Phosphorylation of proteins during human myometrial contractions: A phosphoproteomic approach

Biochem Biophys Res Commun. 2017 Jan 22;482(4):1393-1399. doi: 10.1016/j.bbrc.2016.12.047. Epub 2016 Dec 9.


Phasic myometrial contractility is a key component of human parturition and the contractions are driven by reversible phosphorylation of myosin light chains catalyzed by the calcium (Ca2+)-dependent enzyme myosin light chain kinase (MYLK). Other yet unknown phosphorylation or de-phosphorylation events may contribute to myometrial contraction and relaxation. In this study we have performed a global phosphoproteomic analysis of human myometrial tissue using tandem mass tagging to detect changes in the phosphorylation status of individual myometrial proteins during spontaneous and oxytocin-driven phasic contractions. We were able to detect 22 individual phosphopeptides whose relative ratio changed (fold > 2 or < 0.5) in response to spontaneous or oxytocin-stimulated contraction. The most significant changes in phosphorylation were to MYLK on serine 1760, a site associated with reductions in calmodulin binding and subsequent kinase activity. Phosphorylated MYLK (ser1760) increased significantly during spontaneous (9.83 ± 3.27 fold, P < 0.05) and oxytocin -induced (18.56 ± 8.18 fold, P < 0.01) contractions and we were able to validate these data using immunoblotting. Pathway analysis suggested additional proteins involved in calcium signalling, cGMP-PRKG signalling, adrenergic signalling and oxytocin signalling were also phosphorylated during contractions. This study demonstrates that a global phosphoproteomic analysis of myometrial tissue is a sensitive approach to detect changes in the phosphorylation of proteins during myometrial contractions, and provides a platform for further validation of these changes and for identification of their functional significance.

Keywords: Contractility; Myometrium; Myosin light chain kinase; Parturition; Phosphoproteomics; Uterus.

MeSH terms

  • Calcium / metabolism
  • Calcium Signaling
  • Calmodulin / chemistry
  • Female
  • Humans
  • Myometrium / metabolism*
  • Myosin-Light-Chain Kinase / metabolism
  • Oxytocin / physiology*
  • Phosphopeptides / chemistry
  • Phosphorylation
  • Proteome*
  • Proteomics
  • Signal Transduction
  • Uterine Contraction*


  • Calmodulin
  • Phosphopeptides
  • Proteome
  • Oxytocin
  • Myosin-Light-Chain Kinase
  • Calcium