Hypoosmolarity and glutamine increased the β‐actin gene transcription in isolated rat hepatocytes

Abstract

The mechanism of action of hydration state was studied on ~-actin gene expression in isolated hepatoeytes. Results obtained with Northern blot analysis and run on transcription assays show that hypoosmolarity increased and hyperosmolarity decreased the ~actin mRNA level through a corresponding modulation of the rate of the gene transcription. Glutamine, which is known to induce cell swelling, also increased the ~-actin mRNA level in a dose-dependent manner and induced a stimulation of the ~-actin gene transcription. Thus, cell hydration state regulates gene expression in the liver through a transcriptional mechanism.

Glutamine‐dependent changes in gene expression and protein activity

“…34 Glutamine has an increasing effect on -actin mRNA levels in a dose-dependent manner, at least in part, due to the cell swelling induced by the sodium-dependent co-transport of the amino acid. 35 Glutamine (at 10 mM) also increases mRNA of -2 macroglobulin in cultured hepatocytes from rat fetuses.…”

Hypo-Osmolar Stress Induces p75NTR Expression by Activating Sp1-Dependent Transcription

“…Cytotoxic edema refers to cell swelling that results from intracellular fluid accumulation that occurs during stroke, trauma, or hypoxia (Papadopoulos et al, 2004), and this can be reproduced in vitro by exposing cells to extracellular hypo-osmolarity (Fischer et al, 1997;Caprini et al, 2003). Several genes, including p75NTR, are activated in response to this treatment (Husson et al, 1996;Meisse et al, 1998;Michalke et al, 2000;Warskulat et al, 2001;Peterson and Bogenmann, 2003), but the mechanisms that support this response and its physiological significance remain uncertain. p75NTR is almost invariably expressed after tissue injury that is accompanied by edema, and Peterson and Bogenmann (2003) have proposed that injury-induced reductions in extracellular osmolarity activate p75NTR transcription in vivo.…”

Glutamine Stimulates Argininosuccinate Synthetase Gene Expression through Cytosolic O-Glycosylation of Sp1 in Caco-2 Cells

“…Among amino acids, glutamine, which is the most abundant circulating amino acid, stimulates or inhibits the expression of various genes. This includes (i) intracellular proteins such as transcription factors (3,4), constitutive proteins of the cytoskeleton (5,6) and of the extracellular matrix (7), heat shock proteins (8) or metabolic enzymes (9,10); (ii) membrane proteins such as the transport system (11); and (iii) secreted proteins such as acute phase proteins (12), cytokines (13,14), and growth factor (15). However, the molecular mechanism(s) involved in the glutamine effect is not totally understood and may depend on the cell type studied.…”

“…However, the molecular mechanism(s) involved in the glutamine effect is not totally understood and may depend on the cell type studied. For example, glutamine metabolism was involved in the stimulation of phosphoenolpyruvate carboxykinase gene expression in isolated rat hepatocytes (16) and c-jun gene expression in enterocytes (3), but amino acid-induced cell swelling was also identified as the inducing pathway on gene expression in hepatocytes (5,6). Moreover, studying the regulation of the expression of argininosuccinate synthetase (ASS) 1 (EC 6.3.4.5.…”