Numazaki M, Tsutsumi K, Tsutsumi R, Ishikawa K
Eur J Biochem. 1984 Jul 2;142(1):165-70. doi: 10.1111/j.1432-1033.1984.tb08265.x.
The regulation of aldolase isozyme expression during development was studied by measuring the concentrations of mRNAs coding for aldolase A and B subunits in fetal and adult rat liver. Poly(A)-containing RNAs were extracted from livers at various stages of development of fetal rats, and the aldolase A and B subunits in the in vitro translation products of these RNAs were analyzed immunologically. The content of aldolase B mRNA in 14-day fetal liver, measured quantitatively as translational activity, was somewhat smaller than that of aldolase A mRNA; immunologically precipitable aldolase B and A amounted to 0.06% and 0.25% respectively, of the total products. Similar experiments using RNAs from fetuses at later stages, however, showed that aldolase B mRNA increased during development, whereas aldolase A mRNA decreased. In newborn rat liver, aldolase B constituted 0.56% of the total translation products of mRNA, but there was little detectable aldolase A (0.03%). The changes of aldolase mRNA levels were analyzed further by northern blot and dot-blot hybridization experiments using cloned aldolase A and B cDNAs. The content of aldolase B mRNA increased in the fetal stage, and that in newborn rat liver was about 12 times that in 14-day fetal liver. In contrast, the aldolase A mRNA content decreased during gestation and that in newborn rat liver was about one-eighth of that in 14-day fetal liver. These observations suggest that the switch of aldolase isozyme expression in fetal liver is controlled by the levels of the respective mRNAs.
通过测量胎鼠和成年大鼠肝脏中编码醛缩酶A和B亚基的mRNA浓度，研究了发育过程中醛缩酶同工酶表达的调控。从胎鼠不同发育阶段的肝脏中提取含Poly(A)的RNA，并对这些RNA体外翻译产物中的醛缩酶A和B亚基进行免疫分析。以翻译活性定量测量，14天胎肝中醛缩酶B mRNA的含量略低于醛缩酶A mRNA；免疫沉淀的醛缩酶B和A分别占总产物的0.06%和0.25%。然而，使用后期胎儿RNA进行的类似实验表明，醛缩酶B mRNA在发育过程中增加，而醛缩酶A mRNA减少。在新生大鼠肝脏中，醛缩酶B占mRNA总翻译产物的0.56%，但几乎检测不到醛缩酶A（0.03%）。使用克隆的醛缩酶A和B cDNA通过Northern印迹和斑点印迹杂交实验进一步分析醛缩酶mRNA水平的变化。醛缩酶B mRNA的含量在胎儿期增加，新生大鼠肝脏中的含量约为14天胎肝中的12倍。相反，醛缩酶A mRNA的含量在妊娠期减少，新生大鼠肝脏中的含量约为14天胎肝中的八分之一。这些观察结果表明，胎肝中醛缩酶同工酶表达的转换受各自mRNA水平的控制。
