Expression of Glutamate Receptor Subtype 3 Is Epigenetically Regulated in Podocytes under Diabetic Conditions

Abstract

Background: Recent studies suggest a role of epigenetics in the pathogenesis of diabetic kidney disease. However, epigenetic changes occurring specifically in kidney cells is poorly understood. Methods: To examine the epigenetic regulation of genes in podocytes under diabetic conditions, we performed DNA methylation and transcriptomic profiling in podocytes exposed to high glucose conditions. Results: Comparative analysis of genes with DNA methylation changes and correspondingly altered mRNA expression identified 337 hypomethylated genes with increased mRNA expression and only 2 hypermethyated genes (ESX1 and GRIA3) with decreased mRNA expression. Glutamate ionotropic receptor AMPA type subunit 3 (GRIA3) belongs to the ionotropic class of glutamate receptors that mediate fast excitatory synaptic transmission in the central nervous system. As podocytes have glutamate-containing vesicles and various glutamate receptors mediate important biological effects in podocytes, we further examined GRIA3 expression and its function in podocytes. Real-time PCR and western blots confirmed the suppression of GRIA3 expression in podocytes under high glucose conditions, which were abolished in the presence of a DNA methyltransferase inhibitor. Sites of DNA hypermethylation were also confirmed by bisulfite sequencing of the GRIA3 promoter region. GRIA3 mRNA and protein expression was suppressed in diabetic kidneys of human and mouse models, and knockdown of GRIA3 exacerbated high glucose-induced apoptosis in cultured podocytes. Conclusion: These results indicate that decreased GRIA3 expression in podocytes in diabetic condition heightens podocyte apoptosis and loss.

Sirt6-mediated Nrf2/HO-1 activation alleviates angiotensin II-induced DNA DSBs and apoptosis in podocytes

“…[22][23][24] Accumulating evidence has revealed that DNA methylation in podocytes is involved in the pathogenesis of CKD, and impaired DNA DSB repair is recently implicated in the induction of altered DNA methylation in podocytes. 19,[37][38][39][40][41] Thus, we suppose that overproduction of DNA DSBs in podocytes contributes to glomerular disorders. In this regard, it makes sense to explore the key molecules and the potential signaling pathways involved in DNA DSB regulation in podocytes.…”

Activation of the Renin–Angiotensin System Disrupts the Cytoskeletal Architecture of Human Urine-Derived Podocytes

“…Unique genes from our data that are associated with the filtration barrier or cytoskeleton of podocytes include the genes C-X3-C motif chemokine ligand 1 ( CX3CL1) [ 43 ], dynamin3 ( DNM3) [ 44 ], dipeptidyl peptidase 4 ( DPP4) [ 45 ], and neurexin 1 ( NRXN1) [ 46 ]. Unique genes from our data that are associated with podocyte function or survival include brain-derived neurotrophic factor (BDNF) [ 47 ], C-X-C motif chemokine ligand 16 ( CXCL16) [ 48 ], glutamate ionotropic receptor AMPA type subunit 3 ( GRIA3) [ 49 ], platelet-derived growth factor C ( PDGF-C) [ 50 ], RAB3A, member RAS oncogene family (RAB3A) [ 51 ], and vascular endothelial growth factor C ( VEGF-C) [ 52 ]. Members of the semaphorin gene family SEMA3A and SEMA3C were also significantly upregulated.…”

Angiotensin II disrupts the cytoskeletal architecture of human urine-derived podocytes and results in activation of the renin-angiotensin system

“…Unique genes from our data that are associated with the filtration barrier or cytoskeleton of podocytes include the genes CX3CL1 [37], DNM3 [38], DPP4 [39] and NRX1 [40]. Unique genes from our data that are associated with podocyte function or survival include BDNF [41], CXCL16 , [42] GRIA3 [43], PDGF-C [44], RAB3A [45] and VEGF-C [46]. Members of Semaphorin gene family SEMA3A and SEMA3C were also significantly upregulated.…”