Absence Of Butyrate Research Articles

The effect of sodium butyrate on acetylation in vitro of chromosomal proteins in three classes of liver nuclei from different ages of rats

The optimum conditions of in vitro incorporation of sodium [ 3H]acetate into sliced rat liver were studied. The incubations with sliced liver from three different ages of rats were performed in the presence of sodium n-butyrate. It was found that butyrate decreases the incorporation of sodium [ 3H]acetate into the homogenate, isolated nuclei, non-histone chromosomal proteins and histones for all age groups. The acetylations of non-histone chromosomal proteins and histones increase with age upto 2-months and decrease in 4-month-old rats both in the absence and presence of butyrate. Liver nuclei were fractionated by the simple method of zonal centrifugation into three classes, namely diploid stromal, diploid parenchymal and tetraploid parenchymal nuclei. The acetylations of non-histone chromosomal proteins and histones in three classes of nuclei of three ages of rats were studied in the presence and absence of butyrate. Butyrate can decrease the overall acetylations of non-histone chromosomal proteins and histones but increase the amount of polyacetylated histone H4 in all classes of nuclei of the three ages.

Effects of butyrate on ouabain-sensitive respiration of hamster brown adipocytes.

Brown adipose tissue is an important site of cold-induced nonshivering thermogenesis in many mammals. The plasma membrane-bound Na+-K+-ATPase has been shown to be significantly involved in this thermogenesis although its exact role is unknown at present. Evidence that coupling of oxidative phosphorylation to electron transport may become loosened during thermogenesis has prompted an investigation of potential roles of the Na+-K+ pump that would be compatible with altered respiratory coupling. One such role is that of modulating norepinephrine (NE)-induced lipolysis and hence provision of free fatty acids to the mitochondria. Under such conditions, inhibition of the pump would reduce NE-induced respiration by limiting substrate availability. If, in fact, the primary role of the pump in NE-induced thermogenesis is to facilitate substrate availability, provision of exogenous substrate should bypass this involvement and ameliorate the ouabain inhibition of respiration. In the present study, this possibility was examined by determining the effect of an exogenous substrate, butyrate, on the contribution of the Na+-K+ pump to NE-stimulated respiration of isolated hamster brown adipocytes. Although exogenous butyrate was able to serve as a substrate for brown adipocyte respiration, its presence had no significant effect on the ouabain sensitivity of NE-induced rates of oxygen consumption. That is, ouabain (1 mM) inhibited the NE-evoked thermogenesis of the adipocytes by 77.7 +/- 6.5% in the absence of butyrate (2 mM) and by 73.4 +/- 9.9% in its presence. It appears, therefore, that the contribution of the Na+-K+ membrane pump to brown fat thermogenesis does not simply reflect modulation of NE-evoked lipolysis.

The effect of butyrate on sulfated glycoprotein biosynthesis by human kidney tumor cells.

Human kidney tumor cells in culture incorporate [3H]glucosamine and 35SO4 into several classes of glycoconjugate products. After a 24-h labeling period, the 3H/35S-glycosaminoglycans and 3H-glycoproteins synthesized were found associated with both the cell layer and the culture medium. These tumor cells also synthesized a class of 35S-glycoproteins which contained alkali-stable 35S-oligosaccharide chains. These 35S-glycoproteins did not accumulate with the cell layers but were preferentially found in the culture medium (82-96%). After treatment with 2.5 mM butyrate for 24 h, the tumor cells assumed a more flattened and spread morphology with more clearly defined cell borders. These butyrate-treated cell cultures showed less than a 2-fold increase in the cell-associated form of both 3H/35S-glycosaminoglycans and 3H-glycoproteins, compared to cells cultured in the absence of butyrate. In contrast, butyrate-treated cell cultures had a 3-fold increase in the total incorporation of 35SO4 into glycoproteins and a dramatic 10-30-fold increase in the cell-associated form of these 35S-glycoprotein products as compared to untreated cell cultures.

Morphological and biochemical differentiation in HeLa cells: Effects of cycloheximide on butyrate-induced process formation and ganglioside metabolism

When butyrate-treated HeLa cells are trypsinized and replated in the absence of butyrate, their neurite-like processes re-extend transiently. Process formation after replating is prevented when the cells are exposed to cycloheximide during butyrate treatment, whereas it is not prevented by prior exposure to the calcium ionophore A23187 plus butyrate. These results indicate that butyrate induces protein(s) required for process extension which can accumulate in the absence of processing and promote processing in the absence of inducer. Transient process re-extension is followed by spontaneous retraction of processes and reversion to normal morphology. Reversion is not prevented or delayed by puromycin. Surprisingly, however, cycloheximide completely prevents reversion even at low concentrations (< 0.5 μg/ml). Levels of the ganglioside sialolactosylceramide (G M3), synthesis of which is induced by butyrate, return to basal levels after removal of the inducer. Cycloheximide at 0.5 μg/ml prevents the decline of G M3 levels after removal of butyrate although the biosynthetic enzyme sialyltransferase decays at the same rate in the presence or absence of the drug and the activity of the sialidase is not affected. The results further support the hypothesis that the ganglioside G M3 is necessary for the morphological differentiation induced in HeLa cells by butyrate.