title: TRA2β controls Mypt1 exon 24 splicing in the developmental maturation of mouse mesenteric artery smooth muscle.
abstract: Diversity of smooth muscle within the vascular system is generated by alternative splicing of exons, yet there is limited understanding of its timing or control mechanisms. We examined splicing of myosin phosphatase regulatory subunit (Mypt1) exon 24 (E24) in relation to smooth muscle myosin heavy chain (Smmhc) and smoothelin (Smtn) alternative exons (Smmhc E6 and Smtn E20) during maturation of mouse mesenteric artery (MA) smooth muscle. The role of transformer 2β (Tra2β), a master regulator of splicing in flies, in maturation of arterial smooth muscle was tested through gene inactivation. Splicing of alternative exons in bladder smooth muscle was examined for comparative purposes. MA smooth muscle maturation began after postnatal week 2 and was complete at maturity, as indicated by switching to Mypt1 E24+ and Smtn E20- splice variants and 11-fold induction of Smmhc. Similar changes in bladder were complete by postnatal day 3. Splicing of Smmhc E6 was temporally dissociated from Mypt1 E24 and Smtn E20 and discordant between arteries and bladder. Tamoxifen-induced smooth muscle-specific inactivation of Tra2β within the first week of life but not in maturity reduced splicing of Mypt1 E24 in MAs. Inactivation of Tra2β causing a switch to the isoform of MYPT1 containing the COOH-terminal leucine zipper motif (E24-) increased arterial sensitivity to cGMP-mediated relaxation. In conclusion, maturation of mouse MA smooth muscle begins postnatally and continues until sexual maturity. TRA2β is required for specification during this period of maturation, and its inactivation alters the contractile properties of mature arterial smooth muscle.
authors.affiliation: Division of Cardiovascular Medicine, School of Medicine, University of Maryland, Baltimore, Maryland;
authors.forename: Xiaoxu
authors.initials: X
authors.lastname: Zheng
authors.affiliation: Division of Cardiovascular Medicine, School of Medicine, University of Maryland, Baltimore, Maryland;
authors.forename: John J
authors.initials: JJ
authors.lastname: Reho
authors.affiliation: Institute of Human Genetics, University of Cologne, Cologne, Germany; Institute for Genetics, University of Cologne, Cologne, Germany; and Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.
authors.forename: Brunhilde
authors.initials: B
authors.lastname: Wirth
authors.affiliation: Division of Cardiovascular Medicine, School of Medicine, University of Maryland, Baltimore, Maryland; sfisher1@medicine.umaryland.edu.
authors.forename: Steven A
authors.initials: SA
authors.lastname: Fisher
mesh_terms: D000367:Age Factors; D017398:Alternative Splicing; D000818:Animals; D002454:Cell Differentiation; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005091:Exons; D005260:Female; D018507:Gene Expression Regulation, Developmental; D005838:Genotype; D066298:In Vitro Techniques; D008297:Male; D008638:Mesenteric Arteries / Q000201:enzymology; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000201:enzymology*; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000235:genetics / Q000378:metabolism*; D043263:Myosin-Light-Chain Phosphatase; D009687:Nuclear Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D000068103:Serine-Arginine Splicing Factors; D024745:Smooth Muscle Myosins / Q000235:genetics / Q000378:metabolism; D014664:Vasodilation; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D003598:Cytoskeletal Proteins; D009124:Muscle Proteins; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; C491050:Smtn protein, mouse; C100345:Tra2b protein, mouse; D014665:Vasodilator Agents; D000068103:Serine-Arginine Splicing Factors; C016276:8-bromocyclic GMP; D009219:Myosin-Light-Chain Kinase; D043263:Myosin-Light-Chain Phosphatase; C510645:Ppp1r12a protein, mouse; D024745:Smooth Muscle Myosins; D018995:Myosin Heavy Chains; D006152:Cyclic GMP
keywords: alternative splicing; cGMP; development; myosin phosphatase; smooth muscle