转录活性蛋白1在实验性近视眼豚鼠巩膜重塑中对Ⅰ型胶原表达的调控作用

Effect of specificity protein 1 (Sp1) transcription factor on the expression of type Ⅰ collagen in sclera remodeling of experimentally myopic guinea pigs

目的研究近视巩膜重塑中转录活性蛋白1(specificity protein 1,Sp1)作为转化生长因子-β1(transforming growth factor-β1,TGF-β1)下游信号转录因子的表达情况和调节I型胶原(CollagenⅠ)表达的作用。方法出生7 d的有色豚鼠75只,随机选取50只左眼使用6号无色半透明乳胶气球作为头套诱导形觉剥夺性近视(form deprivation myopia,FDM)动物模型为FDM组,右眼作为自身对照组,另外25只不作处理为正常组。记录各组豚鼠屈光度及眼轴长度变化。Western blot和RT-PCR检测正常组和FDM组豚鼠遮盖后0周(遮盖前)、2周、4周、6周及遮盖4周去遮盖1周(4/-1周)时巩膜中Sp1和CollagenⅠ蛋白和mRNA的表达变化,并分析两者的关系。结果 FDM组豚鼠眼随着遮盖时间延长,由遮盖前远视状态逐渐变为近视状态,眼轴长度也逐渐增长。与正常组相比,FDM组巩膜内Sp1和CollagenⅠ的蛋白和mRNA表达均下调,且随遮盖时间的延长,其表达不断减弱。正常组及FDM组遮盖后0周、2周、4周、4/-1周、6周,Sp1蛋白相对表达量分别为1.864±0.014、1.856±0.016、1.215±0.016、0.752±0.013、0.945±0.017、0.518±0.012;CollagenⅠ蛋白相对表达量分别为2.922±0.005、2.836±0.001、2.336±0.002、1.500±0.003、1.754±0.006、1.082±0.001;Sp1 mRNA:0.599±0.025、0.557±0.024、0.510±0.013、0.349±0.013、0.457±0.009、0.168±0.012;CollagenⅠmRNA:1.071±0.014、1.010±0.021、0.947±0.006、0.626±0.010、0.770±0.020、0.331±0.004。遮盖2周后各时间点与正常组相比,Sp1和CollagenⅠ蛋白和mRNA表达差异均有统计学意义(均为P<0.05)。Sp1与CollagenⅠ的蛋白和mRNA表达均呈明显正相关(均为r=1.00,P<0.05)。结论 Sp1作为TGF-β1的下游信号转录因子可能参与了近视巩膜重塑中CollagenⅠ的调控,提示Sp1信号转录因子可能通过TGF-β1-Sp1-CollagenⅠ信号通路在近视巩膜重塑中发挥重要作用。

Objective To investigate the expression of transcriptional specificity protein 1 (Sp1) as a downstream transcription factor of transforming growth factor-β1 (TGF-β1) and its regulation on the expression of Collagen Ⅰ in myopic sclera collagen remodeling in guinea pigs. Methods Totally 75 seven-day’s guinea pigs were studied:the left eyes of 50 guinea pigs,which were randomly selected to induce form deprivation myopia (FDM) with No.6 colorless translucent latex balloons (FDM group),and the uncovered right eyes as self-control group;the other 25 as normal group were untreated.Changes in refractive power and axial length were measured and recorded at each group.Collagen Ⅰ and Sp1 mRNA and protein expression in normal group and FDM group,in which the left eyes were covered for 0 week,2 weeks,4 weeks,6 weeks and FDM recovery 1 week after 4 weeks treatment (4/-1 weeks),were detected via Western bolt and RT-PCR,and their relationship was analyzed. Results With the coverage time prolonging,refractive state in the FDM group gradually became myopic state,while the axial length was gradually prolonged.Compared with the data of the normal group,Sp1 and Collagen Ⅰ protein and mRNA expression in the FDM sclera were gradually weakened with the prolonged coverage time.The relative expression levels of Sp1 protein in the normal group and the FDM group at 0 week,2 weeks,4 weeks,4/-1 weeks and 6 weeks were 1.864±0.014,1.856±0.016,1.215±0.016,0.752±0.013,0.945±0.017,0.518±0.012,respectively;Collagen Ⅰ protein:2.922±0.005,2.836±0.001,2.336±0.002,1.500±0.003,1.754±0.006,1.082±0.001,respectively;Sp1 mRNA:0.599±0.025,0.557±0.024,0.510±0.013,0.349±0.013,0.457±0.009,0.168±0.012,respectively;Collagen Ⅰ mRNA:1.071±0.014,1.010±0.021,0.947±0.006,0.626±0.010,0.770±0.020,0.331±0.004,respectively.After 2 weeks covering,compared to the normal group at different time points,Sp1 and Collagen Ⅰ protein and mRNA expression were found significant difference statistically (all P <0.05) and an obvious correlation respectively (all r =1.00,all P <0.05). Conclusion As the downstream transcription factor of TGF-β1,Sp1 is likely to take part in regulating the synthesis of Collagen Ⅰ in myopic sclera remodeling,suggesting that Sp1 plays an important role in myopic sclera remodeling through TGF-β1-Sp1-Collagen Ⅰ signal transduction pathway.