Development of the Ornithine Cycle in Rat Liver: Zonation of A Metabolic Pathway

Abstract

Metabolic zonation in the liver parenchyma, i.e., heterogene-hepatocytes, gradually declining toward the pericentral ones. 3,4 For the detoxification of ammonia, the liver contains both ureaity of the hepatocytes along the portocentral radius of the liver lobule, has been studied extensively. 1,2 The metabolism of and glutamine-synthesizing enzyme systems that have a reciprocal distribution pattern. In adult rat liver, carbamoyl phosamino acids for example, occurs predominantly in the periportal phate synthetase I (CPS), which is involved in the production of urea via the ornithine cycle, is present periportally, with a portal-to-central gradient over the liver lobule. This accounts other ornithine cycle enzymes in the rat are not known.

Exocrine pancreas trans-differentiation to hepatocytes—A physiological response to elevated glucocorticoid in vivo

“…2C). GS expression is strongly compartmentalized from liver-specific carbamoyl phosphate synthase I (CPS) that is expressed in the periportal region [25]. Both GS (Fig.…”

A transgenic approach to study argininosuccinate synthetase gene expression

“…Zonation of metabolic pathways is believed to be a mechanism leading to efficient use of precursor pools and energy in an organism [14]. In the rodent, urea cycle enzymes in the liver show zonation distribution, i.e., they are present predominantly in the periportal hepatocytes and declining gradually toward the pericentral hepatocytes.…”

“…In the rodent, urea cycle enzymes in the liver show zonation distribution, i.e., they are present predominantly in the periportal hepatocytes and declining gradually toward the pericentral hepatocytes. Such a distribution pattern occurs not only at the protein level but also in the mRNAs of these enzymes [14]. To study whether zonation can be visualized by EGFP fluorescence, frozen sections of the liver were examined.…”

Transcriptional control in the mammalian liver: liver development, perinatal repression, and zonal gene regulation

“…Certain factors must be post-translationally modified to be fully active, and zonal control of such modifications has not been investigated. CPS is expressed in the periportal regions of the adult mouse liver and is a well-studied example of periportal expression [142]. CPS transcription is first detected in a subset of hepatocytes at mid-gestation.…”