Differentiation-dependent expression of interferon gamma and toll-like receptor 9 in 3T3-F442A adipocytes.
3T3-F442A and BFC-1 cells are widely used for studying adipocyte differentiation and metabolism. Macrophage markers were previously reported in these cell lines. We examined whether 3T3-F442A and BFC-1 would produce interferon-gamma (IFN-gamma), the expression of which is a matter of debate in cells other than T-lymphocytes and natural killer cells, like macrophages or dendritic. IFN-gamma was absent from preadipocytes. However 3T3-F442A, but not BFC-1, presented a differentiation-dependent induction of IFN-gamma mRNA and protein. Immunofluorescence studies showed that IFN-gamma was located in mature adipocytes. IFN-gamma was retrieved in the culture medium. Then, we examined the expression of other markers of T-lymphocytes or macrophages, like the CD3/T-cell receptor complex or Toll-like receptors (TLR) -2 and -9, in these cells. Transcripts for the three subunits of CD3 were undetectable whatever the differentiation stage. In contrast, TLR-2 and -9 genes were expressed differentially during the differentiation process. TLR-2 mRNA was induced early then decreased while TLR9 transcript appeared at later days and increased in parallel to IFN-gamma. In contrast to what was expected from 3T3-F442A cells, IFN-gamma was absent from adipocytes isolated either from subcutaneous or periepidydimal mouse adipose tissue. However, TLR-2 and -9 mRNAs were present in both adipose depots although at various levels. Hence, we detect the presence of two markers of innate immunity, TLR-2 and -9, in in vivo-derived adipocytes and we demonstrate that differentiated 3T3-F442A cells selectively express IFN-gamma and TLR-9 in a manner that resembles what is occurring for natural killer dendritic cells.
Khazen
Wael
W
Institut National de la Santé et de la Recherche Médicale, unit 747 (Inserm UMR-S 747); Université Paris Descartes, Centre Universitaire des Saints-Pères, 45 rue des Saints-Pères, 75006 Paris, France.
M'Bika
Jean-Pierre
JP
Collinet
Martine
M
Tramoni
Mathieu
M
Chany
Charles
C
Achour
Ammar
A
Forest
Claude
C
D016475:3T3 Cells; D017667:Adipocytes / Q000166:cytology* / Q000276:immunology; D000818:Animals; D002454:Cell Differentiation / Q000235:genetics*; D005786:Gene Expression Regulation / Q000276:immunology; D007113:Immunity, Innate; D007371:Interferon-gamma / Q000235:genetics*; D051379:Mice; D012333:RNA, Messenger / Q000032:analysis; D051217:Toll-Like Receptor 9 / Q000235:genetics*
D012333:RNA, Messenger; C495370:Tlr9 protein, mouse; D051217:Toll-Like Receptor 9; D007371:Interferon-gamma