Protein kinase-C involvement in thymocyte apoptosis induced by hydrocortisone.

The involvement of protein kinase-C in thymocytes death induced by hydrocortisone was studied. Thymus cells were incubated 6 hr or in the presence of hydrocortisone, labeled with Acridine orange, and the DNA content of each nuclei was estimated by cytofluorimetry. The results indicate that hydrocortisone-induced DNA fragmentation can be prevented by adding the protein kinase-C inhibitor H-7 to the cell suspension. Incubation of the H-A 1004, an inhibitor of c-AMP-dependent protein kinase, with low effect on on protein kinase-C, did not interfere with the cortisone-mediated DNA fragmentation. Therefore, it can be concluded that protein kinase-C plays an important role in the process of lympholysis mediated by corticoids.