Retinoic acid receptor-alpha gene expression is modulated by dietary vitamin A and by retinoic acid in chicken T lymphocytes.
The effects of dietary vitamin A and retinoic acid in vitro on the proliferative response and gene expression of retinoic acid receptor-alpha (RAR-alpha) in chicken T lymphocytes were studied. Antigen-specific proliferative responses of T lymphocytes increased with dietary vitamin A intake from 0 to 6.6 mg/kg diet; however, at high dietary vitamin A (13.2 mg/kg diet), the proliferative response declined. RAR-alpha mRNA expression in T lymphocytes peaked in chicks fed low levels of vitamin A (830 and 1500 micrograms/kg diet) and declined at higher intakes. In vitro effects of retinoic acid on the modulation of RAR-alpha mRNA were studied in stimulated T lymphocytes. Retinoic acid (0.01 mumol/L) increased RAR-alpha mRNA levels within 2 or 16 h of incubation with concanavalin A- or beta-casein-stimulated T cells, respectively. This effect was transient. Expression of RAR-alpha mRNA in concanavalin A-stimulated T lymphocytes was up-regulated by retinoic acid in a dose-dependent manner, and maximal expression occurred in response to 1 mumol/L retinoic acid. The proliferative response of these cells was also modulated by retinoic acid in a dose-dependent manner, and highest effects were observed at 0.01 mumol/L retinoic acid. Our results indicate that RAR-alpha mRNA expression and antigen-specific proliferative responses of T lymphocytes are influenced by vitamin A status in vivo, and directly modulated by retinoic acid.
Department of Animal Science, Faculty of Agriculture, Hebrew University, Rehovot, Israel.
O
O
Halevy
Y
Y
Arazi
D
D
Melamed
A
A
Friedman
D
D
Sklan
D000284:Administration, Oral; D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002645:Chickens; D002851:Chromatography, High Pressure Liquid; D015870:Gene Expression / Q000187:drug effects*; D007111:Immunity, Cellular; D008297:Male; D018168:Receptors, Retinoic Acid / Q000187:drug effects* / Q000235:genetics*; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D014212:Tretinoin / Q000494:pharmacology*; D014801:Vitamin A / Q000494:pharmacology*
D018168:Receptors, Retinoic Acid; D014801:Vitamin A; D014212:Tretinoin