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De la Cruz A, Wu X, Rainer QC, Hiniesto-Iñigo I, Perez ME, Edler I, Liin SI, Larsson HP. Pharmacological Screening of Kv7.1 and Kv7.1/KCNE1 Activators as Potential Antiarrhythmic Drugs in the Zebrafish Heart. Int J Mol Sci 2023; 24:12092. [PMID: 37569465 PMCID: PMC10418701 DOI: 10.3390/ijms241512092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 07/24/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
Long QT syndrome (LQTS) can lead to ventricular arrhythmia and sudden cardiac death. The most common congenital cause of LQTS is mutations in the channel subunits generating the cardiac potassium current IKs. Zebrafish (Danio rerio) have been proposed as a powerful system to model human cardiac diseases due to the similar electrical properties of the zebrafish heart and the human heart. We used high-resolution all-optical electrophysiology on ex vivo zebrafish hearts to assess the effects of IKs analogues on the cardiac action potential. We found that chromanol 293B (an IKs inhibitor) prolonged the action potential duration (APD) in the presence of E4031 (an IKr inhibitor applied to drug-induced LQT2), and to a lesser extent, in the absence of E4031. Moreover, we showed that PUFA analogues slightly shortened the APD of the zebrafish heart. However, PUFA analogues failed to reverse the APD prolongation in drug-induced LQT2. However, a more potent IKs activator, ML-277, partially reversed the APD prolongation in drug-induced LQT2 zebrafish hearts. Our results suggest that IKs plays a limited role in ventricular repolarizations in the zebrafish heart under resting conditions, although it plays a more important role when the IKr is compromised, as if the IKs in zebrafish serves as a repolarization reserve as in human hearts. This study shows that potent IKs activators can restore the action potential duration in drug-induced LQT2 in the zebrafish heart.
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Affiliation(s)
- Alicia De la Cruz
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, 1600 NW 10th Avenue, Miami, FL 33136, USA
| | - Xiaoan Wu
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, 1600 NW 10th Avenue, Miami, FL 33136, USA
| | - Quinn C. Rainer
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, 1600 NW 10th Avenue, Miami, FL 33136, USA
| | - Irene Hiniesto-Iñigo
- Department of Biomedical and Clinical Sciences, Linköping University, SE-581 85 Linköping, Sweden
| | - Marta E. Perez
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, 1600 NW 10th Avenue, Miami, FL 33136, USA
| | - Isak Edler
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, 1600 NW 10th Avenue, Miami, FL 33136, USA
- Department of Biomedical and Clinical Sciences, Linköping University, SE-581 85 Linköping, Sweden
| | - Sara I. Liin
- Department of Biomedical and Clinical Sciences, Linköping University, SE-581 85 Linköping, Sweden
| | - H. Peter Larsson
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, 1600 NW 10th Avenue, Miami, FL 33136, USA
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Wu X, Cunningham KP, Ramentol R, Perez ME, Larsson HP. Similar voltage-sensor movement in spHCN channels can cause closing, opening, or inactivation. J Gen Physiol 2023; 155:e202213170. [PMID: 36752823 PMCID: PMC9948645 DOI: 10.1085/jgp.202213170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 11/22/2022] [Accepted: 01/27/2023] [Indexed: 02/09/2023] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels contribute to the rhythmic firing of pacemaker neurons and cardiomyocytes. Mutations in HCN channels are associated with cardiac arrhythmia and epilepsy. HCN channels belong to the superfamily of voltage-gated K+ channels, most of which are activated by depolarization. HCN channels, however, are activated by hyperpolarization. The mechanism behind this reversed gating polarity of HCN channels is not clear. We here show that sea urchin HCN (spHCN) channels with mutations in the C-terminal part of the voltage sensor use the same voltage-sensor movement to either close or open in response to hyperpolarizations depending on the absence or presence of cAMP. Our results support that non-covalent interactions at the C-terminal end of the voltage sensor are critical for HCN gating polarity. These interactions are also critical for the proper closing of the channels because these mutations exhibit large constitutive currents. Since a similar voltage-sensor movement can cause both depolarization- and hyperpolarization-activation in the same channel, this suggests that the coupling between the voltage sensor and the pore is changed to create channels opened by different polarities. We also show an identical voltage-sensor movement in activated and inactivated spHCN channels and suggest a model for spHCN activation and inactivation. Our results suggest the possibility that channels open by opposite voltage dependence, such as HCN and the related EAG channels, use the same voltage-sensor movement but different coupling mechanisms between the voltage sensor and the gate.
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Affiliation(s)
- Xiaoan Wu
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Kevin P. Cunningham
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Rosamary Ramentol
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Marta E. Perez
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
| | - H. Peter Larsson
- Department of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, FL, USA
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3
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Wu X, Cunningham KP, Perez ME, Larsson PH. S5-S6 interactions important for the electromechanical coupling in HCN channels. Biophys J 2023; 122:390a. [PMID: 36783983 DOI: 10.1016/j.bpj.2022.11.2132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- Xiaoan Wu
- Department of Physiology and Biophysics, University of Miami, Miami, FL, USA
| | - Kevin P Cunningham
- Department of Physiology and Biophysics, University of Miami, Miami, FL, USA
| | - Marta E Perez
- Department of Physiology and Biophysics, University of Miami, Miami, FL, USA
| | - Peter H Larsson
- Department of Physiology and Biophysics, University of Miami, Miami, FL, USA
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Hinojo-Perez A, Cunningham KP, Edmond M, Perez ME, Barro-Soria R. KCNQ channels open with at least two S4 activation. Biophys J 2023; 122:385a-386a. [PMID: 36783953 DOI: 10.1016/j.bpj.2022.11.2111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
| | - Kevin P Cunningham
- Department of Physiology and Biophysics, University of Miami, Miami, FL, USA
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Judah Y, de la Cruz A, Jowais J, Perez ME, Larsson HP. The effects of polyunsaturated fatty acids on the cardiac I KR channel. Biophys J 2023; 122:243a. [PMID: 36783194 DOI: 10.1016/j.bpj.2022.11.1417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023] Open
Affiliation(s)
- Yahnell Judah
- Physiology and Biophysics, University of Miami, Miami, FL, USA
| | | | - Jessica Jowais
- Physiology and Biophysics, University of Miami, Miami, FL, USA
| | - Marta E Perez
- Physiology and Biophysics, University of Miami, Miami, FL, USA
| | - H Peter Larsson
- Physiology and Biophysics, University of Miami, Miami, FL, USA
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Jowais J, Castro Glez L, Larsson PH, Tieleman P, Perez ME. Optimization of novel lead compounds for treatment of long QT syndrome. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.1536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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7
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Edmond MA, Hinojo-Perez A, Perez ME, Barro-Soria R. Distinctive mechanisms of epilepsy-causing mutants discovered by measuring S4 movement in KCNQ2 channels. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.1278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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8
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Judah Y, Wu X, Perez ME, Larsson HP. The effects of long QT syndrome associated mutation R231C on the cardiac IKs channel. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.1542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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9
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Hinojo-Perez A, Perez ME, Barro-Soria R. Opening of KCNQ2 channels does not require concerted movement of all four voltage sensors. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.1551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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10
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Wu X, Ramentol R, Perez ME, Larsson PH. Side chain interactions in C-terminal S4 helix required for gating polarity of HCN channels. Biophys J 2022. [DOI: 10.1016/j.bpj.2021.11.1276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
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11
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Wu X, Perez ME, Noskov SY, Larsson HP. A general mechanism of KCNE1 modulation of KCNQ1 channels involving non-canonical VSD-PD coupling. Commun Biol 2021; 4:887. [PMID: 34285340 PMCID: PMC8292421 DOI: 10.1038/s42003-021-02418-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 07/05/2021] [Indexed: 01/10/2023] Open
Abstract
Voltage-gated KCNQ1 channels contain four separate voltage-sensing domains (VSDs) and a pore domain (PD). KCNQ1 expressed alone opens when the VSDs are in an intermediate state. In cardiomyocytes, KCNQ1 co-expressed with KCNE1 opens mainly when the VSDs are in a fully activated state. KCNE1 also drastically slows the opening of KCNQ1 channels and shifts the voltage dependence of opening by >40 mV. We here show that mutations of conserved residues at the VSD-PD interface alter the VSD-PD coupling so that the mutant KCNQ1/KCNE1 channels open in the intermediate VSD state. Using recent structures of KCNQ1 and KCNE beta subunits in different states, we present a mechanism by which KCNE1 rotates the VSD relative to the PD and affects the VSD-PD coupling of KCNQ1 channels in a non-canonical way, forcing KCNQ1/KCNE1 channels to open in the fully-activated VSD state. This would explain many of the KCNE1-induced effects on KCNQ1 channels.
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Affiliation(s)
- Xiaoan Wu
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Marta E Perez
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Sergei Yu Noskov
- Centre for Molecular Simulation, Department of Biological Sciences, University of Calgary, Calgary, AB, Canada
| | - H Peter Larsson
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL, USA.
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Bohannon BM, Wu X, Wu X, Perez ME, Liin SI, Larsson HP. Polyunsaturated fatty acids produce a range of activators for heterogeneous IKs channel dysfunction. J Gen Physiol 2021; 152:133474. [PMID: 31865382 PMCID: PMC7062506 DOI: 10.1085/jgp.201912396] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 09/05/2019] [Accepted: 11/27/2019] [Indexed: 01/28/2023] Open
Abstract
Repolarization and termination of the ventricular cardiac action potential is highly dependent on the activation of the slow delayed-rectifier potassium IKs channel. Disruption of the IKs current leads to the most common form of congenital long QT syndrome (LQTS), a disease that predisposes patients to ventricular arrhythmias and sudden cardiac death. We previously demonstrated that polyunsaturated fatty acid (PUFA) analogues increase outward K+ current in wild type and LQTS-causing mutant IKs channels. Our group has also demonstrated the necessity of a negatively charged PUFA head group for potent activation of the IKs channel through electrostatic interactions with the voltage-sensing and pore domains. Here, we test whether the efficacy of the PUFAs can be tuned by the presence of different functional groups in the PUFA head, thereby altering the electrostatic interactions of the PUFA head group with the voltage sensor or the pore. We show that PUFA analogues with taurine and cysteic head groups produced the most potent activation of IKs channels, largely by shifting the voltage dependence of activation. In comparison, the effect on voltage dependence of PUFA analogues with glycine and aspartate head groups was half that of the taurine and cysteic head groups, whereas the effect on maximal conductance was similar. Increasing the number of potentially negatively charged moieties did not enhance the effects of the PUFA on the IKs channel. Our results show that one can tune the efficacy of PUFAs on IKs channels by altering the pKa of the PUFA head group. Different PUFAs with different efficacy on IKs channels could be developed into more personalized treatments for LQTS patients with a varying degree of IKs channel dysfunction.
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Affiliation(s)
- Briana M Bohannon
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL
| | - Xiaoan Wu
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL
| | - Xiongyu Wu
- Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden
| | - Marta E Perez
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL
| | - Sara I Liin
- Department of Clinical and Experimental Medicine, Linköping University, Linköping, Sweden
| | - H Peter Larsson
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL
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13
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Hinojo-Perez A, Perez ME, Barro-Soria R. Voltage Activation Mechanisms of Epilepsy- and ASD-Associated Mutations in Neuronal KCNQ Chanels. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.1587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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14
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Edmond M, Perez ME, Barro-Soria R. Voltage-Sensing Mechanism of Neuronal KCNQ Channels. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.1586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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15
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de la Cruz A, Perez ME, Rainer QC, Larsson H. Polyunsaturated Fatty Acids Therapeutic Potential for Long QT Syndrome. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.2083] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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16
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Wu X, Perez ME, Larsson PH. Non-Canonical Mechanism of the VSD-PD Coupling in KCNQ1/KCNE1 Channels. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.1584] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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17
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Bohannon BM, de la Cruz A, Wu X, Jowais JJ, Perez ME, Dykxhoorn DM, Liin SI, Larsson HP. Correction: Polyunsaturated fatty acid analogues differentially affect cardiac Na V, Ca V, and K V channels through unique mechanisms. eLife 2020; 9:60141. [PMID: 32553105 PMCID: PMC7302875 DOI: 10.7554/elife.60141] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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18
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Bohannon BM, de la Cruz A, Wu X, Jowais JJ, Perez ME, Dykxhoorn DM, Liin SI, Larsson HP. Polyunsaturated fatty acid analogues differentially affect cardiac Na V, Ca V, and K V channels through unique mechanisms. eLife 2020; 9:51453. [PMID: 32207683 PMCID: PMC7159882 DOI: 10.7554/elife.51453] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 03/24/2020] [Indexed: 12/15/2022] Open
Abstract
The cardiac ventricular action potential depends on several voltage-gated ion channels, including NaV, CaV, and KV channels. Mutations in these channels can cause Long QT Syndrome (LQTS) which increases the risk for ventricular fibrillation and sudden cardiac death. Polyunsaturated fatty acids (PUFAs) have emerged as potential therapeutics for LQTS because they are modulators of voltage-gated ion channels. Here we demonstrate that PUFA analogues vary in their selectivity for human voltage-gated ion channels involved in the ventricular action potential. The effects of specific PUFA analogues range from selective for a specific ion channel to broadly modulating cardiac ion channels from all three families (NaV, CaV, and KV). In addition, a PUFA analogue selective for the cardiac IKs channel (Kv7.1/KCNE1) is effective in shortening the cardiac action potential in human-induced pluripotent stem cell-derived cardiomyocytes. Our data suggest that PUFA analogues could potentially be developed as therapeutics for LQTS and cardiac arrhythmia.
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Affiliation(s)
- Briana M Bohannon
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| | - Alicia de la Cruz
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| | - Xiaoan Wu
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| | - Jessica J Jowais
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| | - Marta E Perez
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| | - Derek M Dykxhoorn
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, United States
| | - Sara I Liin
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - H Peter Larsson
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
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Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are essential for rhythmic activity in the heart and brain, and mutations in HCN channels are linked to heart arrhythmia and epilepsy. HCN channels belong to the family of voltage-gated K+ (Kv) channels. However, why HCN channels are activated by hyperpolarization whereas Kv channels are activated by depolarization is not clear. Here we reverse the voltage dependence of HCN channels by mutating only two residues located at the interface between the voltage sensor and the pore domain such that the channels now open upon depolarization instead of hyperpolarization. Our data indicate that what determines whether HCN channels open by hyperpolarizations or depolarizations are small differences in the energies of the closed and open states, due to different interactions between the voltage sensor and the pore in the different channels.
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Affiliation(s)
- Rosamary Ramentol
- Department of Physiology and Biophysics, University of Miami, Miami, FL, 33136, USA
| | - Marta E Perez
- Department of Physiology and Biophysics, University of Miami, Miami, FL, 33136, USA
| | - H Peter Larsson
- Department of Physiology and Biophysics, University of Miami, Miami, FL, 33136, USA.
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Wu X, Perez ME, Larsson PH. Identification of Residues Contributing to the VSD-PD Coupling in IKS Channels. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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21
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Andersson L, Perez ME, Liin SI, Elinder F, Larsson PH, Barro-Soria R. Effect of Lipophilic Molecules on Epilepsy-Causing Mutations of Neuronal KCNQ Channels. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.2907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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22
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Ramentol R, Perez ME, Larsson HP. Conserved Residues at the Interface between the S4 and S5 Segments are Critical for Normal Gating of HCN Channels. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.2921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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23
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Wu X, Perez ME, Sampson KJ, Kass RS, Larsson PH. Determining Functional KCNQ1/KCNE1 Subunit Interactions in the KCNQ1/KCNE1 Channel. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.2900] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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24
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Bohannon BM, Perez ME, Liin SI, Larsson HP. ω-6 and ω-9 polyunsaturated fatty acids with double bonds near the carboxyl head have the highest affinity and largest effects on the cardiac I K s potassium channel. Acta Physiol (Oxf) 2019; 225:e13186. [PMID: 30184322 PMCID: PMC6335172 DOI: 10.1111/apha.13186] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 08/30/2018] [Accepted: 09/02/2018] [Indexed: 02/06/2023]
Abstract
Aim The IKs channel is important for termination of the cardiac action potential. Hundreds of loss‐of‐function mutations in the IKs channel reduce the K+ current and, thereby, delay the repolarization of the action potential, causing Long QT Syndrome. Long QT predisposes individuals to Torsades de Pointes which can lead to ventricular fibrillation and sudden death. Polyunsaturated fatty acids (PUFAs) are potential therapeutics for Long QT Syndrome, as they affect IKs channels. However, it is unclear which properties of PUFAs are essential for their effects on IKs channels. Methods To understand how PUFAs influence IKs channel activity, we measured effects on IKs current by two‐electrode voltage clamp while changing different properties of the hydrocarbon tail. Results There was no, or weak, correlation between the tail length or number of double bonds in the tail and the effects on or apparent binding affinity for IKs channels. However, we found a strong correlation between the positions of the double bonds relative to the head group and effects on IKs channels. Conclusion Polyunsaturated fatty acids with double bonds closer to the head group had higher apparent affinity for IKs channels and increased IKs current more; shifting the bonds further away from the head group reduced apparent binding affinity for and effects on the IKs current. Interestingly, we found that ω‐6 and ω‐9 PUFAs, with the first double bond closer to the head group, left‐shifted the voltage dependence of activation the most. These results allow for informed design of new therapeutics targeting IKs channels in Long QT Syndrome.
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Affiliation(s)
- Briana M. Bohannon
- Department of Physiology and Biophysics; Miller School of Medicine; University of Miami; Miami Florida
| | - Marta E. Perez
- Department of Physiology and Biophysics; Miller School of Medicine; University of Miami; Miami Florida
| | - Sara I. Liin
- Department of Clinical and Experimental Medicine; Linköping University; Linköping Sweden
| | - Hans Peter Larsson
- Department of Physiology and Biophysics; Miller School of Medicine; University of Miami; Miami Florida
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Bustamante PA, Lopez Celani NM, Perez ME, Quintero Montoya OL. Recognition and regionalization of emotions in the arousal-valence plane. Annu Int Conf IEEE Eng Med Biol Soc 2016; 2015:6042-5. [PMID: 26737669 DOI: 10.1109/embc.2015.7319769] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The emotion recognition systems have become important for the diversity of its applications. Several methodologies have been proposed based on how emotions are reflected in biological systems, such as facial expressions, the activity of the nervous system or the prosody of voice. The detection of emotions by voice processing is an approach that involves a noninvasive procedure that produces results with an acceptable rate of detection. In this work an algorithm for features extraction was developed, that efficiently classify different emotional states. Thus, emotions that have not been trained can be associated with a trained emotion both belonging to the same region of the valence-arousal plane.
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Tamayo P, Montes C, Perez ME, Martin E, García-Talavera JR. A novel, fully automated, observer-independent program for semiquantifying striatal ¹²³I-FP-CIT uptake. Rev Esp Med Nucl Imagen Mol 2014; 34:89-94. [PMID: 25304848 DOI: 10.1016/j.remn.2014.08.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 08/18/2014] [Accepted: 08/20/2014] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To describe and validate a novel, fully automated program specifically designed for the semiquantification of striatal (123)I-FP-CIT uptake using volumes of interest (VOI) analysis. MATERIAL AND METHODS The proposed algorithm is based on a template that mimics the striatal (123)I-FP-CIT uptake in a healthy subjects, derived from defined anatomical VOIs available from WFU PickAtlas. Four SPECT studies of the anthropomorphic Alderson phantom filled with variable radioactive concentrations were acquired for the experimental validation. Experimental SPECT images were spatially normalized with respect to the previously created template. The binary VOIs corresponding to left caudate and putamen and right caudate and putamen, which were used to construct the template, were projected onto the experimental images to obtain the counts for these regions. To minimize the partial volume effect, a percentage of the voxels in these regions (threshold), rather than all of them, was used. A binary occipital VOI was used to quantify the non-specific uptake. Experimental binding potentials (BPs) were calculated from the counts in these regions. True BPs were calculated from aliquots taken from the solutions used to fill the phantom. RESULTS There were statistically significant differences in the experimental BP values (p<0.002) according to the percentage of voxels used. A highly significant correlation was achieved between true and experimental BP values, regardless of the percentage of voxels included for quantification. CONCLUSIONS Our novel, observer-independent program automatically performs the semiquantification of striatal (123)I-FP-CIT uptake in experimental studies.
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Affiliation(s)
- P Tamayo
- Nuclear Medicine Department, University Hospital of Salamanca, Spain; Institute of Biomedical Research of Salamanca, Spain.
| | - C Montes
- Medical Physics Department, University Hospital of Salamanca, Spain; Institute of Biomedical Research of Salamanca, Spain
| | - M E Perez
- Medical Physics Department, University Hospital of Salamanca, Spain
| | - E Martin
- Nuclear Medicine Department, University Hospital of Salamanca, Spain
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Barro-Soria R, Rebolledo S, Liin SI, Perez ME, Sampson K, Kass RS, Larsson HP. KCNE1 Separates the Main Voltage Sensor Movement and Channel Opening in KCNQ1/KCNE1 Channels. Biophys J 2014. [DOI: 10.1016/j.bpj.2013.11.825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Abstract
Voltage-gated proton (Hv) channels play an essential role in phagocytic cells by generating a hyperpolarizing proton current that electrically compensates for the depolarizing current generated by the NADPH oxidase during the respiratory burst, thereby ensuring a sustained production of reactive oxygen species by the NADPH oxidase in phagocytes to neutralize engulfed bacteria. Despite the importance of the voltage-dependent Hv current, it is at present unclear which residues in Hv channels are responsible for the voltage activation. Here we show that individual neutralizations of three charged residues in the fourth transmembrane domain, S4, all reduce the voltage dependence of activation. In addition, we show that the middle S4 charged residue moves from a position accessible from the cytosolic solution to a position accessible from the extracellular solution, suggesting that this residue moves across most of the membrane electric field during voltage activation of Hv channels. Our results show for the first time that the charge movement of these three S4 charges accounts for almost all of the measured gating charge in Hv channels.
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Affiliation(s)
- Carlos Gonzalez
- Department of Physiology and Biophysics, University of Miami, Miami, FL 33136, USA. carlos.gonzalezl@uv
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29
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Perez ME, Haramboure M, Mirande L, Romanelli GP, Schneider MI, Autino JC. Biological activity of three alkyl cinnamates on young larvae of Tuta absoluta. Commun Agric Appl Biol Sci 2013; 78:299-303. [PMID: 25145249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The "tomato moth," Tuto absoluta (Meyrick) (Lepidoptera: Gelechiidae), is a neotropical oligophagous insect considered a key pest of tomato crops. It was detected in Europe seven years ago and quickly spread to several regions of Asia and North Africa. In Argentina, its control is done by chemical pesticides mainly. The indiscriminate use of chemical broad spectrum pesticides have caused several problems in the control of this pest due to resistance mechanism involved to several insecticides including pyrethroids, organophosphates and biopesticides. In this context, the searching and evaluation of new compounds- compatible with integrated pest management programs- has become relevant. Within the phenylpropanoids, alkyl cinnamates, whether natural or synthetic, have been reported with biological activity: repellence, antifeedant and insecticide. Therefore, the cinnamates could be a valuable alternative to replace the conventional insecticides. The aim of this work was to study the antifeedant effect of three alkyl cinnamates (methyl, ethyl and propyl cinnamate) on the consumption rate patterns of second instar larvae of T. absoluta. A series of concentrations of each compound (100, 250 and 500 micrograms/milliliter) were prepared using acetone (analytical grade) - distilled water as solvent and a surfactant (Tween 80) was added to each solution to improve the wet of leaves. Tomato leaf disks of 2 cm diameter were treated by immersion in each solution during 15 seconds. Afterward, the treated discs were dried under fume hood and each disk was placed in a plastic capsule. A larva with 6-8 hours of starvation was added to each experimental unit. Each treatment was replicated between 24-30 times. The area consumed by each larva was measured after 24, 48 and 72 hours post-treatment. We also evaluated development time, weight of the pupa, adult emergence, fecundity and fertility as sublethal effects. The results were analyzed using ANOVA test. None of the compounds tested at the aforementioned concentrations exhibited insecticidal effect. However, ethyl cinnamate showed a strong antifeedant effect. The results observed on the leaf consumption and other sublethal effects assessed will be discussed. According to these preliminary results, further studies are needed to complete its toxicological profile by other exposure methods.
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Toledo C, Perez ME, Rocchi M, Gribaudo G, Mangiaterra S, Monterisi A. [Isolation of enterococci species causative of infections and sensitivity to antimicrobial drugs]. Rev Argent Microbiol 2004; 36:31-5. [PMID: 15174747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/29/2023] Open
Abstract
Between April 1, 1999 and June 30, 2000, 144 isolates of enterococci (one per patient) from cultures of several anatomic sites were collected. One hundred and nineteen (82.6%) E. faecalis, 11 (7.6%) E. faecium and 14 (9.7%) of other species (5 E. raffinosus, 4 E. avium, 3 E. casseliflavus, 1 E. pseudoavium, and 1 E. dispar) were associated with clinical infections. The most common sites of isolation were: the urinary tract 54.9%, abdominal cavity 12.5%, surgical wounds 12.5%, abscesses 6.9% and diabetic foot 6.2%. High-level resistance to gentamicin or streptomycin or both was detected in 48.6% of the isolates. E. faecium and E. raffinosus were significantly more resistant than E. faecalis to ampicilin and imipenem. None of the strains exhibited beta-lactamase activity. One strain of E. faecium (0.7%) was resistant to vancomicin and teicoplanin (Van A phenotype) and two strains of E. casseliflavus (1.4%) showed low level of resistance to vancomicin (Van C phenotype). Because of these diverse antimicrobial resistance mechanisms, successful treatment and control of enterococcal infections with current antimicrobial agents are becoming increasingly difficult.
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Affiliation(s)
- C Toledo
- Division Bacteriología, Laboratorio Central, Hospital Nacional de Clínicas, Santa Rosa 1564, X5000ETF Córdoba, Argentina
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Yasuhara S, Perez ME, Kanakubo E, Yasuhara Y, Shin YS, Kaneki M, Fujita T, Martyn JA. Skeletal muscle apoptosis after burns is associated with activation of proapoptotic signals. Am J Physiol Endocrinol Metab 2000; 279:E1114-21. [PMID: 11052967 DOI: 10.1152/ajpendo.2000.279.5.e1114] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Critical illness is associated with muscle wasting and muscle weakness. Using burn injury as a model of local and systemic inflammatory response, we tested the hypothesis that thermal injury causes apoptosis in muscle. After a 40% body surface area burn to rats, abdominal muscles beneath the burn and limb muscles distant from the burn were examined for apoptosis at varying times after burn. Ladder assay, ELISA, and histological methods showed evidence of apoptosis in the abdominal muscles within 4-12 h with peak changes occurring at 3-7 days. Maximal apoptosis was also evident at distant limb muscles at 3-7 days. Investigation of proapoptotic pathways indicated mitochondrial membrane potential to be altered by 1 h after burn. Starting at 15 min after burn, cytochrome c was released from the mitochondria into the cytosol, followed by increased activity of caspase-3, starting at 6 h after burn. These studies suggest that mitochondria and caspase-mediated apoptotic pathways may be an additional mechanism of muscle weight loss in burns and may be potential therapeutic targets for prevention of muscle wasting.
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Affiliation(s)
- S Yasuhara
- Department of Anesthesiology and Critical Care, Massachusetts General Hospital, Boston 02114, USA
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Yasuhara S, Kanakubo E, Perez ME, Kaneki M, Fujita T, Okamoto T, Martyn JA. The 1999 Moyer award. Burn injury induces skeletal muscle apoptosis and the activation of caspase pathways in rats. J Burn Care Rehabil 1999; 20:462-70. [PMID: 10613683 DOI: 10.1097/00004630-199920060-00007] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Burn injury induces many metabolic disorders, including altered protein kinetics with muscle weakness. The skeletal muscle weakness that occurs as a result of the loss of muscle mass causes hypoventilation and dependence on respirators, a condition that increases morbidity and mortality. The presence or absence of apoptosis in muscle, which can be a cause of the loss of muscle mass, was studied in rats after they had received scald burns to 40% of their body surface areas. The potential pro-apoptotic pathways that were activated were also examined. The burn injury produced did not directly destroy the muscle beneath; muscles just beneath the burned surface showed dramatic apoptotic changes according to assessments with the cell death enzyme-linked immunosorbent assay and in situ TdT-mediated dUTP-X nick-end labeling staining. The extent of apoptosis reached a peak on postburn days 3 and 7. Of note is that apoptosis was also confirmed in muscles at sites distant from the burn injury (eg, tibialis anterior) on both postburn days 3 and 7, a condition that is suggestive of the systemic effects of pro-apoptotic factors. To show that heat itself causes the initiation of the pro-apoptotic signaling, muscle-derived C2C12 cells were subjected to heat treatment at 55 degrees C. Ceramide, a key apoptotic second messenger, was observed to increase in the caveolae fraction but not in non-caveolae fraction of these muscle cells. In muscle tissue from burned rats, stress-activated protein kinase (a downstream-signaling kinase of ceramide) was activated soon after burn injury; this finding is consistent with the hypothesis that ceramide plays a role in burn-induced apoptosis. Caspase-1, -3, and -9, important final apoptotic enzymes involved with the downstream signaling of stress-activated protein kinase, were also activated after burn injury in muscle tissue from burned rats. These findings confirm the hypothesis that apoptosis occurs in skeletal muscle and that major apoptotic pathways are activated after a burn injury. Further characterization of these apoptotic signaling cascades may provide new therapeutic targets for the prevention of burn-induced muscle wasting.
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Affiliation(s)
- S Yasuhara
- Department of Anesthesiology, Harvard Medical School, Massachusetts General Hospital, Shriners Burns Institute, Boston, USA
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