Ca2+ regulation in equine muscle is important for horse performance, yet little is known about this species-specific regulation. We reported recently that horse encode unique gene and protein sequences for the sarcoplasmic reticulum (SR) Ca2+-transporting ATPase (SERCA) and the regulatory subunit sarcolipin (SLN). Here we quantified gene transcription and protein expression of SERCA and its inhibitory peptides in horse gluteus, as compared to commonly-studied rabbit skeletal muscle. RNA sequencing and protein immunoblotting determined that horse gluteus expresses the ATP2A1 gene (SERCA1) as the predominant SR Ca2+-ATPase isoform and the SLN gene as the most-abundant SERCA inhibitory peptide, as also found in rabbit skeletal muscle. Equine muscle expresses an insignificant level of phospholamban (PLN), another key SERCA inhibitory peptide expressed commonly in a variety of mammalian striated muscles. Surprisingly in horse, the RNA transcript ratio of SLN-to-ATP2A1 is an order of magnitude higher than in rabbit, while the corresponding protein expression ratio is an order of magnitude lower than in rabbit. Thus, SLN is not efficiently translated or maintained as a stable protein in horse muscle, suggesting a non-coding role for supra-abundant SLN mRNA. We propose that the lack of SLN and PLN inhibition of SERCA activity in equine muscle is an evolutionary adaptation that potentiates Ca2+ cycling and muscle contractility in a prey species domestically selected for speed.
Bibliographical noteFunding Information:
Funding: Research reported in this publication was supported in part by the Morris Animal Foundation under award number D16EQ-004 to S.J.V., J.M.A., and D.D.T., plus award number D14EQ-021 to E.C.M. and S.J.V. Morris Animal Foundation is the global leader in supporting science that advances animal health. Research reported in this publication was supported in part by the National Institutes of Health under award numbers R01GM027906, R01HL139065, and R37AG026160 to D.D.T. The content of this publication is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The funding agencies had no role in study design, data collection, data analysis, manuscript preparation, or decision to publish.
© 2020 by the authors. Licensee MDPI, Basel, Switzerland.
- Gene expression profiling
- Intracellular membranes
- Long noncoding RNA
- Protein subunits
- Sarcoplasmic reticulum calcium-transporting ATPases
- Western blotting
PubMed: MeSH publication types
- Journal Article