), whereas the inactive analog PP3 was without effect. These data provide further evidence for the hypothesis that Gbetagamma leads to stimulation of Cav currents in rabbit portal vein myocytes via a signaling pathway that includes PI3K, PKC, and c-Src.
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Affiliation(s)
- Brid Callaghan
- Dept. of Physiology and Cell Biology, Univ. of Nevada, School of Medicine, Reno, NV 89573, USA
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Gui P, Wu X, Ling S, Stotz SC, Winkfein RJ, Wilson E, Davis GE, Braun AP, Zamponi GW, Davis MJ. Integrin Receptor Activation Triggers Converging Regulation of Cav1.2 Calcium Channels by c-Src and Protein Kinase A Pathways. J Biol Chem 2006; 281:14015-25. [PMID: 16554304 DOI: 10.1074/jbc.m600433200] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
L-type, voltage-gated Ca2+ channels (CaL) play critical roles in brain and muscle cell excitability. Here we show that currents through heterologously expressed neuronal and smooth muscle CaL channel isoforms are acutely potentiated following alpha5beta1 integrin activation. Only the alpha1C pore-forming channel subunit is critical for this process. Truncation and site-directed mutagenesis strategies reveal that regulation of Cav1.2 by alpha5beta1 integrin requires phosphorylation of alpha1C C-terminal residues Ser1901 and Tyr2122. These sites are known to be phosphorylated by protein kinase A (PKA) and c-Src, respectively, and are conserved between rat neuronal (Cav1.2c) and smooth muscle (Cav1.2b) isoforms. Kinase assays are consistent with phosphorylation of these two residues by PKA and c-Src. Following alpha5beta1 integrin activation, native CaL channels in rat arteriolar smooth muscle exhibit potentiation that is completely blocked by combined PKA and Src inhibition. Our results demonstrate that integrin-ECM interactions are a common mechanism for the acute regulation of CaL channels in brain and muscle. These findings are consistent with the growing recognition of the importance of integrin-channel interactions in cellular responses to injury and the acute control of synaptic and blood vessel function.
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Affiliation(s)
- Peichun Gui
- Department of Medical Pharmacology & Physiology, University of Missouri School of Medicine, Columbia, Missouri 65212, USA
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Stirnweiss J, Valkova C, Ziesché E, Drube S, Liebmann C. Muscarinic M2 receptors mediate transactivation of EGF receptor through Fyn kinase and without matrix metalloproteases. Cell Signal 2005; 18:1338-49. [PMID: 16337776 DOI: 10.1016/j.cellsig.2005.10.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Accepted: 10/25/2005] [Indexed: 12/11/2022]
Abstract
Transactivation of epidermal growth factor receptor (EGFR) by G protein-coupled receptors (GPCRs) has been attributed to the activation of matrix metalloproteases (MMPs) and the release of EGF family ligands such as HB-EGF. This mode of transactivation leads to signalling downstream of EGFR which is indistinguishable from that induced by the ligand. Here we provide evidence that in the COS-7 cell model EGFR transactivation via the muscarinic M2 receptor (M2R) is independent of MMPs and results in an incomplete EGFR signalling including ERK and Akt but not PLCgamma1. Using dominant-negative mutants of c-Src and Fyn and Src-deficient SYF cells as well as by co-immunoprecipitation studies, we can demonstrate that the M2R-mediated transactivation of EGFR specifically involves Fyn but not c-Src or Yes. This specific role of Fyn can be verified in SH-SY5Y human neuroblastoma cells with endogenously expressed M2 receptors.
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Affiliation(s)
- Jörg Stirnweiss
- Institute of Biochemistry and Biophysics, Biological and Pharmaceutical Faculty, Friedrich-Schiller-University, Philosophenweg 12, D-07743 Jena, Germany
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30
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Yamboliev IA, Mutafova-Yambolieva VN. PI3K and PKC contribute to membrane depolarization mediated by alpha2-adrenoceptors in the canine isolated mesenteric vein. BMC PHYSIOLOGY 2005; 5:9. [PMID: 15958164 PMCID: PMC1183225 DOI: 10.1186/1472-6793-5-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/09/2004] [Accepted: 06/15/2005] [Indexed: 11/10/2022]
Abstract
BACKGROUND Norepinephrine (NE), a classic neurotransmitter in the sympathetic nervous system, induces vasoconstriction of canine isolated mesenteric vein that is accompanied by a sustained membrane depolarization. The mechanisms underlying the NE-elicited membrane depolarization remain undefined. In the present study we hypothesized that phosphatidylinositol 3-kinase (PI3K) and protein kinase C (PKC) are involved in the electrical field stimulation (EFS)-induced slow membrane depolarization (SMD) in canine isolated mesenteric vein. EFS (0.1-2 Hz, 0.1 ms, 15V, 10 s)-induced changes in the membrane potential were recorded with a conventional intracellular microelectrode technique and evaluated in the absence and presence of inhibitors of neuronal activity, alpha-adrenoceptors, membrane ion channels, PI3K, inositol 1,4,5-triphosphate (InsP3) receptors, and PKC. Activation of PI3Kgamma and PKCzeta in response to exogenous NE and clonidine in the absence and presence of receptor and kinase inhibitors were also determined. RESULTS Contractile responses to NE and clonidine (0.05 - 10 microM) were significantly diminished in the presence of yohimbine (0.1 microM). Exogenous NE (0.1 microM) and clonidine (1 microM) elicited SMD. The resting membrane potential of canine mesenteric vein smooth muscle cells was -68.8 +/- 0.8 mV. EFS elicited a biphasic depolarization comprised of excitatory junction potentials and SMD that are purinergic and adrenergic in nature, respectively. The magnitude of the SMD in response to EFS at 0.5 Hz was 9.4 +/- 0.7 mV. This response was reduced by 65-98% by the fast Na+ channel inhibitor tetrodotoxin (1 microM), by the inhibitor of N-type Ca2+ channels omega-conotoxin GVIA (5 nM), the non-selective alpha-adrenoceptor blocker phentolamine (1 microM), the selective alpha2-adrenoceptor blocker yohimbine (0.1 microM), the ion channel inhibitors niflumic acid (NFA, 100 microM), 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB, 30 microM), 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS, 200 microM), and Gd3+ (30 microM), and the PI3K inhibitors wortmannin (100 nM) and LY-294002 (10 microM). The SMD remained unchanged in the presence of the L-type Ca2+ channel blocker nicardipine (1 microM) and the InsP3 receptor blockers 2-aminoethoxydiphenylborate (2APB, 50 microM) and xestospongin C (3 microM). The inhibitor of PKC chelerythrine (1 microM), but not calphostin C (10 microM), diminished the SMD. Exogenous NE and clonidine (1 microM each) activated both PI3Kgamma and PKCzeta, and the activation of these kinases was abolished by preincubation of tissue with the alpha2-adrenoceptor blocker yohimbine. CONCLUSION Neuronally-released NE stimulates smooth muscle alpha2-adrenoceptors and activates PI3K and atypical PKC in the canine mesenteric vein. Events downstream of PKC lead to SMD and vasoconstriction. This represents a novel pathway for NE-induced membrane depolarization in a vascular smooth muscle preparation.
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Affiliation(s)
- Ilia A Yamboliev
- Department of Pharmacology and Center of Biomedical Research Excellence, University of Nevada School of Medicine, Reno, Nevada 89557, USA
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Gerthoffer WT. Signal-transduction pathways that regulate visceral smooth muscle function. III. Coupling of muscarinic receptors to signaling kinases and effector proteins in gastrointestinal smooth muscles. Am J Physiol Gastrointest Liver Physiol 2005; 288:G849-53. [PMID: 15826932 DOI: 10.1152/ajpgi.00530.2004] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Stimulation of muscarinic M3 and M2 receptors on gastrointestinal smooth muscle elicits contraction via activation of G proteins that are coupled to a diverse set of downstream signaling pathways and effector proteins. Many studies suggest a canonical excitation-contraction coupling pathway that includes activation of phospholipases, production of inositol 1,4,5-trisphosphate and diacylglycerol, release of calcium from the sarcoplasmic reticulum, activation of L-type calcium channels, and activation of nonselective cation channels. These events lead to elevated intracellular calcium concentration, which activates myosin light chain kinase to phosphorylate and activate myosin II thus causing contraction. In addition, muscarinic receptors are coupled to signaling pathways that modulate the effect of activator calcium. The Rho/Rho kinase pathway inhibits myosin light chain phosphatase, one of the key steps in sensitization of the contractile proteins to calcium. Phosphatidylinositol 3-kinases and Src family tyrosine kinases are also activated by muscarinic agonists. Src family tyrosine kinases regulate L-type calcium and nonselective cation channels. Src activation also leads to activation of ERK and p38 MAPKs. ERK MAPKs phosphorylate caldesmon, an actin filament binding protein. P38 MAPKs activate phospholipases and MAPKAP kinase 2/3, which phosphorylate HSP27. HSP27 may regulate cross-bridge function, actin filament formation, and actin filament attachment to the cell membrane. In addition to the well-known role of M3 muscarinic receptors to regulate myoplasmic calcium levels, the integrated effect of muscarinic activation probably also includes signaling pathways that modulate phospholipases, cyclic nucleotides, contractile protein function, and cytoskeletal protein function.
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Affiliation(s)
- William T Gerthoffer
- University of Nevada School of Medicine, Department of Pharmacology, Reno, Nevada 89557-0270, USA.
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Akbarali HI. Signal-transduction pathways that regulate smooth muscle function. II. Receptor-ion channel coupling mechanisms in gastrointestinal smooth muscle. Am J Physiol Gastrointest Liver Physiol 2005; 288:G598-602. [PMID: 15764809 DOI: 10.1152/ajpgi.00402.2004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Regulation of membrane ion channels by second messengers is an important mechanism by which gastrointestinal smooth muscle excitability is controlled. Receptor-mediated phosphorylation of Ca(2+) channels has been known for some time; however, recent findings indicate that these channels may also modulate intracellular signaling. The plasmalemma ion channels may also function as a point of convergence between different receptor types. In this review, the molecular mechanisms that link channel function and signal transduction are discussed. Emerging evidence also indicates altered second-messenger modulation of the Ca(2+) channel in the pathophysiology of smooth muscle dysmotility.
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Affiliation(s)
- Hamid I Akbarali
- Dept. of Physiology, Univ. of Oklahoma Health Sciences Center, 940 Stanton L. Young Blvd., Oklahoma City, OK 73104, USA.
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Welling A, Hofmann F, Wegener JW. Inhibition of L-Type Cav1.2 Ca2+Channels by 2,(4-Morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002) and 2-[1-(3-Dimethyl-aminopropyl)-5-methoxyindol-3-yl]-3-(1H-indol-3-yl) Maleimide (Gö6983). Mol Pharmacol 2004; 67:541-4. [PMID: 15537868 DOI: 10.1124/mol.104.006049] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Phosphatidylinositol 3-kinase (PI3-K) is involved in physiological processes of cellular proliferation and inflammation and, as postulated recently, in the regulation of L-type Ca(2+) channels. The latter conclusion arose in part from the inhibitory action of the compound 2,(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), which has been established as a selective PI3-K inhibitor (IC(50) = 1.4 microM). Herein we show, however, that LY294002 and an inhibitor of protein kinase C (PKC), 2-[1-(3-dimethylaminopropyl)-5-methoxyindol-3-yl]-3-(1H-indol-3-yl) maleimide (Go6983), act as direct Ca(2+)-channel inhibitors, with IC(50) values of approximately 20 and 10 microM, respectively. Because both drugs are commonly used at concentrations of approximately 10 microM or higher, the interpretation of such experiments is questionable with respect to a regulatory action of PI3-K or PKC on L-type Ca(2+) channels.
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Affiliation(s)
- A Welling
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Biedersteiner Str. 29, 80802 München, Germany
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Le Blanc C, Mironneau C, Barbot C, Henaff M, Bondeva T, Wetzker R, Macrez N. Regulation of Vascular L-type Ca2+Channels by Phosphatidylinositol 3,4,5-Trisphosphate. Circ Res 2004; 95:300-7. [PMID: 15242973 DOI: 10.1161/01.res.0000138017.76125.8b] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Modulation of voltage-gated L-type Ca2+ channels by phosphoinositide 3-kinase (PI3K) regulates Ca2+ entry and plays a crucial role in vascular excitation-contraction coupling. Angiotensin II (Ang II) activates Ca2+ entry by stimulating L-type Ca2+ channels through Gbeta-sensitive PI3K in portal vein myocytes. Moreover, PI3K and Ca2+ entry activation have been reported to be necessary for receptor tyrosine kinase-coupled and G protein-coupled receptor-induced DNA synthesis in vascular cells. We have previously shown that tyrosine kinase-regulated class Ia and G protein-regulated class Ib PI3Ks are able to modulate vascular L-type Ca2+ channels. PI3Ks display 2 enzymatic activities: a lipid-kinase activity leading to the formation of phosphatidylinositol 3,4,5-trisphosphate [PI(3,4,5)P3 or PIP3] and a serine-kinase activity. Here we show that exogenous PIP3 applied into the cell through the patch pipette is able to reproduce the Ca2+ channel-stimulating effect of Ang II and PI3Ks. Moreover, the Ang II-induced PI3K-mediated stimulation of Ca2+ channel and the resulting increase in cytosolic Ca2+ concentration are blocked by the anti-PIP3 antibody. Mutants of PI3K transfected into vascular myocytes also revealed the essential role of the lipid-kinase activity of PI3K in Ang II-induced Ca2+ responses. These results suggest that PIP3 is necessary and sufficient to activate a Ca2+ influx in vascular myocytes stimulated by Ang II.
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MESH Headings
- Androstadienes/pharmacology
- Angiotensin II/pharmacology
- Animals
- Barium/metabolism
- Calcium/metabolism
- Calcium Channels, L-Type/drug effects
- Calcium Channels, L-Type/physiology
- Calmodulin-Binding Proteins/pharmacology
- Cells, Cultured/drug effects
- Cells, Cultured/physiology
- Class Ib Phosphatidylinositol 3-Kinase
- Cytosol/metabolism
- Dihydropyridines/pharmacology
- Enzyme Inhibitors/pharmacology
- Ion Channel Gating/drug effects
- Ion Transport/drug effects
- Isoenzymes/antagonists & inhibitors
- Isoenzymes/genetics
- Isoenzymes/physiology
- Lipid Metabolism
- Membrane Potentials/drug effects
- Muscle, Smooth, Vascular/cytology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/physiology
- Nerve Tissue Proteins/pharmacology
- Neurogranin
- Patch-Clamp Techniques
- Phosphatidylinositol 3-Kinases/genetics
- Phosphatidylinositol 3-Kinases/physiology
- Phosphatidylinositol Phosphates/antagonists & inhibitors
- Phosphatidylinositol Phosphates/pharmacology
- Phosphatidylinositol Phosphates/physiology
- Phosphoinositide-3 Kinase Inhibitors
- Phosphorylation/drug effects
- Portal Vein
- Protein Processing, Post-Translational/drug effects
- Rats
- Rats, Wistar
- Recombinant Fusion Proteins/physiology
- Substrate Specificity
- Transfection
- Wortmannin
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Affiliation(s)
- Catherine Le Blanc
- Laboratoire de Signalisation et Interactions Cellulaires, Université de Bordeaux II, Bordeaux, France
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35
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Wegener JW, Schulla V, Lee TS, Koller A, Feil S, Feil R, Kleppisch T, Klugbauer N, Moosmang S, Welling A, Hofmann F. An essential role of Cav1.2 L-type calcium channel for urinary bladder function. FASEB J 2004; 18:1159-61. [PMID: 15132976 DOI: 10.1096/fj.04-1516fje] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Mice deficient in the smooth muscle Cav1.2 calcium channel (SMACKO, smooth muscle alpha1c-subunit calcium channel knockout) have a severely reduced micturition and an increased bladder mass. L-type calcium current, protein, and spontaneous contractile activity were absent in the bladder of SMACKO mice. K+ and carbachol (CCh)-induced contractions were reduced to 10-fold in detrusor muscles from SMACKO mice. The dihydropyridine isradipine inhibited K+- and CCh-induced contractions of muscles from CTR but had no effect in muscles from SMACKO mice. CCh-induced contraction was blocked by removing extracellular Ca2+ but was unaffected by the PLC inhibitor U73122 or depletion of intracellular Ca2+ stores by thapsigargin. In muscles from CTR and SMACKO mice, CCh-induced contraction was partially inhibited by the Rho-kinase inhibitor Y27632. These results show that the Cav1.2 Ca2+ channel is essential for normal bladder function. The Rho-kinase and Ca2+-release pathways cannot compensate the lack of the L-type Ca2+ channel.
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Affiliation(s)
- Jörg W Wegener
- Institut für Pharmakologie und Toxikologie, Technische Universität München, Biedersteiner Str. 29, D-80802 München, Germany.
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