title: JNK-mediated turnover and stabilization of the transcription factor p45/NF-E2 during differentiation of murine erythroleukemia cells.
abstract: Regulation of the homeostatic concentrations of specific sets of transcription factors is essential for correct programming of cell proliferation and differentiation. We have characterized the signal transduction pathways regulating the catabolisis of p45/NF-E2, a bZIP factor activating the erythroid and megakaryocytic gene transcription. Through use of different approaches including nano-scale proteomics, we show that activated-JNK, or Phospho-JNK (P-JNK), physically interacts with p45/NF-E2 and phosphorylates its Ser157 residue. This reaction leads to the poly-ubiquitination of p45/NF-E2 at one or more of six Lys residues, one of which being also a sumoylation site, and its degradation through the proteasome pathway. Significantly, this regulatory pathway of p45/NF-E2 by P-JNK exists only in uninduced murine erythroleukemia (MEL) cells but not in differentiated MEL cells in which JNK is inactivated on DMSO induction. Based on the above data and analysis of the chromatin-binding kinetics of p45/NF-E2 and the erythroid gene repressor Bach1 during the early phase of MEL differentiation, we suggest a model for the regulation of erythroid maturation. In the model, the posttranslational modifications and turnover of p45/NF-E2, as mediated by P-JNK, contribute to the control of its homeostatic concentration and consequently, its regulatory functions in the progression of erythroid differentiation and erythroid gene expression.
authors: Institute of Molecular Biology, Academia Sinica, Taipei 115, Taiwan, Republic of China.
authors: Tung-Liang
authors: TL
authors: Lee
authors: Yu-Chiau
authors: YC
authors: Shyu
authors: Pang-Hung
authors: PH
authors: Hsu
authors: Chiung-Wen
authors: CW
authors: Chang
authors: Shau-Ching
authors: SC
authors: Wen
authors: Wei-Yuan
authors: WY
authors: Hsiao
authors: Ming-Daw
authors: MD
authors: Tsai
authors: Che-Kun James
authors: CK
authors: Shen
mesh_terms: D000818:Animals; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D045744:Cell Line, Tumor; D051856:Fanconi Anemia Complementation Group Proteins / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D004915:Leukemia, Erythroblastic, Acute / Q000378:metabolism*; D051379:Mice; D050984:NF-E2 Transcription Factor, p45 Subunit / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*
chemical_list: C102108:BACH1 protein, human; D050976:Basic-Leucine Zipper Transcription Factors; D051856:Fanconi Anemia Complementation Group Proteins; D050984:NF-E2 Transcription Factor, p45 Subunit; D011993:Recombinant Fusion Proteins; D048031:JNK Mitogen-Activated Protein Kinases; D046988:Proteasome Endopeptidase Complex