Developmental and thyroid hormone-dependent regulation of pancreatic genes in Xenopus laevis.
We have isolated and sequenced a cDNA encoding Xenopus laevis pancreatic trypsin, which has approximately 70% amino acid sequence identity to mammalian trypsinogen. Northern blotting analysis shows that the trypsin gene is activated just before the tadpole starts to feed, reaches peak activity in the swimming tadpole (premetamorphosis), and is then repressed during prometamorphosis, attaining its lowest activity at the climax of metamorphosis. The same gene is then activated again in frogs but to a much lower level. The pattern of the changes in trypsin gene expression is followed by at least two other pancreas-specific genes and marks the remodeling of the pancreas of the animal at metamorphosis. Thyroid hormone, which is the causative agent of metamorphosis, can down-regulate trypsin gene expression prematurely.
Department of Embryology, Carnegie Institution of Washington, Baltimore, Maryland 21210.
Y B
YB
Shi
D D
DD
Brown
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D004247:DNA / Q000235:genetics; D004790:Enzyme Induction / Q000187:drug effects; D007814:Larva; D008675:Metamorphosis, Biological; D008969:Molecular Sequence Data; D010179:Pancreas / Q000201:enzymology; D051381:Rats; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D013974:Thyroxine / Q000494:pharmacology / Q000502:physiology*; D014357:Trypsin / Q000096:biosynthesis / Q000235:genetics*; D014362:Trypsinogen / Q000235:genetics; D014982:Xenopus laevis / Q000235:genetics* / Q000254:growth & development
D014362:Trypsinogen; D004247:DNA; D014357:Trypsin; D013974:Thyroxine