title: The Q510E mutation in Shp2 perturbs heart valve development by increasing cell migration.
abstract: Tightly regulated cellular signaling is critical for correct heart valve development, but how and why signaling is dysregulated in congenital heart disease is not very well known. We focused on protein tyrosine phosphatase Shp2, because mutations in this signaling modulator frequently cause valve malformations associated with Noonan syndrome or Noonan syndrome with multiple lentigines (NSML). To model NSML-associated valve disease, we targeted overexpression of Q510E-Shp2 to mouse endocardial cushions (ECs) using a Tie2-Cre-based approach. At midgestation, Q510E-Shp2 expression increased the size of atrioventricular ECs by 80%. To dissect the underlying cellular mechanisms, we explanted ECs from chick embryonic hearts and induced Q510E-Shp2 expression using adenoviral vectors. Valve cell outgrowth from cultured EC explants into surrounding matrix was significantly increased by Q510E-Shp2 expression. Because focal adhesion kinase (FAK) is a critical regulator of cell migration, we tested whether FAK inhibition counteracts the Q510E-Shp2-induced effects in explanted ECs. The FAK/src inhibitor PP2 normalized valve cell outgrowth from Q510E-Shp2-expressing ECs. Next, chick ECs were further dissociated to assess cell proliferation and migration. Valve cell proliferation was not increased by Q510E-Shp2 as determined by label incorporation. In contrast, valve cell migration as reflected in a wound-healing assay was increased by Q510E-Shp2 expression, indicating that increased migration is the predominant effect of Q510E-Shp2 expression in ECs. In conclusion, PP2-sensitive signaling mediates the pathogenic effects of Q510E-Shp2 on cell migration in EC explant cultures. This suggests a central role for FAK and provides new mechanistic insight into the molecular basis of valve defects in NSML.
authors.affiliation: Department of Medical Pharmacology & Physiology and the Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia Missouri.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Edwards
authors.affiliation: Department of Medical Pharmacology & Physiology and the Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia Missouri.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Crombie
authors.affiliation: Department of Medical Pharmacology & Physiology and the Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia Missouri.
authors.forename: Christine
authors.initials: C
authors.lastname: Schramm
authors.affiliation: Department of Medical Pharmacology & Physiology and the Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia Missouri krenzm@missouri.edu.
authors.forename: Maike
authors.initials: M
authors.lastname: Krenz
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000235:genetics*; D049109:Cell Proliferation / Q000235:genetics; D002642:Chick Embryo; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000235:genetics; D006351:Heart Valves / Q000196:embryology*; D051379:Mice; D008822:Mice, Transgenic; D009154:Mutation; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11 / Q000235:genetics*; D015398:Signal Transduction / Q000235:genetics
chemical_list: D051416:Focal Adhesion Protein-Tyrosine Kinases; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11
keywords: LEOPARD syndrome; Noonan syndrome with multiple lentigines; PTPN11; Shp2; focal adhesion kinase; valve development