Department of Biological Sciences, University of Delaware, Newark, DE, 19716, USA.
Department of Biological Sciences, University of Delaware, Newark, DE, 19716, USA; Center for Bioinformatics and Computational Biology, University of Delaware, Newark, DE, 19716, USA.
Exp Eye Res. 2019 Nov;188:107787. doi: 10.1016/j.exer.2019.107787. Epub 2019 Aug 31.
Cataract-associated gene discovery in human and animal models have informed on key aspects of human lens development, homeostasis and pathology. Additionally, in vitro models such as the culture of permanent human lens epithelium-derived cell lines (LECs) have also been utilized to understand the molecular biology of lens cells. However, these resources remain uncharacterized, specifically regarding their global gene expression and suitability to model lens cell biology. Therefore, we sought to molecularly characterize gene expression in the human LEC, SRA01/04, which is commonly used in lens studies. We first performed short tandem repeat (STR) analysis and validated SRA01/04 LEC for its human origin, as recommended by the eye research community. Next, we used Illumina HumanHT-12 v3.0 Expression BeadChip arrays to gain insights into the global gene expression profile of SRA01/04. Comparative analysis of SRA01/04 microarray data was performed using other resources such as the lens expression database iSyTE (integrated Systems Tool for Eye gene discovery), the cataract gene database Cat-Map and the published lens literature. This analysis showed that SRA01/04 significantly expresses >40% of the top iSyTE lens-enriched genes (313 out of 749) across different developmental stages. Further, SRA01/04 also significantly expresses ~53% (168 out of 318) of cataract-associated genes in Cat-Map. We also performed comparative gene expression analysis between SRA01/04 cells and the previously validated mouse LEC 21EM15. To gain insight into whether SRA01/04 reflects epithelial or fiber cell characteristics, we compared its gene expression profile to previously reported differentially expressed genes in isolated mouse lens epithelial and fiber cells. This analysis suggests that SRA01/04 has reduced expression of several fiber cell-enriched genes. In agreement with these findings, cell culture analysis demonstrates that SRA01/04 has reduced potential to initiate spontaneous lentoid body formation compared to 21EM15 cells. Next, to independently validate SRA01/04 microarray gene expression, we subjected several candidate genes to RT-PCR and RT-qPCR assays. This analysis demonstrates that SRA01/04 supports expression of many key genes associated with lens development and cataract, including CRYAB, CRYBB2, CRYGS, DKK3, EPHA2, ETV5, GJA1, HSPB1, INPPL1, ITGB1, PAX6, PVRL3, SFRP1, SPARC, TDRD7, and VIM, among others, and therefore can be relevant for understanding the mechanistic basis of these factors. At the same time, SRA01/04 cells do not exhibit robust expression of several genes known to be important to lens biology and cataract such as ALDH1A1, COL4A6, CP, CRYBA4, FOXE3, HMX1, HSF4, MAF, MEIS1, PITX3, PRX, SIX3, and TRPM3, among many others. Therefore, the present study offers a rich transcript-level resource for case-by-case evaluation of the potential advantages and limitations of SRA01/04 cells prior to their use in downstream investigations. In sum, these data show that the human LEC, SRA01/04, exhibits lens epithelial cell-like character reflected in the expression of several lens-enriched and cataract-associated genes, and therefore can be considered as a useful in vitro resource when combined with in vivo studies to gain insight into specific aspects of human lens epithelial cells.
白内障相关基因在人类和动物模型中的发现为人类晶状体发育、内稳态和病理学的关键方面提供了信息。此外,体外模型,如永久人晶状体上皮细胞系(LEC)的培养,也被用于了解晶状体细胞的分子生物学。然而,这些资源仍未被描述,特别是关于它们的全局基因表达和适合模拟晶状体细胞生物学的特性。因此,我们试图对 SRA01/04 人晶状体上皮细胞的基因表达进行分子特征分析,SRA01/04 是人晶状体研究中常用的细胞系。我们首先进行短串联重复序列(STR)分析,并按照眼研究界的建议,验证 SRA01/04 的人源性。接下来,我们使用 Illumina HumanHT-12 v3.0 Expression BeadChip 阵列深入了解 SRA01/04 的全局基因表达谱。使用其他资源,如 iSyTE(集成系统工具用于眼基因发现)、白内障基因数据库 Cat-Map 和已发表的晶状体文献,对 SRA01/04 微阵列数据进行了比较分析。分析表明,SRA01/04 在不同发育阶段显著表达 >40%的顶级 iSyTE 晶状体富集基因(749 个中的 313 个)。此外,SRA01/04 还显著表达 Cat-Map 中约 53%(318 个中的 168 个)的白内障相关基因。我们还对 SRA01/04 细胞和之前验证的小鼠 LEC 21EM15 之间的比较基因表达进行了分析。为了深入了解 SRA01/04 是否反映了上皮细胞或纤维细胞的特征,我们将其基因表达谱与之前报道的在分离的小鼠晶状体上皮细胞和纤维细胞中差异表达的基因进行了比较。分析表明,SRA01/04 对几个纤维细胞富集基因的表达减少。与这些发现一致,细胞培养分析表明,与 21EM15 细胞相比,SRA01/04 自发形成晶状体小体的潜力降低。接下来,为了独立验证 SRA01/04 微阵列基因表达,我们对几个候选基因进行了 RT-PCR 和 RT-qPCR 检测。分析表明,SRA01/04 支持许多与晶状体发育和白内障相关的关键基因的表达,包括 CRYAB、CRYBB2、CRYGS、DKK3、EPHA2、ETV5、GJA1、HSPB1、INPPL1、ITGB1、PAX6、PVRL3、SFRP1、SPARC、TDRD7 和 VIM 等,因此对于理解这些因素的机制基础可能具有重要意义。同时,SRA01/04 细胞对一些已知对晶状体生物学和白内障很重要的基因表达不活跃,如 ALDH1A1、COL4A6、CP、CRYBA4、FOXE3、HMX1、HSF4、MAF、MEIS1、PITX3、PRX、SIX3 和 TRPM3 等。因此,本研究为 SRA01/04 细胞在下游研究中的潜在优势和局限性提供了丰富的转录水平资源,以便在使用前进行个体化评估。总之,这些数据表明,人晶状体上皮细胞 SRA01/04 表现出晶状体上皮细胞的特征,这反映在几个晶状体富集和白内障相关基因的表达上,因此,当与体内研究结合使用时,它可以被认为是一种有用的体外资源,以深入了解人类晶状体上皮细胞的特定方面。