Protein network study of human AF4 reveals its central role in RNA Pol II-mediated transcription and in phosphorylation-dependent regulatory mechanisms

Gabriella Esposito, Armando Cevenini, Alessandro Cuomo, Francesca De Falco, Dario Sabbatino, Fabrizio Pane, Margherita Ruoppolo, Francesco Salvatore

Research output: Contribution to journalArticle

Abstract

AF4 belongs to a family of proteins implicated in childhood lymphoblastic leukaemia, FRAXE (Fragile X E site) mental retardation and ataxia. AF4 is a transcriptional activator that is involved in transcriptional elongation. Although AF4 has been implicated in MLL (mixed-lineage leukaemia)-related leukaemogenesis, AF4-dependent physiological mechanisms have not been clearly defined. Proteins that interact with AF4 may also play important roles in mediating oncogenesis, and are potential targets for novel therapies. Using a functional proteomic approach involving tandem MS and bioinformatics, we identified 51 AF4-interacting proteins of various Gene Ontology categories. Approximately 60% participate in transcription regulatory mechanisms, including the Mediator complex in eukaryotic cells. In the present paper we report one of the first extensive proteomic studies aimed at elucidating AF4 protein cross-talk.Moreover, we found that the AF4 residues Thr 220 and Ser 212 are phosphorylated, which suggests that AF4 function depends on phosphorylation mechanisms.We also mapped the AF4-interaction site withCDK9 (cyclin-dependent kinase 9), which is a direct interactor crucial for the function and regulation of the protein. The findings of the present study significantly expand the number of putative members of the multiprotein complex formed by AF4, which is instrumental in promoting the transcription/elongation of specific genes in human cells.

Original languageEnglish
Pages (from-to)121-131
Number of pages11
JournalBiochemical Journal
Volume438
Issue number1
DOIs
Publication statusPublished - Aug 15 2011

Keywords

  • Acute lymphoblastic leukaemia
  • AF4 - ENL - P-TEFb complex (AEP complex)
  • AF4 interactome
  • Mediator complex
  • Mixed-lineage leukaemia chimaera (MLL chimaera)
  • Protein - Protein interaction
  • RNA polymerase II-mediated transcription elongation

ASJC Scopus subject areas

  • Biochemistry
  • Cell Biology
  • Molecular Biology

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    Esposito, G., Cevenini, A., Cuomo, A., De Falco, F., Sabbatino, D., Pane, F., Ruoppolo, M., & Salvatore, F. (2011). Protein network study of human AF4 reveals its central role in RNA Pol II-mediated transcription and in phosphorylation-dependent regulatory mechanisms. Biochemical Journal, 438(1), 121-131. https://doi.org/10.1042/BJ20101633