Genome-wide analysis of 4-day old (P4) Tdrd7 null mouse lens

Analysis of Tdrd7 deficiency in mouse lens epithelial-derived cell line at gene expression level. The hypothesis tested was that Tdrd7 is involved in post-transcriptional control of gene expression in the lens. Results provide evidence for differential regulation of genes involved in lens homeostasis and cataract formation in the absence of Tdrd7. In eukaryotic cells, cytoplasmic RNA granules (RGs) function in the post-transcriptional control of gene expression. However, the involvement of RGs and their component proteins in vertebrate organogenesis is unknown. We report two independent cases of pediatric cataract with loss-of-function mutations in TDRD7, which encodes a Tudor domain RNA binding protein. TDRD7 deficiency in chick lens produces cataracts, and Tdrd7 null mouse mutants develop cataracts, as well as features of glaucoma and male sterility due to azoospermia. In lens fiber cells, TDRD7 is necessary for the RG-mediated post-transcriptional control of critical lens mRNAs, while in the testis it functions as a component of a specialized RG, the chromatoid body. These findings define a new role for RGs in vertebrate organogenesis, and a novel mechanism for cataractogenesis. Total RNA obtained from P4 Lens from Tdrd7 null mice compared to that of Tdrd7 heterozygous mice.本研究针对小鼠晶状体上皮源性细胞系中的Tdrd7缺陷开展基因表达水平分析。本次实验验证的假说为：Tdrd7参与晶状体中基因表达的转录后调控。研究结果证实，在Tdrd7缺失情况下，晶状体稳态与白内障形成相关基因存在差异调控。在真核细胞中，细胞质RNA颗粒（RNA Granules, RGs）参与基因表达的转录后调控，但目前尚不清楚RNA颗粒及其组成蛋白是否参与脊椎动物器官发生过程。本研究报道了两例独立的儿童白内障病例，其致病原因为编码Tudor结构域RNA结合蛋白（Tudor domain RNA binding protein）的TDRD7基因发生功能丧失性突变。鸡晶状体中TDRD7缺陷可诱发白内障，而Tdrd7基因敲除小鼠不仅会出现白内障，还会表现出青光眼特征以及因无精子症导致的雄性不育。在晶状体纤维细胞中，TDRD7是RNA颗粒介导的关键晶状体mRNA转录后调控所必需的蛋白；而在睾丸组织中，TDRD7作为一种特化RNA颗粒——染色质体（chromatoid body）的组成成分发挥功能。上述研究明确了RNA颗粒在脊椎动物器官发生中的全新功能，同时揭示了白内障发生的全新机制。本研究对Tdrd7基因敲除小鼠与杂合子小鼠出生后第4天（P4）的晶状体总RNA进行了对比分析。