Regulation of histone H1(0) accumulation during induced differentiation of murine erythroleukemia cells.

Histone H1(0) is one of the potential candidates that may contribute to the onset and stabilization of a genetic program during induced differentiation of murine erythroleukemia cells. In an attempt to understand better the role of H1(0) in this process we have tried to determine at which level the regulation of its induced accumulation occurs. Protein H1(0) was found to increase by a factor of 3 while its mRNA increased by a factor of 14, due to activation of gene transcription. As shown by H1(0) half-life measurements, the difference between the actual amount of H1(0) and that expected from the amount of mRNA was not due to increased turnover of the protein. Fractionation of the translational apparatus at several times during induction, revealed that H1(0) mRNA was efficiently transferred to the high molecular weight polysomes. The rate of synthesis of H1(0) was also increased by a factor of 4. Taken together, these results suggest the existence of a strong control at the translational level, which regulates H1(0) accumulation.