Effects of deletions in mouse chromosome 7 on expression of genes encoding the urea-cycle enzymes and phosphoenolpyruvate carboxykinase (GTP) in liver, kidney, and intestine.

Chromosomal deletions at and around the albino locus on chromosome 7 of the mouse affect the enzyme activities and steady-state levels of mRNAs for five urea-cycle enzymes in liver. In newborn c3H homozygotes, activities of these enzymes were 43-62% of normal, while corresponding mRNA levels were 14-29% of normal. c14CoS deletion homozygotes expressed mRNA levels for these enzymes which were 32-48% of normal. However, transcription rates of these genes in hepatic nuclei of c3H/c3H mice were reduced only to 57-84% of normal. Since effects of the deletions had previously been noted in the kidney, mRNA levels for three enzymes expressed also in the kidney were examined. Mice homozygous for the c3H deletion, shown previously to have drastically reduced mRNA levels for phosphoenolpyruvate carboxykinase in the liver, expressed the same deficiency in the kidney, while mRNA levels for argininosuccinate synthetase and argininosuccinate lyase were reduced in the liver but remained unaffected in the kidney. However, mRNA levels for phosphoenolpyruvate carboxykinase, carbamyl phosphate synthetase I, and ornithine transcarbamylase were unaffected in the intestine of c3H homozygotes. The results suggest that a regulatory factor(s) encoded in the DNA encompassed by the deletion is involved in the normal developmental maturation of hepatocytes and certain cells in the kidney.