Identification of Smad3-related transcriptomes in type-2 diabetic nephropathy by whole transcriptome RNA sequencing

Therapeutic potential for renal fibrosis by targeting Smad3-dependent noncoding RNAs

Renal fibrosis is a characteristic hallmark of chronic kidney disease (CKD) that ultimately results in renal failure, leaving patients with few therapeutic options. TGF-β is a master regulator of renal fibrosis and mediates progressive renal fibrosis via both canonical and noncanonical signaling pathways. In the canonical Smad signaling, Smad3 is a key mediator in tissue fibrosis and mediates renal fibrosis via a number of noncoding RNAs (ncRNAs). In this regard, targeting Smad3-dependent ncRNAs may offer a specific therapy for renal fibrosis. This review highlights the significance and innovation of TGF-β/Smad3-associated ncRNAs as biomarkers and therapeutic targets in renal fibrogenesis. In addition, the underlying mechanisms of these ncRNAs and their future perspectives in the treatment of renal fibrosis are discussed.

The role of lncRNAs in regulation of DKD and diabetes-related cancer

Diabetes mellitus often results in several complications, such as diabetic kidney disease (DKD) and end-stage renal diseases (ESRDs). Cancer patients often have the dysregulated glucose metabolism. Abnormal glucose metabolism can enhance the tumor malignant progression. Recently, lncRNAs have been reported to regulate the key proteins and signaling pathways in DKD development and progression and in cancer patients with diabetes. In this review article, we elaborate the evidence to support the function of lncRNAs in development of DKD and diabetes-associated cancer. Moreover, we envisage that lncRNAs could be diagnosis and prognosis biomarkers for DKD and cancer patients with diabetes. Furthermore, we delineated that targeting lncRNAs might be an alternative approach for treating DKD and cancer with dysregulated glucose metabolism.

Neat1 promotes acute kidney injury to chronic kidney disease by facilitating tubular epithelial cells apoptosis via sequestering miR-129-5p

Acute kidney injury (AKI) is increasingly identified as a crucial risk factor for progression to CKD. However, the factors governing AKI to CKD progression remain largely unknown. By high-throughput RNA sequencing, we found that Neat1_2, a transcript variant of Neat1, was upregulated in 40-min ischemia/reperfusion injury (IRI), which resulted in the development of renal fibrotic lesions. The upregulation of Neat1_2 in hypoxia-treated TECs was attributed to p53 transcriptional regulation. Gain- and loss-of-function studies, both in vitro and in vivo, demonstrated that Neat1_2 promoted apoptosis of injured TECs induced by IRI and caused tubulointerstitial inflammation and fibrosis. Mechanistically, Neat1_2 shares miRNA response elements with FADD, CASP-8, and CASP-3. Neat1_2 competitively binds to miR-129-5p and prevents miR-129-5p from decreasing the levels of FADD, CASP-8, and CASP-3, and ultimately facilitates TEC apoptosis. Increased expression of Neat1_2 associated with kidney injury and TEC apoptosis was recapitulated in human AKI, highlighting its clinical relevance. These findings suggest that preventing TEC apoptosis by hindering Neat1_2 expression may be a potential therapeutic strategy for AKI to CKD progression.

TGF-Beta as a Master Regulator of Diabetic Nephropathy

Diabetic nephropathy (DN) is one of the most common complications in diabetes mellitus and the leading cause of end-stage renal disease. TGF-β is a pleiotropic cytokine and has been recognized as a key mediator of DN. However, anti-TGF-β treatment for DN remains controversial due to the diverse role of TGF-β1 in DN. Thus, understanding the regulatory role and mechanisms of TGF-β in the pathogenesis of DN is the initial step towards the development of anti-TGF-β treatment for DN. In this review, we first discuss the diverse roles and signaling mechanisms of TGF-β in DN by focusing on the latent versus active TGF-β1, the TGF-β receptors, and the downstream individual Smad signaling molecules including Smad2, Smad3, Smad4, and Smad7. Then, we dissect the regulatory mechanisms of TGF-β/Smad signaling in the development of DN by emphasizing Smad-dependent non-coding RNAs including microRNAs and long-non-coding RNAs. Finally, the potential therapeutic strategies for DN by targeting TGF-β signaling with various therapeutic approaches are discussed.

Identification of Smad3-related transcriptomes in type-2 diabetic nephropathy by whole transcriptome RNA sequencing

Smad3 deficiency prevents the development of type 2 diabetic nephropathy; however, the underlying molecular mechanisms remain unknown. In this study, we aimed to identify Smad3‐related genes involved in the pathogenesis of diabetic kidney disease. High‐throughput RNA sequencing was performed to profile the whole transcriptome in the diabetic kidney of Smad3 WT‐db/db, Smad3 KO‐db/db, Smad3^+/− db/db and their littermate control db/m mice at 20 weeks. The gene ontology, pathways and alternative splicing of differentially expressed protein‐coding genes and long non‐coding RNAs related to Smad3 in diabetic kidney were analysed. Compared to Smad3 WT‐db/db mice, Smad3 KO‐db/db mice exhibited an alteration of genes associated with RNA splicing and metabolism, whereas heterozygosity deletion of Smad3 (Smad3^+/− db/db mice) significantly altered genes related to cell division and cell cycle. Notably, three protein‐coding genes (Upk1b, Psca and Gdf15) and two lncRNAs (NONMMUG023520.2 and NONMMUG032975.2) were identified to be Smad3‐dependent and to be associated with the development of diabetic nephropathy. By using whole transcriptome RNA sequencing, we identified novel Smad3 transcripts related to the development of diabetic nephropathy. Thus, targeting these transcripts may represent a novel and effective therapy for diabetic nephropathy.