Brand S J, Fuller P J
Massachusetts General Hospital, Department of Medicine, Harvard Medical School, Boston 02114.
J Biol Chem. 1988 Apr 15;263(11):5341-7.
Gastrin gene expression exhibits a complex pattern of tissue-specific expression during the neonatal development of the gastrointestinal tract and pancreas. In the rat fetus, the pancreas is the major site of gastrin expression; very little gastrin is found in the antrum which is the major site of adult expression. Pancreatic gastrin mRNA is identical to the antral species having the same transcriptional initiation site. The post-translational processing of the pancreatic gastrin peptide, however, differs in being fully tyrosine sulfated, and thus it resembles gastrin's homologue, cholecystokinin. Pancreatic gastrin is maximally expressed during late fetal gestation before the marked rise in somatostatin, insulin, and glucagon mRNA levels which occurs during the last 4 days of gestation. After birth, gastrin mRNA levels rapidly disappear as the other islet mRNAs achieve stable maximal levels. Unlike the pancreas, gastrin gene expression in the duodenum and antrum is similar to the development profiles of somatostatin and glucagon gene expression. In the duodenum, however, expression of cholecystokinin differs from the common developmental pattern in being expressed only after birth. Thus, pancreatic gastrin gene expression shows a reciprocal relationship to the developmental expression of cholecystokinin in the duodenum.
在胃肠道和胰腺的新生儿发育过程中，胃泌素基因表达呈现出复杂的组织特异性表达模式。在大鼠胎儿中，胰腺是胃泌素表达的主要部位；在胃窦中发现的胃泌素很少，而胃窦是成年期表达的主要部位。胰腺胃泌素mRNA与具有相同转录起始位点的胃窦mRNA相同。然而，胰腺胃泌素肽的翻译后加工有所不同，它完全硫酸化酪氨酸，因此类似于胃泌素的同源物胆囊收缩素。在妊娠晚期，胰腺胃泌素表达最高，此时生长抑素、胰岛素和胰高血糖素mRNA水平在妊娠最后4天显著升高之前。出生后，随着其他胰岛mRNA达到稳定的最高水平，胃泌素mRNA水平迅速消失。与胰腺不同，十二指肠和胃窦中的胃泌素基因表达与生长抑素和胰高血糖素基因表达的发育模式相似。然而，在十二指肠中，胆囊收缩素的表达与常见的发育模式不同，仅在出生后才表达。因此，胰腺胃泌素基因表达与十二指肠中胆囊收缩素的发育表达呈反比关系。
