ABSTRACT
BACKGROUND: Chronic alcohol consumption may act as a cellular stressor for brain cells, as has been found for aging. In this study we examined one component of the cellular stress response (heat shock proteins) as a function of age and alcohol exposure. We have found that the level of constitutively expressed heat shock protein 70 (heat shock cognate 70, or Hsc70) increases in the aged rat brain. Among many heat shock proteins and molecular chaperones, Hsc70 might be important not only for the normal protein folding pathway but also for refolding of denatured proteins produced by mild and chronic stress. METHODS: Male Wistar rats that were 5.5 to 28.5 months old were fed a liquid diet that contained 5% (w/v) alcohol or a control diet for 6 weeks. The effects of alcohol consumption and aging on the expression of Hsc70 in the brain were investigated. The cytosol proteins in the 12,000 x g supernatant fraction were heat-treated at 42 degrees C for 1 hr. After the heat treatment, proteins that transferred from the soluble to insoluble aggregated fraction were estimated as heat-unstable proteins. RESULTS: In the 24- and 30-month-old rat brain, chronic consumption of alcohol increased levels of Hsc70 and heat-unstable proteins. On the other hand, those changes were not detected in the younger rat brain. CONCLUSION: Chronic alcohol intake causes a stress response in the aged rat brain. It is thought that the increased level of Hsc70 is brought about by an increase of denatured proteins.
Subject(s)
Aging/metabolism , Alcohol Drinking/metabolism , Brain/metabolism , Stress, Physiological/chemically induced , Stress, Physiological/metabolism , Age Factors , Aging/drug effects , Animals , Brain/drug effects , HSC70 Heat-Shock Proteins , HSP70 Heat-Shock Proteins/biosynthesis , Male , Rats , Rats, WistarABSTRACT
To clarify the function of integrin alpha(v)beta3 in the early stage of liver metastasis, we investigated the interactions of metastatic cells with their target organ under the actual blood flow by using positron emission tomography (PET). The cells used were CHO-K1 cells and their transfectants bearing human integrin alpha(v)beta3 cDNA (alpha(v)beta3-CHO-K1 cells). The liver accumulation of alpha(v)beta3-CHO-K1 cells was significantly higher than that of CHO-K1 cells after injection via the portal vein, whereas no significant difference was observed in the lung accumulation after tail vein injection, suggesting a specific interaction of alpha(v)beta3-CHO-K1 cells with the hepatic sinusoids. Furthermore, to clarify the precise location of each cell in the liver, i.e., to determine whether individual cells were intravascularly localized or had extravasated, we performed intravital fluorescence microscopy (IVM) on the liver by using stable transfectants bearing the green fluorescent protein (GFP) gene, namely, GFP-CHO-K1 and GFP-alpha(v)beta3-CHO-K1 cells. Both types of cells remained in the hepatic blood vessels 1 h after injection via the portal vein. On the other hand, expression of integrin alpha(v)beta3 promoted the cells to reach the extravascular region after 24 h. These results suggest the possibility that the specific accumulation of alpha(v)beta3-CHO-K1 cells in the liver is followed by migration of the cells into the extravascular region. Interestingly, the adhesion of the two types of cells to hepatic sinusoidal endothelial cells in vitro did not correspond to in vivo accumulation of these cells. Therefore, integrin alpha(v)beta3 may function to promote extravasation of integrin alpha(v)beta3-expressing tumor cells in liver through a process possibly mediated by vitronectin produced by this organ.
