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Influence of Hyperglycemia During Different Phases of Ischemic Preconditioning on Cardioprotection-A Focus on Apoptosis and Aggregation of Granulocytes. Shock 2021; 53:637-645. [PMID: 31306347 DOI: 10.1097/shk.0000000000001406] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
BACKGROUND Ischemic preconditioning (IPC) protects the myocardium against ischemia/reperfusion injury. Evidence suggests that hyperglycemia inhibits IPC-induced cardioprotection. The effects of hyperglycemia initiated during different phases of IPC on myocardial injury were characterized with emphasis on apoptosis and aggregation of polymorphonuclear granulocytes (PMN). METHODS Male Wistar rats were subjected to 35 min of myocardial ischemia and 2 h of reperfusion. Control animals were not further treated. IPC was induced by three cycles of 3 min ischemia and 5 min of reperfusion before major ischemia. Hyperglycemia (blood glucose more than 22.2 mmol/L) was induced by glucose administration with or without IPC during different phases (trigger- (before ischemia), mediator- (during ischemia), early reperfusion-phase). One additional group received an anti-PMN-antibody before ischemia. Infarct size was quantified by triphenyltetrazolium chloride staining. Cytochrome C release and B-cell lymphoma two (Bcl-2) expression were assessed by western blot analysis. Poly-ADP-Ribose staining and PMN accumulation were quantified with immunohistochemistry and histochemistry. RESULTS IPC reduced infarct size compared with control. Hyperglycemia completely abolished IPC-induced cardioprotection independent of the time point of initiation. Hyperglycemia before and during major ischemia but without IPC also slightly reduced infarct size. IPC reduced the accumulation of PMNs. This effect was reversed by hyperglycemia during trigger- and mediator-phase but not by hyperglycemia during reperfusion. Hyperglycemia alone had no effect on PMN accumulation. In all treatment groups, signs of myocardial apoptosis were reduced compared with control. IPC alone, combined with hyperglycemia and anti-PMN treatment, reduced apoptosis by a Bcl-2-associated mechanism. Hyperglycemia alone reduced apoptosis by a Bcl-2-independent pathway. CONCLUSION Hyperglycemia inhibits IPC-induced cardioprotection independent of its onset. Furthermore, hyperglycemia prevents apoptosis and IPC-induced reduction of PMN aggregation.
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Shigemizu D, Aiba T, Nakagawa H, Ozaki K, Miya F, Satake W, Toda T, Miyamoto Y, Fujimoto A, Suzuki Y, Kubo M, Tsunoda T, Shimizu W, Tanaka T. Exome Analyses of Long QT Syndrome Reveal Candidate Pathogenic Mutations in Calmodulin-Interacting Genes. PLoS One 2015; 10:e0130329. [PMID: 26132555 PMCID: PMC4488844 DOI: 10.1371/journal.pone.0130329] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Accepted: 05/19/2015] [Indexed: 12/20/2022] Open
Abstract
Long QT syndrome (LQTS) is an arrhythmogenic disorder that can lead to sudden death. To date, mutations in 15 LQTS-susceptibility genes have been implicated. However, the genetic cause for approximately 20% of LQTS patients remains elusive. Here, we performed whole-exome sequencing analyses on 59 LQTS and 61 unaffected individuals in 35 families and 138 unrelated LQTS cases, after genetic screening of known LQTS genes. Our systematic analysis of familial cases and subsequent verification by Sanger sequencing identified 92 candidate mutations in 88 genes for 23 of the 35 families (65.7%): these included eleven de novo, five recessive (two homozygous and three compound heterozygous) and seventy-three dominant mutations. Although no novel commonly mutated gene was identified other than known LQTS genes, protein-protein interaction (PPI) network analyses revealed ten new pathogenic candidates that directly or indirectly interact with proteins encoded by known LQTS genes. Furthermore, candidate gene based association studies using an independent set of 138 unrelated LQTS cases and 587 controls identified an additional novel candidate. Together, mutations in these new candidates and known genes explained 37.1% of the LQTS families (13 in 35). Moreover, half of the newly identified candidates directly interact with calmodulin (5 in 11; comparison with all genes; p=0.042). Subsequent variant analysis in the independent set of 138 cases identified 16 variants in the 11 genes, of which 14 were in calmodulin-interacting genes (87.5%). These results suggest an important role of calmodulin and its interacting proteins in the pathogenesis of LQTS.
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Affiliation(s)
- Daichi Shigemizu
- Laboratory for Medical Science Mathematics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Takeshi Aiba
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Hidewaki Nakagawa
- Laboratory for Genome Sequencing Analysis, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Kouichi Ozaki
- Laboratory for Cardiovascular Diseases, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Fuyuki Miya
- Laboratory for Medical Science Mathematics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Wataru Satake
- Division of Neurology/Molecular Brain Science, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Tatsushi Toda
- Division of Neurology/Molecular Brain Science, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Yoshihiro Miyamoto
- Department of Preventive Cardiology, National Cerebral and Cardiovascular Center, Suita, Japan
| | - Akihiro Fujimoto
- Laboratory for Genome Sequencing Analysis, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Yutaka Suzuki
- Department of Computational Biology, Division of Biosystem Sciences, University of Tokyo, Chiba, Japan
| | - Michiaki Kubo
- Laboratory for Genotyping Development, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Tatsuhiko Tsunoda
- Laboratory for Medical Science Mathematics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Wataru Shimizu
- Department of Cardiovascular Medicine, National Cerebral and Cardiovascular Center, Suita, Japan
- Department of Cardiovascular Medicine, Nippon Medical School, Tokyo, Japan
- * E-mail: (WS); (TT)
| | - Toshihiro Tanaka
- Laboratory for Cardiovascular Diseases, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
- Department of Human Genetics and Disease Diversity, Tokyo Medical and Dental University Graduate School of Medical and Dental Sciences, Tokyo, Japan
- * E-mail: (WS); (TT)
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Ivanov SM, Lagunin AA, Pogodin PV, Filimonov DA, Poroikov VV. Identification of Drug Targets Related to the Induction of Ventricular Tachyarrhythmia Through a Systems Chemical Biology Approach. Toxicol Sci 2015; 145:321-36. [DOI: 10.1093/toxsci/kfv054] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Wu M, Obara Y, Norota I, Nagasawa Y, Ishii K. Insulin suppresses IKs (KCNQ1/KCNE1) currents, which require β-subunit KCNE1. Pflugers Arch 2013; 466:937-46. [PMID: 24068254 DOI: 10.1007/s00424-013-1352-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2013] [Revised: 09/06/2013] [Accepted: 09/07/2013] [Indexed: 11/29/2022]
Abstract
Abnormal QT prolongation in diabetic patients has become a clinical problem because it increases the risk of lethal ventricular arrhythmia. In an animal model of type 1 diabetes mellitus, several ion currents, including the slowly activating delayed rectifier potassium current (IKs), are altered. The IKs channel is composed of KCNQ1 and KCNE1 subunits, whose genetic mutations are well known to cause long QT syndrome. Although insulin is known to affect many physiological and pathophysiological events in the heart, acute effects of insulin on cardiac ion channels are poorly understood at present. This study was designed to investigate direct electrophysiological effects of insulin on IKs (KCNQ1/KCNE1) currents. KCNQ1 and KCNE1 were co-expressed in Xenopus oocytes, and whole cell currents were measured by a two-microelectrode voltage-clamp method. Acute application of insulin suppressed the KCNQ1/KCNE1 currents and phosphorylated Akt and extracellular signal-regulated kinase (ERK), the two major downstream effectors, in a concentration-dependent manner. Wortmannin (10(-6) M), a phosphoinositide 3-kinase (PI3K) inhibitor, attenuated the suppression of the currents and phosphorylation of Akt by insulin, whereas U0126 (10(-5) M), a mitogen-activated protein kinase kinase (MEK) inhibitor, had no effect on insulin-induced suppression of the currents. In addition, insulin had little effect on KCNQ1 currents without KCNE1, which indicated an essential role of KCNE1 in the acute suppressive effects of insulin. Mutagenesis studies revealed amino acid residues 111-118 within the distal third C-terminus of KCNE1 as an important region. Insulin has direct electrophysiological effects on IKs currents, which may affect cardiac excitability.
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Affiliation(s)
- Minghua Wu
- Department of Pharmacology, Yamagata University School of Medicine, 2-2-2 Iida-nishi, Yamagata, 990-9585, Japan
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