IL-32α down-regulates β2 integrin (CD18) expression by suppressing PU.1 expression in myeloid cells.
Myeloid-specific CD18 associates with CD11 and plays a critical role in leukocyte adhesion to the endothelium. In this study, we observed that CD18 expression was decreased by IL-32α in THP-1 and K562 cells upon PMA stimulation, and investigated the mechanism by which IL-32α down-regulated CD18 expression. We found that IL-32α suppressed the expression of PU.1, a major transcription factor for CD18. Because we previously demonstrated that IL-32α mediated STAT3 S727 phosphorylation by PKCε, and STAT3 regulates PU.1 expression, we performed time-course analyses of STAT3 S727 phosphorylation and found that IL-32α induces prolonged phosphorylation of STAT3 S727 until 72h after PMA stimulation. The expression pattern of C/EBPα, another transcriptional regulator of PU.1, was not affected by IL-32α. In addition, we showed that STAT3 binding to the PU.1 promoter was suppressed by IL-32α. Thus, we examined the relatedness among these factors and found that IL-32α-mediated STAT3 S727 phosphorylation induced C/EBPα association. When STAT3 was mutated at S727 to proline (S727P), the mutant STAT3 S727P did not interact with C/EBPα. We further demonstrated that only the intact STAT3 interacted with the basic leucine zipper region of C/EBPα. The PU.1 promoter was activated by co-expression of STAT3 and IL-32α upon PMA stimulation. However, the promoter activity was inhibited with STAT3 and C/EBPα co-expression. Therefore, our data suggest that IL-32α-mediated STAT3 S727 phosphorylation induced C/EBPα association, which inhibited PU.1 expression, and then resulted in the down-regulation of CD18 expression.
Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea.
Jeong-Woo
JW
Kang
Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea.
Yun Sun
YS
Park
Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea.
Man Sub
MS
Kim
Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea.
Dong Hun
DH
Lee
Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea.
Yesol
Y
Bak
Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea.
Sun Young
SY
Ham
Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea.
Yong-Seok
YS
Song
College of Pharmacy and Medical Research Center, Chungbuk National University, 12 Gashin-dong, Heungduk-gu, Cheongju, Chungbuk 361-463, Republic of Korea.
Jin Tae
JT
Hong
Department of Bioscience and Biotechnology, Bio/Molecular Informatics Center, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul 143-701, Republic of Korea. Electronic address: ydy4218@konkuk.ac.kr.
Do-Young
DY
Yoon
D019943:Amino Acid Substitution; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000096:biosynthesis / Q000235:genetics*; D018845:CD11 Antigens; D018821:CD18 Antigens / Q000096:biosynthesis*; D045744:Cell Line, Tumor; D015536:Down-Regulation; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D007378:Interleukins / Q000378:metabolism*; D022423:Myeloid Cells / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis*; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000235:genetics; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015534:Trans-Activators / Q000096:biosynthesis*; D014158:Transcription, Genetic; D000099232:Proto-Oncogene Protein Spi-1
D022763:CCAAT-Enhancer-Binding Protein-alpha; D018845:CD11 Antigens; D018821:CD18 Antigens; D007378:Interleukins; D011518:Proto-Oncogene Proteins; D050796:STAT3 Transcription Factor; D013755:Tetradecanoylphorbol Acetate; D015534:Trans-Activators; D000099232:Proto-Oncogene Protein Spi-1; C496971:IL32 protein, human; C494086:STAT3 protein, human
C/EBPα; CD18; Immunoprecipitation; Interleukin-32α; PKCε; STAT3