Identification and characterization of alternative splice variants of the mouse Trek2/Kcnk10 gene.

Two-pore domain K(+) (K(2P)) channels underlie leak or background potassium conductances in many cells. The Trek subfamily of K(2P) channels, which includes Trek1/Kcnk2 and Trek2/Kcnk10 and has been implicated in depression, nociception, and cognition, exhibits complex regulation and can modulate cell excitability in response to a wide array of stimuli. While alternative translation initiation and alternative splicing contribute to the structural and functional diversity of Trek1, the impact of post-transcriptional modifications on the expression and function of Trek2 is unclear. Here, we characterized two novel splice isoforms of the mouse Trek2 gene. One variant is a truncated form of Trek2 that possesses two transmembrane segments and one pore domain (Trek2-1p), while the other (Trek2b) differs from two known mouse Trek2 isoforms (Trek2a and Trek2c) at the extreme amino terminus. Both Trek2-1p and Trek2b, and Trek2a and Trek2c, showed prominent expression in the mouse CNS. Expression patterns of the Trek2 variants within the CNS were largely overlapping, though some isoform-specific differences were noted. Heterologous expression of Trek2-1p yielded no novel whole-cell currents in transfected human embryonic kidney (HEK) 293 cells. In contrast, expression of Trek2b correlated with robust K(+) currents that were ~fivefold larger than currents measured in cells expressing Trek2a or Trek2c, a difference mirrored by significantly higher levels of Trek2b found at the plasma membrane. This study provides new insights into the molecular diversity of Trek channels and suggests a potential role for the Trek2 amino terminus in channel trafficking and/or stability.