Effect of taurine on protein kinase C isoforms: role in taurine's actions?

Taurine is generally found to be cytoprotective, diminishing damage resulting from ischemia and from initiators of heart failure. Also linked to similar events in the heart is the protein kinase C (PKC) family, which consists of at least 12 different isoforms. Therefore, we proposed that PKC might contribute to the beneficial effects of taurine on cell viability and growth. One of the PKC isoforms that has been advanced as an important mediator of cytoprotection during ischemia is PKCepsilon. In this study, we found that incubation of isolated cardiomyocytes with medium containing 20 mM taurine led to the translocation of PKCepsilon into the membrane, an event commonly associated with the cardioprotective actions of the PKC isozyme. In addition, taurine promoted the upregulation of PKCalpha PKCbeta2 and PKCzeta. Because the effects of taurine and angiotensin II on PKC distribution were largely additive, PKC does not appear to contribute to the antagonism between taurine and angiotensin II. However, the upregulation of PKC by taurine is consistent with a role of taurine in normal cell growth. In the taurine deficient heart, cardiomyocyte size is reduced, an effect that is consistent with the effect of taurine on PKCepsilon. In conclusion, the cytoprotective and pro-growth actions of taurine appears to be mediated in part by the activation of PKCepsilon.