Early transcriptional changes of retinal and choroidalTGFβ-2, RALDH-2, and ZENK following imposed positive andnegative defocus in chickens

[摘要] Purpose: Imposing defocus to the retina results in compensatorychanges of axial eye growth. It is not clear which factors initiallycontribute to this process and whether they act on thepost-translational, translational, or transcriptional level. We havemeasured early changes in mRNA levels, in response to imposed negativeand positive defocus, of the transcription factor ZENK, the retinoicacid synthesis enzyme RALDH-2, and the growth factorTGFβ-2.Methods: Chickens 11 days of age were unilaterally treated withpositive or negative spectacle lenses of 7 D power. After 0, 15, 30, and120 min, mRNA was extracted from retina and choroid, and theconcentration of the mRNAs of the three candidates was measured byquantitative real time PCR in both eyes.Results: ZENK in the retina and RALDH-2 in the choroiddisplayed parallel signs of defocus dependent changes in mRNA levelsafter 15 or 30 min, respectively. ZENK mRNA levels were reduced inthe retina after 15 min with both types of lenses but were then upregulated at 30 min with positive lenses and down regulated withnegative lenses, similar to the previously observed changes in ZENKprotein levels. Changes of RALDH-2 and TGFβ-2 mRNA levelswere confined to the choroid. Treatment with negative lenses resulted ina rapid (15 min) and persistent decrease in TGFβ-2 mRNAconcentration in the choroid. Negative lenses provoked parallel but lesspronounced alterations in the open fellow eyes.Conclusions: Imposed defocus triggers extensive transcriptionalchanges of ZENK in the retina, and of TGFβ-2 and RALHD-2in the choroid. Changes in retina and choroid are rapid, show no phasedelay with respect to each other, and can be considered, in the case ofRALDH-2 and ZENK, as specific for the sign of imposed defocus.They occur prior to any morphological changes. This is consistent with arole in causing or controlling later changes in eye growth.

[学科分类] 生物化学/生物物理