title: The cytoplasmic domain of TGFβR3 through its interaction with the scaffolding protein, GIPC, directs epicardial cell behavior.
abstract: The epicardium is a major contributor of the cells that are required for the formation of coronary vessels. Mice lacking both copies of the gene encoding the Type III Transforming Growth Factor β Receptor (TGFβR3) fail to form the coronary vasculature, but the molecular mechanism by which TGFβR3 signals coronary vessel formation is unknown. We used intact embryos and epicardial cells from E11.5 mouse embryos to reveal the mechanisms by which TGFβR3 signals and regulates epicardial cell behavior. Analysis of E13.5 embryos reveals a lower rate of epicardial cell proliferation and decreased epicardially derived cell invasion in Tgfbr3(-/-) hearts. Tgfbr3(-/-) epicardial cells in vitro show decreased proliferation and decreased invasion in response to TGFβ1 and TGFβ2. Unexpectedly, loss of TGFβR3 also decreases responsiveness to two other important regulators of epicardial cell behavior, FGF2 and HMW-HA. Restoring full length TGFβR3 in Tgfbr3(-/-) cells rescued deficits in invasion in vitro in response TGFβ1 and TGFβ2 as well as FGF2 and HMW-HA. Expression of TGFβR3 missing the 3 C-terminal amino acids that are required to interact with the scaffolding protein GIPC1 did not rescue any of the deficits. Overexpression of GIPC1 alone in Tgfbr3(-/-) cells did not rescue invasion whereas knockdown of GIPC1 in Tgfbr3(+/+) cells decreased invasion in response to TGFβ2, FGF2, and HMW-HA. We conclude that TGFβR3 interaction with GIPC1 is critical for regulating invasion and growth factor responsiveness in epicardial cells and that dysregulation of epicardial cell proliferation and invasion contributes to failed coronary vessel development in Tgfbr3(-/-) mice.
authors.affiliation: Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN 37232-6600, USA.
authors.forename: Nora S
authors.initials: NS
authors.lastname: Sánchez
authors.forename: Cynthia R
authors.initials: CR
authors.lastname: Hill
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Love
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Soslow
authors.forename: Evisabel
authors.initials: E
authors.lastname: Craig
authors.forename: Anita F
authors.initials: AF
authors.lastname: Austin
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Brown
authors.forename: Andras
authors.initials: A
authors.lastname: Czirok
authors.forename: Todd D
authors.initials: TD
authors.lastname: Camenisch
authors.forename: Joey V
authors.initials: JV
authors.lastname: Barnett
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000187:drug effects; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology; D049109:Cell Proliferation / Q000187:drug effects; D003330:Coronary Vessel Anomalies / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects; D005260:Female; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D051379:Mice; D057507:Mice, 129 Strain; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008955:Models, Cardiovascular; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D009479:Neuropeptides / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010496:Pericardium / Q000166:cytology* / Q000196:embryology / Q000378:metabolism*; D011247:Pregnancy; D054730:Protein Interaction Domains and Motifs; D011509:Proteoglycans / Q000737:chemistry* / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D018125:Receptors, Transforming Growth Factor beta / Q000737:chemistry* / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D059008:Time-Lapse Imaging; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D053781:Transforming Growth Factor beta2 / Q000494:pharmacology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D017931:DNA Primers; C115271:Gipc1 protein, mouse; D009479:Neuropeptides; D011509:Proteoglycans; D018125:Receptors, Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D053781:Transforming Growth Factor beta2; C071736:betaglycan