title: The Phosphorylation of PDX-1 by Protein Kinase CK2 Is Crucial for Its Stability.
abstract: The homeodomain protein PDX-1 is a critical regulator of pancreatic development and insulin production in pancreatic β-cells. We have recently shown that PDX-1 is a substrate of protein kinase CK2; a multifunctional protein kinase which is implicated in the regulation of various cellular aspects, such as differentiation, proliferation, and survival. The CK2 phosphorylation site of PDX-1 is located within the binding region of the E3 ubiquitin ligase adaptor protein PCIF1. To study the interaction between PDX-1 and PCIF1 we used immunofluorescence analysis, co-immunoprecipitation, GST-pull-down studies, and proximity ligation assay (PLA). For the analysis of the stability of PDX-1 we performed a cycloheximide chase. We used PDX-1 in its wild-type form as well as phosphomutants of the CK2 phosphorylation site. In pancreatic β-cells PDX-1 binds to PCIF1. The phosphorylation of PDX-1 by CK2 increases the ratio of PCIF1 bound to PDX-1. The stability of PDX-1 is extended in the absence of CK2 phosphorylation. Our results identified protein kinase CK2 as new important modulator of the stability of PDX-1.
authors.affiliation: Medical Biochemistry and Molecular Biology, Saarland University, 66424 Homburg, Germany. klein.sabrina@outlook.de.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Klein
authors.affiliation: Medical Biochemistry and Molecular Biology, Saarland University, 66424 Homburg, Germany. mengruivip@163.com.|Cancer Center of Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, No. 156 Wujiadun, Hankou, Wuhan 430045, China. mengruivip@163.com.
authors.forename: Rui
authors.initials: R
authors.lastname: Meng
authors.affiliation: Medical Biochemistry and Molecular Biology, Saarland University, 66424 Homburg, Germany. mathias.montenarh@uks.eu.
authors.forename: Mathias
authors.initials: M
authors.lastname: Montenarh
authors.affiliation: Medical Biochemistry and Molecular Biology, Saarland University, 66424 Homburg, Germany. claudia.goetz@uks.eu.
authors.forename: Claudia
authors.initials: C
authors.lastname: Götz
keywords: PDX-1 C-terminus interacting factor PCIF1; pancreatic and duodenal homeobox protein PDX-1; protein kinase CK2; protein stability