Decrease of phenylalanine hydroxylase during hepatocyte proliferation

In partially hepatectomized rats, the activity of phenylalanine hydroxylase decreased in the regenerating liver but not in the kidney. The concentration of corticosterone in the plasma of hepatectomized rats increased, and phenylalanine hydroxylase, despite being cortisol inducible, decreased in these as well as simultaneously adrenalectomized rats, showing lack of correlation between the changes of the steroid and the enzyme during the regeneration process. The decrease in the enzyme activity could be prevented by administering, during hepatic regeneration, only noradrenaline and adrenergic blocking agents, among the many hormones and phenyl compounds tested. A decrease in hepatic phenylalanine hydroxylase was also observed during two other conditions of hepatocyte cell proliferation obtained after giving chlorophenoxyisobutyrate and α-hexachlorocyclohexane.

Nature of the stimulation of biogenesis of cholesterol in the liver by noradrenaline

1.Administration of noradrenaline increased the incorporation of [1-14C]acetate into hepatic sterols and the activity of liver microsomal 3-hydroxy-3-methylglutaryl-CoA reductase. 2. The stimulation was observed at short time-intervals with a maximum at 4h and was progressive with increasing concentrations of noradrenaline. 3. Protein synthesis de novo was a necessary factor for the effect. 4. The stimulatory effect was not mediated through the adrenergic receptors, but appears to involve a direct action of the hormone within the hepatocyte.

Non-viral ex vivo hepatic gene transfer by in situ lipofection of liver and intraperitoneal transplantation of hepatocytes

Perfusion of liver with plasmid DNA-lipofectin complexes via the portal vein results in efficient accumulation of the vector in hepatocytes. Such hepatocytes, when administered intraperitoneally into a hepatectomized rat, repopulate the liver and express the transgene efficiently. This procedure obviates the need for large-scale hepatocyte culture for ex vivo gene transfer. Further, intraperitoneal transplantation is a simple and cost-effective strategy of introducing genetically modified hepatocytes into liver. Thus, in situ lipofection of liver and intraperitoneal transfer of hepatocytes can be developed into a novel method of non-viral ex vivo gene transfer technique that has applications in the treatment of metabolic disorders of liver and hepatic gene therapy.

Characterization of type I interferon pathway during hepatic differentiation of human pluripotent stem cells and hepatitis C virus infection

Pluripotent stem cells are being actively studied as a cell source for regenerating damaged liver. For long-term survival of engrafting cells in the body, not only do the cells have to execute liver-specific function but also withstand the physical strains and invading pathogens. The cellular innate immune system orchestrated by the interferon (IFN) pathway provides the first line of defense against pathogens. The objective of this study is to assess the innate immune function as well as to systematically profile the IFN-induced genes during hepatic differentiation of pluripotent stem cells. To address this objective, we derived endodermal cells (day 5 post-differentiation), hepatoblast (day 15) and hepatocyte-like cells (day 21) from human embryonic stem cells (hESCs). Day 5, 15 and 21 cells were stimulated with IFN-alpha and subjected to IFN pathway analysis. Transcriptome analysis was carried out by RNA sequencing. The results showed that the IFN-alpha treatment activated STAT-JAK pathway in differentiating cells. Transcriptome analysis indicated stage specific expression of classical and non-classical IFN-stimulated genes (ISGs). Subsequent validation confirmed the expression of novel ISGs including RASGRP3, CLMP and TRANK1 by differentiated hepatic cells upon IFN treatment. Hepatitis C virus replication in hESC-derived hepatic cells induced the expression of ISGs - LAMP3, ETV7, RASGRP3, and TRANK1. The hESC-derived hepatic cells contain intact innate system and can recognize invading pathogens. Besides assessing the tissue-specific functions for cell therapy applications, it may also be important to test the innate immune function of engrafting cells to ensure adequate defense against infections and improve graft survival. (C) 2015 The Authors. Published by Elsevier B.V.