Abstract
Jun dimerization protein 2 (JDP2) was identified as a bZIP protein that forms dimers with Jun proteins. JDP2 represses transcriptional activation of reporter constructs containing 12-O-tetradecanoylphorbol 13-acetate (TPA)-responsive elements (TRE) or cyclic AMP responsive elements (CRE). JDP2, overexpressed by the avian retroviral vector RCAS, induces partial oncogenic transformation of chicken embryo fibroblasts. JDP2-expressing cells form multilayered foci in monolayer cultures but do not show anchorage-independent growth. Both the carboxyl and the amino terminus of JDP2 are required for the transforming activity. Chimeric constructs of JDP2 carrying the leucine zipper domain of Fos, GCN4 or EB1 fail to transform CEF. The leucine zipper of Fos mediates only heterodimerization; it cannot homodimerize. In contrast, the leucine zippers of GCN4 and of EB1 exclusively homodimerize and do not form dimers with other bZip proteins. The results with the JDP2 chimeras suggest that the JDP2 homodimer and the JDP2/Jun heterodimer (or other bZip heterodimers formed with the Fos leucine zipper) are nontransforming, leaving as possible transforming combination the JDP2/Fos heterodimer. The unexpected transforming activity of a negative regulator of TRE- and CRE-dependent transcription raises an important question concerning the mechanisms of transformation by the related bZIP proteins Jun and Fos that address the same target sequences.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.