Changes in the nuclear matrix of chicken erythrocytes that accompany maturation.
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ABSTRACT:
SUBMITTER: Chen HY
PROVIDER: S-EPMC1217926 | biostudies-other | 1996 Nov
REPOSITORIES: biostudies-other
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Project description:Histone H2B is deacetylated more rapidly than H3 and H4 in chicken immature erythrocytes. Histone deacetylase from chicken immature erythrocytes was partially purified, and the histone specificities of the multiple histone deacetylase forms were determined. Ion-exchange (Q-Sepharose) and gel-exclusion (Superdex 200) chromatography of extracts from erythrocyte nuclei showed two forms (HD1 and HD2) of histone deacetylase. HD1, with a molecular mass of about 55 kDa, preferred free H3-H4 relative to H2A-H2B, while HD2, with a molecular mass of approx. 220 kDa, had a slight preference for H3-H4. HD1 and HD2 differed in pH- and ion-strength-dependence. HD2 dissociated into HD1 when treated with 1.6 M NaCl or when applied to a Q-Sepharose column. The enzymic properties of nuclear-matrix-bound histone deacetylase showed a striking difference from that of HD1 and HD2, particularly in its strong preference for H2A-H2B. Treatment of the nuclear matrix with 1.6 M NaCl and 1% 2-mercaptoethanol solubilized histone deacetylase which chromatographed as 400 and 220 kDa forms on a Superdex 200 column. The solubilized enzyme retained its histone preference for H2A-H2B. Chromatography of the nuclear-matrix-derived enzyme on Q-Sepharose yielded one peak of enzyme activity with chromatographic properties and histone specificities similar to those of HD1. These results provide support for the active form of the enzyme in situ being a high-molecular mass complex associated with proteins that are components of the nuclear matrix. Substrate preference of the enzyme is governed by the proteins associated with the histone deacetylase.
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Project description:A simple culture technique was used to follow sheep reticulocyte maturation. Cells remained in good condition without lysis for at least 7 days and maintained normal intracellular ATP concentrations. Amino acid and nucleoside transport were measured during maturation together with changes in reduced glutathione (GSH), amino acid, K+ and Na+ concentrations. Reticulocytes of the genetic types high-K+ and low-K+, high-GSH and low-GSH; nucleoside-permeable and nucleoside-impermeable were indistinguishable both in transport properties and cellular constituents. Cell maturation was associated with marked decreases in L-alanine transport (Na+-dependent and independent), uridine transport and GSH and K+ concentrations. Typical mature-cell levels for all parameters were reached within the culture period, during which time predicted differences between cells of different genotypes became apparent. Loss of amino acid-transport activity from low-GSH cells was accompanied by an increase in intracellular ornithine and lysine concentrations. The rates at which different parameters changed during culture were compared.
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