Ocular expression of avian thymic hormone: changes during the recovery from induced myopia

[摘要] Purpose: Several studies suggest thatpostnatal ocular growth is under the control of factors within the eyethat regulate the rate of scleral extracellular matrix remodeling andthe rate of ocular elongation. A microarray analysis was employed toidentify some of the factors involved in the regulation of visuallyguided ocular growth. Gene expression was compared in the retina-retinalpigmented epithelium (RPE)-choroid of chick eyes that were deceleratingin the rate of ocular growth (“recovering” from myopia) as comparedwith contralateral control eyes. Methods: Form-deprivation myopia wasinduced in the right eyes of two-day-old chicks by the application oftranslucent occluders. Following 10 days of deprivation, occluders wereremoved and chicks were provided unrestricted vision for an additional1–7 days (recovery). After one and four days of recovery, chicks weresacrificed, retina, RPE, and choroid were isolated, and mRNA wassubjected to microarray analysis using a chicken immune system 4000gene microarray. In addition, whole eyes and isolated ocular tissues(retina and RPE, choroid, sclera, and extraocular muscle) of treatedand control eyes were subjected to real-time PCR, immunohistochemistry,and western blot analyses to verify gene expression results. Results: Following one day of recovery,only one gene, avian thymic hormone (ATH) was highly upregulated(+12.3 fold). ATH gene and protein expression were confirmed in theretina and choroid as well as in the sclera and extraocular muscle. Asignificant increase in ATH protein was detected in choroids fromtreated eyes following four days of recovery as compared tocontralateral controls (p<0.05; Wilcoxon signed-rank test). Conclusions: ATH is expressed in severalocular tissues and is specifically and rapidly (within one day)upregulated in the choroids of chick eyes recovering from inducedmyopia. This upregulation corresponds to the onset of choroidalthickening and increased choroidal vascular permeability. Theidentification of ATH in ocular tissues and its increased proteinaccumulation in the choroid during recovery from induced myopia suggesta novel role for this protein in the choroidal response to myopicdefocus.

[学科分类] 生物化学/生物物理