Temporal changes of novel transcripts in the chicken retinafollowing imposed defocus

[摘要] Purpose: Changes in retinal gene expression are one of the firststeps in the signaling pathway underlying the visual control of eyegrowth. We tried to identify novel, yet unknown, genes, that alter theirexpression pattern following imposed defocus, wearing of diffusers, orduring recovery from myopia. Sequences found earlier by differentialdisplay studies were applied to 5'-RACE and identified as 15 kDaselenoprotein P and prolidase. Moreover, we obtained more sequenceinformation for a yet unidentified gene. We have studied the time courseof expressions of these genes following lens or diffuser treatment.Methods: Ten to 14 day old white leghorn chickens (4-7) were treatedwith a monocular +7 D or -7 D lenses for 2, 4, 6, or 24 h, or treatedwith monocular or binocular diffusers for 2, 4, or 6 h. Chickens ofanother group were allowed to recover from 4 days of diffuser wear for 4h. Untreated chicks served as a control for contralateral eye effects.Following the extraction of retinal RNA, the relative expression of thethree genes was determined by semi-quantitative real time PCR.Results: We found a significant up regulation of selenoprotein Pexpression after 24 h of treatment with positive (+380%) or negativelenses (+387%) which was even more prominent in the contralateraluntreated eyes (positive: +542%; negative: +786%). A rapid change inselenoprotein mRNA levels was induced by binocular diffuser wear for 2 h(+425%), whereas defocus blur in one eye led to an increase only after 6h (+261%). There was a significant upregulation of prolidase mRNA after24 h of treatment with positive (+75%) but not with negative lenses.Moreover, blur induced by diffusers resulted in a highly significantrise of prolidase mRNA levels after 4 h, both with monocular (142%) andbinocular (106%) treatment. This is similar to what was found in theprevious differential display (DD) screening of monocularly treatedeyes. In contrast to the findings of the DD screening, the mRNAexpression of the unknown gene remained unchanged both after hyperopicand myopic defocus. Again, blur induced by diffusers evoked the mostprominent change after 6 h of binocular treatment. There were nosignificant alterations in the mRNA levels of the three investigatedgenes after 4 h of recovery from myopia that was induced by a 4 dayperiod of diffuser treatment.Conclusions: The mRNA expression of selenoprotein P, prolidase, andof the not yet identified gene (sequence 3) is clearly altered byretinal image degradation imposed by diffuser wearing and, in part, bydefocus imposed by spectacle lenses. However, none of the candidates areregulated by the sign of imposed defocus, suggesting a role in retinalcontrast processing.

[学科分类] 生物化学/生物物理