| Age-related cataract (ARC), which increases in prevalence with age, is a major publichealth problem worldwide and ranks as the leading cause of blindness among the elderly.People who suffer from ARC manifest painless visual loss. Although phacoemulsificationcan bring better visual acuity than before in ARC patients, it still may have seriousconplications. At the same time, blindness caused by ARC is a great burden for elderlypeople. ARC is a multifactorial disease in which physiological conditions, environmentalcomponents and genetic differences result in the development of the clinical manifestation.RNA granules (RGs) are ribonucleoprotein complexes found in the cytoplasm ofeukaryotic cells that are consisted of various mRNA and protein, and RGs play a vital rolein post-transcriptional regulation of gene expression. Recently, the gene named TDRD7(tudor domain-containing7protein), an RNA granule component with rich expression inthe vertebrate lens, has been shown to play an essential role in cataract formation.Additionally, this study indicated that TDRD7-RNA granules may affect specific genes thatare critical for lens development, including some well-known genes such as “classical”crystallin, beta B3(CRYBB3) and the heat shock gene: Heat shock27kDa Protein1(HSPB1). Already, there is reliable evidence that the TDRD7gene might be an importantdeterminant of lens transparency and that the perturbation of TDRD7may influencesusceptibility to cataract. Now there is no document and literature was published aboutspecific mechanism between TDRD7and ARC.Purpose:The aim of this study was to examine whether TDRD7polymorphisms were associatedwith susceptibility and preliminarily investigate the mechanism with positive SNP of ARCassociation to ARC in a Han Chinese population. For the HSPB1and CRYBB3signalpathway within TDRD7, we hope to verify the probably meaning with positive SNP on the formation of ARC.Methods1. Download the SNP of TDRD7gene from HapMap database, and selected thepotentially biological SNPs with online biofomatic software.2. Venous blood samples were obtained from study participants, and DNA wasextracted. Genotyped the selected SNPs by using SNaPshot assay and test the difference ingenotype and allele frequency within ARC association.3. IHC was used to detect the TDRD7protein localization in lens. RT-PCR was usedto detect mRNA relative expression of TDRD7, HSPB1and CRYBB3in different age rangeand different genotype within cortical ARC lens epithelial cells. Western-Blot was useddetect protein relative expression of HSPB1and CRYBB3in different age range anddifferent genotype within cortical ARC lens epithelial cells.Results1. According to the Minor Allele Frequecy was more than10%and the potentialeffects of the SNPs in TDRD7, we selected five SNPs by using bioinformatic onlinesoftware. The five SNPs are rs2045732which causes missense mutation and the other fourSNPs were located on5’ flanking region (rs1462091, rs11793735, rs10981985, rs1462089).2. We used SNaPshot assay to detect the five SNPs genotype and allele frequency in271healthy controls and218ARC patients, all of the five SNPs were accordance with H-Wequilibrium. The five SNPs study were analysed in dominant, recessive, allele dose genticmodel. The association study results showed that rs10981985was significantly associatedwith ARC in a dominant genetic model (pc=0.02) and allele dose model (pc=0.01).The Aallele of rs10981985maybe protective against ARC (OR:0.619,95%CI:0.455-0.841). Theindividuals which was AA and GA genotype maybe has lower ARC morbidity than the GGgenotype individuals (OR:0.561,95%CI:0.388-0.809). The other four SNPs were notassociated with ARC morbidity in three genetic model analysis (pc>0.05).3. ARC subtype analysis revealed that rs10981985was significantly associated withcortical ARC in a dominant genetic model (pc=0.016) and allele dose model (pc=0.012),and A allele maybe a protective fator (OR:0.502,95%CI:0.315-0.801). The individualswhich was AA and GA genotype maybe has lower cortical ARC morbidity than the GGgenotype individuals (OR:0.431,95%CI:0.251-0.740).rs10981985was associated with mix-type ARC in a dominant genetic model (pc=0.048), and the individuals which was A Aand GA genotype maybe has lower mix-type ARC morbidity than the GG genotypeindividuals (OR:0.433,95%CI:0.235-0.797).4. After anylysis by different age range (<65vs≥65), the results showed thatrs10981985polymorphism was significantly associated with ARC in the individuals wereolder than65years within a recessive genetic model (pc=0.016) and allele dose model(pc=0.004). The A allele of rs10981985maybe protective against ARC (OR:0.476,95%CI:0.299-0.759) in the individuls which were more than65years. The individuals which was AA genotype maybe has lower ARC morbidity than the GG and GA genotype individuals(OR:0.086,95%CI:0.011-0.671).5. After anylysis by different age range (<65vs≥65) in cortical ARC, the resultsshowed that rs10981985polymorphism was significantly associated with cortical ARC inthe individuals were older than65years within a dominant genetic model (pc=0.028) andallele dose model (pc=0.004). The A allele of rs10981985maybe protective against ARC(OR:0.307,95%CI:0.140-0.674) in the individuls which were more than65years. Theindividuals which was AA and GA genotype individuals maybe has lower ARC morbiditythan the GG genotype individuals (OR:0.320,95%CI:0.136-0.755).6. TDRD7was located on the cytoplasm of human lens epithelial cells and wasabundantly exsited on inner cortex of lens. TDRD7relatively mRNA expression wasnegatively correlated with age of cortical ARC patients(r=-0.487, p=0.001). It have higherTDRD7relatively mRNA expression in <65age range than≥65age range (p=0.019). Therelative TDRD7mRNA expression of rs10981985AA and GA genotype was higher thanrs10981985GG genotype (p=0.001).7. HSPB1was located on the cytoplasm of human lens epithelial cells and wasabundantly exsited on inner cortex of lens.The HSPB1relative mRNA (p=0.006) andprotein (p=0.045) expression of rs10981985AA genotype was lower than rs10981985GGand GA genotype cortical ARC patients.8. CRYBB3relatively mRNA expression was negatively correlated with age ofcortical ARC patients(r=-0.337, p=0.031). It have higher CRYBB3relatively IOD proteinexpression in <65age range than≥65age range (p=0.001). It had no association betweenrs10981985genotype difference and CRYBB3mRNA and IOD protein expression (p>0.05) in three different genetic model.Conculsion1. The TDRD7rs10981985polymorphism was significantly associated with corticalARC in a Chinese Han population in Chongqing district, especially in older than65individuals. The A allele maybe play a protective role in ARC. The probable mechanism isthat the protective A allele can maintain enough TDRD7mRNA expression and decreasethe cortical ARC morbidity.2. The TDRD7rs10981985polymorphism was associated with HSPB1expressionwithin cortical ARC pathogenesis.3. According to the literature and the results in the study, we make a hypothesis thatRNA component TDRD7maybe interactive infulence with other key genes via HSPB1regulation for lens clarity. |
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