title: Role of serine-threonine phosphoprotein phosphatases in smooth muscle contractility.
abstract: The degree of phosphorylation of myosin light chain 20 (MLC20) is a major determinant of force generation in smooth muscle. Myosin phosphatases (MPs) contain protein phosphatase (PP) 1 as catalytic subunits and are the major enzymes that dephosphorylate MLC20. MP regulatory targeting subunit 1 (MYPT1), the main regulatory subunit of MP in all smooth muscles, is a key convergence point of contractile and relaxatory pathways. Combinations of regulatory mechanisms, including isoform splicing, multiple phosphorylation sites, and scaffolding proteins, modulate MYPT1 activity with tissue and agonist specificities to affect contraction and relaxation. Other members of the PP1 family that do not target myosin, as well as PP2A and PP2B, dephosphorylate a range of proteins that affect smooth muscle contraction. This review discusses the role of phosphatases in smooth muscle contractility with a focus on MYPT1 in uterine smooth muscle. Myometrium shares characteristics of vascular and other visceral smooth muscles yet, during healthy pregnancy, undergoes hypertrophy, hyperplasia, quiescence, and labor as physiological processes. Myometrium presents an accessible model for the study of normal and pathological smooth muscle function, and a better understanding of myometrial physiology may allow the development of novel therapeutics for the many disorders of myometrial physiology from preterm labor to dysmenorrhea.
authors: Mothers and Babies Research Centre, Faculty of Health, University of Newcastle, Callaghan, NSW 2308, Australia.
authors: Trent
authors: T
authors: Butler
authors: Jonathan
authors: J
authors: Paul
authors: Nick
authors: N
authors: Europe-Finner
authors: Roger
authors: R
authors: Smith
authors: Eng-Cheng
authors: EC
authors: Chan
mesh_terms: D000818:Animals; D005260:Female; D006801:Humans; D007473:Ion Channels / Q000378:metabolism; D051379:Mice; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000201:enzymology / Q000502:physiology*; D009215:Myometrium / Q000201:enzymology / Q000502:physiology*; D018994:Myosin Light Chains / Q000378:metabolism; D043263:Myosin-Light-Chain Phosphatase / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism; D010766:Phosphorylation; D011247:Pregnancy; D051381:Rats
chemical_list: D007473:Ion Channels; D018994:Myosin Light Chains; D043263:Myosin-Light-Chain Phosphatase; C490372:PPP1R12A protein, human; D009218:Myosins