The hematopoietic cell-specific transcription factor PU.1 is critical for expression of CD11c.
PU.1 is a hematopoietic cell-specific transcription factor belonging to the Ets family, which plays an important role in the development of dendritic cells (DCs). CD11c (encoded by Itgax) is well established as a characteristic marker of hematopoietic lineages including DCs. In the present study, we analyzed the role of PU.1 (encoded by Spi-1) in the expression of CD11c. When small interfering RNA (siRNA) for Spi-1 was introduced into bone marrow-derived DCs (BMDCs), the mRNA level and cell surface expression of CD11c were dramatically reduced. Using reporter assays, the TTCC sequence at -56/-53 was identified to be critical for PU.1-mediated activation of the promoter. An EMSA showed that PU.1 directly bound to this region. ChIP assays demonstrated that a significant amount of PU.1 bound to this region on chromosomal DNA in BMDCs, which was decreased in LPS-stimulated BMDCs in accordance with the reduced levels of mRNAs of Itgax and Spi-1, and the histone acetylation degree. Enforced expression of exogenous PU.1 induced the expression of the CD11c protein on the cell surface of mast cells, whereas control transfectants rarely expressed CD11c. Quantitative RT-PCR also showed that the expression of a transcription factor Irf4, which is a partner molecule of PU.1, was reduced in PU.1-knocked down BMDCs. IRF4 transactivated the Itgax gene in a synergistic manner with PU.1. Taken together, these results indicate that PU.1 functions as a positive regulator of CD11c gene expression by directly binding to the Itgax promoter and through transactivation of the Irf4 gene.
['Yashiro|Takuya|T|', 'Kasakura|Kazumi|K|', 'Oda|Yoshihito|Y|', 'Kitamura|Nao|N|', 'Inoue|Akihito|A|', 'Nakamura|Shusuke|S|', 'Yokoyama|Hokuto|H|', 'Fukuyama|Kanako|K|', 'Hara|Mutsuko|M|', 'Ogawa|Hideoki|H|', 'Okumura|Ko|K|', 'Nishiyama|Makoto|M|', 'Nishiyama|Chiharu|C|']
D000107:Acetylation D000818:Animals D039521:CD11c Antigen D002478:Cells, Cultured D004268:DNA-Binding Proteins D003713:Dendritic Cells D005786:Gene Expression Regulation D006410:Hematopoiesis D006657:Histones D050835:Interferon Regulatory Factors D051379:Mice D008807:Mice, Inbred BALB C D009928:Organ Specificity D011401:Promoter Regions, Genetic D011518:Proto-Oncogene Proteins D034741:RNA, Small Interfering D015534:Trans-Activators D015533:Transcriptional Activation
transcription factor dendritic cell CD11c/Itgax IRF4/Irf4 PU.1/Spi-1