Lipid rafts association and anti-apoptotic function of prohibitin in ultraviolet B light-irradiated HaCaT keratinocytes.

Upon UVB irradiation, an alternation of major lipid raft components can lead to the recruitment/activation of rafts-associated proteins and initiation of downstream apoptotic signalling pathways. We used two-dimensional gel electrophoresis (2-DE) to identify potential regulators of UVB-induced apoptosis and mass spectrometry fingerprint analysis to identify proteins that are altered in the rafts after UVB irradiation. Our data show that levels of several proteins, including prohibitin (PHB), were changed in lipid rafts after UVB irradiation. We also demonstrate that while total PHB expression was not changed, the protein was enriched in lipid rafts after UVB irradiation. Reduced expression of PHB using siRNA knockdown resulted in an increase in cellular apoptosis after UVB irradiation. Based on these results, we propose that PHB protects keratinocytes from UVB-induced apoptosis.