title: The E3 ubiquitin ligase thyroid hormone receptor-interacting protein 12 targets pancreas transcription factor 1a for proteasomal degradation.
abstract: Pancreas transcription factor 1a (PTF1a) plays a crucial role in the early development of the pancreas and in the maintenance of the acinar cell phenotype. Several transcriptional mechanisms regulating expression of PTF1a have been identified. However, regulation of PTF1a protein stability and degradation is still unexplored. Here, we report that inhibition of proteasome leads to elevated levels of PTF1a and to the existence of polyubiquitinated forms of PTF1a. We used the Sos recruitment system, an alternative two-hybrid system method to detect protein-protein interactions in the cytoplasm and to map the interactome of PTF1a. We identified TRIP12 (thyroid hormone receptor-interacting protein 12), an E3 ubiquitin-protein ligase as a new partner of PTF1a. We confirmed PTF1a/TRIP12 interaction in acinar cell lines and in co-transfected HEK-293T cells. The protein stability of PTF1a is significantly increased upon decreased expression of TRIP12. It is reduced upon overexpression of TRIP12 but not a catalytically inactive TRIP12-C1959A mutant. We identified a region of TRIP12 required for interaction and identified lysine 312 of PTF1a as essential for proteasomal degradation. We also demonstrate that TRIP12 down-regulates PTF1a transcriptional and antiproliferative activities. Our data suggest that an increase in TRIP12 expression can play a part in PTF1a down-regulation and indicate that PTF1a/TRIP12 functional interaction may regulate pancreatic epithelial cell homeostasis.
authors.affiliation: From the INSERM UMR1037, Cancer Research Center of Toulouse (CRCT), University of Toulouse III Paul Sabatier, 31037 Toulouse, France.
authors.forename: Naïma
authors.initials: N
authors.lastname: Hanoun
authors.affiliation: From the INSERM UMR1037, Cancer Research Center of Toulouse (CRCT), University of Toulouse III Paul Sabatier, 31037 Toulouse, France.
authors.forename: Samuel
authors.initials: S
authors.lastname: Fritsch
authors.affiliation: the Cancer Research Center of Marseille, INSERM UMR1068, Paoli-Calmettes Institute, University of Aix-Marseille, CNRS UMR7258, 13273 Marseille, France.
authors.forename: Odile
authors.initials: O
authors.lastname: Gayet
authors.affiliation: EA 4552, University of Toulouse III Paul Sabatier, 31432 Toulouse, France, and.
authors.forename: Véronique
authors.initials: V
authors.lastname: Gigoux
authors.affiliation: From the INSERM UMR1037, Cancer Research Center of Toulouse (CRCT), University of Toulouse III Paul Sabatier, 31037 Toulouse, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Cordelier
authors.affiliation: the Cancer Research Center of Marseille, INSERM UMR1068, Paoli-Calmettes Institute, University of Aix-Marseille, CNRS UMR7258, 13273 Marseille, France.
authors.forename: Nelson
authors.initials: N
authors.lastname: Dusetti
authors.affiliation: From the INSERM UMR1037, Cancer Research Center of Toulouse (CRCT), University of Toulouse III Paul Sabatier, 31037 Toulouse, France.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Torrisani
authors.affiliation: From the INSERM UMR1037, Cancer Research Center of Toulouse (CRCT), University of Toulouse III Paul Sabatier, 31037 Toulouse, France, marlene.dufresne@inserm.fr.
authors.forename: Marlène
authors.initials: M
authors.lastname: Dufresne
mesh_terms: D061354:Acinar Cells / Q000378:metabolism / Q000473:pathology; D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D003593:Cytoplasm / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D020125:Mutation, Missense; D010190:Pancreatic Neoplasms / Q000473:pathology; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011485:Protein Binding; D055550:Protein Stability; D059748:Proteolysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D002352:Carrier Proteins; D014157:Transcription Factors; C062602:transcription factor PTF1; C530813:TRIP12 protein, human; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex
keywords: Basic Helix-Loop-Helix Transcription Factor (bHLH); E3 Ubiquitin Ligase; Pancreas; Pancreatic Cancer; Proteasome; Protein Degradation; Protein-Protein Interaction; Transcription Factor; Ubiquitylation (Ubiquitination); Yeast Two-Hybrid