title: DLX5, FGF8 and the Pin1 isomerase control ΔNp63α protein stability during limb development: a regulatory loop at the basis of the SHFM and EEC congenital malformations.
abstract: Ectrodactyly, or Split-Hand/Foot Malformation (SHFM), is a congenital condition characterized by the loss of central rays of hands and feet. The p63 and the DLX5;DLX6 transcription factors, expressed in the embryonic limb buds and ectoderm, are disease genes for these conditions. Mutations of p63 also cause the ectodermal dysplasia-ectrodactyly-cleft lip/palate (EEC) syndrome, comprising SHFM. Ectrodactyly is linked to defects of the apical ectodermal ridge (AER) of the developing limb buds. FGF8 is the key signaling molecule in this process, able to direct proximo-distal growth and patterning of the skeletal primordial of the limbs. In the limb buds of both p63 and Dlx5;Dlx6 murine models of SHFM, the AER is poorly stratified and FGF8 expression is severely reduced. We show here that the FGF8 locus is a downstream target of DLX5 and that FGF8 counteracts Pin1-ΔNp63α interaction. In vivo, lack of Pin1 leads to accumulation of the p63 protein in the embryonic limbs and ectoderm. We show also that ΔNp63α protein stability is negatively regulated by the interaction with the prolyl-isomerase Pin1, via proteasome-mediated degradation; p63 mutant proteins associated with SHFM or EEC syndromes are resistant to Pin1 action. Thus, DLX5, p63, Pin1 and FGF8 participate to the same time- and location-restricted regulatory loop essential for AER stratification, hence for normal patterning and skeletal morphogenesis of the limb buds. These results shed new light on the molecular mechanisms at the basis of the SHFM and EEC limb malformations.
authors.affiliation: Department of Biosciences, University of Milano, Milano I-20133, Italy.
authors.forename: Michela
authors.initials: M
authors.lastname: Restelli
authors.affiliation: Department of Biosciences, University of Milano, Milano I-20133, Italy.
authors.forename: Teresa
authors.initials: T
authors.lastname: Lopardo
authors.affiliation: Department of Biosciences, University of Milano, Milano I-20133, Italy.
authors.forename: Nadia
authors.initials: N
authors.lastname: Lo Iacono
authors.affiliation: Telethon Laboratory, Department of Molecular Biotechnologies and Health Sciences, University of Torino, Torino I-10126, Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Garaffo
authors.affiliation: Telethon Laboratory, Department of Molecular Biotechnologies and Health Sciences, University of Torino, Torino I-10126, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Conte
authors.affiliation: Molecular Oncology Unit, LNCIB Area Science Park, Trieste I-34149, Italy.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Rustighi
authors.affiliation: Department of Biochemistry and Molecular Biology, Center for Genetics & Genomics, and Center for Stem Cell & Developmental Biology, MD Anderson, Houston, TX, USA.
authors.forename: Marco
authors.initials: M
authors.lastname: Napoli
authors.affiliation: Molecular Oncology Unit, LNCIB Area Science Park, Trieste I-34149, Italy.
authors.forename: Giannino
authors.initials: G
authors.lastname: Del Sal
authors.affiliation: Laboratoire de Parasitologie Moléculaire, IBMM-DBM, Université Libre de Bruxelles, Gosselies B-6041, Belgium and.
authors.forename: David
authors.initials: D
authors.lastname: Perez-Morga
authors.affiliation: Department of Dermatology, University of Rome 'Tor Vergata', Rome I-00133, Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Costanzo
authors.affiliation: Telethon Laboratory, Department of Molecular Biotechnologies and Health Sciences, University of Torino, Torino I-10126, Italy.
authors.forename: Giorgio Roberto
authors.initials: GR
authors.lastname: Merlo
authors.affiliation: Department of Biosciences, University of Milano, Milano I-20133, Italy luisa.guerrini@unimi.it.
authors.forename: Luisa
authors.initials: L
authors.lastname: Guerrini
mesh_terms: D000818:Animals; D019521:Body Patterning; D002460:Cell Line; D004195:Disease Models, Animal; D004475:Ectoderm / Q000196:embryology* / Q000378:metabolism; D051524:Fibroblast Growth Factor 8 / Q000378:metabolism*; D055786:Gene Knockout Techniques; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D018878:Limb Buds / Q000196:embryology; D017880:Limb Deformities, Congenital / Q000378:metabolism* / Q000473:pathology; D051379:Mice; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D019696:Peptidylprolyl Isomerase / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D055550:Protein Stability; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
chemical_list: C501120:Dlx5 protein, mouse; D018398:Homeodomain Proteins; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D010750:Phosphoproteins; D015534:Trans-Activators; C486419:Trp63 protein, mouse; D051524:Fibroblast Growth Factor 8; C000606846:PIN1 protein, human; D019696:Peptidylprolyl Isomerase; C000606850:Pin1 protein, mouse