Comparison of the spectra of proteins synthesized in mouse thymocytes after irradiation or hydrocortisone treatment.

The proteins synthesized in mouse thymocytes after irradiation and hydrocortisone treatment were analyzed by two-dimensional electrophoresis. An exposure to lympholytic agents induced different changes in the biosynthesis of proteins; however the induction of a few common proteins by these agents was revealed. The increase in the synthesis of five nuclear polypeptides occurred at early times (15-75 min) after irradiation. At least two of them (proteins of the nuclear matrix) are also induced by hydrocortisone. Synthesis of three of these 'early proteins' soon terminated, while the synthesis of the other two increased, and by 3.5 h they were found in large quantities after both treatments. At the same time, another protein common for both agents was induced. Three of these nuclear proteins are part of the nuclear matrix. Participation of these proteins in realization of the cell death program is discussed.