Purpose
Molecular mechanisms of retinal ganglion cell (RGC) survival and death are required to search for neuroprotective strategies. Previous study revealed that one of the prostaglandin analogues, latanoprost, prevents RGC death from hypoxic stresses (Yamagishi et al., 2011 Exp Eye Res.). Here we examined its mechanisms of the neuroprotection, especially of the role in the activity of NF-kB, a key controller of apoptosis, to understand how we could utilize latanoprost for the treatment of glaucomatous optic neuropathy.
Methods
Using primary cultured rat RGCs, the changes of several proteins concerning apoptosis, including NF-kB p65 and its post translational modifications, were examined. Addition of 500 µM cobalt chloride to the culture medium was used as mimic hypoxic stress. Western blotting was used to analyze whether 100 nM of latanoprost changed the phosphorylation of the protein induced by hypoxic stresses.
Results
Hypoxia significantly down-regulated the phosphorylation of NF-kB p65 at serine 468, a phosphorylation site for suppression of NF-kB activity, in cultured rat RGCs 5 min after addition of CoCl2. With the normalization using actin, we can assure the decrease in phosphorylation in the amount of protein level at serine 468 to 72.2 % (p = 0.046). Moreover, addition of 100 nM latanoprost suppressed phosphorylated protein level more (72.2 % to 42.2 %, p= 0.012). On the other hands, phosphorylation of NF-kB at serine 536, a phosphorylation site for activation of NF-kB, was not significantly changed by addition of CoCl2.
Conclusions
These findings support that the role for latanoprost in protection of RGCs by activation of NF-kB through down-regulation of phosphorylation at serine 468 of NF-kB p65.
Keywords: 531 ganglion cells •
615 neuroprotection •
449 cell survival