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Stevanović KS, Čepkenović B, Križak S, Pajić T, Todorović NV, Živić MŽ. ATP modulation of osmotically activated anionic current in the membrane of Phycomyces blakesleeanus sporangiophore. Sci Rep 2023; 13:11897. [PMID: 37488205 PMCID: PMC10366193 DOI: 10.1038/s41598-023-39021-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 07/19/2023] [Indexed: 07/26/2023] Open
Abstract
Ion channels are vital components of filamentous fungi signaling in communication with their environment. We exploited the ability of the apical region of growing sporangiophores of Phycomyces blakesleeanus to form membrane-enveloped cytoplasmic droplets (CDs), to examine ion currents in the filamentous fungi native plasma membrane. In hypoosmotic conditions, the dominant current in the CDs is ORIC, an osmotically activated, anionic, outwardly rectified, fast inactivating instantaneous current that we have previously characterized. Here, we examined the effect of ATP on ORIC. We show that CDs contain active mitochondria, and that respiration inhibition by azide accelerates ORIC inactivation. ATP, added intracellularly, reduced ORIC run-down and shifted the voltage dependence of inactivation toward depolarized potentials, in a manner that did not require hydrolysis. Notably, ATP led to slowing down of ORIC inactivation, as evidenced by an increased time constant of inactivation, τin, and slower decline of τin during prolonged recordings. Flavonoids (genistein and quercetin) had the effect on ORIC opposite to ATP, acting as current inhibitors, possibly by disrupting the stabilizing effect of ATP on ORIC. The integration of osmotic sensing with ATP dependence of the anionic current, typical of vertebrate cells, is described here for the first time in filamentous fungi.
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Affiliation(s)
- Katarina S Stevanović
- Faculty of Biology, Institute of Physiology and Biochemistry, University of Belgrade, Studentski Trg 16, Belgrade, 11158, Serbia
| | - Bogdana Čepkenović
- Faculty of Biology, Institute of Physiology and Biochemistry, University of Belgrade, Studentski Trg 16, Belgrade, 11158, Serbia
| | - Strahinja Križak
- Institute of Multidisciplinary Research, University of Belgrade, Kneza Višeslava 1, Belgrade, 11030, Serbia
| | - Tanja Pajić
- Faculty of Biology, Institute of Physiology and Biochemistry, University of Belgrade, Studentski Trg 16, Belgrade, 11158, Serbia
| | - Nataša V Todorović
- Institute for Biological Research "Siniša Stanković", University of Belgrade, National Institute of the Republic of Serbia, Bulevar Despota Stefana 142, Belgrade, 11000, Serbia.
| | - Miroslav Ž Živić
- Faculty of Biology, Institute of Physiology and Biochemistry, University of Belgrade, Studentski Trg 16, Belgrade, 11158, Serbia
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Ayala-Calvillo E, Rodríguez-Fragoso L, Álvarez-Ayala E, Leija-Salas A. EGF-receptor phosphorylation and downstream signaling are activated by genistein during subacute liver damage. J Mol Histol 2023:10.1007/s10735-023-10127-8. [PMID: 37227557 DOI: 10.1007/s10735-023-10127-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 05/05/2023] [Indexed: 05/26/2023]
Abstract
The epidermal growth factor receptor (EGFR) plays an important role on hepatic protection in acute and chronic liver injury. The aim of this study was to investigate the role of genistein on EGFR expression, phosphorylation and signaling pathways in experimental subacute liver damage induced by carbon tetrachloride (CCl4). We used male Wistar rats that were randomly divided into four groups: (1) Control; (2) Genistein 5 mg/kg per oral; (3) Subacute liver damage induced by CCl4 4 mg/kg subcutaneously; and (4) Animals received CCl4 and genistein at the dosage indicated. The effect of genistein on EGFR expression, phosphorylation and signaling pathways were investigated by western blot and densitometric analyses. Histological changes were evaluated on slices stained with Hematoxylin-Eosin and Masson´s trichromic, as well as an immunohistochemical analysis for proliferating cell nuclear antigen (PCNA). Additionally, pro-inflammatory cytokines and liver enzymes were quantified. Our study showed that genistein increased EGFR expression, EGFR-specific tyrosine residues phosphorylation (pY1068-EGFR and pY84-EGFR), signal transducer and activator of transcription phosphorylation (pSTAT5), protein kinase B phosphorylation (pAKT) and PCNA in animals with CCl4-induced subacute liver damage. It was found a significant reduction of pro-inflammatory cytokines in serum from animals with subacute liver damage treated with genistein. Those effects were reflected in an improvement in the architecture and liver function. In conclusion, genistein can induce a transactivation of EGFR leading to downstream cell signaling pathways as early events associated with regeneration and hepatoprotection following subacute liver damage.
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Affiliation(s)
- Erick Ayala-Calvillo
- Facultad de Farmacia, Universidad Autónoma del Estado de Morelos. Av Universidad, 1001 Col. Chamilpa CP 62210, Cuernavaca, Morelos, México
| | - Lourdes Rodríguez-Fragoso
- Facultad de Farmacia, Universidad Autónoma del Estado de Morelos. Av Universidad, 1001 Col. Chamilpa CP 62210, Cuernavaca, Morelos, México
| | - Elizabeth Álvarez-Ayala
- Facultad de Farmacia, Universidad Autónoma del Estado de Morelos. Av Universidad, 1001 Col. Chamilpa CP 62210, Cuernavaca, Morelos, México
| | - Alfonso Leija-Salas
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Av. Universidad 2001, CP62210 Col. Chamilpa, Morelos, Cuernavaca, Mexico.
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Richter-Laskowska M, Trybek P, Delfino DV, Wawrzkiewicz-Jałowiecka A. Flavonoids as Modulators of Potassium Channels. Int J Mol Sci 2023; 24:1311. [PMID: 36674825 PMCID: PMC9861088 DOI: 10.3390/ijms24021311] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 01/02/2023] [Accepted: 01/04/2023] [Indexed: 01/12/2023] Open
Abstract
Potassium channels are widely distributed integral proteins responsible for the effective and selective transport of K+ ions through the biological membranes. According to the existing structural and mechanistic differences, they are divided into several groups. All of them are considered important molecular drug targets due to their physiological roles, including the regulation of membrane potential or cell signaling. One of the recent trends in molecular pharmacology is the evaluation of the therapeutic potential of natural compounds and their derivatives, which can exhibit high specificity and effectiveness. Among the pharmaceuticals of plant origin, which are potassium channel modulators, flavonoids appear as a powerful group of biologically active substances. It is caused by their well-documented anti-oxidative, anti-inflammatory, anti-mutagenic, anti-carcinogenic, and antidiabetic effects on human health. Here, we focus on presenting the current state of knowledge about the possibilities of modulation of particular types of potassium channels by different flavonoids. Additionally, the biological meaning of the flavonoid-mediated changes in the activity of K+ channels will be outlined. Finally, novel promising directions for further research in this area will be proposed.
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Affiliation(s)
- Monika Richter-Laskowska
- The Centre for Biomedical Engineering, Łukasiewicz Research Network—Krakow Institute of Technology, 30-418 Krakow, Poland
| | - Paulina Trybek
- Faculty of Science and Technology, University of Silesia in Katowice, 41-500 Chorzów, Poland
| | | | - Agata Wawrzkiewicz-Jałowiecka
- Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, 44-100 Gliwice, Poland
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Effects of equol on multiple K+ channels stably expressed in HEK 293 cells. PLoS One 2017; 12:e0183708. [PMID: 28832658 PMCID: PMC5568406 DOI: 10.1371/journal.pone.0183708] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 08/09/2017] [Indexed: 12/11/2022] Open
Abstract
The present study investigated the effects of equol on cardiovascular K+ channel currents. The cardiovascular K+ channel currents were determined in HEK 293 cells stably expressing cloned differential cardiovascular K+ channels with conventional whole-cell patch voltage-clamp technique. We found that equol inhibited hKv1.5 (IC50: 15.3 μM), hKv4.3 (IC50: 29.2 μM and 11.9 μM for hKv4.3 peak current and charge area, respectively), IKs (IC50: 24.7 μM) and IhERG (IC50: 31.6 and 56.5 μM for IhERG.tail and IhERG.step, respectively), but not hKir2.1 current, in a concentration-dependent manner. Interestingly, equol increased BKCa current with an EC50 of 0.1 μM. It had no significant effect on guinea pig ventricular action potentials at concentrations of ≤3 μM. These results demonstrate that equol inhibits several cardiac K+ currents at relatively high concentrations, whereas it increases BKCa current at very low concentrations, suggesting that equol is a safe drug candidate for treating patients with cerebral vascular disorders.
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Aréchiga-Figueroa IA, Morán-Zendejas R, Delgado-Ramírez M, Rodríguez-Menchaca AA. Phytochemicals genistein and capsaicin modulate Kv2.1 channel gating. Pharmacol Rep 2017; 69:1145-1153. [PMID: 29128793 DOI: 10.1016/j.pharep.2017.05.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Revised: 05/11/2017] [Accepted: 05/29/2017] [Indexed: 11/25/2022]
Abstract
BACKGROUND Phytochemicals are a large group of plant-derived compounds that have a broad range of pharmacological effects. Some of these effects are derived from their action on transport proteins, including ion channels. The present study investigates the effects of the phytochemicals genistein and capsaicin on voltage-gated potassium Kv2.1 channels. METHODS The whole-cell patch clamp technique was used to explore the regulation of Kv2.1 channels expressed in HEK293 cells by genistein and capsaicin. RESULTS Both phytochemicals had a profound effect on the gating properties of Kv2.1 channels; the voltage dependence of activation and inactivation was shifted to hyperpolarized potentials, the closed-state inactivation was accelerated, and the recovery from inactivation was delayed. Moreover, genistein and capsaicin inhibited Kv2.1 currents in a concentration dependent manner. CONCLUSION This study effectively demonstrated the inhibitory effects of genistein and capsaicin on Kv2.1 channels. As Kv2.1 channels play a prominent role in glucose-stimulated insulin secretion, our findings contribute to our understanding of the putative mechanism by which these phytochemicals exert their reported hypoglycemic effects.
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Affiliation(s)
| | - Rita Morán-Zendejas
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
| | - Mayra Delgado-Ramírez
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico
| | - Aldo A Rodríguez-Menchaca
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico.
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Xiao GS, Zhang YH, Wu W, Sun HY, Wang Y, Li GR. Genistein and tyrphostin AG556 decrease ultra-rapidly activating delayed rectifier K + current of human atria by inhibiting EGF receptor tyrosine kinase. Br J Pharmacol 2017; 174:454-467. [PMID: 28072464 DOI: 10.1111/bph.13710] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 12/16/2016] [Accepted: 01/05/2017] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND AND PURPOSE The ultra-rapidly activating delayed rectifier K+ current IKur (encoded by Kv 1.5 or KCNA5) plays an important role in human atrial repolarization. The present study investigates the regulation of this current by protein tyrosine kinases (PTKs). EXPERIMENTAL APPROACH Whole-cell patch voltage clamp technique and immunoprecipitation and Western blotting analysis were used to investigate whether the PTK inhibitors genistein, tyrphostin AG556 (AG556) and PP2 regulate human atrial IKur and hKv1.5 channels stably expressed in HEK 293 cells. KEY RESULTS Human atrial IKur was decreased by genistein (a broad-spectrum PTK inhibitor) and AG556 (a highly selective EGFR TK inhibitor) in a concentration-dependent manner. Inhibition of IKur induced by 30 μM genistein or 10 μM AG556 was significantly reversed by 1 mM orthovanadate (a protein tyrosine phosphatase inhibitor). Similar results were observed in HEK 293 cells stably expressing hKv 1.5 channels. On the other hand, the Src family kinase inhibitor PP2 (1 μM) slightly enhanced IKur and hKv 1.5 current, and the current increase was also reversed by orthovanadate. Immunoprecipitation and Western blotting analysis showed that genistein, AG556, and PP2 decreased tyrosine phosphorylation of hKv 1.5 channels and that the decrease was countered by orthovanadate. CONCLUSION AND IMPLICATIONS The PTK inhibitors genistein and AG556 decrease human atrial IKur and cloned hKv 1.5 channels by inhibiting EGFR TK, whereas the Src kinase inhibitor PP2 increases IKur and hKv 1.5 current. These results imply that EGFR TK and the soluble Src kinases may have opposite effects on human atrial IKur .
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Affiliation(s)
- Guo-Sheng Xiao
- Xiamen Cardiovascular Hospital, Xiamen University, Xiamen, Fujian, China
| | - Yan-Hui Zhang
- Xiamen Cardiovascular Hospital, Xiamen University, Xiamen, Fujian, China.,Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Wei Wu
- Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Hai-Ying Sun
- Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China
| | - Yan Wang
- Xiamen Cardiovascular Hospital, Xiamen University, Xiamen, Fujian, China
| | - Gui-Rong Li
- Xiamen Cardiovascular Hospital, Xiamen University, Xiamen, Fujian, China.,Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China
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Wang X, Zhao T, Zhou S, Sun L, Zhang L, Yu G. Mg2+-Dependent Modulation of BKCaChannels by Genistein in Rat Arteriolar Smooth Muscle Cells. J Cell Physiol 2014; 229:1981-9. [PMID: 24729485 DOI: 10.1002/jcp.24648] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 04/11/2014] [Indexed: 12/15/2022]
Affiliation(s)
- Xiaoran Wang
- Department of Neurology; The First Affiliated Hospital of Harbin Medical University; Harbin PR China
| | - Tingting Zhao
- Department of Neurology; The First Affiliated Hospital of Harbin Medical University; Harbin PR China
| | - Shanshan Zhou
- Department of Neurology; The First Affiliated Hospital of Harbin Medical University; Harbin PR China
| | - Lina Sun
- Department of Neurology; The First Affiliated Hospital of Harbin Medical University; Harbin PR China
| | - Liming Zhang
- Department of Neurology; The First Affiliated Hospital of Harbin Medical University; Harbin PR China
| | - Guichun Yu
- Department of Neurology; The First Affiliated Hospital of Harbin Medical University; Harbin PR China
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Guerra-Laso JM, González-García S, González-Cortés C, Diez-Tascón C, López-Medrano R, Rivero-Lezcano OM. Macrophages from elders are more permissive to intracellular multiplication of Mycobacterium tuberculosis. AGE (DORDRECHT, NETHERLANDS) 2013; 35:1235-50. [PMID: 22791369 PMCID: PMC3705107 DOI: 10.1007/s11357-012-9451-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Accepted: 06/24/2012] [Indexed: 05/15/2023]
Abstract
The elderly account for a disproportionate share of all tuberculosis cases, and the population ageing may not fully explain this phenomenon. We have performed in vitro infection experiments to investigate whether there is an immunological basis for the apparent susceptibility of elders to tuberculosis. In our infection model, Mycobacterium tuberculosis induces a higher production of interleukin (IL)-6 and reactive oxygen species in macrophages from elders than from younger adults. This response did not prevent, however, an increased multiplication of M. tuberculosis in macrophages from elders as compared with the growth observed within cells from adults. By performing a factorial experiment, we have found that IFN-γ, but not IL-1β, IL-6 or TNF-α, stimulate the macrophages to restrict the multiplication of the bacterium in macrophages from elders. Although monocytes from elders seem to be in a higher level of activation, we present evidences that protein tyrosine phosphorylation response induced by M. tuberculosis is stronger in monocytes from adults than from elders. Using a protein array that detects 71 tyrosine phosphorylated kinases, we identified Pyk2 as the only kinase that displayed a difference of intensity larger than 50 % in adults than in elders. Furthermore, monocytes from elders that were incubated in the presence of tyrosine kinase inhibitors (genistein and PP2) allowed a higher level of bacterial multiplication. These observations may help to explain the susceptibility of elders to tuberculosis. An unexpected result was that both genistein and its negative control, daidzein, abundant soy isoflavones, promoted intracellular mycobacterial growth.
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Affiliation(s)
- José M. Guerra-Laso
- />Servicio de Medicina Interna, Hospital de León, Altos de Nava s/n, 24008 León, Spain
| | - Sandra González-García
- />Unidad de Investigación, Hospital de León, Edif. S. Antonio Abad, Altos de Nava s/n, 24008 León, Spain
| | - Carolina González-Cortés
- />Unidad de Investigación, Hospital de León, Edif. S. Antonio Abad, Altos de Nava s/n, 24008 León, Spain
| | - Cristina Diez-Tascón
- />Servicio de Anatomía Patológica, Hospital de León, Altos de Nava s/n, 24008 León, Spain
| | - Ramiro López-Medrano
- />Servicio de Microbiología, Hospital Comarcal del Bierzo, Médicos sin Fronteras, 7, 24411 Fuentesnuevas, Spain
| | - Octavio M. Rivero-Lezcano
- />Unidad de Investigación, Hospital de León, Edif. S. Antonio Abad, Altos de Nava s/n, 24008 León, Spain
- />Fundación Instituto de Estudios de Ciencias de la Salud de Castilla y León, Parque de Santa Clara s/n, 42002 Soria, Spain
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Hong DH, Choi IW, Son YK, Kim DJ, Na SH, Jung WK, Yoon YW, Park WS. The effect of PI3 kinase inhibitor LY294002 on voltage-dependent K+ channels in rabbit coronary arterial smooth muscle cells. Life Sci 2013; 92:916-22. [DOI: 10.1016/j.lfs.2013.03.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 02/21/2013] [Accepted: 03/15/2013] [Indexed: 10/27/2022]
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Tang YQ, Liang P, Zhou J, Lu Y, Lei L, Bian X, Wang K. Auxiliary KChIP4a suppresses A-type K+ current through endoplasmic reticulum (ER) retention and promoting closed-state inactivation of Kv4 channels. J Biol Chem 2013; 288:14727-41. [PMID: 23576435 DOI: 10.1074/jbc.m113.466052] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In the brain and heart, auxiliary Kv channel-interacting proteins (KChIPs) co-assemble with pore-forming Kv4 α-subunits to form a native K(+) channel complex and regulate the expression and gating properties of Kv4 currents. Among the KChIP1-4 members, KChIP4a exhibits a unique N terminus that is known to suppress Kv4 function, but the underlying mechanism of Kv4 inhibition remains unknown. Using a combination of confocal imaging, surface biotinylation, and electrophysiological recordings, we identified a novel endoplasmic reticulum (ER) retention motif, consisting of six hydrophobic and aliphatic residues, 12-17 (LIVIVL), within the KChIP4a N-terminal KID, that functions to reduce surface expression of Kv4-KChIP complexes. This ER retention capacity is transferable and depends on its flanking location. In addition, adjacent to the ER retention motif, the residues 19-21 (VKL motif) directly promote closed-state inactivation of Kv4.3, thus leading to an inhibition of channel current. Taken together, our findings demonstrate that KChIP4a suppresses A-type Kv4 current via ER retention and enhancement of Kv4 closed-state inactivation.
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Affiliation(s)
- Yi-Quan Tang
- Department of Neurobiology, Neuroscience Research Institute, Peking University Health Science Center, Peking University School of Pharmaceutical Sciences, Beijing 100191, China
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Son YK, Hong DH, Choi TH, Choi SW, Shin DH, Kim SJ, Jung ID, Park YM, Jung WK, Kim DJ, Choi IW, Park WS. The inhibitory effect of BIM (I) on L-type Ca²⁺ channels in rat ventricular cells. Biochem Biophys Res Commun 2012; 423:110-5. [PMID: 22634012 DOI: 10.1016/j.bbrc.2012.05.091] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Accepted: 05/16/2012] [Indexed: 02/04/2023]
Abstract
We investigated the effect of a specific protein kinase C (PKC) inhibitor, bisindolylmaleimide I [BIM (I)], on L-type Ca(2+) channels in rat ventricular myocytes. BIM (I) alone inhibited the L-type Ca(2+) current in a concentration-dependent manner, with a K(d) value of 3.31 ± 0.25 μM, and a Hill coefficient of 2.34 ± 0.23. Inhibition was immediate after applying BIM (I) in the bath solution and then it partially washed out. The steady-state activation curve was not altered by applying 3μ M BIM (I), but the steady-state inactivation curve shifted to a more negative potential with a change in the slope factor. Other PKC inhibitors, PKC-IP and chelerythrine, showed no significant effects either on the L-type Ca(2+) current or on the inhibitory effect of BIM (I) on the L-type Ca(2+) current. The results suggest that the inhibitory effect of BIM (I) on the L-type Ca(2+) current is independent of the PKC pathway. Thus, our results should be considered in studies using BIM (I) to inhibit PKC activity and ion channel modulation.
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Affiliation(s)
- Youn Kyoung Son
- Department of Physiology, Kangwon National University School of Medicine, Chuncheon, Republic of Korea
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Zhang YH, Wu W, Sun HY, Deng XL, Cheng LC, Li X, Tse HF, Lau CP, Li GR. Modulation of human cardiac transient outward potassium current by EGFR tyrosine kinase and Src-family kinases. Cardiovasc Res 2011; 93:424-33. [PMID: 22198508 DOI: 10.1093/cvr/cvr347] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
AIMS The human cardiac transient outward K(+) current I(to) (encoded by Kv4.3 or KCND3) plays an important role in phase 1 rapid repolarization of cardiac action potentials in the heart. However, modulation of I(to) by intracellular signal transduction is not fully understood. The present study was therefore designed to determine whether/how human atrial I(to) and hKv4.3 channels stably expressed in HEK 293 cells are regulated by protein tyrosine kinases (PTKs). METHODS AND RESULTS Whole-cell patch voltage-clamp, immunoprecipitation, western blotting, and site-directed mutagenesis approaches were employed in the present study. We found that human atrial I(to) was inhibited by the broad-spectrum PTK inhibitor genistein, the selective epidermal growth factor receptor (EGFR) kinase inhibitor AG556, and the Src-family kinases inhibitor PP2. The inhibitory effect was countered by the protein tyrosine phosphatase inhibitor orthovanadate. In HEK 293 cells stably expressing human KCND3, genistein, AG556, and PP2 significantly reduced the hKv4.3 current, and the reduction was antagonized by orthovanadate. Interestingly, orthovanadate also reversed the reduced tyrosine phosphorylation level of hKv4.3 channels by genistein, AG556, or PP2. Mutagenesis revealed that the hKv4.3 mutant Y136F lost the inhibitory response to AG556, while Y108F lost response to PP2. The double-mutant Y108F-Y136F hKv4.3 channels showed no response to either AG556 or PP2. CONCLUSION Our results demonstrate that human atrial I(to) and cloned hKv4.3 channels are modulated by EGFR kinase via phosphorylation of the Y136 residue and by Src-family kinases via phosphorylation of the Y108 residue; tyrosine phosphorylation of the channel may be involved in regulating cardiac electrophysiology.
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Affiliation(s)
- Yan-Hui Zhang
- Department of Medicine, Li Ka Shing Faculty of Medicine, The University of Hong Kong, L4-59, Laboratory Block, FMB, 21 Sassoon Road, Pokfulam, Hong Kong, China
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Kim HJ, Ahn HS, Choi JS, Choi BH, Hahn SJ. Effects of Ranolazine on Cloned Cardiac Kv4.3 Potassium Channels. J Pharmacol Exp Ther 2011; 339:952-8. [DOI: 10.1124/jpet.111.184176] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
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