Original Article

Estrogen prevents bovine aortic endothelial cells from TNF-alpha-induced apoptosis via opposing effects on p38 and p44/42 CCDPK.

Authors: Wen-Lan LIU, Xun GUO, Zhao-Gui GUO

Abstract

AIM: To investigate the effect of 17beta-estradiol (E2) on TNF-alpha-induced
apoptosis in cultured bovine aortic endothelial cells (BAEC) and the underlied
mechanism.
METHODS: BAEC were cultured and passaged in Dulbecco's modified Eagle's medium
(DMEM). Morphologic changes and quantification of apoptotic cells were determined
under fluorescence microscope with Hoechst 33258 staining. Cell viability was
detected with MTT method. DNA fragmentation was visualized by agarose gel
electrophoresis. The expression of phospho-p38 and phospho-p44/42 Ca2+-calmodulin
dependent protein kinase (CCDPK) was measured by Western blotting.
RESULTS: TNF-alpha 5000 kU/L elicited typical apoptotic morphologic changes
(chromatic condensation, nucleus fragmentation, and DNA fragmentation). E2 0.1
pmol/L-100 nmol/L enhanced the expression of phospho-p44/42 CCDPK induced by
TNF-alpha, at the same time, inhibited TNF-alpha induced activation of p38 CCDPK.
E2 protected BAEC from apoptosis induced by TNF-alpha in a
concentration-dependent manner. DNA fragmentation induced by TNF-alpha 5000 kU/L
was also reduced by E2 1 nmol/L. Both the E2-induced upregulation of
phospho-p44/42 CCDPK and its anti-apoptotic action were prevented by the specific
p44/42 CCDPK inhibitor U0126.
CONCLUSION: Activation of p44/42 CCDPK signaling together with inhibition of p38
CCDPK signaling by E2 appears to be an important mechanism for its survival
effect on endothelial cells.
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