NF-kappaB activation in light-induced retinal degeneration in a mouse model.

PURPOSE

To investigate the modulation of nuclear factor (NF)-kappaB in light-induced photoreceptor degeneration in a mouse model.

METHODS

Mice were exposed to intense green light. Light-induced activation of NF-kappaB and its nuclear localization were studied by immunohistochemistry. The NF-kappaB DNA-binding activity in the retinas after exposure to light was measured by electrophoretic mobility shift assay (EMSA). Nuclear transactivation of NF-kappaB in the photoreceptor cells was determined by quantitative real-time (qRT)-PCR. The amount of NF-kappaB p65 in the photoreceptor cells after exposure to light was assessed by Western blot analysis. To obtain more photoreceptor-specific information, microdissected photoreceptor cells were used in some studies.

RESULTS

By an immunohistochemical method, the perinuclear region of the photoreceptor cells was heavily labeled with an antibody to activated NF-kappaB after a 1-hour exposure to light. Nuclear localization of NF-kappaB in the photoreceptor nucleus was seen at 12 hours. In the experiments involving 3 hours of exposure to light followed by recovery in the dark, nuclear localization of NF-kappaB was also noted after 12 hours' recovery in the dark. During continuous exposure to light, the NF-kappaB DNA-binding activity gradually increased and reached its maximum at 12 hours. There was an increase of NF-kappaB p65 protein at 3 hours. The mRNA levels of IkappaBalpha were upregulated after 6 hours' exposure to light.

CONCLUSIONS

Intense light activated NF-kappaB in the photoreceptor cells in vivo, increased the NF-kappaB DNA-binding activity, and increased the expression of mRNA of IkappaBalpha, a target gene of NF-kappaB.