Purchase this article with an account.
S.J. Semaan, Y. Li, V. Babcic, S. John, R.W. Nickells; Differential Regulation of the Pro–Apoptotic Gene Bax in DBA/2J and 129B6 Inbred Mice Affects Retinal Ganglion Cell Death After Optic Nerve Crush . Invest. Ophthalmol. Vis. Sci. 2005;46(13):1279.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose:To investigate the effects of Bax gene dosage on retinal ganglion cell (RGC) death after optic nerve crush in DBA/2J and 129B6 inbred mice. Methods:Optic nerve crush was performed on one eye of 12 week old DBA/2J and 129B6 inbred mice wild–type (+/+), heterozygous (+/–), and mutant (–/–) for Bax. The fellow eye was left intact as a control. After 2 weeks, animals were sacrificed and the loss of RGCs was measured as percentage of cells remaining relative to the fellow, control eye. Bax cDNA was PCR amplified from each mouse line, cloned, and sequenced. Neuronal Bax mRNA levels were quantified by ribonuclease protection assay (RPA). Results:Significant RGC loss after optic nerve crush was exhibited in 129B6 +/+ and DBA/2J +/+ (P<0.005, P<0.001 respectively). Conversely, 129B6 –/– and DBA/2J –/– showed no significant RGC loss in response to crush (P>0.10, P>0.25 respectively). Heterozygous mice from each line exhibit distinctly different phenotypes in response to optic nerve crush, however. Bax +/– 129B6 displayed significant RGC loss (P<0.005), comparable to wild–type mice. Bax +/– DBA/2J showed no significant RGC loss (P<0.25), comparable to Bax mutant animals. Sequence analysis confirmed that each inbred line expressed an identical BAX protein. RPA indicated DBA/2J have only 22.8 ± 9% of the latent neuronal Bax mRNA in 129B6 animals (P<0.001). Conclusions:Latent neuronal Bax mRNA levels are differentially regulated in 129B6 and DBA/2J which may account for the phenotypic difference observed in heterozygous mice. These results suggest there is a threshold level of Bax required for RGC death after crush. Currently, we are investigating if this variation in Bax mRNA levels is due to differences in the Bax promoter and/or transacting factors affecting transcription.
This PDF is available to Subscribers Only