Olsen D R, Hickok N J, Uitto J
Department of Dermatology, Jefferson Medical College, Philadelphia, Pennsylvania.
J Invest Dermatol. 1990 Jan;94(1):33-6. doi: 10.1111/1523-1747.ep12873328.
Modulation of ornithine decarboxylase (ODC) gene expression by retinoids was analyzed in human keratinocyte cultures maintained in serum-free medium containing 0.15 mM Ca++. Cells were incubated with all-trans-retinoic acid, 13-cis-retinoic acid or arotinoid Ro15-0778 (10(-10) to 10(-5) M), total RNA was isolated, and mRNA transcripts for ODC were analyzed by Northern and slot blot hybridizations with a human ODC cDNA. Treatment of cells for 24 h resulted in a dose-dependent decrease in ODC mRNA levels, with an estimated IC50 of approximately 1 X 10(-8) M for all-trans- and 13-cis-retinoic acid, while Ro15-0778 was somewhat less effective (IC50 approximately 1-5 X 10(-7) M). The suppression of ODC mRNA levels by retinoids was detectable at approximately 3 h of incubation, with essentially a maximal inhibition at 12 h. Reduced ODC mRNA levels noted after 24 h of incubation with 5 X 10(-7) M all-trans-retinoic acid were accompanied by a reduction in ODC enzyme activity. To determine if all-trans-retinoic acid was regulating ODC gene expression directly, or if protein synthesis was required, ODC expression was analyzed in cultures treated with protein synthesis inhibitors. In the presence of cycloheximide or puromycin, all-trans-retinoic acid did not suppress ODC mRNA levels. These findings suggest that suppression of ODC gene expression is not a direct effect of all-trans-retinoic acid, but depends on ongoing protein synthesis.
在含有0.15 mM钙离子的无血清培养基中培养的人角质形成细胞培养物中，分析了类视黄醇对鸟氨酸脱羧酶（ODC）基因表达的调节作用。将细胞与全反式维甲酸、13 - 顺式维甲酸或芳维甲酸Ro15 - 0778（10^(-10)至10^(-5) M）一起孵育，分离总RNA，并用人ODC cDNA通过Northern和狭缝印迹杂交分析ODC的mRNA转录本。细胞处理24小时导致ODC mRNA水平呈剂量依赖性下降，全反式和13 - 顺式维甲酸的估计IC50约为1×10^(-8) M，而Ro15 - 0778的效果稍差（IC50约为1 - 5×10^(-7) M）。类视黄醇对ODC mRNA水平的抑制在孵育约3小时时可检测到，在12小时时基本达到最大抑制。用5×10^(-7) M全反式维甲酸孵育24小时后观察到的ODC mRNA水平降低伴随着ODC酶活性的降低。为了确定全反式维甲酸是直接调节ODC基因表达，还是需要蛋白质合成，在用蛋白质合成抑制剂处理的培养物中分析了ODC表达。在存在环己酰亚胺或嘌呤霉素的情况下，全反式维甲酸不会抑制ODC mRNA水平。这些发现表明，ODC基因表达的抑制不是全反式维甲酸的直接作用，而是取决于正在进行的蛋白质合成。
