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Sun X, Lee HC, Lu T. Sorbs2 Deficiency and Vascular BK Channelopathy in Diabetes. Circ Res 2024; 134:858-871. [PMID: 38362769 PMCID: PMC10978258 DOI: 10.1161/circresaha.123.323538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 02/02/2024] [Indexed: 02/17/2024]
Abstract
BACKGROUND Vascular large conductance Ca2+-activated K+ (BK) channel, composed of the α-subunit (BK-α) and the β1-subunit (BK-β1), is a key determinant of coronary vasorelaxation and its function is impaired in diabetic vessels. However, our knowledge of diabetic BK channel dysregulation is incomplete. The Sorbs2 (Sorbin homology [SoHo] and Src homology 3 [SH3] domains-containing protein 2), is ubiquitously expressed in arteries, but its role in vascular pathophysiology is unknown. METHODS The role of Sorbs2 in regulating vascular BK channel activity was determined using patch-clamp recordings, molecular biological techniques, and in silico analysis. RESULTS Sorbs2 is not only a cytoskeletal protein but also an RNA-binding protein that binds to BK channel proteins and BK-α mRNA, regulating BK channel expression and function in coronary smooth muscle cells. Molecular biological studies reveal that the SH3 domain of Sorbs2 is necessary for Sorbs2 interaction with BK-α subunits, while both the SH3 and SoHo domains of Sorbs2 interact with BK-β1 subunits. Deletion of the SH3 or SoHo domains abolishes the Sorbs2 effect on the BK-α/BK-β1 channel current density. Additionally, Sorbs2 is a target gene of the Nrf2 (nuclear factor erythroid-2-related factor 2), which binds to the promoter of Sorbs2 and regulates Sorbs2 expression in coronary smooth muscle cells. In vivo studies demonstrate that Sorbs2 knockout mice at 4 months of age display a significant decrease in BK channel expression and function, accompanied by impaired BK channel Ca2+-sensitivity and BK channel-mediated vasodilation in coronary arteries, without altering their body weights and blood glucose levels. Importantly, Sorbs2 expression is significantly downregulated in the coronary arteries of db/db type 2 diabetic mice. CONCLUSIONS Sorbs2, a downstream target of Nrf2, plays an important role in regulating BK channel expression and function in vascular smooth muscle cells. Vascular Sorbs2 is downregulated in diabetes. Genetic knockout of Sorbs2 manifests coronary BK channelopathy and vasculopathy observed in diabetic mice, independent of obesity and glucotoxicity.
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Affiliation(s)
- Xiaojing Sun
- The Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN
| | - Hon-Chi Lee
- The Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN
| | - Tong Lu
- The Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN
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Xu J, Zhang D, Ma Y, Du H, Wang Y, Luo W, Wang R, Yi F. ROS in diabetic atria regulate SK2 degradation by Atrogin-1 through the NF-κB signaling pathway. J Biol Chem 2024; 300:105735. [PMID: 38336298 PMCID: PMC10938124 DOI: 10.1016/j.jbc.2024.105735] [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: 06/23/2023] [Revised: 01/13/2024] [Accepted: 01/19/2024] [Indexed: 02/12/2024] Open
Abstract
One of the independent risk factors for atrial fibrillation is diabetes mellitus (DM); however, the underlying mechanisms causing atrial fibrillation in DM are unknown. The underlying mechanism of Atrogin-1-mediated SK2 degradation and associated signaling pathways are unclear. The aim of this study was to elucidate the relationship among reactive oxygen species (ROS), the NF-κB signaling pathway, and Atrogin-1 protein expression in the atrial myocardia of DM mice. We found that SK2 expression was downregulated comitant with increased ROS generation and enhanced NF-κB signaling activation in the atrial cardiomyocytes of DM mice. These observations were mimicked by exogenously applicating H2O2 and by high glucose culture conditions in HL-1 cells. Inhibition of ROS production by diphenyleneiodonium chloride or silencing of NF-κB by siRNA decreased the protein expression of NF-κB and Atrogin-1 and increased that of SK2 in HL-1 cells with high glucose culture. Moreover, chromatin immunoprecipitation assay demonstrated that NF-κB/p65 directly binds to the promoter of the FBXO32 gene (encoding Atrogin-1), regulating the FBXO32 transcription. Finally, we evaluated the therapeutic effects of curcumin, known as a NF-κB inhibitor, on Atrogin-1 and SK2 expression in DM mice and confirmed that oral administration of curcumin for 4 weeks significantly suppressed Atrogin-1 expression and protected SK2 expression against hyperglycemia. In summary, the results from this study indicated that the ROS/NF-κB signaling pathway participates in Atrogin-1-mediated SK2 regulation in the atria of streptozotocin-induced DM mice.
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Affiliation(s)
- Jian Xu
- Department of Cardiovascular Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an, China; Senior Department of Cardiology, The Sixth Medical Center of PLA General Hospital, Beijing, China
| | - Dong Zhang
- Department of Cardiovascular Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Yibo Ma
- Department of Cardiovascular Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Hui Du
- Department of Cardiovascular Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Yi Wang
- Department of Cardiovascular Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Wenping Luo
- Institute of Cardiovascular and Vascular Disease, Shaanxi University of Traditional Chinese Medicine, Xianyang, China
| | - Ruxing Wang
- Department of Cardiology, Wuxi People's Hospital Affiliated to Nanjing Medical University, Wuxi, Jiangsu, China
| | - Fu Yi
- Department of Cardiovascular Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an, China.
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Chen Q, Xie C, Tang K, Luo M, Zhang Z, Jin Y, Liu Y, Zhou L, Kong Y. The E3 ligase Trim63 promotes podocyte injury and proteinuria by targeting PPARα to inhibit fatty acid oxidation. Free Radic Biol Med 2023; 209:40-54. [PMID: 37793501 DOI: 10.1016/j.freeradbiomed.2023.09.039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 09/21/2023] [Accepted: 09/30/2023] [Indexed: 10/06/2023]
Abstract
Podocyte injury is a hallmark of glomerular disease and one of the leading causes of chronic kidney disease (CKD). Peroxisome proliferator-activated receptor α (PPARα) plays a key role in podocyte fatty acid oxidation (FAO). However, the underlying regulatory mechanisms remain unresolved. Trim63 is an E3 ubiquitin ligase that has been shown to inhibit PPARα activity; however, its role in fatty acid metabolism in the kidney has not been elucidated to date. In this study, we investigated the effects of overexpression and knockdown of Trim63 in Adriamycin (ADR)-induced nephropathy and diabetic nephropathy models and a podocyte cell line. In both rodents and human patients with proteinuric CKD, Trim63 was upregulated, particularly in the podocytes of injured glomeruli. In the ADR-induced nephropathy model, ectopic Trim63 application aggravated FAO deficiency and mitochondrial dysfunction and triggered intense lipid deposition, podocyte injury, and proteinuria. Notably, Trim63 inhibition alleviated FAO deficiency and mitochondrial dysfunction, and markedly restored podocyte injury and renal fibrosis in ADR-induced and diabetic nephropathy (DN) models. Additionally, Trim63 was observed to mediate PPARα ubiquitination and degradation, leading to podocyte injury. We demonstrate the pathological role of Trim63, which was previously unrecognized in kidney tissue, in FAO deficiency and podocyte injury. Targeting Trim63 may represent a viable therapeutic strategy for podocyte injury and proteinuria.
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Affiliation(s)
- Qiyan Chen
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Guangdong Provincial Institute of Nephrology, and Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China; Division of Nephrology, The First People's Hospital of Foshan, Foshan, China
| | - Chao Xie
- Division of Nephrology, The First People's Hospital of Foshan, Foshan, China
| | - Kaiyue Tang
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Guangdong Provincial Institute of Nephrology, and Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Mujin Luo
- Division of Nephrology, The First People's Hospital of Foshan, Foshan, China
| | - Zhe Zhang
- Division of Nephrology, The First People's Hospital of Foshan, Foshan, China
| | - Yabin Jin
- Clinical Research Institute, The First People's Hospital of Foshan, Foshan, China
| | - Youhua Liu
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Guangdong Provincial Institute of Nephrology, and Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China.
| | - Lili Zhou
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Guangdong Provincial Institute of Nephrology, and Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, China.
| | - Yaozhong Kong
- Division of Nephrology, The First People's Hospital of Foshan, Foshan, China.
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Ca 2+-Activated K + Channels and the Regulation of the Uteroplacental Circulation. Int J Mol Sci 2023; 24:ijms24021349. [PMID: 36674858 PMCID: PMC9867535 DOI: 10.3390/ijms24021349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/06/2023] [Accepted: 01/08/2023] [Indexed: 01/13/2023] Open
Abstract
Adequate uteroplacental blood supply is essential for the development and growth of the placenta and fetus during pregnancy. Aberrant uteroplacental perfusion is associated with pregnancy complications such as preeclampsia, fetal growth restriction (FGR), and gestational diabetes. The regulation of uteroplacental blood flow is thus vital to the well-being of the mother and fetus. Ca2+-activated K+ (KCa) channels of small, intermediate, and large conductance participate in setting and regulating the resting membrane potential of vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) and play a critical role in controlling vascular tone and blood pressure. KCa channels are important mediators of estrogen/pregnancy-induced adaptive changes in the uteroplacental circulation. Activation of the channels hyperpolarizes uteroplacental VSMCs/ECs, leading to attenuated vascular tone, blunted vasopressor responses, and increased uteroplacental blood flow. However, the regulation of uteroplacental vascular function by KCa channels is compromised in pregnancy complications. This review intends to provide a comprehensive overview of roles of KCa channels in the regulation of the uteroplacental circulation under physiological and pathophysiological conditions.
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Wang M, Li S, Liu H, Liu M, Zhang J, Wu Y, Xiao C, Huang H. Large-conductance Ca 2 +-activated K + channel β1-subunit maintains the contractile phenotype of vascular smooth muscle cells. Front Cardiovasc Med 2022; 9:1062695. [PMID: 36568562 PMCID: PMC9780463 DOI: 10.3389/fcvm.2022.1062695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 11/24/2022] [Indexed: 12/14/2022] Open
Abstract
Background Vascular smooth muscle cells (VSMCs) phenotype switching is very important during the pathogenesis and progression of vascular diseases. However, it is not well understood how normal VSMCs maintain the differentiated state. The large-conductance Ca2+-activated K+ (BKCa) channels are widely expressed in VSMCs and regulate vascular tone. Nevertheless, there is limited understanding of the role of the BKCa channel in modulation of the VSMC phenotype. Methods and results We assessed BKCa channel expression levels in normal and injured carotid arteries from rats of the balloon-injury model. A strong decrease of BKCa-β1 was seen in the injured carotid arteries, accompanied by a parallel decrease of the VSMC contractile markers. BKCa-β1 in primary rat aortic VSMCs was decreased with the increase of passage numbers and the stimulation of platelet-derived growth factor (PDGF)-BB. Conversely, transforming growth factor β upregulated BKCa-β1. Meanwhile, the BKCa-β1 level was positively associated with the levels of VSMC contractile proteins. Intravenous injection of PDGF-BB induced downregulation of BKCa-β1 expression in the carotid arteries. Knockdown of BKCa-β1 favored VSMC dedifferentiation, characterized by altered morphology, abnormal actin fiber organization, decreased contractile proteins expression and reduced contractile ability. Furthermore, the resultant VSMC dedifferentiated phenotype rendered increased proliferation, migration, enhanced inflammatory factors levels, and matrix metalloproteinases activity. Studies using primary cultured aortic VSMCs from human recapitulated key findings. Finally, protein level of BKCa-β1 was reduced in human atherosclerotic arteries. Conclusion BKCa-β1 is important in the maintenance of the contractile phenotype of VSMCs. As a novel endogenous defender that prevents pathological VSMC phenotype switching, BKCa-β1 may serve as a potential therapeutic target for treating vascular diseases including post-injury restenosis and atherosclerosis.
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Affiliation(s)
- Meili Wang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Shuanglei Li
- Division of Adult Cardiac Surgery, Department of Cardiology, The Sixth Medical Center, Chinese PLA General Hospital, Beijing, China
| | - Hongshan Liu
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Mingyuan Liu
- Department of Vascular Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China
| | - Jin Zhang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China
| | - Yang Wu
- Division of Adult Cardiac Surgery, Department of Cardiology, The Sixth Medical Center, Chinese PLA General Hospital, Beijing, China
| | - Cangsong Xiao
- Division of Adult Cardiac Surgery, Department of Cardiology, The Sixth Medical Center, Chinese PLA General Hospital, Beijing, China,Cangsong Xiao,
| | - Haixia Huang
- Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing, China,*Correspondence: Haixia Huang,
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Lu T, Lee HC. Coronary Large Conductance Ca 2+-Activated K + Channel Dysfunction in Diabetes Mellitus. Front Physiol 2021; 12:750618. [PMID: 34744789 PMCID: PMC8567020 DOI: 10.3389/fphys.2021.750618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/14/2021] [Indexed: 11/24/2022] Open
Abstract
Diabetes mellitus (DM) is an independent risk of macrovascular and microvascular complications, while cardiovascular diseases remain a leading cause of death in both men and women with diabetes. Large conductance Ca2+-activated K+ (BK) channels are abundantly expressed in arteries and are the key ionic determinant of vascular tone and organ perfusion. It is well established that the downregulation of vascular BK channel function with reduced BK channel protein expression and altered intrinsic BK channel biophysical properties is associated with diabetic vasculopathy. Recent efforts also showed that diabetes-associated changes in signaling pathways and transcriptional factors contribute to the downregulation of BK channel expression. This manuscript will review our current understandings on the molecular, physiological, and biophysical mechanisms that underlie coronary BK channelopathy in diabetes mellitus.
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Affiliation(s)
- Tong Lu
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, United States
| | - Hon-Chi Lee
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, United States
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Glucose fluctuations promote vascular BK channels dysfunction via PKCα/NF-κB/MuRF1 signaling. J Mol Cell Cardiol 2020; 145:14-24. [PMID: 32511969 DOI: 10.1016/j.yjmcc.2020.05.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2019] [Revised: 05/27/2020] [Accepted: 05/31/2020] [Indexed: 01/01/2023]
Abstract
Glucose fluctuations may contribute to large conductance calcium activated potassium (BK) channel dysfunction. However, the underlying mechanisms remain elusive. The aim of this study was to investigate the molecular mechanisms involved in BK channel dysfunction as a result of glucose fluctuations. A rat diabetic model was established through the injection of streptozotocin. Glucose fluctuations in diabetic rats were induced via consumption and starvation. Rat coronary arteries were isolated and coronary vascular tensions were measured after three weeks. Rat coronary artery smooth muscle cells were isolated and whole-cell BK channel currents were recorded using a patch clamp technique. Human coronary artery smooth muscle cells in vitro were used to explore the underlying mechanisms. After incubation with iberiotoxin (IBTX), the Δ tensions (% Max) of rat coronary arteries in the controlled diabetes mellitus (C-DM), the uncontrolled DM (U-DM) and the DM with glucose fluctuation (GF-DM) groups were found to be 84.46 ± 5.75, 61.89 ± 10.20 and 14.77 ± 5.90, respectively (P < .05), while the current densities of the BK channels in the three groups were 43.09 ± 4.35 pA/pF, 34.23 ± 6.07 pA/pF and 17.87 ± 4.33 pA/pF, respectively (P < .05). The Δ tensions (% Max) of rat coronary arteries after applying IBTX in the GF-DM rats injected with 0.9% sodium chloride (NaCl) (GF-DM + NaCl) and the GF-DM rats injected with N-acetyl-L-cysteine (NAC) (GF-DM + NAC) groups were found to be 8.86 ± 1.09 and 48.90 ± 10.85, respectively (P < .05). Excessive oxidative stress and the activation of protein kinase C (PKC) α and nuclear factor (NF)-κB induced by glucose fluctuations promoted the decrease of BK-β1 expression, while the inhibition of reactive oxygen species (ROS), PKCα, NF-κB and muscle ring finger protein 1 (MuRF1) reversed this effect. Glucose fluctuations aggravate BK channel dysfunction via the ROS overproduction and the PKCα/NF-κB/MuRF1 signaling pathway.
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8
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Qian LL, Liu XY, Yu ZM, Wang RX. BK Channel Dysfunction in Diabetic Coronary Artery: Role of the E3 Ubiquitin Ligases. Front Physiol 2020; 11:453. [PMID: 32547406 PMCID: PMC7274077 DOI: 10.3389/fphys.2020.00453] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 04/09/2020] [Indexed: 01/11/2023] Open
Abstract
Diabetic coronary arterial disease is a leading cause of morbidity and mortality in diabetic patients. The impaired function of large-conductance calcium-activated potassium channels (BK channels) is involved in diabetic coronary arterial disease. Many studies have indicated that the reduced BK channel expression in diabetic coronary artery is attributed to ubiquitin-mediated protein degradation by the ubiquitin-proteasome system. This review focuses on the influence and the mechanisms of BK channel regulation by E3 ubiquitin ligases in diabetic coronary arterial disease. Thus, BK channels regulated by E3 ubiquitin ligase may play a pivotal role in the coronary pathogenesis of diabetic mellitus and, as such, is a potentially attractive target for therapeutic intervention.
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Affiliation(s)
| | | | | | - Ru-xing Wang
- Department of Cardiology, Wuxi People’s Hospital Affiliated to Nanjing Medical University, Wuxi, China
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Zhu YR, Jiang XX, Ye P, Wang ZM, Zheng Y, Liu Z, Chen SL, Zhang DM. Knockout of AKAP150 improves impaired BK channel-mediated vascular dysfunction through the Akt/GSK3β signalling pathway in diabetes mellitus. J Cell Mol Med 2020; 24:4716-4725. [PMID: 32163656 PMCID: PMC7176888 DOI: 10.1111/jcmm.15143] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 02/05/2020] [Accepted: 02/19/2020] [Indexed: 12/15/2022] Open
Abstract
Vascular dysfunction resulting from diabetes is an important factor in arteriosclerosis. Previous studies have shown that during hyperglycaemia and diabetes, AKAP150 promotes vascular tone enhancement by intensifying the remodelling of the BK channel. However, the interaction between AKAP150 and the BK channel remains open to discussion. In this study, we investigated the regulation of impaired BK channel‐mediated vascular dysfunction in diabetes mellitus. Using AKAP150 null mice (AKAP150−/−) and wild‐type (WT) control mice (C57BL/6J), diabetes was induced by intraperitoneal injection of streptozotocin. We found that knockout of AKAP150 reversed vascular remodelling and fibrosis in mice with diabetes and in AKAP150−/− diabetic mice. Impaired Akt/GSK3β signalling contributed to decreased BK‐β1 expression in aortas from diabetic mice, and the silencing of AKAP150 increased Akt phosphorylation and BK‐β1 expression in MOVAS cells treated with HG medium. The inhibition of Akt activity caused a decrease in BK‐β1 expression, and treatment with AKAP150 siRNA suppressed GSK3β expression in the nuclei of MOVAS cells treated with HG. Knockout of AKAP150 reverses impaired BK channel‐mediated vascular dysfunction through the Akt/GSK3β signalling pathway in diabetes mellitus.
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Affiliation(s)
- Yan-Rong Zhu
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Xiao-Xin Jiang
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Peng Ye
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Zhi-Mei Wang
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Yaguo Zheng
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Zhizhong Liu
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Shao-Liang Chen
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
| | - Dai-Min Zhang
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
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Sun X, Qian LL, Li Y, Pfiefer TM, Wang XL, Lee HC, Lu T. Regulation of KCNMA1 transcription by Nrf2 in coronary arterial smooth muscle cells. J Mol Cell Cardiol 2020; 140:68-76. [PMID: 32147517 DOI: 10.1016/j.yjmcc.2020.03.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2019] [Revised: 02/21/2020] [Accepted: 03/03/2020] [Indexed: 02/08/2023]
Abstract
The large conductance Ca2+-activated K+ (BK) channels, composed of the pore-forming α subunits (BK-α, encoded by KCNMA1 gene) and the regulatory β1 subunits (BK-β1, encoded by KCNMB1 gene), play a unique role in the regulation of coronary vascular tone and myocardial perfusion by linking intracellular Ca2+ homeostasis with excitation-contraction coupling in coronary arterial smooth muscle cells (SMCs). The nuclear factor erythroid 2-related factor 2 (Nrf2) belongs to a member of basic leucine zipper transcription factor family that regulates the expression of antioxidant and detoxification enzymes by binding to the antioxidant response elements (AREs) of these target genes. We have previously reported that vascular BK-β1 protein expression was tightly regulated by Nrf2. However, the molecular mechanism underlying the regulation of BK channel expression by Nrf2, particularly at transcription level, is unknown. In this study, we hypothesized that KCNMA1 and KCNMB1 are the target genes of Nrf2 transcriptional regulation. We found that BK channel protein expression and current density were diminished in freshly isolated coronary arterial SMCs of Nrf2 knockout (KO) mice. However, BK-α mRNA expression was reduced, but not that of BK-β1 mRNA expression, in the arteries of Nrf2 KO mice. Promoter-Nrf2 luciferase reporter assay confirmed that Nrf2 binds to the ARE of KCNMA1 promoter, but not that of KCNMB1. Adenoviral expression and pharmacological activation of Nrf2 increased BK-α and BK-β1 protein levels and enhanced BK channel activity in coronary arterial SMCs. Hence, our results indicate that Nrf2 is a key determinant of BK channel expression and function in vascular SMCs. Nrf2 facilitates BK-α expression through a direct increase in gene transcription, whereas that on BK-β1 is through a different mechanism.
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Affiliation(s)
- Xiaojing Sun
- The Department of Cardiovascular Medicine, Mayo Clinic, 200 First Street SW, Rochester 55905, MN, USA
| | - Ling-Ling Qian
- The Department of Cardiovascular Medicine, Mayo Clinic, 200 First Street SW, Rochester 55905, MN, USA; The Department of Cardiology, Wuxi People's Hospital Affiliated to Nanjing Medical University, 299 Qingyang Road, Wuxi 214023, Jiangsu Province, PR China
| | - Yong Li
- The Department of Cardiovascular Medicine, Mayo Clinic, 200 First Street SW, Rochester 55905, MN, USA; The Department of Cardiology, the Affiliated Wujin Hospital of Jiangsu University, Changzhou 213017, Jiangsu Province, PR China
| | - Teresa M Pfiefer
- The Department of Cardiovascular Medicine, Mayo Clinic, 200 First Street SW, Rochester 55905, MN, USA
| | - Xiao-Li Wang
- The Department of Cardiovascular Medicine, Mayo Clinic, 200 First Street SW, Rochester 55905, MN, USA
| | - Hon-Chi Lee
- The Department of Cardiovascular Medicine, Mayo Clinic, 200 First Street SW, Rochester 55905, MN, USA
| | - Tong Lu
- The Department of Cardiovascular Medicine, Mayo Clinic, 200 First Street SW, Rochester 55905, MN, USA.
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Lu T, Chai Q, Jiao G, Wang XL, Sun X, Furuseth JD, Stulak JM, Daly RC, Greason KL, Cha YM, Lee HC. Downregulation of BK channel function and protein expression in coronary arteriolar smooth muscle cells of type 2 diabetic patients. Cardiovasc Res 2020; 115:145-153. [PMID: 29850792 DOI: 10.1093/cvr/cvy137] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 05/22/2018] [Indexed: 12/20/2022] Open
Abstract
Aims Type 2 diabetes (T2D) is strongly associated with cardiovascular morbidity and mortality in patients. Vascular large conductance Ca2+-activated potassium (BK) channels, composed of four pore-forming α subunits (BK-α), and four regulatory β1 subunits (BK-β1), are densely expressed in coronary arterial smooth muscle cells (SMCs) and play an important role in regulating vascular tone and myocardial perfusion. However, the role of BK channels in coronary microvascular dysfunction of human subjects with diabetes is unclear. In this study, we examined BK channel function and protein expression, and BK channel-mediated vasodilation in freshly isolated coronary arterioles from T2D patients. Methods and results Atrial tissues were obtained from 16 patients with T2D and 25 matched non-diabetic subjects during cardiopulmonary bypass procedure. Microvessel videomicroscopy and immunoblot analysis were performed in freshly dissected coronary arterioles and inside-out single BK channel currents was recorded in enzymatically isolated coronary arteriolar SMCs. We found that BK channel sensitivity to physiological Ca2+ concentration and voltage was downregulated in the coronary arteriolar SMCs of diabetic patients, compared with non-diabetic controls. BK channel kinetics analysis revealed that there was significant shortening of the mean open time and prolongation of the mean closed time in diabetic patients, resulting in a remarkable reduction of the channel open probability. Functional studies showed that BK channel activation by dehydrosoyasaponin-1 was diminished and that BK channel-mediated vasodilation in response to shear stress was impaired in diabetic coronary arterioles. Immunoblot experiments confirmed that the protein expressions of BK-α and BK-β1 subunits were significantly downregulated, but the ratio of BK-α/BK-β1 was unchanged in the coronary arterioles of T2D patients. Conclusions Our results demonstrated for the first time that BK channel function and BK channel-mediated vasodilation were abnormal in the coronary microvasculature of diabetic patients, due to decreased protein expression and altered intrinsic properties of BK channels.
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Affiliation(s)
- Tong Lu
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW., Rochester, Minnesota, USA
| | - Qiang Chai
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW., Rochester, Minnesota, USA.,Department of Physiology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, 89 Jingshi Road, Jinan, Shandong, PR China
| | - Guoqing Jiao
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW., Rochester, Minnesota, USA.,Department of Cardiovascular Surgery, Wuxi People's Hospital Affiliated to Nanjing Medical University, 299 Qingyang Road, Wuxi, Jiangsu, PR China
| | - Xiao-Li Wang
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW., Rochester, Minnesota, USA
| | - Xiaojing Sun
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW., Rochester, Minnesota, USA
| | - Jonathan D Furuseth
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW., Rochester, Minnesota, USA
| | - John M Stulak
- Department of Cardiovascular Surgery, Mayo Clinic, 200 First Street, SW., Rochester, Minnesota, USA
| | - Richard C Daly
- Department of Cardiovascular Surgery, Mayo Clinic, 200 First Street, SW., Rochester, Minnesota, USA
| | - Kevin L Greason
- Department of Cardiovascular Surgery, Mayo Clinic, 200 First Street, SW., Rochester, Minnesota, USA
| | - Yong-Mei Cha
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW., Rochester, Minnesota, USA
| | - Hon-Chi Lee
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW., Rochester, Minnesota, USA
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Wang XL, Lu T, Sun X, Lee HC. Membrane trafficking of large conductance Ca 2+- and voltage-activated K + (BK) channels is regulated by Rab4 GTPase. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1867:118646. [PMID: 31926210 DOI: 10.1016/j.bbamcr.2020.118646] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 12/26/2019] [Accepted: 01/06/2020] [Indexed: 12/28/2022]
Abstract
The large conductance voltage- and Ca2+-activated K+ (BK) channel is a major ionic determinant of vascular tone, vasodilation, and blood pressure. The activity of BK channels is regulated in part by membrane presentation. Rab GTPase (Rab) regulates important cellular processes, including ion channel membrane trafficking. We hypothesize that Rab4a participates in the regulation of BK channel α-subunit (BK-α) membrane trafficking. We found that vascular BK-α interacts physically with Rab4a. Co-expression of dominant-negative Rab4a reduced BK-α surface expression, whereas that of constitutively-active Rab4a augmented BK-α surface presentation. These novel findings suggest that vascular BK channel membrane expression is regulated by Rab4a through channel membrane trafficking.
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Affiliation(s)
- Xiao-Li Wang
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA.
| | - Tong Lu
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Xiaojing Sun
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Hon-Chi Lee
- Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
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13
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Feng X, Li X, Yang C, Ren Q, Zhang W, Li N, Zhang M, Zhang B, Zhang L, Zhou X, Xu Z. Maternal High-Sucrose Diet Accelerates Vascular Stiffness in Aged Offspring via Suppressing Ca v 1.2 and Contractile Phenotype of Vascular Smooth Muscle Cells. Mol Nutr Food Res 2019; 63:e1900022. [PMID: 31067604 DOI: 10.1002/mnfr.201900022] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 04/26/2019] [Indexed: 12/21/2022]
Abstract
SCOPE The fetal programming in response to over-nutrition during pregnancy is involved in pathogenesis of cardiovascular diseases later in life. The authors' previous work reported that prenatal high-sucrose (HS) diet impaired functions of large-conductance Ca2+ -activated K+ channels (BK) in mesenteric arteries in the adolescent offspring rats. This study determines whether prenatal HS has a long-term impact on resistance vasculature in the aged offspring rats. METHODS AND RESULTS Pregnant rats are fed with a high-sucrose diet until delivery. Aged offspring from prenatal HS exhibit elevated fasting insulin level, insulin resistance index, and diastolic pressure. Both pressure-induced myogenic responses and phenylephrine-stimulated contraction of mesenteric arteries in HS are weakened. Electrophysiological tests and western blot indicate that BK and L-type calcium channels (Cav 1.2) are impaired in HS group. On the other hand, expression of matrix metalloproteinase 2 of mesenteric arteries is reduced in HS group while expression of tissue inhibitors of metalloproteinase is increased, indicating that extra cellular matrix (ECM) is remodeled. Furthermore, expression of α-smooth muscle actin is decreased, and insulin/insulin receptor/phosphoinositide3-kinase (PI3K) signaling pathway is downregulated. CONCLUSION The results suggest that prenatal HS induced stiffness of mesenteric arteries in aged offspring by inhibiting Cav 1.2 function and PI3K-associated contractile phenotype of VSMCs.
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Affiliation(s)
- Xueqin Feng
- Institute for Fetology, First Hospital of Soochow University, Suzhou, 215006, China
| | - Xiang Li
- Institute for Fetology, First Hospital of Soochow University, Suzhou, 215006, China
| | - Chunli Yang
- Institute for Fetology, First Hospital of Soochow University, Suzhou, 215006, China
| | - Qinggui Ren
- Department of Gastrointestinal Surgery, Tengzhou Central People's Hospital, Zaozhuang, 277500, China
| | - Wenna Zhang
- Institute for Fetology, First Hospital of Soochow University, Suzhou, 215006, China
| | - Na Li
- Institute for Fetology, First Hospital of Soochow University, Suzhou, 215006, China
| | - Meng Zhang
- Obstetrics and Gynecology, Tengzhou Central People's Hospital, Zaozhuang, 277500, China
| | - Bo Zhang
- Department of Gastrointestinal Surgery, Tengzhou Central People's Hospital, Zaozhuang, 277500, China
| | - Lubo Zhang
- Institute for Fetology, First Hospital of Soochow University, Suzhou, 215006, China.,Center for Prenatal Biology, Loma Linda University, Loma Linda, CA, 92350, USA
| | - Xiuwen Zhou
- Institute for Fetology, First Hospital of Soochow University, Suzhou, 215006, China
| | - Zhice Xu
- Institute for Fetology, First Hospital of Soochow University, Suzhou, 215006, China
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14
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Ling TY, Yi F, Lu T, Wang XL, Sun X, Willis MS, Wu LQ, Shen WK, Adelman JP, Lee HC. F-box protein-32 down-regulates small-conductance calcium-activated potassium channel 2 in diabetic mouse atria. J Biol Chem 2019; 294:4160-4168. [PMID: 30635400 DOI: 10.1074/jbc.ra118.003837] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 12/28/2018] [Indexed: 11/06/2022] Open
Abstract
Diabetes mellitus (DM) is an independent risk factor for atrial fibrillation, but the underlying ionic mechanism for this association remains unclear. We recently reported that expression of the small-conductance calcium-activated potassium channel 2 (SK2, encoded by KCCN2) in atria from diabetic mice is significantly down-regulated, resulting in reduced SK currents in atrial myocytes from these mice. We also reported that the level of SK2 mRNA expression is not reduced in DM atria but that the ubiquitin-proteasome system (UPS), a major mechanism of intracellular protein degradation, is activated in vascular smooth muscle cells in DM. This suggests a possible role of the UPS in reduced SK currents. To test this possibility, we examined the role of the UPS in atrial SK2 down-regulation in DM. We found that a muscle-specific E3 ligase, F-box protein 32 (FBXO-32, also called atrogin-1), was significantly up-regulated in diabetic mouse atria. Enhanced FBXO-32 expression in atrial cells significantly reduced SK2 protein expression, and siRNA-mediated FBXO-32 knockdown increased SK2 protein expression. Furthermore, co-transfection of SK2 with FBXO-32 complementary DNA in HEK293 cells significantly reduced SK2 expression, whereas co-transfection with atrogin-1ΔF complementary DNA (a nonfunctional FBXO-32 variant in which the F-box domain is deleted) did not have any effects on SK2. These results indicate that FBXO-32 contributes to SK2 down-regulation and that the F-box domain is essential for FBXO-32 function. In conclusion, DM-induced SK2 channel down-regulation appears to be due to an FBXO-32-dependent increase in UPS-mediated SK2 protein degradation.
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Affiliation(s)
- Tian-You Ling
- From the Department of Cardiology, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai 200025, China.,the Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota 55905
| | - Fu Yi
- the Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota 55905, .,the Department of Cardiovascular Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China
| | - Tong Lu
- the Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota 55905
| | - Xiao-Li Wang
- the Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota 55905
| | - Xiaojing Sun
- the Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota 55905
| | - Monte S Willis
- the Department of Pathology and Laboratory Medicine, Indiana Center for Musculoskeletal Health, Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Li-Qun Wu
- From the Department of Cardiology, Ruijin Hospital, Shanghai JiaoTong University School of Medicine, Shanghai 200025, China
| | - Win-Kuang Shen
- the Department of Cardiovascular Diseases, Mayo Clinic, Phoenix, Arizona 85259, and
| | - John P Adelman
- the Vollum Institute, Oregon Health and Science University, Portland, Oregon 97239
| | - Hon-Chi Lee
- the Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota 55905,
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15
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Zhu Y, Ye P, Chen SL, Zhang DM. Functional regulation of large conductance Ca 2+-activated K + channels in vascular diseases. Metabolism 2018; 83:75-80. [PMID: 29373813 DOI: 10.1016/j.metabol.2018.01.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Revised: 01/03/2018] [Accepted: 01/18/2018] [Indexed: 12/17/2022]
Abstract
The large conductance Ca2+-activated potassium channels, the BK channels, is widely expressed in various tissues and activated in a Ca2+- and voltage-dependent manner. The activation of BK channels hyperpolarizes vascular smooth muscle cell membrane potential, resulting in vasodilation. Under pathophysiological conditions, such as diabetes mellitus and hypertension, impaired BK channel function exacerbates vascular vasodilation and leads to organ ischemia. The vascular BK channel is composed of 4 pore-forming subunits, BK-α together with 4 auxiliary subunits: β1 subunits (BK-β1) or γ1 subunits (BK-γ1). Recent studies have shown that down-regulation of the BK β1 subunit in diabetes mellitus induced vascular dysfunction; however, the molecular mechanism of these vascular diseases is not well understood. In this review, we summarize the potential mechanisms regarding BK channelopathy and the potential therapeutic targets of BK channels for vascular diseases.
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Affiliation(s)
- Yanrong Zhu
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu 210006, China
| | - Peng Ye
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu 210006, China
| | - Shao-Liang Chen
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu 210006, China
| | - Dai-Min Zhang
- Department of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu 210006, China.
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16
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Qian LL, Sun MQ, Wang RX, Lu T, Wu Y, Dang SP, Tang X, Ji Y, Liu XY, Zhao XX, Wang W, Chai Q, Pan M, Yi F, Zhang DM, Lee HC. Mechanisms of BK Channel Activation by Docosahexaenoic Acid in Rat Coronary Arterial Smooth Muscle Cells. Front Pharmacol 2018; 9:223. [PMID: 29636681 PMCID: PMC5881017 DOI: 10.3389/fphar.2018.00223] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 02/27/2018] [Indexed: 02/05/2023] Open
Abstract
Aim: Docosahexaenoic acid (DHA) is known to activate the vascular large-conductance calcium-activated potassium (BK) channels and has protective effects on the cardiovascular system. However, the underlying mechanisms through which DHA activates BK channels remain unclear. In this study, we determined such mechanisms by examining the effects of different concentrations of DHA on BK channels in freshly isolated rat coronary arterial smooth muscle cells (CASMCs) using patch clamp techniques. Methods and Results: We found that BK channels are the major potassium currents activated by DHA in rat CASMCs and the effects of DHA on BK channels are concentration dependent with a bimodal distribution. At concentrations of <1 μM, DHA activated whole-cell BK currents with an EC50 of 0.24 ± 0.05 μM and the activation effects were abolished by pre-incubation with SKF525A (10 μM), a cytochrome P450 (CYP) epoxygenase inhibitor, suggesting the role of DHA-epoxide. High concentrations of DHA (1-10 μM) activated whole-cell BK currents with an EC50 of 2.38 ± 0.22 μM and the activation effects were unaltered by pre-incubation with SKF525A. Single channel studies showed that the open probabilities of BK channels were unchanged in the presence of low concentrations of DHA, while significantly increased with high concentrations of DHA. In addition, DHA induced a dose-dependent increase in cytosolic calcium concentrations with an EC50 of 0.037 ± 0.01 μM via phospholipase C (PLC)-inositol triphosphate (IP3)-Ca2+ signal pathway, and inhibition of this pathway reduced DHA-induced BK activation. Conclusion: These results suggest that DHA can activate BK channels by multiple mechanisms. Low concentration DHA-induced BK channel activation is mediated through CYP epoxygenase metabolites, while high concentration DHA can directly activate BK channels. In addition, DHA at low and high concentrations can both activate BK channels by elevated cytosolic calcium through the PLC-IP3-Ca2+ signal pathway.
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Affiliation(s)
- Ling-Ling Qian
- Department of Cardiology, Wuxi People's Hospital Affiliated to Nanjing Medical UniversityWuxi, China
| | - Man-Qing Sun
- Department of Cardiology, Wuxi People's Hospital Affiliated to Nanjing Medical UniversityWuxi, China
| | - Ru-Xing Wang
- Department of Cardiology, Wuxi People's Hospital Affiliated to Nanjing Medical UniversityWuxi, China
| | - Tong Lu
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, United States
| | - Ying Wu
- Department of Cardiology, Wuxi People's Hospital Affiliated to Nanjing Medical UniversityWuxi, China
| | - Shi-Peng Dang
- Department of Cardiology, Wuxi People's Hospital Affiliated to Nanjing Medical UniversityWuxi, China
| | - Xu Tang
- Department of Cardiology, Wuxi People's Hospital Affiliated to Nanjing Medical UniversityWuxi, China
| | - Yuan Ji
- Department of Cardiology, Wuxi People's Hospital Affiliated to Nanjing Medical UniversityWuxi, China
| | - Xiao-Yu Liu
- Department of Cardiology, Wuxi People's Hospital Affiliated to Nanjing Medical UniversityWuxi, China
| | - Xiao-Xi Zhao
- Department of Cardiology, Wuxi People's Hospital Affiliated to Nanjing Medical UniversityWuxi, China
| | - Wen Wang
- State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, Nanjing, China
| | - Qiang Chai
- Department of Physiology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan, China
| | - Min Pan
- Department of Cardiology, Affiliated Hospital Nantong University, Nantong, China
| | - Fu Yi
- Department of Cardiovascular Diseases, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | | | - Hon-Chi Lee
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, United States
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17
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Severino P, D'Amato A, Netti L, Pucci M, De Marchis M, Palmirotta R, Volterrani M, Mancone M, Fedele F. Diabetes Mellitus and Ischemic Heart Disease: The Role of Ion Channels. Int J Mol Sci 2018. [PMID: 29534462 PMCID: PMC5877663 DOI: 10.3390/ijms19030802] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Diabetes mellitus is one the strongest risk factors for cardiovascular disease and, in particular, for ischemic heart disease (IHD). The pathophysiology of myocardial ischemia in diabetic patients is complex and not fully understood: some diabetic patients have mainly coronary stenosis obstructing blood flow to the myocardium; others present with coronary microvascular disease with an absence of plaques in the epicardial vessels. Ion channels acting in the cross-talk between the myocardial energy state and coronary blood flow may play a role in the pathophysiology of IHD in diabetic patients. In particular, some genetic variants for ATP-dependent potassium channels seem to be involved in the determinism of IHD.
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Affiliation(s)
- Paolo Severino
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy.
| | - Andrea D'Amato
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy.
| | - Lucrezia Netti
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy.
| | - Mariateresa Pucci
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy.
| | - Marialaura De Marchis
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy.
| | - Raffaele Palmirotta
- Department of Biomedical Sciences and Clinical Oncology Oncogenomic Research Center, 'Aldo Moro' University of Bari, 70124 Bari, Italy.
| | - Maurizio Volterrani
- Department of Cardiac Rehabilitation, IRCCS San Raffaele, 00163 Rome, Italy.
| | - Massimo Mancone
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy.
| | - Francesco Fedele
- Department of Cardiovascular, Respiratory, Nephrology, Anesthesiology and Geriatric Sciences, Sapienza University of Rome, 00161 Rome, Italy.
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18
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Song T, Liang S, Liu J, Zhang T, Yin Y, Geng C, Gao S, Feng Y, Xu H, Guo D, Roberts A, Gu Y, Cang Y. CRL4 antagonizes SCFFbxo7-mediated turnover of cereblon and BK channel to regulate learning and memory. PLoS Genet 2018; 14:e1007165. [PMID: 29370161 PMCID: PMC5800687 DOI: 10.1371/journal.pgen.1007165] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 02/06/2018] [Accepted: 12/25/2017] [Indexed: 12/18/2022] Open
Abstract
Intellectual disability (ID), one of the most common human developmental disorders, can be caused by genetic mutations in Cullin 4B (Cul4B) and cereblon (CRBN). CRBN is a substrate receptor for the Cul4A/B-DDB1 ubiquitin ligase (CRL4) and can target voltage- and calcium-activated BK channel for ER retention. Here we report that ID-associated CRL4CRBN mutations abolish the interaction of the BK channel with CRL4, and redirect the BK channel to the SCFFbxo7 ubiquitin ligase for proteasomal degradation. Glioma cell lines harbouring CRBN mutations record density-dependent decrease of BK currents, which can be restored by blocking Cullin ubiquitin ligase activity. Importantly, mice with neuron-specific deletion of DDB1 or CRBN express reduced BK protein levels in the brain, and exhibit similar impairment in learning and memory, a deficit that can be partially rescued by activating the BK channel. Our results reveal a competitive targeting of the BK channel by two ubiquitin ligases to achieve exquisite control of its stability, and support changes in neuronal excitability as a common pathogenic mechanism underlying CRL4CRBN-associated ID.
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Affiliation(s)
- Tianyu Song
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Shenghui Liang
- Translational and Regenerative Medicine Center, Aston Medical School, Aston University, Birmingham, United Kingdom
| | - Jiye Liu
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Tingyue Zhang
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yifei Yin
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Chenlu Geng
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Shaobing Gao
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Yan Feng
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
| | - Hao Xu
- Laboratory of Molecular Pharmacology, Institute of Molecular Medicine, Peking University, Peking, China
| | - Dongqing Guo
- Laboratory of Molecular Pharmacology, Institute of Molecular Medicine, Peking University, Peking, China
| | - Amanda Roberts
- Molecular and Cellular Neurosciences Department, The Scripps Research Institute, University of California, San Diego, La Jolla, California, United States of America
| | - Yuchun Gu
- Translational and Regenerative Medicine Center, Aston Medical School, Aston University, Birmingham, United Kingdom
- * E-mail: (YC); (YG)
| | - Yong Cang
- Life Sciences Institute and Innovation Center for Cell Signalling Network, Zhejiang University, Hangzhou, Zhejiang, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- * E-mail: (YC); (YG)
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19
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Tang X, Qian LL, Wang RX, Yao Y, Dang SP, Wu Y, Wang W, Ji Y, Sun MQ, Xia DY, Liu XY, Zhang DM, Chai Q, Lu T. Regulation of Coronary Arterial Large Conductance Ca2+-Activated K+ Channel Protein Expression and Function by n-3 Polyunsaturated Fatty Acids in Diabetic Rats. J Vasc Res 2017; 54:329-343. [PMID: 29040972 DOI: 10.1159/000479870] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 07/28/2017] [Indexed: 12/22/2022] Open
Abstract
AIM The objective of this study was to examine the effects of n-3 polyunsaturated fatty acids (n-3 PUFAs) on coronary arterial large conductance Ca2+-activated K+ (BK) channel function in coronary smooth muscle cells (SMCs) of streptozotocin-induced diabetic rats. METHODS The effects of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on coronary BK channel open probabilities were determined using the patch clamp technique. The mRNA and protein expressions of BK channel subunits were measured using qRT-PCR and Western blots. The coronary artery tension and coronary SMC Ca2+ concentrations were measured using a myograph system and fluorescence Ca2+ indicator. RESULTS Compared to nondiabetic control rats, the BK channel function was impaired with a reduced response to EPA and DHA in freshly isolated SMCs of diabetic rats. Oral administration of n-3 PUFAs had no effects on protein expressions of BK channel subunits in nondiabetic rats, but significantly enhanced those of BK-β1 in diabetic rats without altering BK-α protein levels. Moreover, coronary ring tension induced by iberiotoxin (a specific BK channel blocker) was increased and cytosolic Ca2+ concentrations in coronary SMCs were decreased in diabetic rats, but no changes were found in nondiabetic rats. CONCLUSIONS n-3 PUFAs protect the coronary BK channel function and coronary vasoreactivity in diabetic rats as a result of not only increasing BK-β1 protein expressions, but also decreasing coronary artery tension and coronary smooth muscle cytosolic Ca2+ concentrations.
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Affiliation(s)
- Xu Tang
- Department of Cardiology, Wuxi People's Hospital Affiliated to Nanjing Medical University, Wuxi, China
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20
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Affiliation(s)
- Sarah J Chapple
- King's British Heart Foundation Centre of Research Excellence, Cardiovascular Division, Faculty of Life Sciences & Medicine, King's College London, London, U.K.
| | - Giovanni E Mann
- King's British Heart Foundation Centre of Research Excellence, Cardiovascular Division, Faculty of Life Sciences & Medicine, King's College London, London, U.K
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21
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Lu T, Sun X, Li Y, Chai Q, Wang XL, Lee HC. Role of Nrf2 Signaling in the Regulation of Vascular BK Channel β1 Subunit Expression and BK Channel Function in High-Fat Diet-Induced Diabetic Mice. Diabetes 2017; 66:2681-2690. [PMID: 28465407 PMCID: PMC5606315 DOI: 10.2337/db17-0181] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 04/17/2017] [Indexed: 01/13/2023]
Abstract
The large conductance Ca2+-activated K+ (BK) channel β1-subunit (BK-β1) is a key modulator of BK channel electrophysiology and the downregulation of BK-β1 protein expression in vascular smooth muscle cells (SMCs) underlies diabetic vascular dysfunction. In this study, we hypothesized that the nuclear factor erythroid-2-related factor 2 (Nrf2) signaling pathway plays a significant role in the regulation of coronary BK channel function and vasodilation in high-fat diet (HFD)-induced obese/diabetic mice. We found that the protein expressions of BK-β1 and Nrf2 were markedly downregulated, whereas those of the nuclear factor-κB (NF-κB) and the muscle ring finger protein 1 (MuRF1 [a ubiquitin E3 ligase for BK-β1]) were significantly upregulated in HFD mouse arteries. Adenoviral expression of Nrf2 suppressed the protein expressions of NF-κB and MuRF1 but enhanced BK-β1 mRNA and protein expressions in cultured coronary SMCs. Knockdown of Nrf2 resulted in reciprocal changes of these proteins. Patch-clamp studies showed that coronary BK-β1-mediated channel activation was diminished in HFD mice. Importantly, the activation of Nrf2 by dimethyl fumarate significantly reduced the body weight and blood glucose levels of HFD mice, enhanced BK-β1 transcription, and attenuated MuRF1-dependent BK-β1 protein degradation, which in turn restored coronary BK channel function and BK channel-mediated coronary vasodilation in HFD mice. Hence, Nrf2 is a novel regulator of BK channel function with therapeutic implications in diabetic vasculopathy.
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Affiliation(s)
- Tong Lu
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN
| | - Xiaojing Sun
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN
| | - Yong Li
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN
- Department of Cardiology, The Affiliated Wujin Hospital of Jiangsu University, Changzhou, Jiangsu, People's Republic of China
| | - Qiang Chai
- Department of Physiology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan, Shandong, People's Republic of China
| | - Xiao-Li Wang
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN
| | - Hon-Chi Lee
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN
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22
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Han YY, Wang LJ, Zhang L, Zhang WW, Ma KT, Li L, Si JQ. Association between potassium channel SNPs and essential hypertension in Xinjiang Kazak Chinese patients. Exp Ther Med 2017; 14:1999-2006. [PMID: 28962116 PMCID: PMC5609208 DOI: 10.3892/etm.2017.4734] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 05/05/2017] [Indexed: 12/27/2022] Open
Abstract
The aim of the present study was to examine whether single-nucleotide polymorphisms (SNPs) of β1 subunit of large-conductance Ca2+-activated K+ channel (KCNMB1) and inwardly rectifying K+ channel, subfamily J, member-11 (KCNJ11) are associated with essential hypertension (EH) in Xinjiang Kazak Chinese patients. A polymerase chain reaction-restriction fragment length polymorphism technique was applied to detect the distribution of selected alleles and genotype frequencies in a cohort of Xinjiang Kazak Chinese patients. Samples from 267 patients with EH and 259 normotensive (NT) controls were analyzed. An unconditional logistic regression analysis was used to estimate the odds ratio and 95% confidence interval of the risk factors that are associated with the development of EH. Genotype and allele frequency analyses revealed that the frequency of genotypes KCNJ11-rs2285676 and KCNMB1-rs11739136 was not significantly different between the EH and NT groups. Individuals carrying the GG genotype of KCNJ11-rs5219 had a 2.08 times higher risk of having EH than individuals carrying the GA+AA genotype of KCNJ11-rs5219. Furthermore, the G allele frequency of KCNJ11-rs5219 in the EH group was significantly higher than that of the NT group (P=0.048). Additionally, logistic regression analysis revealed that the body weight and GG genotype of KCNJ11-rs5219 were positively associated with EH in Xinjiang Kazak Chinese patients (P<0.01).
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Affiliation(s)
- Yuan-Yuan Han
- Department of Physiology, Medical College of Shihezi University, Shihezi, Xinjiang 832002, P.R. China
| | - Li-Jie Wang
- Department of Physiology, Medical College of Shihezi University, Shihezi, Xinjiang 832002, P.R. China
| | - Liang Zhang
- Department of Physiology, Medical College of Shihezi University, Shihezi, Xinjiang 832002, P.R. China.,The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, Xinjiang 832002, P.R. China
| | - Wen-Wen Zhang
- Department of Physiology, Medical College of Shihezi University, Shihezi, Xinjiang 832002, P.R. China
| | - Ke-Tao Ma
- Department of Physiology, Medical College of Shihezi University, Shihezi, Xinjiang 832002, P.R. China.,The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, Xinjiang 832002, P.R. China
| | - Li Li
- Department of Physiology, Medical College of Shihezi University, Shihezi, Xinjiang 832002, P.R. China.,The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, Xinjiang 832002, P.R. China
| | - Jun-Qiang Si
- Department of Physiology, Medical College of Shihezi University, Shihezi, Xinjiang 832002, P.R. China.,The Key Laboratory of Xinjiang Endemic and Ethnic Diseases, Medical College of Shihezi University, Shihezi, Xinjiang 832002, P.R. China.,Department of Physiology, Huazhong University of Science and Technology of Basic Medical Sciences, Wuhan, Hubei 430070, P.R. China.,Department of Physiology, Wuhan University School of Basic Medical Sciences, Wuhan, Hubei 430070, P.R. China
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23
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Ma YG, Liang L, Zhang YB, Wang BF, Bai YG, Dai ZJ, Xie MJ, Wang ZW. Berberine reduced blood pressure and improved vasodilation in diabetic rats. J Mol Endocrinol 2017; 59:191-204. [PMID: 28515053 DOI: 10.1530/jme-17-0014] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 05/17/2017] [Indexed: 12/14/2022]
Abstract
Hyperglycemia and hypertension are considered to be the two leading risk factors for vascular disease in diabetic patients. However, few pharmacologic agents could provide a combinational therapy for controlling hyperglycemia and hypertension at the same time in diabetes. The objectives of this study are to investigate whether berberine treatment could directly reduce blood pressure and identify the molecular mechanism underlying the vascular protection of berberine in diabetic rats. Berberine was intragastrically administered with different dosages of 50, 100 and 200 mg/kg/day to diabetic rats for 8 weeks since the injection of streptozotocin. The endothelium-dependent/-independent relaxation in middle cerebral arteries was investigated. The activity of large-conductance Ca2+-activated K+ channel (BKCa) was investigated by recording whole-cell currents, analyzing single-channel activities and assessing the expressions of α- and β1-subunit at protein or mRNA levels. Results of the study suggest that chronic administration of 100 mg/kg/day berberine not only lowered blood glucose but also reduced blood pressure and improved vasodilation in diabetic rats. Furthermore, berberine markedly increased the function and expression of BKCa β1-subunit in cerebral vascular smooth muscle cells (VSMCs) isolated from diabetic rats or when exposed to hyperglycemia condition. The present study provided initial evidences that berberine reduced blood pressure and improved vasodilation in diabetic rats by activation of BKCa channel in VSMCs, which suggested that berberine might provide a combinational therapy for controlling hyperglycemia and blood pressure in diabetes. Furthermore, our work indicated that activation of BKCa channel might be the underlying mechanism responsible for the vascular protection of berberine in diabetes.
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Affiliation(s)
- Yu-Guang Ma
- Department of OncologyThe Second Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
| | - Liang Liang
- Department of OncologyThe Second Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
| | - Yin-Bin Zhang
- Department of OncologyThe Second Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
| | - Bao-Feng Wang
- Department of OncologyThe Second Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
| | - Yun-Gang Bai
- Department of OncologyThe Second Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
| | - Zhi-Jun Dai
- Department of OncologyThe Second Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
| | - Man-Jiang Xie
- Department of Aerospace PhysiologyKey Laboratory of Aerospace Medicine of Ministry of Education, Fourth Military Medical University, Xi'an, Shaanxi Province, China
| | - Zhong-Wei Wang
- Department of OncologyThe Second Affiliated Hospital of Medical College, Xi'an Jiaotong University, Xi'an, Shaanxi Province, China
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24
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Lu T, Wang XL, Chai Q, Sun X, Sieck GC, Katusic ZS, Lee HC. Role of the endothelial caveolae microdomain in shear stress-mediated coronary vasorelaxation. J Biol Chem 2017; 292:19013-19023. [PMID: 28924052 DOI: 10.1074/jbc.m117.786152] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Revised: 09/08/2017] [Indexed: 12/31/2022] Open
Abstract
In this study, we determined the role of caveolae and the ionic mechanisms that mediate shear stress-mediated vasodilation (SSD). We found that both TRPV4 and SK channels are targeted to caveolae in freshly isolated bovine coronary endothelial cells (BCECs) and that TRPV4 and KCa2.3 (SK3) channels are co-immunoprecipitated by anti-caveolin-1 antibodies. Acute exposure of BCECs seeded in a capillary tube to 10 dynes/cm2 of shear stress (SS) resulted in activation of TRPV4 and SK currents. However, after incubation with HC067047 (TRPV4 inhibitor), SK currents could no longer be activated by SS, suggesting SK channel activation by SS was mediated through TRPV4. SK currents in BCECs were also activated by isoproterenol or by GSK1016790A (TRPV4 activator). In addition, preincubation of isolated coronary arterioles with apamin (SK inhibitor) resulted in a significant diminution of SSD whereas preincubation with HC067047 produced vasoconstriction by SS. Exposure of BCECs to SS (15 dynes/cm2 16 h) enhanced the production of nitric oxide and prostacyclin (PGI2) and facilitated the translocation of TRPV4 to the caveolae. Inhibition of TRPV4 abolished the SS-mediated intracellular Ca2+ ([Ca2+] i ) increase in BCECs. These results indicate a dynamic interaction in the vascular endothelium among caveolae TRPV4 and SK3 channels. This caveolae-TRPV4-SK3 channel complex underlies the molecular and ionic mechanisms that modulate SSD in the coronary circulation.
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Affiliation(s)
- Tong Lu
- From the Department of Cardiovascular Medicine
| | | | - Qiang Chai
- From the Department of Cardiovascular Medicine.,the Department of Physiology, Institute of Basic Medicine, Shandong Academy of Medical Science, Jinan 250062, China
| | | | - Garry C Sieck
- Department of Physiology and Biomedical Engineering, and
| | - Zvonimir S Katusic
- Department of Anesthesiology, Mayo Clinic, Rochester, Minnesota 55905 and
| | - Hon-Chi Lee
- From the Department of Cardiovascular Medicine,
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25
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Ma YG, Wang JW, Zhang YB, Wang BF, Dai ZJ, Xie MJ, Kang HF. Salidroside improved cerebrovascular vasodilation in streptozotocin-induced diabetic rats through restoring the function of BKCa channel in smooth muscle cells. Cell Tissue Res 2017; 370:365-377. [DOI: 10.1007/s00441-017-2671-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 07/18/2017] [Indexed: 12/16/2022]
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26
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Li Y, Wang XL, Sun X, Chai Q, Li J, Thompson B, Shen WK, Lu T, Lee HC. Regulation of vascular large-conductance calcium-activated potassium channels by Nrf2 signalling. Diab Vasc Dis Res 2017; 14:353-362. [PMID: 28429615 DOI: 10.1177/1479164117703903] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
BK channels are major ionic determinants of vasodilation. BK channel function is impaired in diabetic vessels due to accelerated proteolysis of its beta-1 (BK-β1) subunits in response to increased oxidative stress. The nuclear factor E2-related factor-2 (Nrf2) signalling pathway has emerged as a master regulator of cellular redox status, and we hypothesized that it plays a central role in regulating BK channel function in diabetic vessels. We found that Nrf2 expression was markedly reduced in db/db diabetic mouse aortas, and this was associated with significant downregulation of BK-β1. In addition, the muscle ring finger protein 1 (MuRF1), a known E-3 ligase targeting BK-β1 ubiquitination and proteasomal degradation, was significantly augmented. These findings were reproduced by knockdown of Nrf2 by siRNA in cultured human coronary artery smooth muscle cells. In contrast, adenoviral transfer of Nrf2 gene in these cells downregulated MuRF1 and upregulated BK-β1 expression. Activation of Nrf2 by dimethyl fumarate preserved BK-β1 expression and protected BK channel and vascular function in db/db coronary arteries. These results indicate that expression of BK-β1 is closely regulated by Nrf2 and vascular BK channel function can be restored by Nrf2 activation. Nrf2 should be considered a novel therapeutic target in the treatment of diabetic vasculopathy.
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Affiliation(s)
- Yong Li
- 1 Department of Cardiology, Affiliated Wujin Hospital of Jiangsu University, Changzhou, China
- 2 Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Xiao-Li Wang
- 2 Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Xiaojing Sun
- 2 Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Qiang Chai
- 2 Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
- 3 Department of Physiology, Institute of Basic Medicine, Shandong Academy of Medical Sciences, Jinan, P.R. China
| | - Jingchao Li
- 2 Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
- 4 Department of Emergency Medicine, Henan Provincial People's Hospital, Affiliated Hospital of Zhengzhou University, Zhengzhou, P.R. China
| | - Benjamin Thompson
- 2 Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Win-Kuang Shen
- 5 Department of Cardiovascular Medicine, Mayo Clinic, Scottsdale, AZ, USA
| | - Tong Lu
- 2 Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
| | - Hon-Chi Lee
- 2 Department of Cardiovascular Medicine, Mayo Clinic, Rochester, MN, USA
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27
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Hu XQ, Dasgupta C, Chen M, Xiao D, Huang X, Han L, Yang S, Xu Z, Zhang L. Pregnancy Reprograms Large-Conductance Ca 2+-Activated K + Channel in Uterine Arteries: Roles of Ten-Eleven Translocation Methylcytosine Dioxygenase 1-Mediated Active Demethylation. Hypertension 2017; 69:1181-1191. [PMID: 28396535 DOI: 10.1161/hypertensionaha.117.09059] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 02/03/2017] [Accepted: 03/07/2017] [Indexed: 12/15/2022]
Abstract
The large-conductance Ca2+-activated K+ (BKCa) channel is of critical importance in pregnancy-mediated increase in uterine artery vasodilation and blood flow. The present study tested the hypothesis that active DNA demethylation plays a key role in pregnancy-induced reprogramming and upregulation of BKCa channel β1 subunit (BKβ1) in uterine arteries. Uterine arteries were isolated from nonpregnant and near-term pregnant sheep. Pregnancy significantly increased the expression of ten-eleven translocation methylcytosine dioxygenase 1 (TET1) in uterine arteries. A half-palindromic estrogen response element was identified at the TET1 promoter, and estrogen treatment increased TET1 promoter activity and TET1 expression in uterine arteries. In accordance, pregnancy and steroid hormone treatment resulted in demethylation of BKβ1 promoter by increasing 5-hydroxymethylcytosine and decreasing 5-methylcytosine at the CpG in the Sp1-380 binding site that is of critical importance in the regulation of the promoter activity and BKβ1 expression. Inhibition of TET1 with fumarate significantly decreased BKβ1 expression in uterine arteries of pregnant animals and blocked steroid hormone-induced upregulation of BKβ1. Functionally, fumarate treatment inhibited pregnancy and steroid hormone-induced increases in BKCa channel current density and BKCa channel-mediated relaxations. In addition, fumarate blocked pregnancy and steroid hormone-induced decrease in pressure-dependent myogenic tone of the uterine artery. The results demonstrate a novel mechanism of estrogen-mediated active DNA demethylation in reprogramming of BKCa channel expression and function in the adaption of uterine circulation during pregnancy.
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Affiliation(s)
- Xiang-Qun Hu
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China (X.-Q.H., Z.X., L.Z.); Lawrence D. Longo MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA (X.-Q.H., C.D., D.X., X.H., Z.X., L.Z.); Department of Chemistry and Biochemistry, California State University, San Bernardino (S.Y.)
| | - Chiranjib Dasgupta
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China (X.-Q.H., Z.X., L.Z.); Lawrence D. Longo MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA (X.-Q.H., C.D., D.X., X.H., Z.X., L.Z.); Department of Chemistry and Biochemistry, California State University, San Bernardino (S.Y.)
| | - Man Chen
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China (X.-Q.H., Z.X., L.Z.); Lawrence D. Longo MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA (X.-Q.H., C.D., D.X., X.H., Z.X., L.Z.); Department of Chemistry and Biochemistry, California State University, San Bernardino (S.Y.)
| | - Daliao Xiao
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China (X.-Q.H., Z.X., L.Z.); Lawrence D. Longo MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA (X.-Q.H., C.D., D.X., X.H., Z.X., L.Z.); Department of Chemistry and Biochemistry, California State University, San Bernardino (S.Y.)
| | - Xiaohui Huang
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China (X.-Q.H., Z.X., L.Z.); Lawrence D. Longo MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA (X.-Q.H., C.D., D.X., X.H., Z.X., L.Z.); Department of Chemistry and Biochemistry, California State University, San Bernardino (S.Y.)
| | - Limin Han
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China (X.-Q.H., Z.X., L.Z.); Lawrence D. Longo MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA (X.-Q.H., C.D., D.X., X.H., Z.X., L.Z.); Department of Chemistry and Biochemistry, California State University, San Bernardino (S.Y.)
| | - Shumei Yang
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China (X.-Q.H., Z.X., L.Z.); Lawrence D. Longo MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA (X.-Q.H., C.D., D.X., X.H., Z.X., L.Z.); Department of Chemistry and Biochemistry, California State University, San Bernardino (S.Y.)
| | - Zhice Xu
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China (X.-Q.H., Z.X., L.Z.); Lawrence D. Longo MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA (X.-Q.H., C.D., D.X., X.H., Z.X., L.Z.); Department of Chemistry and Biochemistry, California State University, San Bernardino (S.Y.)
| | - Lubo Zhang
- Institute for Fetology, First Hospital of Soochow University, Suzhou, China (X.-Q.H., Z.X., L.Z.); Lawrence D. Longo MD Center for Perinatal Biology, Department of Basic Sciences, Loma Linda University School of Medicine, CA (X.-Q.H., C.D., D.X., X.H., Z.X., L.Z.); Department of Chemistry and Biochemistry, California State University, San Bernardino (S.Y.).
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28
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Kuntamallappanavar G, Bisen S, Bukiya AN, Dopico AM. Differential distribution and functional impact of BK channel beta1 subunits across mesenteric, coronary, and different cerebral arteries of the rat. Pflugers Arch 2016; 469:263-277. [PMID: 28012000 DOI: 10.1007/s00424-016-1929-z] [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: 11/15/2016] [Revised: 12/06/2016] [Accepted: 12/12/2016] [Indexed: 12/12/2022]
Abstract
Large conductance, Ca2+i- and voltage-gated K+ (BK) channels regulate myogenic tone and, thus, arterial diameter. In smooth muscle (SM), BK channels include channel-forming α and auxiliary β1 subunits. BK β1 increases the channel's Ca2+ sensitivity, allowing BK channels to negatively feedback on depolarization-induced Ca2+ entry, oppose SM contraction and favor vasodilation. Thus, endothelial-independent vasodilation can be evoked though targeting of SM BK β1 by endogenous ligands, including lithocholate (LCA). Here, we investigated the expression of BK β1 across arteries of the cerebral and peripheral circulations, and the contribution of such expression to channel function and BK β1-mediated vasodilation. Data demonstrate that endothelium-independent, BK β1-mediated vasodilation by LCA is larger in coronary (CA) and basilar (BA) arteries than in anterior cerebral (ACA), middle cerebral (MCA), posterior cerebral (PCA), and mesenteric (MA) arteries, all arterial segments having a similar diameter. Thus, differential dilation occurs in extracranial arteries which are subjected to similar vascular pressure (CA vs. MA) and in arteries that irrigate different brain regions (BA vs. ACA, MCA, and PCA). SM BK channels from BA and CA displayed increased basal activity and LCA responses, indicating increased BK β1 functional presence. Indeed, in the absence of detectable changes in BK α, BA and CA myocytes showed an increased location of BK β1 in the plasmalemma/subplasmalemma. Moreover, these myocytes distinctly showed increased BK β1 messenger RNA (mRNA) levels. Supporting a major role of enhanced BK β1 transcripts in artery dilation, LCA-induced dilation of MCA transfected with BK β1 complementary DNA (cDNA) was as high as LCA-induced dilation of untransfected BA or CA.
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Affiliation(s)
- Guruprasad Kuntamallappanavar
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center, 71 South Manassas St, Memphis, TN, 38103, USA
| | - Shivantika Bisen
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center, 71 South Manassas St, Memphis, TN, 38103, USA
| | - Anna N Bukiya
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center, 71 South Manassas St, Memphis, TN, 38103, USA
| | - Alex M Dopico
- Department of Pharmacology, College of Medicine, The University of Tennessee Health Science Center, 71 South Manassas St, Memphis, TN, 38103, USA.
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29
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Lu T, Jiang B, Wang XL, Lee HC. Coronary arterial BK channel dysfunction exacerbates ischemia/reperfusion-induced myocardial injury in diabetic mice. Appl Physiol Nutr Metab 2016; 41:992-1001. [PMID: 27574914 DOI: 10.1139/apnm-2016-0048] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/01/2024]
Abstract
The large conductance Ca(2+)-activated K(+) (BK) channels, abundantly expressed in coronary artery smooth muscle cells (SMCs), play a pivotal role in regulating coronary circulation. A large body of evidence indicates that coronary arterial BK channel function is diminished in both type 1 and type 2 diabetes. However, the consequence of coronary BK channel dysfunction in diabetes is not clear. We hypothesized that impaired coronary BK channel function exacerbates myocardial ischemia/reperfusion (I/R) injury in streptozotocin-induced diabetic mice. Combining patch-clamp techniques and cellular biological approaches, we found that diabetes facilitated the colocalization of angiotensin II (Ang II) type 1 receptors and BK channel α-subunits (BK-α), but not BK channel β1-subunits (BK-β1), in the caveolae of coronary SMCs. This caveolar compartmentation in vascular SMCs not only enhanced Ang II-mediated inhibition of BK-α but also produced a physical disassociation between BK-α and BK-β1, leading to increased infarct size in diabetic hearts. Most importantly, genetic ablation of caveolae integrity or pharmacological activation of coronary BK channels protected the cardiac function of diabetic mice from experimental I/R injury in both in vivo and ex vivo preparations. Our results demonstrate a vascular ionic mechanism underlying the poor outcome of myocardial injury in diabetes. Hence, activation of coronary BK channels may serve as a therapeutic target for cardiovascular complications of diabetes.
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MESH Headings
- Angiotensin II/metabolism
- Angiotensin II Type 1 Receptor Blockers/pharmacology
- Animals
- Benzimidazoles/pharmacology
- Caveolae/drug effects
- Caveolae/metabolism
- Cells, Cultured
- Coronary Vessels/drug effects
- Coronary Vessels/metabolism
- Coronary Vessels/pathology
- Coronary Vessels/physiopathology
- Diabetic Cardiomyopathies/drug therapy
- Diabetic Cardiomyopathies/metabolism
- Diabetic Cardiomyopathies/pathology
- Diabetic Cardiomyopathies/physiopathology
- HEK293 Cells
- Humans
- Kv1.3 Potassium Channel
- Large-Conductance Calcium-Activated Potassium Channel alpha Subunits/agonists
- Large-Conductance Calcium-Activated Potassium Channel alpha Subunits/antagonists & inhibitors
- Large-Conductance Calcium-Activated Potassium Channel alpha Subunits/genetics
- Large-Conductance Calcium-Activated Potassium Channel alpha Subunits/metabolism
- Large-Conductance Calcium-Activated Potassium Channel beta Subunits/agonists
- Large-Conductance Calcium-Activated Potassium Channel beta Subunits/antagonists & inhibitors
- Large-Conductance Calcium-Activated Potassium Channel beta Subunits/genetics
- Large-Conductance Calcium-Activated Potassium Channel beta Subunits/metabolism
- Male
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/pathology
- Muscle, Smooth, Vascular/physiopathology
- Mutation
- Myocardial Reperfusion Injury/drug therapy
- Myocardial Reperfusion Injury/metabolism
- Myocardial Reperfusion Injury/pathology
- Myocardial Reperfusion Injury/physiopathology
- Protein Transport/drug effects
- Receptor, Angiotensin, Type 1/agonists
- Receptor, Angiotensin, Type 1/metabolism
- Recombinant Proteins/metabolism
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Affiliation(s)
- Tong Lu
- b Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Bin Jiang
- a Department of Cardiology, The First Affiliated Hospital of Soochow University, 108 Shixin Street, Soochow, Jiangsu 215006, P.R. China
- b Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Xiao-Li Wang
- b Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - Hon-Chi Lee
- b Department of Cardiovascular Diseases, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
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30
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Potassium Channels in Regulation of Vascular Smooth Muscle Contraction and Growth. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 78:89-144. [PMID: 28212804 DOI: 10.1016/bs.apha.2016.07.001] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Potassium channels importantly contribute to the regulation of vascular smooth muscle (VSM) contraction and growth. They are the dominant ion conductance of the VSM cell membrane and importantly determine and regulate membrane potential. Membrane potential, in turn, regulates the open-state probability of voltage-gated Ca2+ channels (VGCC), Ca2+ influx through VGCC, intracellular Ca2+, and VSM contraction. Membrane potential also affects release of Ca2+ from internal stores and the Ca2+ sensitivity of the contractile machinery such that K+ channels participate in all aspects of regulation of VSM contraction. Potassium channels also regulate proliferation of VSM cells through membrane potential-dependent and membrane potential-independent mechanisms. VSM cells express multiple isoforms of at least five classes of K+ channels that contribute to the regulation of contraction and cell proliferation (growth). This review will examine the structure, expression, and function of large conductance, Ca2+-activated K+ (BKCa) channels, intermediate-conductance Ca2+-activated K+ (KCa3.1) channels, multiple isoforms of voltage-gated K+ (KV) channels, ATP-sensitive K+ (KATP) channels, and inward-rectifier K+ (KIR) channels in both contractile and proliferating VSM cells.
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31
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Shipston MJ, Tian L. Posttranscriptional and Posttranslational Regulation of BK Channels. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2016; 128:91-126. [PMID: 27238262 DOI: 10.1016/bs.irn.2016.02.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Large conductance calcium- and voltage-activated potassium (BK) channels are ubiquitously expressed and play an important role in the regulation of an eclectic array of physiological processes. Their diverse functional role requires channels with a wide variety of properties even though the pore-forming α-subunit is encoded by a single gene, KCNMA1. To achieve this, BK channels exploit some of the most fundamental posttranscriptional and posttranslational mechanisms that allow proteomic diversity to be generated from a single gene. These include mechanisms that diversify mRNA variants and abundance such as alternative pre-mRNA splicing, editing, and control by miRNA. The BK channel is also subject to a diverse array of posttranslational modifications including protein phosphorylation, lipidation, glycosylation, and ubiquitination to control the number, properties, and regulation of BK channels in specific cell types. Importantly, "cross talk" between these posttranscriptional and posttranslational modifications typically converge on disordered domains of the BK channel α-subunit. This allows both wide physiological diversity to be generated and a diversity of mechanisms to allow conditional regulation of BK channels and is emerging as an important determinant of BK channel function in health and disease.
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Affiliation(s)
- M J Shipston
- Centre for Integrative Physiology, College of Medicine & Veterinary Medicine, University of Edinburgh, Edinburgh, United Kingdom.
| | - L Tian
- Centre for Integrative Physiology, College of Medicine & Veterinary Medicine, University of Edinburgh, Edinburgh, United Kingdom
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32
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Cushing L, Costinean S, Xu W, Jiang Z, Madden L, Kuang P, Huang J, Weisman A, Hata A, Croce CM, Lü J. Disruption of miR-29 Leads to Aberrant Differentiation of Smooth Muscle Cells Selectively Associated with Distal Lung Vasculature. PLoS Genet 2015; 11:e1005238. [PMID: 26020233 PMCID: PMC4447351 DOI: 10.1371/journal.pgen.1005238] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 04/26/2015] [Indexed: 12/11/2022] Open
Abstract
Differentiation of lung vascular smooth muscle cells (vSMCs) is tightly regulated during development or in response to challenges in a vessel specific manner. Aberrant vSMCs specifically associated with distal pulmonary arteries have been implicated in the pathogenesis of respiratory diseases, such as pulmonary arterial hypertension (PAH), a progressive and fatal disease, with no effective treatment. Therefore, it is highly relevant to understand the underlying mechanisms of lung vSMC differentiation. miRNAs are known to play critical roles in vSMC maturation and function of systemic vessels; however, little is known regarding the role of miRNAs in lung vSMCs. Here, we report that miR-29 family members are the most abundant miRNAs in adult mouse lungs. Moreover, high levels of miR-29 expression are selectively associated with vSMCs of distal vessels in both mouse and human lungs. Furthermore, we have shown that disruption of miR-29 in vivo leads to immature/synthetic vSMC phenotype specifically associated with distal lung vasculature, at least partially due to the derepression of KLF4, components of the PDGF pathway and ECM-related genes associated with synthetic phenotype. Moreover, we found that expression of FBXO32 in vSMCs is significantly upregulated in the distal vasculature of miR-29 null lungs. This indicates a potential important role of miR-29 in smooth muscle cell function by regulating FBXO32 and SMC protein degradation. These results are strongly supported by findings of a cell autonomous role of endogenous miR-29 in promoting SMC differentiation in vitro. Together, our findings suggested a vessel specific role of miR-29 in vSMC differentiation and function by targeting several key negative regulators. The pathogenesis of some vascular diseases, such as PAH is selectively associated with aberrant differentiation and proliferation of vSMCs of distal arteries. While significant progresses have been made in understanding the core mechanism of differentiation and proliferation of vSMCs, little is known regarding vessel specific regulations. By investigating the expression and function of miR-29 in vivo, we found a vessel selective enriched expression and function of miR-29 during mouse lung development. Interestingly, disruption of miR-29 results in defects in vSMCs differentiation of distal vessels, reminiscent of vSMC phenotype observed in the early stage of PAH in which immature/synthetic vSMCs of distal arteries failed to differentiate and were unable to tune down the expression of collagens and other extracellular-related genes. This is the first evidence that miR-29 selectively regulates vSMCs differentiation and vessel wall formation. Future implications are to study the expression and function of miR-29 in human pulmonary vascular diseases, which might lead to establishing miR-29 as a therapeutic target for disease intervention.
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Affiliation(s)
- Leah Cushing
- Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Stefan Costinean
- Department of Pathology, Ohio State Wexner Medical Center, The Ohio State University, Columbus, Ohio, United States of America
| | - Wei Xu
- Columbia Center for Human Development, Division of Pulmonary, Allergy & Critical Care Medicine, Department of Medicine, Columbia University, College of Physicians & Surgeons, New York, New York, United States of America
| | - Zhihua Jiang
- Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Lindsey Madden
- Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Pingping Kuang
- Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Jingshu Huang
- Columbia Center for Human Development, Division of Pulmonary, Allergy & Critical Care Medicine, Department of Medicine, Columbia University, College of Physicians & Surgeons, New York, New York, United States of America
| | - Alexandra Weisman
- Molecular Cardiology Research Institute, Tufts Medical Center, Boston, Massachusetts, United States of America
| | - Akiko Hata
- Molecular Cardiology Research Institute, Tufts Medical Center, Boston, Massachusetts, United States of America
- Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California, United States of America
| | - Carlo M. Croce
- Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University, Columbus, Ohio, United States of America
| | - Jining Lü
- Columbia Center for Human Development, Division of Pulmonary, Allergy & Critical Care Medicine, Department of Medicine, Columbia University, College of Physicians & Surgeons, New York, New York, United States of America
- * E-mail:
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Bhattarai Y, Fernandes R, Kadrofske MM, Lockwood LR, Galligan JJ, Xu H. Western blot analysis of BK channel β1-subunit expression should be interpreted cautiously when using commercially available antibodies. Physiol Rep 2014; 2:2/10/e12189. [PMID: 25355855 PMCID: PMC4254108 DOI: 10.14814/phy2.12189] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Large conductance Ca2+‐activated K+ (BK) channels consist of pore‐forming α‐ and accessory β‐subunits. There are four β‐subunit subtypes (β1–β4), BK β1‐subunit is specific for smooth muscle cells (SMC). Reduced BK β1‐subunit expression is associated with SMC dysfunction in animal models of human disease, because downregulation of BK β1‐subunit reduces channel activity and increases SMC contractility. Several anti‐BK β1‐subunit antibodies are commercially available; however, the specificity of most antibodies has not been tested or confirmed in the tissues from BK β1‐subunit knockout (KO) mice. In this study, we tested the specificity and sensitivity of six commercially available antibodies from five manufacturers. We performed western blot analysis on BK β1‐subunit enriched tissues (mesenteric arteries and colons) and non‐SM tissue (cortex of kidney) from wild‐type (WT) and BK β1‐KO mice. We found that antibodies either detected protein bands of the appropriate molecular weight in tissues from both WT and BK β1‐KO mice or failed to detect protein bands at the appropriate molecular weight in tissues from WT mice, suggesting that these antibodies may lack specificity for the BK β1‐subunit. The absence of BK β1‐subunit mRNA expression in arteries, colons, and kidneys from BK β1‐KO mice was confirmed by RT‐PCR analysis. We conclude that these commercially available antibodies might not be reliable tools for studying BK β1‐subunit expression in murine tissues under the denaturing conditions that we have used. Data obtained using commercially available antibodies should be interpreted cautiously. Our studies underscore the importance of proper negative controls in western blot analyses. Commercially available anti‐BK β1‐subunit antibodies either detected protein bands of the appropriate molecular weight in tissues from both WT and BK β1‐KO mice or failed to detect protein bands at the appropriate molecular weight in tissues from WT mice. These commercially available antibodies are not reliable tools for studying BK β1‐subunit expression in murine tissues. Data obtained using these antibodies should be interpreted cautiously.
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Affiliation(s)
- Yogesh Bhattarai
- Neuroscience Program, Michigan State University, East Lansing, Michigan
| | - Roxanne Fernandes
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Mark M Kadrofske
- Department of Pediatrics and Human Development, Michigan State University, East Lansing, Michigan
| | - Lizbeth R Lockwood
- Department of Pediatrics and Human Development, Michigan State University, East Lansing, Michigan
| | - James J Galligan
- Neuroscience Program, Michigan State University, East Lansing, Michigan Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
| | - Hui Xu
- Neuroscience Program, Michigan State University, East Lansing, Michigan Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan
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Kyle BD, Braun AP. The regulation of BK channel activity by pre- and post-translational modifications. Front Physiol 2014; 5:316. [PMID: 25202279 PMCID: PMC4141542 DOI: 10.3389/fphys.2014.00316] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 08/02/2014] [Indexed: 11/17/2022] Open
Abstract
Large conductance, Ca2+-activated K+ (BK) channels represent an important pathway for the outward flux of K+ ions from the intracellular compartment in response to membrane depolarization, and/or an elevation in cytosolic free [Ca2+]. They are functionally expressed in a range of mammalian tissues (e.g., nerve and smooth muscles), where they can either enhance or dampen membrane excitability. The diversity of BK channel activity results from the considerable alternative mRNA splicing and post-translational modification (e.g., phosphorylation) of key domains within the pore-forming α subunit of the channel complex. Most of these modifications are regulated by distinct upstream cell signaling pathways that influence the structure and/or gating properties of the holo-channel and ultimately, cellular function. The channel complex may also contain auxiliary subunits that further affect channel gating and behavior, often in a tissue-specific manner. Recent studies in human and animal models have provided strong evidence that abnormal BK channel expression/function contributes to a range of pathologies in nerve and smooth muscle. By targeting the upstream regulatory events modulating BK channel behavior, it may be possible to therapeutically intervene and alter BK channel expression/function in a beneficial manner.
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Affiliation(s)
- Barry D Kyle
- Department of Physiology and Pharmacology, Cumming School of Medicine, Libin Cardiovascular Research Institute, University of Calgary Calgary, AB, Canada
| | - Andrew P Braun
- Department of Physiology and Pharmacology, Cumming School of Medicine, Libin Cardiovascular Research Institute, University of Calgary Calgary, AB, Canada
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