title: p19(Arf) limits primary vitreous cell proliferation driven by PDGF-B.
abstract: Arf encodes an important tumor suppressor, p19(Arf), which also plays a critical role to control hyperplasia in the primary vitreous during mouse eye development. In the absence of Arf, mice are born blind and display a phenotype closely mimicking severe forms of the human eye disease, persistent hyperplastic primary vitreous (PHPV). In this report, we characterize p19(Arf) expression in perivascular cells that normally populate the primary vitreous and express the Arf promoter. Using a new ex vivo model, we show that these cells respond to exogenous Tgfβ, despite being isolated at a time when Tgfβ has already turned on the Arf promoter. Treatment of the cells with PDGF-B ligand doubles the population of cells in S-phase and ectopic expression of Arf blunts that effect. We show this effect is mediated through Pdgfrβ as expression of Arf represses expression of Pdgfrβ mRNA and protein to approximately 60%. p53 is not required for Arf-dependent blockade of PDGF-B driven proliferation and repression of Pdgfrβ protein as ectopic expression of Arf is still able to inhibit the 2-fold increase in the S-phase fraction of cells upon treatment with PDGF-B. Finally, induction of mature miR-34a, a microRNA previously identified to be regulated by p19(Arf) does not depend on p53 while the expression of the primary transcript does require p53. These data corroborate that, as in vivo, p19(Arf) functions to inhibit PDGF-B driven proliferation ex vivo.
authors.affiliation: Division of Hematology/Oncology, Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA.
authors.forename: Nida S
authors.initials: NS
authors.lastname: Iqbal
authors.affiliation: Division of Hematology/Oncology, Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA.
authors.forename: Caitlin C
authors.initials: CC
authors.lastname: Devitt
authors.affiliation: Division of Hematology/Oncology, Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA.
authors.forename: Caroline Y
authors.initials: CY
authors.lastname: Sung
authors.affiliation: Gill Center for Cancer and Blood Disorders, Children's Medical Center, Dallas, TX, USA. Electronic address: Stephen.Skapek@UTSouthwestern.edu.
authors.forename: Stephen X
authors.initials: SX
authors.lastname: Skapek
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002453:Cell Cycle / Q000502:physiology; D049109:Cell Proliferation / Q000502:physiology*; D002478:Cells, Cultured; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000378:metabolism*; D051379:Mice; D020574:Proto-Oncogene Proteins c-sis / Q000502:physiology*; D020797:Receptor, Platelet-Derived Growth Factor beta / Q000494:pharmacology; D012164:Retinal Diseases / Q000503:physiopathology*; D016159:Tumor Suppressor Protein p53; D014822:Vitreous Body / Q000166:cytology* / Q000187:drug effects
chemical_list: C417743:Cdkn2a protein, mouse; D019941:Cyclin-Dependent Kinase Inhibitor p16; D020574:Proto-Oncogene Proteins c-sis; D016159:Tumor Suppressor Protein p53; D020797:Receptor, Platelet-Derived Growth Factor beta
keywords: PHPV; Pdgfrβ; Perivascular cells; Primary vitreous; miR-34a; p19(Arf); p53