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Query: UNIPROT:P17174 (aspartate aminotransferase)
 14,872 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The zonation of the expression and regulation of the cytosolic aspartate aminotransferase (cAspAT) mRNAs in the liver acinus was investigated in diabetic and/or adrenalectomized rats. Dexamethasone increased cAspAT activity two- to threefold alone and up to sixfold in combination with streptozotocin-induced diabetes. Northern blot analysis showed that the cAspAT mRNAs were increased by those treatments; the effect of streptozotocin was reversed by the administration of insulin. In situ hybridization experiments showed that basal cAspAT mRNAs were uniformly distributed within the liver acinus. However, cAspAT mRNAs were induced by glucocorticoids specifically in the periportal zone and by streptozotocin in a larger area including the periportal and intermediary zone. The alpha 2u-globulin mRNAs which are specifically expressed in the perivenous hepatocytes are also induced by glucocorticoids in this zone, suggesting that the specific regulation of the cAspAT gene by glucocorticoids in the periportal zone is not due to the absence of functional glucocorticoid receptors in the other zones. We conclude that the regulation of the cAspAT housekeeping gene is zone specific in the liver. Furthermore, this zonation depends on the gene and on the type of hormonal or pharmacological treatment.
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PMID:Acinar zonation of the hormonal regulation of cytosolic aspartate aminotransferase in the liver. 751 55

A group of genes in the mouse encoding liver-specific gluconeogenic enzymes and mapping on different chromosomes lose their normal competence for hormone-inducible expression in animals homozygous for chromosomal deletions around the albino locus on chromosome 7. The basal expression of these same genes remains normal. In previous investigations, glucocorticoid hormones as well as their receptors were found to be normal in the deletion homozygotes. The results reported here identify an additional unlinked structural gene whose regulation appears to be affected by the deletions--i.e., that encoding cytosolic aspartate aminotransferase, a housekeeping gene that participates in gluconeogenesis in the liver. In normal mice, its mRNA level increases sharply at birth, specifically in the liver, and can be increased even further by dexamethasone and cAMP treatment. These increases fail to occur in mice homozygous for the specific deletions in chromosome 7. Interestingly, prenatally at 18-19 days of gestation, the gene is expressed at the same basal level in liver and brain of both normal and mutant mice. These observations strengthen the evidence implicating the deleted gene(s) as an essential factor(s) in the normal mechanisms of hormone-inducible expression of particular unlinked structural genes.
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PMID:Chromosomal deletions around the albino locus in the mouse cause loss of hormone-inducible expression of the unlinked structural gene encoding cytosolic aspartate aminotransferase. 784 52

We have studied the expression and regulation of the rat testis cytosolic aspartate aminotransferase gene. The cytosolic aspartate aminotransferase activity was 5-fold lower in the testis than in the liver and kidney. A 1.9-kilobase mRNA form was detected in the rat testis in contrast to the 2.1- and 1.8-kilobase forms present in other organs. Using Northern blot and S1 mapping analyses, we found that the proximal polyadenylation site was almost exclusively used in the testis as opposed to other organs where the distal site was preferentially used. RNase protection and primer extension analysis showed that transcription was initiated at multiple sites in all organs, but the pattern of those start sites was different in the testis; in particular, a novel transcription start site was specifically detected in this organ (at position -115 from the translation start site). This site was first observed in 29-day-old rats and was maximally utilized in the adult testis. DNase I footprinting using testis nuclear extracts revealed the presence of three sites of DNA-protein interaction in the 250-base pair proximal promoter, a pattern similar to the one found using liver nuclear extracts. However, the proteins bound had different properties as shown by gel retardation experiments. We conclude that the pattern of transcription initiation and the polyadenylation site selection of a housekeeping gene can be tissue-specific.
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PMID:Testis-specific transcription start site in the aspartate aminotransferase housekeeping gene promoter. 817 62