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C.-C. Chan, D. Shen, M. Zhou, R. J. Ross, K. Zhang, J. Tuo; Upregulation of Human HTRA1 in Archived Eyes With Age-related Macular Degeneration (AMD). Invest. Ophthalmol. Vis. Sci. 2007;48(13):3011.
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© ARVO (1962-2015); The Authors (2016-present)
Human HTRA1 belongs to a widely conserved family of the high temperature requirement family (HTR) of serine proteases that are involved in various aspects of protein quality control and cell fate. A single nucleotide polymorphism (SNP) rs11200638 in the promoter of HTRA1 at chromosome 10q26 is recently reported as the causal variant for age-related macular degeneration (AMD) in two independent studies (DeWan, et al. Science 2006;314:989-92. Yang, et al. Science 2006;314:992-4). The SNP increases production of HTRA1 protein in AMD. This study investigates HTRA1 expression and SNP in archived ocular slides with AMD and non-AMD.
Ocular cells of non-retinal, peripheral retinal, and macular region were microdissected form archived ocular slides with AMD and age-matched, non-AMD control Caucasian subjects. HTRA1 SNP frequencies were examined in non-retinal cells of 38 AMD and 18 controls using PCR and restriction fragment length polymorphism analysis. HTRA1 transcripts from retinal cells of two AMD and control eyes were measured using SYBR Green real-time RT-PCR. HTRA1 protein expression was evaluated using avidin-biotin complex immunohistochemistry in 17 AMD and 16 control cases.
HTRA1 SNP showed frequencies of 28/38 (52.8%) and 8/18 (44.4%) in AMD and control groups, respectively. HTRA1 mRNA was detected both in normal peripheral and macular retinas, higher in the periphery than maculae. Although expression of HTRA1 mRNA was lower in the AMD peripheral retina as compared to the control, it was 14.3 times higher in the macular lesion with choroidal neovascular scar. HTRA1 protein was found in normal retinal vascular endothelia and RPE. Intense immunoreaction against HTRA1 was demonstrated in AMD lesions of abnormal RPE cells, choroidal neovascular vessels, and drusen; slightly more in the wet than dry AMD lesions.
This study successfully analyzed HTRA SNP and transcript expression in microdissected cells from archived paraffin fixed slides. Upregulation of HTRA1 expression is detected in AMD macular lesions. The data add further evidence that rs11200638 in HTRA1 promoter contributes to AMD development, particularly wet AMD.
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