title: Mutual regulation of c-Jun and ATF2 by transcriptional activation and subcellular localization.
abstract: ATF2 and c-Jun are key components of activating protein-1 and function as homodimers or heterodimers. c-Jun-ATF2 heterodimers activate the expression of many target genes, including c-jun, in response to a variety of cellular and environmental signals. Although it has been believed that c-Jun and ATF2 are constitutively localized in the nucleus, where they are phosphorylated and activated by mitogen-activated protein kinases, the molecular mechanisms underlying the regulation of their transcriptional activities remain to be defined. Here we show that ATF2 possesses a nuclear export signal in its leucine zipper region and two nuclear localization signals in its basic region, resulting in continuous shuttling between the cytoplasm and the nucleus. Dimerization with c-Jun in the nucleus prevents the export of ATF2 and is essential for the transcriptional activation of the c-jun promoter. Importantly, c-Jun-dependent nuclear localization of ATF2 occurs during retinoic acid-induced differentiation and UV-induced cell death in F9 cells. Together, these findings demonstrate that ATF2 and c-Jun mutually regulate each other by altering the dynamics of subcellular localization and by positively impacting transcriptional activity.
authors.affiliation: Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Han
authors.initials: H
authors.lastname: Liu
authors.forename: Xuehong
authors.initials: X
authors.lastname: Deng
authors.forename: Y John
authors.initials: YJ
authors.lastname: Shyu
authors.forename: Jian Jian
authors.initials: JJ
authors.lastname: Li
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Taparowsky
authors.forename: Chang-Deng
authors.initials: CD
authors.lastname: Hu
mesh_terms: D051698:Activating Transcription Factor 2 / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D019556:COS Cells; D002454:Cell Differentiation / Q000187:drug effects; D002467:Cell Nucleus / Q000378:metabolism; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D021381:Protein Transport; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014212:Tretinoin / Q000494:pharmacology; D014466:Ultraviolet Rays
chemical_list: C497105:ATF2 protein, human; D051698:Activating Transcription Factor 2; D000970:Antineoplastic Agents; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D014212:Tretinoin