Regulation Of Myosin Heavy Chain Gene Cluster Antisense RNA In Human Vastus Lateralis In Response To Exercise Training

The myosin heavy chain (MYH) gene cluster consists of IIa (MYH2), IIx (MYH1), IIb (MYH4) and the developmentally regulated Neonatal (MYH8) and Embryonic (MYH3). Expression is regulated in response to varying loading stimuli and developmental cues. The MYH genes are also transcribed and regulated from the antisense (AS) DNA strand. An uncharacterized human gene called myosin heavy chain gene cluster antisense RNA (MYHAS; NR_125367.1) is a 4 kb transcript spliced from the 241 kb MYH cluster. PURPOSE: to characterize the regulation of MYHAS and identify and characterize the regulation of additional AS splice variants discovered in the MYH gene cluster. We sought to determine if exercise training was sufficient to induce alterations in these AS transcripts, in association with a IIx to IIa MYH shift that was previously reported with this cohort (doi.org/10.1152/ajpcell.00166.2018). METHODS: Young (22 yr) sedentary subjects (12 M, 9 F) completed 5 wks of aerobic and resistance exercise (AE + RE). VL biopsies were obtained pre and post AE + RE. MYHAS-associated transcripts were sequenced and utilized to identify additional and novel AS genes within the cluster. RNA expression was quantified by real-time PCR. RESULTS: Sequencing of cDNA from human skeletal muscle led to the identification of 5 additional AS products in the MYH cluster with exons overlapping MYH1 and two AS products with exons overlapping MYH2. An AS gene transcribed within the intergenic region between MYH2 and MYH3 was confirmed by DNA sequencing. This linc RNA was decreased in expression in F after AE + RE (0.63-fold), and was slightly increased in M (1.17-fold) with a positive correlation (p < 0.05) with both MYH2 and MYH1 mRNA. An MYHAS splice variant that overlaps MYH1 was found to be decreased in expression in F after AE + RE (0.71-fold) and increased in M (1.54-fold). MYH1 mRNA was significantly decreased (p < 0.05, 0.43-fold) in M and F combined. CONCLUSIONS: The presence of AS genes with exons spanning the cluster of MYH genes may encompass a regulatory mechanism to coordinate the expression of the 5 neighboring MYH genes. The exercise response in the present study was not sufficient to induce large changes in the MYHAS transcripts identified and characterized herein. Further research will be required to determine the function of these AS genes within the MYH cluster. Supported by: National Space Biology Research Institute (NSBRI NCC 9-58-70, MA01601 to G.R.A. and PF02104 to C.E.P.) and the National Institutes of Health (NIH) Grant UCI CTSA UL1 TR000153