βIV-Spectrin regulates TREK-1 membrane targeting in the heart

Hund, Thomas J.; Snyder, John P.; Wu, Xuan; Glynn, Patric; Koval, Olha M.; Önal, Birce; Leymaster, Nicholas D.; Unudurthi, Sathya D.; Curran, James F.; Camardo, Celia; Wright, Patrick; Binkley, Philip F.; Anderson, Mark E.; Mohler, Peter J.

doi:10.1093/cvr/cvu008

Cited by 42 publications

(66 citation statements)

References 42 publications

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“…β IV ‐spectrin was detectable in WT mouse atrium and SAN by both immunoblot and immunostaining and was not affected by TREK‐1 deficiency (Figure 6A, 6B, and 6D). In contrast, SAN myocytes from qv 4J mice lacking spectrin/TREK‐1 interaction8 demonstrated abnormal membrane localization of TREK‐1 (Figure 6C). Based on previous findings that qv 4J animals show increased susceptibility to stress‐induced sinus pause,8 similar to αMHC‐ Kcnk2 f/f animals, spontaneous APs were measured in isolated qv 4J SAN cells (Figure 3A).…”

Section: Resultsmentioning

confidence: 95%

“…TREK‐1 expression has been reported throughout all regions of the heart3, 8, 10, 36; however, few data are available on relative levels of expressed protein in SAN, atrium, and ventricle. TREK‐1 protein expression was assessed in different mouse heart regions to determine whether differential expression could contribute to the predominant SAN phenotypes observed in αMHC‐ Kcnk2 f/f mice.…”

Section: Resultsmentioning

confidence: 99%

“…Experimental mice were generated by crossing these animals with mice expressing Cre under the cardiac promoter α‐myosin heavy chain (αMHC‐Cre), resulting in cardiac‐specific deletion of TREK‐1 (αMHC‐ Kcnk2 f/f ). The qv 4J mice (which express a mutant β IV ‐spectrin allele with a premature stop codon in spectrin repeat 10)8, 17 were obtained from Jackson Laboratory (Bar Harbor, ME). All experiments were performed in male mice aged 2 months (30 wild‐type [WT], 30 αMHC‐ Kcnk2 f/f , and 12 qv 4J animals were used for studies).…”

Section: Methodsmentioning

confidence: 99%

“…In addition, small differences in protein loading were corrected using normalization to levels of actin or GAPDH. Adult heart immunoprecipitations were performed, as described previously 8. The following antibodies were used for immunoblotting, immunoprecipitation, or immunostaining: TREK‐1 (C‐terminal: sc50412, N‐terminal: sc11554; Santa Cruz Biotechnology), β IV ‐spectrin (N‐terminal, HPA043370, lot A96519; Sigma‐Aldrich), K ir 2.1 (Alomone), K v 2.1 (NeuroMab), K v 4.2 (Alomone), K v 4.3, TASK‐1 (APC024; Alomone), HCN4 (32675, lot GR153269‐7; Abcam), N‐cadherin (333900, lot 1397763A; Invitrogen), Connexin43 (MAB3067, lot 23070602; Invitrogen), and GAPDH (10R‐G109A; Fitzgerald).…”

Section: Methodsmentioning

confidence: 99%

“…TREK‐1 is highly expressed in the nervous system, where it regulates depression phenotypes and nociception. Expression of TREK‐1 has also been identified in heart with proposed roles in regulation of myocyte membrane excitability,7, 8, 9, 10, 11, 12, 13, 14 although its role in specific cardiac phenotypes remains unclear.…”

Section: Introductionmentioning

confidence: 99%

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Two‐Pore K ⁺ Channel TREK‐1 Regulates Sinoatrial Node Membrane Excitability

Unudurthi

Lei

et al. 2016

JAHA

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BackgroundTwo‐pore K+ channels have emerged as potential targets to selectively regulate cardiac cell membrane excitability; however, lack of specific inhibitors and relevant animal models has impeded the effort to understand the role of 2‐pore K+ channels in the heart and their potential as a therapeutic target. The objective of this study was to determine the role of mechanosensitive 2‐pore K+ channel family member TREK‐1 in control of cardiac excitability.Methods and ResultsCardiac‐specific TREK‐1–deficient mice (αMHC‐Kcnk f/f) were generated and found to have a prevalent sinoatrial phenotype characterized by bradycardia with frequent episodes of sinus pause following stress. Action potential measurements from isolated αMHC‐Kcnk2 f/f sinoatrial node cells demonstrated decreased background K+ current and abnormal sinoatrial cell membrane excitability. To identify novel pathways for regulating TREK‐1 activity and sinoatrial node excitability, mice expressing a truncated allele of the TREK‐1–associated cytoskeletal protein βIV‐spectrin (qv 4J mice) were analyzed and found to display defects in cell electrophysiology as well as loss of normal TREK‐1 membrane localization. Finally, the βIV‐spectrin/TREK‐1 complex was found to be downregulated in the right atrium from a canine model of sinoatrial node dysfunction and in human cardiac disease.ConclusionsThese findings identify a TREK‐1–dependent pathway essential for normal sinoatrial node cell excitability that serves as a potential target for selectively regulating sinoatrial node cell function.

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Two‐Pore K ⁺ Channel TREK‐1 Regulates Sinoatrial Node Membrane Excitability

Unudurthi

Lei

et al. 2016

JAHA

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The potassium current carried by TREK-1 channels in rat cardiac ventricular muscle

Bodnár

Schlichthörl

Daut

2014

Pflugers Arch - Eur J Physiol

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We studied the potassium current flowing through TREK-1 channels in rat cardiac ventricular myocytes. We separated the TREK-1 current from other current components by blocking most other channels with a blocker cocktail. We tried to inhibit the TREK-1 current by activating protein kinase A (PKA) with a mixture of forskolin and isobutyl-methylxanthine (IBMX). Activation of PKA blocked an outwardly rectifying current component at membrane potentials positive to -40 mV. At 37 °C, application of forskolin plus IBMX reduced the steady-state outward current measured at positive voltages by about 52 %. Application of the potassium channel blockers quinidine or tetrahexylammonium also reduced the steady-state outward current by about 50 %. Taken together, our results suggest that the increase in temperature from 22 to 37 °C increased the TREK-1 current by a factor of at least 5 and that the average density of the TREK-1 current in rat cardiomyocytes at 37 °C is about 1.5 pA/pF at +30 mV. The contribution of TREK-1 to the action potential was assessed by using a dynamic patch clamp technique. After subtraction of simulated TREK-1 currents, action potential duration at 50 or 90 % repolarisation was increased by about 12 %, indicating that TREK-1 may be functionally important in rat ventricular muscle. During sympathetic stimulation, inhibition of TREK-1 channels via PKA is expected to prolong the action potential primarily in subendocardial myocytes; this may decrease the transmural dispersion of repolarisation and thus may serve to prevent the occurrence of arrhythmias.

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