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23 September 2015 Alternatively Spliced Human TREK-1 Variants Alter TREK-1 Channel Function and Localization
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TREK-1, an outward-rectifying potassium channel activated by stretch, is found in the myometrium of pregnant women. Decreased expression of TREK-1 near term suggests that TREK-1 may contribute to uterine quiescence during gestation. Five alternatively spliced TREK-1 variants were identified in the myometrium of mothers who delivered spontaneously preterm (<37 wk), leading to the hypothesis that these TREK-1 variants could interfere with TREK-1 function or expression. To investigate a potential role for these variants, immunofluorescence, cell surface assays, Western blots, and patch clamp were employed to study TREK-1 and TREK-1 variants expressed in HEK293T cells. The results of this study demonstrate that coexpression of TREK-1 with TREK-1 variants alters TREK-1 expression and suppresses channel function. Each variant affected TREK-1 in a disparate manner. In HEK293T cells coexpressing TREK-1 and each variant, TREK-1 membrane expression was diminished with compartmentalization inside the cell. When expressed alone, individual variants displayed channel properties that were significantly decreased compared to full-length TREK-1. In coexpression studies using patch clamp, basal TREK-1 currents were reduced by ∼64% (4.3 vs. 12.0 pA/pF) on average at 0 mV when coexpressed with each variant. TREK-1 currents that were activated by intracellular acidosis were reduced an average of ∼77% (21.4 vs. 94.5 pA/pF) at 0 mV when cells were transfected with TREK-1 and any one of the splice variants. These data correlate the presence of TREK-1 variants to reduced TREK-1 activity, suggesting a pathological role for TREK-1 variants in preterm labor.

Chad L. Cowles, Yi-Ying Wu, Scott D. Barnett, Michael T. Lee, Heather R. Burkin, and Iain L.O. Buxton "Alternatively Spliced Human TREK-1 Variants Alter TREK-1 Channel Function and Localization," Biology of Reproduction 93(5), (23 September 2015).
Received: 17 April 2015; Accepted: 1 September 2015; Published: 23 September 2015

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