TREK-1 regulation by nitric oxide and cGMP-dependent protein kinase. An essential role in smooth muscle inhibitory neurotransmission.

Seungil Ro,Rebecca L. Walker,Kenton M. Sanders,Kevin Monaghan,Sang Don Koh,Burton Horowitz,Gerard P. Sergeant

doi:10.1074/jbc.m108125200

Seungil Ro, Rebecca L. Walker + Show 5 more

Open Access

https://doi.org/10.1074/jbc.m108125200

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Abstract

Potassium channels activated by membrane stretch may contribute to maintenance of relaxation of smooth muscle cells in visceral hollow organs. Previous work has identified K(+) channels in murine colon that are activated by stretch and further regulated by NO-dependent mechanisms. We have screened murine gastrointestinal, vascular, bladder, and uterine smooth muscles for the expression of TREK and TRAAK mRNA. Although TREK-1 was expressed in many of these smooth muscles, TREK-2 was expressed only in murine antrum and pulmonary artery. TRAAK was not expressed in any smooth muscle cells tested. Whole cell currents from TREK-1 expressed in mammalian COS cells were activated by stretch, and single channel recordings showed that the stretch-dependent conductance was due to 90 pS channels. Sodium nitroprusside (10(-6) or 10(-5) m) and 8-Br-cGMP (10(-4) or 10(-3) m) increased TREK-1 currents in perforated whole cell and single channel recordings. Mutation of the PKG consensus sequence at serine 351 blocked the stimulatory effects of sodium nitroprusside and 8-Br-cGMP on open probability without affecting the inhibitory effects of 8-Br-cAMP. TREK-1 encodes a component of the stretch-activated K(+) conductance in smooth muscles and may contribute to nitrergic inhibition of gastrointestinal muscles.

Highlights

Potassium channels activated by membrane stretch may contribute to maintenance of relaxation of smooth muscle cells in visceral hollow organs
The stretch-activated K2P channels belong to the TREK family and include TREK-1, TREK-2, and TRAAK (KCNK2, KCNK4, and KCNK10, respectively)
Effects of sodium nitroprusside (SNP) and cGMP on TREK-1 Currents Expressed in COS Cell—We have found that NO donors and membranepermeable analogs of cGMP that stimulate protein kinase G (PKG) activate stretch-dependent Kϩ (SDK) channels in murine colonic myocytes [13]

Summary

AN ESSENTIAL ROLE IN SMOOTH MUSCLE INHIBITORY NEUROTRANSMISSION*

Kϩ channels can be activated by inhibitory neurotransmitters such as nitric oxide [2, 3], ATP [4], endothelial factors (endothelial-derived relaxing factor and endothelial-derived hyperpolarizing factor) [5,6,7], and ␤-receptor agonists [8, 9] Mechanical stimuli, such as cell stretch, can activate Kϩ channels (10 –12) and may participate in the regulation of excitability in the bladder, uterus, and gastrointestinal tract in response to distension of the organ wall. The native SDK channels in murine colonic myocytes were inactive under atmospheric pressure and displayed a dramatic increase in open probability upon application of negative pressure to the patch pipette in the on-cell configuration These channels were activated in response to smooth muscle cell stretch, which was accomplished by attaching two patch pipettes to either end of the cell and elongating the cell. These channels appear to be responsible for one of the nitric oxide-sensitive conductances in gastrointestinal muscles [13] and possibly vascular smooth muscles

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