Mapping of the contraction-induced phosphoproteome identifies TRIM28 as a significant regulator of skeletal muscle size and function

Abstract

SUMMARY Mechanical signals, such as those evoked by maximal-intensity contractions (MICs), can induce an increase in muscle mass. Rapamycin-sensitive signaling events are widely implicated in the regulation of this process; however, recent studies indicate that rapamycin-insensitive signaling events are also involved. Thus, to identify these events, we generate a map of the MIC-regulated and rapamycin-sensitive phosphoproteome. In total, we quantify more than 10,000 unique phosphorylation sites and find that more than 2,000 of these sites are significantly affected by MICs, but remarkably, only 38 of the MIC-regulated events are mediated through a rapamycin-sensitive mechanism. Further interrogation of the rapamycin-insensitive phosphorylation events identifies the S473 residue on Tripartite Motif-Containing 28 (TRIM28) as one of the most robust MIC-regulated phosphorylation sites, and extensive follow-up studies suggest that TRIM28 significantly contributes to the homeostatic regulation of muscle size and function as well as the hypertrophy that occurs in response to increased mechanical loading.

Daily running enhances molecular and physiological circadian rhythms in skeletal muscle

“…Interestingly, analysis in gProfiler [ 53 ] reveals that this group of transcripts is highly enriched (p < 0.00001) for targets of RNF96 (a.k.a. TRIM28), which was recently shown to be activated by muscle contractions [ 54 ], consistent with the observed enhanced expression of these transcripts late in the active period in mice with access to running wheels.…”

Daily running enhances molecular and physiological circadian rhythms in skeletal muscle

“…Interestingly, analysis in gProfiler [53] reveals that this group of transcripts is highly enriched (p < 0.00001) for targets of RNF96 (a.k.a. TRIM28), which was recently shown to be activated by muscle contractions [54], consistent with the observed enhanced expression of these transcripts late in the active period in mice with access to running wheels. We used differential expression analysis (DESeq2) to identify individual transcripts most impacted by the enhanced activity afforded by access to a running wheel (with zeitgeber time as a confounding factor) (Figure 3A and Supplementary Table S6).…”

Weight Pulling: A Novel Mouse Model of Human Progressive Resistance Exercise

“…Myonuclei staining was performed as previously described [ 27 ]. Briefly, blocked samples were incubated for 1 h at room temp in buffer A containing mouse anti-dystrophin IgG1 (1:20, #NCL-DYS2, Novocastra/Leica, Buffalo Grove, IL, USA).…”