Ades I Z, Stevens T M, Drew P D
Arch Biochem Biophys. 1987 Mar;253(2):297-304. doi: 10.1016/0003-9861(87)90182-2.
The effects of hemin on the concentration of the mRNA for delta-aminolevulinate synthase (ALA synthase) and on the association of the messenger with polysomes were investigated in primary cultures of embryonic chick hepatocytes incubated with allylisopropylacetamide (AIA). A synthetic 24-mer DNA complementary to ALA synthase mRNA was used to determine by solution hybridization the effects of AIA and of AIA plus hemin on the ALA synthase-specific RNA sequences in the cells. The results indicated that ALA synthase mRNA concentrations increased significantly in hepatocytes incubated for 5 h with AIA (0.075 mg/ml), and that hemin in the medium (2 or 10 microM) blocked the increase in the messenger. When delta-aminolevulinic acid (ALA) and FeCl3 were added into the culture medium (1 mM and 5 microM, respectively), the increase in ALA synthase mRNA brought on by AIA was also inhibited. Neither ALA nor FeCl3, when individually added to the cultures, was as effective as the combination of the two. The results with ALA + FeCl3 suggested that stimulation of intracellular production of heme was also effective in blocking the increase in ALA synthase mRNA caused by AIA. Finally, the distributions of ALA synthase mRNA were compared in polysomes isolated from hepatocytes which had been incubated with AIA for 5 h in the presence and absence of 10 microM hemin in the medium. Although a drop was detected in the concentration of ALA synthase mRNA in polysomes from hepatocytes incubated with hemin for 30 min, the decrease was explained by the effect of hemin on the mRNA concentration in the cells.
在与烯丙基异丙基乙酰胺（AIA）一起孵育的鸡胚肝细胞原代培养物中，研究了血红素对δ-氨基乙酰丙酸合酶（ALA合酶）mRNA浓度以及该信使与多核糖体结合的影响。使用与ALA合酶mRNA互补的合成24聚体DNA，通过溶液杂交来确定AIA以及AIA加血红素对细胞中ALA合酶特异性RNA序列的影响。结果表明，用AIA（0.075mg/ml）孵育5小时的肝细胞中，ALA合酶mRNA浓度显著增加，并且培养基中的血红素（2或10μM）可阻止该信使的增加。当向培养基中分别加入δ-氨基乙酰丙酸（ALA）和FeCl3（分别为1mM和5μM）时，AIA引起的ALA合酶mRNA增加也受到抑制。单独添加到培养物中的ALA和FeCl3都不如两者组合有效。ALA + FeCl3的结果表明，刺激细胞内血红素的产生在阻断AIA引起的ALA合酶mRNA增加方面也有效。最后，比较了在培养基中存在和不存在10μM血红素的情况下，与AIA孵育5小时的肝细胞分离的多核糖体中ALA合酶mRNA的分布。尽管在与血红素孵育30分钟的肝细胞多核糖体中检测到ALA合酶mRNA浓度下降，但这种下降是由血红素对细胞中mRNA浓度的影响所解释的。
