Simultaneous expression of c-Jun and p53 in retinal ganglion cells of adult rat retinal slice cultures.
OBJECTIVE
To determine whether the apoptosis-associated transcription factor c-Jun and the regulator protein p53 are expressed together during retinal ganglion cell (RGC) death in slice cultures of adult rat retina, and whether c-Jun expression or p53 expression is altered by glutamate.


METHODS
Newborn rat RGCs were retrogradely labeled by Di-I microinjections into the superior colliculus. Retinas were isolated 2 to 4 months later, cut into 200 microm-thick slices. These slices were cultured with 0-300 microM glutamate in the presence or absence of MK801. Survival was assessed using Sytox green and ethidium homodimer. Cultures also were immunostained for Thy-1, c-Jun and/or p53. The linear density of stained RGCs was determined by confocal laser microscopy.


RESULTS
RGCs in freshly-isolated adult retina slices did not express either c-Jun or p53. By 12 hours in vitro, 12.0 +/- 3.1 cells/mm of RGCs expressed c-Jun and 18.5 +/- 3.5 cells/mm of RGCs expressed p53 in control cultures. Exposure to glutamate increased both c-Jun and p53 positive RGCs in dose-dependent manner, and decreased survival in the RGC layer. Following double staining, up to 58% of cells in the RGC layer simultaneously expressed both c-Jun and p53. Time-course analysis showed that peak c-Jun expression preceded peak p53 expression in control and glutamate-treated cultures.


CONCLUSIONS
The simultaneous expression of both c-Jun and p53 in the cultured adult rat slices raises the possibility that each may contribute to the mechanism of RGC death. This is supported by the increased p53 and c-Jun inductions in the presence of glutamate.
Umihira
Junichi
J
Glaucoma Center, University of California, 9500 Gilman Drive, La Jolla, San Diego, CA 92093-0946, USA.
Lindsey
James D
JD
Weinreb
Robert N
RN
D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D046508:Culture Techniques; D016291:Dizocilpine Maleate / Q000494:pharmacology; D008297:Male; D011189:Potassium Chloride / Q000494:pharmacology; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012160:Retina / Q000033:anatomy & histology / Q000166:cytology* / Q000378:metabolism*; D012165:Retinal Ganglion Cells / Q000378:metabolism* / Q000502:physiology; D013997:Time Factors; D014018:Tissue Distribution; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
D016755:Proto-Oncogene Proteins c-jun; D016159:Tumor Suppressor Protein p53; D011189:Potassium Chloride; D016291:Dizocilpine Maleate