Cell Type–Specific Expression of Long Noncoding RNAs in Human Diabetic Kidneys Identifies TARID as a Key Regulator of Podocyte Function

Long non-coding RNAs (lncRNAs) play essential roles in cellular processes, often exhibiting cell type-specific expression and influencing kidney function. While single-cell RNA sequencing (scRNA-seq) has advanced our understanding of cellular specificity, past studies focus solely on protein-coding genes. We hypothesize that lncRNAs, due to their cell-specific nature, have crucial functions within particular renal cells and thereby play essential roles in renal cell function and disease. Using single-nucleus RNA sequencing (snRNA-seq) data from kidney samples of five healthy individuals and six DKD patients, we explored the non-coding transcriptome. Cell type-specific lncRNAs were identified, and their differential expression in DKD was assessed. Integrative analyses included expression quantitative trait loci (eQTL), genome-wide association studies (GWAS) for estimated glomerular filtration rate (eGFR), and gene regulatory networks. Functional studies focused on TARID, a lncRNA with podocyte-specific expression, to elucidate its role in podocyte health. We identified 174 lncRNAs with cell type-specific expression across kidney cell types. Of these, 54 lncRNAs were differentially expressed in DKD. Integrative analyses, including eQTL data, GWAS results for eGFR and gene regulatory networks, pinpointed TARID, a podocyte-specific lncRNA, as a key candidate upregulated in DKD. Functional studies confirmed TARID's podocyte-specific expression and revealed its central role in actin cytoskeleton reorganization. Our study provides a comprehensive resource of single-cell lncRNA expression in the human kidney and highlights the importance of cell type-specific lncRNAs in kidney function and disease. Specifically, we demonstrate the functional relevance of TARID in podocyte health.