Kvβ2 deletion results in hindlimb muscle fibre type switching and enhanced endurance capabilities

Abstract

The Kvβ2 subunit, a member of the Kv (voltage‐gated potassium channel) auxiliary subunits is a dynamic protein interacting with many protein. Previous research has highlighted Kvβ2's abundance during myogenesis and its interactions with key contractility proteins including calmodulin and myosin filaments. Recently we demonstrated that Kvβ2 knockout (KO) mice have a significant increase (+100%) in type I muscle fiber (MHCI) expression within the Soleus muscle compared with wild‐type control mice. Similarly, a significant increase (+47%) in MHCI expression within the Gastrocnemius muscle was also observed within KO mice compared with wildtype. Based upon the deletion of Kvβ2 resulting in altered myofibre distribution towards a slower phenotype, we hypothesize that Kvβ2 KO mice have greater endurance capabilities via a greater presence of oxidative muscle fibers. Indeed, preliminary data utilizing 12–20 week old Kvβ2 KO male mice showed significantly (p<0.01) increased average time in the inverted hang test (534±52s vs. 159±44s) compared with control wildtype. Additional endurance testing utilizing the rotarod demonstrated Kvβ2 KO mice again performed for longer at a given rpm when compared with control mice. While endurance based activities were significantly increased in Kvβ2 KO mice little change was noted in activities which are predominantly fast‐twitch reliant. Grip strength analysis measuring overall force generated demonstrated no significant difference between Kvβ2 KO and control (111±2gF vs. 118±5gF) mice. Overall, this is the first report identifying that genetic deletion of Kvβ2 leads to an increased endurance capacity resulting from a substantial increase in type I muscle fiber expression in hindlimb muscles.Support or Funding InformationThis Research work was funded by National Institutes of Health (NIH) Grant R01‐HL‐102171 (S. M. Tipparaju).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.