Lack of muscarinic regulation of Ca2+ channels in Gi2α gene knockout mouse hearts

2001 ◽  
Vol 280 (5) ◽  
pp. H1989-H1995 ◽  
Author(s):  
Fuhua Chen ◽  
Karsten Spicher ◽  
Meisheng Jiang ◽  
Lutz Birnbaumer ◽  
Glenn T. Wetzel
Keyword(s):  
Knockout Mouse ◽  
Ventricular Myocytes ◽  
Gene Knockout ◽  
Cell Voltage ◽  
Mouse Heart ◽  
Signaling Proteins ◽  
Muscarinic Agonist ◽  
Gene Knockout Mouse ◽  
G Protein Coupled

The purpose of the present study was to examine the role of Gi2α in Ca2+ channel regulation using Gi2α gene knockout mouse ventricular myocytes. The whole cell voltage-clamp technique was used to study the effects of the muscarinic agonist carbachol (CCh) and the β-adrenergic agonist isoproterenol (Iso) on cardiac L-type Ca2+ currents in both 129Sv wild-type (WT) and Gi2α gene knockout (Gi2α−/−) mice. Perfusion with CCh significantly inhibited the Ca2+ current in WT cells, and this effect was reversed by adding atropine to the CCh-containing solution. In contrast, CCh did not affect Ca2+ currents in Gi2α−/− ventricular myocytes. Addition of CCh to Iso-containing solutions attenuated the Iso-stimulated Ca2+ current in WT cardiomyocytes but not in Gi2α−/− cells. These findings demonstrate that, whereas the Iso-Gsα signal pathway is intact in Gi2α gene knockout mouse hearts, these cells lack the inhibitory regulation of Ca2+ channels by CCh. Therefore, Gi2α is necessary for the muscarinic regulation of Ca2+ channels in the mouse heart. Further studies are needed to delineate the possible interaction of Gi and other cell signaling proteins and to clarify the level of interaction of G protein-coupled regulation of L-type Ca2+ current in the heart.

Cholesterol depletion modulates basal L-type Ca2+ current and abolishes its β-adrenergic enhancement in ventricular myocytes

2008 ◽  
Vol 294 (1) ◽  
pp. H285-H292 ◽  
Author(s):  
Hiroto Tsujikawa ◽  
Yumei Song ◽  
Makino Watanabe ◽  
Haruko Masumiya ◽  
Sachin A. Gupte ◽  
...  
Keyword(s):  
Biochemical Analysis ◽  
Ventricular Myocytes ◽  
Cholesterol Content ◽  
Cholesterol Depletion ◽  
Signaling Proteins ◽  
External Application ◽  
Pipette Solution ◽  
Rat Myocytes ◽  
G Protein Coupled

Cholesterol is a primary constituent of the plasmalemma, including the lipid rafts/caveolae, where various G protein-coupled receptors colocalize with signaling proteins and channels. By manipulating cholesterol in rabbit and rat ventricular myocytes using methyl-β-cyclodextrin (MβCD), we studied the role of cholesterol in the modulation of L-type Ca2+ currents ( ICa,L). MβCD was mainly dialyzed from BAPTA-containing pipette solution during whole cell clamp. In rabbit myocytes dialyzed with 30 mM MβCD for 10 min, a positive shift in membrane potential at half-maximal activation ( V0.5) from −8 to −2 mV developed and was associated with an increase in current density at positive potentials (42% at +20 mV vs. time-matched controls). Isoproterenol (ISO) increased ICa,L approximately threefold and caused a negative shift in V0.5 in control cells, but it did not increase ICa,L in MβCD-treated myocytes, nor did it shift V0.5. The effect of MβCD (10 or 30 mM) was concentration dependent: 30 mM MβCD suppressed the ISO-induced increase in ICa,L more effectively than 10 mM MβCD. MβCD dialysis also abolished the increase in ICa,L elicited by forskolin or dibutyryl cAMP, but not that elicited by (−)BAY K 8644. External application of MβCD-cholesterol complex to rat myocytes attenuated the MβCD-mediated inhibition of the ISO-induced increase of ICa,L. Biochemical analysis confirmed that the myocytes′ cholesterol content was diminished by MβCD and increased by MβCD-cholesterol complex. Cholesterol thus appears to contribute to the regulation of basal ICa,L and β-adrenergic cAMP/PKA-mediated increases in ICa,L. We suggest that cholesterol affects the structural coupling between L-type Ca2+ channels and adjacent regulatory proteins.

Abstract 1568: Loss of Ischemic Postconditioning in the Mouse Hearts Lacking Adenosine A 1 or Bradykinin B 2 Receptors

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Lei Xi ◽  
Anindita Das ◽  
Zhi-Qing Zhao ◽  
Vanessa F Merino ◽  
Michael Bader ◽  
...  
Keyword(s):  
Infarct Size ◽  
G Protein ◽  
Contractile Function ◽  
Gene Knockout ◽  
Myocardial Infarct ◽  
Membrane Receptors ◽  
Ischemic Postconditioning ◽  
Myocardial Infarct Size ◽  
G Protein Coupled

Background: Ischemic postconditioning (PostC) is a recently described cardioprotective modality against reperfusion injury, through a series of brief episodes of reperfusion/ischemia at the very onset of reperfusion. It has been well recognized that PostC can activate cellular signaling cascade, in which the role of G protein-coupled membrane receptors serving as upstream triggers of PostC remains to be established. Hence the goal of this study was to determine a definitive role of adenosine A 1 receptors (A1) and bradykinin B 1 or B 2 receptors (B1 or B2) in PostC, using gene knockout (KO) mice. Methods & Results: The hearts isolated from adult male C57BL/6J wild-type mice (C57-WT) or A1, B1, or B2 KO mice (n=7–9 per group) were subjected to 20 min of zero-flow global ischemia and 30 min of reperfusion with or without PostC in a Langendorff isolated, buffer-perfused heart model. PostC, consisted of 6 cycles of 10 sec of reperfusion and 10 sec of ischemia, significantly reduced myocardial infarct size (22.8±3.1%, Mean±SEM) as compared with C57-WT controls (35.1±2.8%, P<0.05). As shown in Figure below, the infarct-limiting protection of PostC was absent in A1-KO (34.9±2.7%) or B2-KO (33.3±1.7%) and was partially attenuated in B1-KO (25.6±2.9%) mice, as compared with the corresponding non-PostC controls under same genetic background (P>0.05). However, cardiac contractile function and coronary flow at the end of reperfusion were not significantly altered by PostC. Conclusion: PostC-induced infarct size reduction in globally ischemic mouse hearts is triggered by activation of multiple G protein-coupled membrane receptors, which include A1, B2, and, to a lesser extent, B1 receptors.

Tyrosine Hydroxylase Activity and Its mRNA Level in Dopaminergic Neurons of Tenascin Gene Knockout Mouse

1997 ◽  
Vol 231 (2) ◽  
pp. 356-359 ◽  
Author(s):  
Fumihiko Fukamauchi ◽  
Nobuko Mataga ◽  
Yi-Jun Wang ◽  
Shigeo Sato ◽  
Atsushi Yoshiki ◽  
...  
Keyword(s):  
Tyrosine Hydroxylase ◽  
Dopaminergic Neurons ◽  
Knockout Mouse ◽  
Gene Knockout ◽  
Mrna Level ◽  
Hydroxylase Activity ◽  
Tyrosine Hydroxylase Activity ◽  
Gene Knockout Mouse

scholarly journals The Relaxin Gene Knockout Mouse: A Model of Progressive Scleroderma

2005 ◽  
Vol 125 (4) ◽  
pp. 692-699 ◽  
Author(s):  
Chrishan S. Samuel ◽  
Chongxin Zhao ◽  
Qing Yang ◽  
Hong Wang ◽  
Hongsheng Tian ◽  
...  
Keyword(s):  
Knockout Mouse ◽  
Gene Knockout ◽  
Gene Knockout Mouse

Paradoxical behavioral response to apomorphine in tenascin-gene knockout mouse

1997 ◽  
Vol 338 (1) ◽  
pp. 7-10 ◽  
Author(s):  
Fumihiko Fukamauchi ◽  
Yi-Jun Wang ◽  
Nobuko Mataga ◽  
Moriaki Kusakabe
Keyword(s):  
Behavioral Response ◽  
Knockout Mouse ◽  
Gene Knockout ◽  
Gene Knockout Mouse

scholarly journals Neural symptoms in a gene knockout mouse model of Sjögren‐Larsson syndrome are associated with a decrease in 2‐hydroxygalactosylceramide

2018 ◽  
Vol 33 (1) ◽  
pp. 928-941 ◽  
Author(s):  
Tsukasa Kanetake ◽  
Takayuki Sassa ◽  
Koki Nojiri ◽  
Megumi Sawai ◽  
Satoko Hattori ◽  
...  
Keyword(s):  
Mouse Model ◽  
Knockout Mouse ◽  
Gene Knockout ◽  
Knockout Mouse Model ◽  
Gene Knockout Mouse ◽  
Larsson Syndrome

scholarly journals Selection-Independent Generation of Gene Knockout Mouse Embryonic Stem Cells Using Zinc-Finger Nucleases

PLoS ONE ◽  
2011 ◽  
Vol 6 (12) ◽  
pp. e28911 ◽  
Author(s):  
Anna Osiak ◽  
Frank Radecke ◽  
Eva Guhl ◽  
Sarah Radecke ◽  
Nadine Dannemann ◽  
...  
Keyword(s):  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Zinc Finger ◽  
Knockout Mouse ◽  
Gene Knockout ◽  
Embryonic Stem ◽  
Mouse Embryonic Stem Cells ◽  
Zinc Finger Nucleases ◽  
Gene Knockout Mouse

Abstract 16870: Dissociation of Mitochondrial HK-II Triggers Mitochondria Specific Autophagy

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Shigeki Miyamoto ◽  
David J Roberts ◽  
Valerie P Tan-Sah
Keyword(s):  
Energy Production ◽  
Ventricular Myocytes ◽  
Neonatal Rat ◽  
Mouse Heart ◽  
Hexokinase Ii ◽  
Survival Pathway ◽  
Mitochondrial Membrane Depolarization ◽  
Neonatal Rat Ventricular Myocytes

Introduction: There is emerging evidence that the metabolic pathway interplays with the survival pathway to preserve cellular homeostasis. Hexokinases (HKs) catalyze the first step of glucose metabolism and hexokinase-II (HK-II) is the predominant isoform in the heart. Our recent study revealed that HK-II positively regulates general autophagy in the absence of glucose. Mitochondrial HK-II (mitoHK-II) is regulated by Akt and provides cardioprotection while it is decreased in the ischemic heart. Hypothesis: We tested the hypothesis that mitoHK-II dissociation triggers mitochondria specific autophagy (mitophagy). Results: As previously reported, mitoHK-II levels were decreased by ~40% in the perfused mouse heart subjected to global ischemia and in neonatal rat ventricular myocytes (NRVMs) subjected to simulated ischemia. To assess the role of mitoHK-II dissociation, mitoHK-II dissociating peptide (15NG) was expressed in NRVMs. MitoHK-II was decreased by 40% in NRVMs expressing 15NG which was accompanied with Parkin translocation to mitochondria and ubiquitination of mitochondrial proteins. This response was attenuated by Parkin knockdown and reversed by the recovery of mitoHK-II by co-expression of HK-II but not by that of mitochondria binding deficient mutant. 15NG expression did not induce mitochondrial membrane depolarization nor PINK1 stabilization at mitochondria, suggesting that the effects of mitoHK-II dissociation is not dependent on the previously established mitochondria depolarization/PINK1 pathway. This was confirmed by the experiments using PINK1 siRNA. Modest dissociation of mitoHK-II (by 20%) did not induce mitophagic responses but remarkably enhanced FCCP induced mitophagy, indicating that these two pathways are synergetic. We will be analyzing 15NG transgenic mice generated in our lab to determine the mitophagic role of mitoHK-II dissociation in vivo. Conclusions: These results suggest that mitoHK-II dissociation can regulate Parkin dependent mitophagy, in conjunction with depolarization dependent mechanisms and that HK-II could confer cardioprotection by switching the cell from an energy production to an energy conservation mode under ischemia.

Establishment of <italic>Muc1</italic> Gene Knockout Mouse Model

2014 ◽  
Vol 44 (2) ◽  
pp. 143-150
Author(s):  
Ying KUANG ◽  
Lei HUANG ◽  
Jie YANG ◽  
Wei JIN ◽  
WenYing MAO ◽  
...  
Keyword(s):  
Mouse Model ◽  
Knockout Mouse ◽  
Gene Knockout ◽  
Knockout Mouse Model ◽  
Gene Knockout Mouse
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