Lona-Durazo Frida, Omachi Kohei, Fermin Damian, Eichinger Felix, Troost Jonathan P, Lin Meei-Hua, Dinsmore Ian R, Mirshahi Tooraj, Chang Alexander R, Miner Jeffrey H, Paterson Andrew D, Barua Moumita, Gagliano Taliun Sarah A
Montreal Heart Institute, Montreal, Quebec, Canada.
Faculty of Medicine, Université de Montréal, Montreal, Quebec, Canada.
J Am Soc Nephrol. 2025 Jan 1;36(1):48-59. doi: 10.1681/ASN.0000000000000480. Epub 2024 Aug 27.
Using transcriptome-wide association studies, we identified an association between splicing out of exon 27 of COL4A4 and hematuria. We confirmed the presence of COL4A4 exon 27 splicing in an independent cohort. Functional assays revealed that the COL4A4 transcript with exon 27 spliced out affects collagen IV trimer assembly and secretion.
Hematuria is an established sign of glomerular disease and can be associated with kidney failure, but there has been limited scientific study of this trait.
Here, we combined genetic data from the UK Biobank with predicted gene expression and splicing from Genotype Tissue Expression kidney cortex samples (=65) in a transcriptome-wide association study to identify additional potential biological mechanisms influencing hematuria.
The transcriptome-wide association study using kidney cortex identified significant associations for five genes in expression and three significant splicing events. Notably, we identified an association between the skipping of exon 27, which is genetically predicted by intronic rs11898094 (minor allele frequency 13%), and hematuria. Association between this variant was also found with urinary albumin excretion. We found independent evidence supporting the same variant predicting this skipping event in glomeruli-derived mRNA transcriptomics data (=245) from the Nephrotic Syndrome Study Network. The functional significance of loss of exon 27 was demonstrated using the split NanoLuc-based 345(IV) heterotrimer assay, in which type IV collagen heterotrimer formation was quantified by luminescence. The causal splicing variant for this skipping event is yet to be identified.
In summary, by integrating multiple data types, we identified a potential splicing event associated with hematuria and albuminuria.
通过全转录组关联研究，我们发现COL4A4基因第27外显子的剪接与血尿之间存在关联。我们在一个独立队列中证实了COL4A4基因第27外显子剪接的存在。功能分析表明，缺失第27外显子的COL4A4转录本会影响IV型胶原三聚体的组装和分泌。
血尿是肾小球疾病的既定体征，可能与肾衰竭有关，但对这一特征的科学研究有限。
在此，我们将英国生物银行的遗传数据与来自基因型组织表达肾皮质样本（n = 65）的预测基因表达和剪接数据相结合，进行全转录组关联研究，以确定影响血尿的其他潜在生物学机制。
使用肾皮质进行的全转录组关联研究确定了5个基因在表达方面的显著关联以及3个显著的剪接事件。值得注意的是，我们发现内含子rs11898094（次要等位基因频率为13%）在基因上预测的第27外显子跳跃与血尿之间存在关联。在肾病综合征研究网络的肾小球来源的mRNA转录组数据（n = 245）中也发现了该变体与尿白蛋白排泄之间的关联。我们发现了独立证据，支持相同变体在预测该剪接事件方面的作用。使用基于分裂纳米荧光素酶的α345（IV）异源三聚体分析证明了第27外显子缺失的功能意义，其中通过发光对IV型胶原异源三聚体的形成进行定量。该跳跃事件的因果剪接变体尚未确定。
总之，通过整合多种数据类型，我们确定了一个与血尿和蛋白尿相关的潜在剪接事件。
