MetaTOC stay on top of your field, easily

The cytokine response of primary human myotubes in an in vitro exercise model

, , , , , , , , ,

AJP Cell Physiology

Published online on

Abstract

Muscle contraction during exercise is a major stimulus for the release of peptides and proteins (myokines) that are supposed to take part in the beneficial adaptation to exercise. We hypothesize that application of an in vitro exercise stimulus as electric pulse stimulation (EPS) to human myotubes enables the investigation of the molecular response to exercise in a clearly defined model. We applied EPS for 24 h to primary human myotubes and studied the whole genome-wide transcriptional response as well as the release of candidate myokines. We observed 183 differentially regulated transcripts with fold-changes > 1.3. The transcriptional response resembles several properties of the in vivo situation in the skeletal muscle after endurance exercise, namely significant enrichment of pathways associated with interleukin and chemokine signaling, lipid metabolism, and anti-oxidant defense. Multiplex immunoassays verified the translation of the transcriptional response of several cytokines into high secretion levels (IL6, IL8, CXCL1, LIF, CSF3, IL1B, TNF) and the increased secretion of further myokines such as angiopoietin-like 4. Notably, EPS did not induce the release of creatine kinase. Inhibitor studies and immunoblotting revealed the participation of ERK1/2, JNK and NFB-dependent pathways in the upregulation of myokines. To conclude, our data highlight the importance of skeletal muscle cells as endocrine cells. This in vitro exercise model is not only suitable to identify exercise-regulated myokines but it might be applied to primary human myotubes obtained from different muscle biopsy donors to study the molecular mechanisms of the individual response to exercise.