title: Alternatively Spliced Human TREK-1 Variants Alter TREK-1 Channel Function and Localization.
abstract: 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.
authors.affiliation: Myometrial Function Laboratory, Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada.
authors.forename: Chad L
authors.initials: CL
authors.lastname: Cowles
authors.affiliation: Myometrial Function Laboratory, Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada.
authors.forename: Yi-Ying
authors.initials: YY
authors.lastname: Wu
authors.affiliation: Myometrial Function Laboratory, Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada.
authors.forename: Scott D
authors.initials: SD
authors.lastname: Barnett
authors.affiliation: Myometrial Function Laboratory, Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Lee
authors.affiliation: Myometrial Function Laboratory, Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada.
authors.forename: Heather R
authors.initials: HR
authors.lastname: Burkin
authors.affiliation: Myometrial Function Laboratory, Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada ibuxton@medicine.nevada.edu.
authors.forename: Iain L O
authors.initials: IL
authors.lastname: Buxton
mesh_terms: D000328:Adult; D017398:Alternative Splicing; D016022:Case-Control Studies; D005260:Female; D057809:HEK293 Cells; D006801:Humans; D009215:Myometrium / Q000378:metabolism*; D007752:Obstetric Labor, Premature / Q000378:metabolism*; D024683:Potassium Channels, Tandem Pore Domain / Q000378:metabolism*; D011247:Pregnancy; D055815:Young Adult
chemical_list: D024683:Potassium Channels, Tandem Pore Domain; C103742:potassium channel protein TREK-1
keywords: TREK-1; electrophysiology; human myometrial smooth muscle; labor; myometrium; potassium channels; pregnancy; preterm labor; splice variants; uterus