単核食細胞における血小板由来成長因子の発現機構 単球からマクロファージへの分化に伴う発現の変化

Abstract

Platelet-derived growth factor (PDGF) -A and -B gene expression was studied using resting monocytes, in vitromatured monocytes and alveolar macrophages. Resting monocytes constitutively transcribed both PDGF-A and -B genes. When monocytes were matured to macrophagesin vitro, the transcription rates of both genes increased markedly. Consistent with the transcription rates, resting monocytes constitutively expressed both PDGF-A and -B mRNAs. Interestingly, PDGF-B mRNA levels increased markedly after the maturation, whereas PDGF-A mRNA levels did not change. Alveolar macrophages constitutively transcribed both PDGF-A and -B genes at almost the same rates. However, these cells expressed 5-fold more PDGF-B mRNA than PDGF-A mRNA. Immunohistochemical study using anti-PDGF-AA and anti-PDGF-BB antibodies suggested that PDGF-BB homodimers were more abundant than -AA homodimers or -AB heterodimers in alveolar macrophages and in vitromatured monocytes.These observations indicate that PDGF-B mRNA is preferentially expressed and PDGF-BB homodimers are abundantly produced after the maturation of monocytes to macrophages, despite the equal transcription rates for both PDGF-A and -B genes.