miR-29b attenuates histone deacetylase-4 mediated podocyte dysfunction and renal fibrosis in diabetic nephropathy.

PURPOSE: As epigenetic modifications like chromatin histone modifications have been suggested to play a role in the pathophysiology of Diabetic Nephropathy (DN) and are also found to be regulated by microRNAs. Our main purpose was to explore the role of microRNA in histone modulations associated with DN. There is downregulation of miR-29b due to advanced glycation end products in diabetes. Histone Deacetylase-4 (HDAC4) is amongst the histone modulators which promotes podocytes' impairment and upregulates transforming growth factor-1 (TGF-ß1) leading to renal fibrosis. Moreover, macrophage infiltration causes podocytes' apoptosis and IL-6 mediated inflammation. As miR-29b is downregulated in diabetes and HDAC4, TGF-ß1 and IL-6 could be the possible therapeutic targets in DN, our study was focussed on unveiling the role of miR-29b in modulation of HDAC4 and hence, in podocyte dysfunction and renal fibrosis in DN. METHODS: In silico analysis and luciferase assay were done to study the interaction between miR-29b and HDAC4. In-vitro DN model was developed in podocytes and miR-29b mimics were transfected. Also, podocytes were co-cultured with macrophage and miR-29b mimics were transfected. At the end, in-vivo DN model was generated in C57BL/6 J male mice and the effect of miR-29b mimics was reconfirmed. RESULTS: It was found that miR-29b targets the 3' untranslated region of HDAC4. In both in-vitro and in-vivo DN model, downregulation of miR-29b and subsequent increase in HDAC4 expression was observed. The miR-29b mimics suppressed podocytes' inflammation mediated through macrophages and attenuated HDAC4 expression, glomerular damage and renal fibrosis. CONCLUSION: This study concludes that miR-29b regulates the expression of HDAC4 which plays a role in controlling renal fibrosis and podocytes' impairment in DN.

A therapeutic approach towards microRNA29 family in vascular diabetic complications: A boon or curse?

Diabetes Mellitus (DM) is one of the major metabolic disorders and its severity leads to death. Enhancement in hyperglycaemic conditions of DM gives rise to endothelial impairment in small and large blood vessels contributing towards microvascular and macrovascular complications respectively. The pathogenesis of diabetic complications is associated with interruption of various signal transduction pathways due to epigenetic modifications such as aberrant histone modifications, DNA methylation and expression of miRNAs along with the long non-coding RNAs (lncRNAs). Amongst these epigenetic alterations, modulated expressions of miRNAs confer to apoptosis and endothelial dysfunction of organs that gives rise to vascular complications. In this review, we principally focussed on physiological role of miR29 family in DM and have discussed crosstalk between miR29 family and numerous genes involved in signal transduction pathways of Diabetic vascular complications. Incidences of diabetic retinopathy exploiting the role of miR29 in regulation of EMT process, differential expression patterns of miR29 and promising therapeutic role of miR29 have been discussed. We have summarised the therapeutic role of miR29 in podocyte impairment and how miR29 regulates the expressions of profibrotic, inflammatory and ECM encoding genes in renal fibrosis under diabetic conditions. We have also highlighted impact of miR29 expression patterns in cardiac angiopathy, cardiomyocyte's apoptosis and cardiac fibrosis. Additionally, we have also presented the contradictory actions of miR29 family in amelioration as well as in enhancement of diabetic complications.

Correction: miR29b regulates aberrant methylation in In-Vitro diabetic nephropathy model of renal proximal tubular cells.

[This corrects the article DOI: 10.1371/journal.pone.0208044.].

miR29b regulates aberrant methylation in In-Vitro diabetic nephropathy model of renal proximal tubular cells.

The role of DNA methylation has not been enough explored in pathophysiology of diabetic nephropathy (DN). However, according to recent reports it has been inferred that hypermethylation could be one of the principle cause associated with the enhancement of DN. An interrelationship between miR29b and DNA methylation has been studied via in-silico analysis. We have validated that miR29b prominently targets DNA methyl transferase (DNMT), specifically DNMT1, DNMT3A and DNMT3B. We have developed in vitro DN model using renal proximal tubule epithelial cells (RPTECs), contributed to a significant alleviation in RNA and protein expression levels of DNMT3A, DNMT3B and DNMT1. The developed model has also demonstrated downregulation in expression of miR29b. Our studies have also suggested that miR29b targets DNMT1 via targeting its transcription factor SP1. In addition to this, downregulation of a specific biomarker for kidney injury, tubular kidney injury molecule-1 (KIM-1) and fibrosis causing glycoprotein i.e. fibronectin, was also demonstrated. Hence, the developed model revealed that hypermethylation is a key factor incorporated in DN, and miR29b could effectively ameliorate defensive actions in DN pathogenesis.