Reduced PKC α Activity Induces Senescent Phenotype in Erythrocytes

الملخص EN

The molecular mechanism mediating expression of senescent cell antigen-aggregated or cleaved band 3 and externalized phosphatidylserine (PS) on the surface of aged erythrocytes and their premature expression in certain anemias is not completely elucidated.

The erythrocytes with these surface modifications undergo macrophage-mediated phagocytosis.

In this study, the role of protein kinase C (PKC) isoforms in the expression of these surface modifications was investigated.

Inhibition of PKC α by 30 μM rottlerin (R30) and 2.3 nM Gö 6976 caused expression of both the senescent cell marker-externalized PS measured by FACS analysis and aggregated band 3 detected by western blotting.

In contrast to this observation, but in keeping with literature, PKC activation by phorbol-12-myristate-13-acetate (PMA) also led to the expression of senescence markers.

We explain this antithesis by demonstrating that PMA-treated cells show reduction in the activity of PKC α, thereby simulating inhibition.

The reduction in PKC α activity may be attributed to the known downregulation of PMA-activated PKC α, caused by its membrane translocation and proteolysis.

We demonstrate membrane translocation of PKC α in PMA-treated cells to substantiate this inference.

Thus loss of PKC α activity either by inhibition or downregulation can cause surface modifications which can trigger erythrophagocytosis.