Modulation of SRF-dependent gene expression by association of SPT16 with MKL1.
MKL1 (MRTF-A/MAL) is a member of the myocardin-related transcription factor family that plays a key role in the development and differentiation of smooth muscle cells (SMCs) via activation of serum response factor (SRF)-dependent SMC gene expression. MKL1 associates with SRF and stimulates its transcriptional activity. Here, by performing matrix-assisted laser desorption/ionization-time of flight mass spectrometric analysis combined with in vitro glutathione S-transferase pull-down assay, we identified 4 candidate proteins that associate with MKL1 through the N-terminus region of MKL1. SPT16, ATP citrate lyase, nucleolin and radixin were identified, and the physical and functional interactions between MKL1 and SPT16 were examined. SPT16 is a component of the FACT (facilitating chromatin transcription) complex that allows RNA polymerase II to traverse the nucleosomes. SPT16 associates with MKL1 in vitro and in vivo; moreover, SSRP1, another component of the FACT complex, associates with the N-terminus region of MKL1 in vitro. SPT16 synergistically activates the transcriptional activity of MKL1. These results show that the expression of nucleosomal SRF-dependent genes, including the SMC gene, is activated by MKL1 via activation of SRF and recruitment of the FACT complex.
Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan. tkihara@will.dpc.u-tokyo.ac.jp <tkihara@will.dpc.u-tokyo.ac.jp>
Takanori
T
Kihara
Fumi
F
Kano
Masayuki
M
Murata
D001275:ATP Citrate (pro-S)-Lyase / Q000235:genetics; D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D002875:Chromosomes / Q000235:genetics / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D005786:Gene Expression Regulation / Q000235:genetics*; D006609:High Mobility Group Proteins / Q000235:genetics; D046911:Macromolecular Substances / Q000378:metabolism; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000235:genetics; D051379:Mice; D041681:NIH 3T3 Cells; D009707:Nucleosomes / Q000235:genetics*; D010750:Phosphoproteins / Q000235:genetics; D011485:Protein Binding; D017434:Protein Structure, Tertiary / Q000235:genetics; D016601:RNA-Binding Proteins / Q000235:genetics; D026362:Serum Response Factor / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics; D015533:Transcriptional Activation / Q000235:genetics*; D000097796:Nucleolin
D001275:ATP Citrate (pro-S)-Lyase; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; D006609:High Mobility Group Proteins; D046911:Macromolecular Substances; D008565:Membrane Proteins; D009707:Nucleosomes; D010750:Phosphoproteins; D016601:RNA-Binding Proteins; D026362:Serum Response Factor; D015534:Trans-Activators; D014157:Transcription Factors; D000097796:Nucleolin; C511173:Mrtfa protein, mouse; C465039:Supt16 protein, mouse; C070454:Ssrp1 protein, mouse; C071776:radixin