Myeloid cell differentiation in response to calcitriol for expression CD11b and CD14 is regulated by myeloid zinc finger-1 protein downstream of phosphatidylinositol 3-kinase.
Immature cells of the mononuclear phagocyte series differentiate in response to calcitriol. This is accompanied by increased expression of both CD11b and CD14 and has been shown to be phosphatidylinositol 3-kinase (PI3K) dependent. The events downstream of PI3K that regulate mononuclear phagocyte gene expression, however, remain to be fully understood. In the present study, we show that incubation of THP-1 cells with calcitriol brings about activation of the myeloid zinc finger-1 (MZF-1) transcription factor dependent upon PI3K. In addition, we show that the proximal promoter regions of both CD11b and CD14 contain functional MZF-1 binding sites that are calcitriol responsive. Site-directed mutagenesis of the putative MZF-1 elements abolished MZF-1 binding to the promoters of both CD11b and CD14. Not only did calcitriol treatment increase MZF-1 DNA binding activity to these sites, but it also up-regulated cellular levels of MZF-1. Silencing of MZF-1 resulted in a markedly blunted response to calcitriol for induction of both CD11b and CD14 mRNA transcript levels. Cell surface expression of CD11b and CD14 was also reduced, but to a lesser extent. Taken together, these results show that MZF-1 is involved downstream of PI3K in a calcitriol-induced signaling pathway leading to myeloid cell differentiation and activation of CD11b and CD14.
Moeenrezakhanlou
Alireza
A
Department of Medicine (Division of Infectious Diseases), University of British Columbia, Rm. 452D, 2733 Heather St., Vancouver, BC V5Z 3J5, Canada.
Shephard
Lindsay
L
Lam
Lucia
L
Reiner
Neil E
NE
D015703:Antigens, CD / Q000235:genetics; D001483:Base Sequence; D039481:CD11b Antigen / Q000235:genetics*; D002117:Calcitriol / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000276:immunology; D006367:HeLa Cells; D006801:Humans; D018950:Lipopolysaccharide Receptors / Q000235:genetics*; D008969:Molecular Sequence Data; D022423:Myeloid Cells / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D015703:Antigens, CD; D039481:CD11b Antigen; C509295:ITGAM protein, human; D018950:Lipopolysaccharide Receptors; D019869:Phosphatidylinositol 3-Kinases; D002117:Calcitriol