The ERG1 Potassium Channel is More Abundant in Skeletal Muscle from Cachectic than Healthy Humans

Abstract Background: The ERG1a potassium channel has been detected in the atrophying skeletal muscle of mice experiencing either muscle disuse or cancer cachexia and further evidenced to contribute to muscle deterioration by enhancing ubiquitin proteolysis; however, to our knowledge, ERG1 has not been reported in human skeletal muscle. Methods and Results: Here, using immunohistochemistry, we detect ERG1 immunofluorescence in human Rectus abdominis skeletal muscle sarcolemma. Further, using single point brightness data, we report detection of ERG1 immunofluorescence at low levels in the Rectus abdominis muscle sarcolemma of young adult humans and show that it trends toward greater levels (10.6%) in healthy aged adults. Interestingly, we detect ERG1 immunofluorescence at a statistically greater level (53.6%; p<0.05) in the skeletal muscle of older people having cancer cachexia than in age-matched adults. Importantly, using immunoblot, we reveal that ERG1 protein is 38% (p<0.09) more abundant in the skeletal muscle of cachectic older adults than in healthy age-matched controls. Additionally, we report that the ERG1 fluorescent pattern is consistent with I-band localization. Conclusions: The data suggest that ERG1 may be related to muscle loss in humans and is located in t-tubules where it could influence calcium handling.