Department of Biological Sciences
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Item YAP/TAZ Are Mechanoregulators of TGF-β-Smad Signaling and Renal Fibrogenesis(JASN, 2016-10) Majumder, SyamantakLike many organs, the kidney stiffens after injury, a process that is increasingly recognized as an important driver of fibrogenesis. Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) are related mechanosensory proteins that bind to Smad transcription factors, the canonical mediators of profibrotic TGF-β responses. Here, we investigated the role of YAP/TAZ in the matrix stiffness dependence of fibroblast responses to TGF-β. In contrast to growth on a stiff surface, fibroblast growth on a soft matrix led to YAP/TAZ sequestration in the cytosol and impaired TGF-β–induced Smad2/3 nuclear accumulation and transcriptional activity. YAP knockdown or treatment with verteporfin, a drug that was recently identified as a potent YAP inhibitor, elicited similar changes. Furthermore, verteporfin reduced YAP/TAZ levels and decreased the total cellular levels of Smad2/3 after TGF-β stimulation. Verteporfin treatment of mice subjected to unilateral ureteral obstruction similarly reduced YAP/TAZ levels and nuclear Smad accumulation in the kidney, and attenuated renal fibrosis. Our data suggest that organ stiffening cooperates with TGF-β to induce fibrosis in a YAP/TAZ- and Smad2/3-dependent manner. Interference with this YAP/TAZ and TGF-β/Smad crosstalk likely underlies the antifibrotic activity of verteporfin. Finally, through repurposing of a clinically used drug, we illustrate the therapeutic potential of a novel mechanointerference strategy that blocks TGF-β signaling and renal fibrogenesis.Item YAP/TAZ Are Mechanoregulators of TGF-β-Smad Signaling and Renal Fibrogenesis(JASN, 2016-10) Majumder, SyamantakLike many organs, the kidney stiffens after injury, a process that is increasingly recognized as an important driver of fibrogenesis. Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) are related mechanosensory proteins that bind to Smad transcription factors, the canonical mediators of profibrotic TGF-β responses. Here, we investigated the role of YAP/TAZ in the matrix stiffness dependence of fibroblast responses to TGF-β. In contrast to growth on a stiff surface, fibroblast growth on a soft matrix led to YAP/TAZ sequestration in the cytosol and impaired TGF-β–induced Smad2/3 nuclear accumulation and transcriptional activity. YAP knockdown or treatment with verteporfin, a drug that was recently identified as a potent YAP inhibitor, elicited similar changes. Furthermore, verteporfin reduced YAP/TAZ levels and decreased the total cellular levels of Smad2/3 after TGF-β stimulation. Verteporfin treatment of mice subjected to unilateral ureteral obstruction similarly reduced YAP/TAZ levels and nuclear Smad accumulation in the kidney, and attenuated renal fibrosis. Our data suggest that organ stiffening cooperates with TGF-β to induce fibrosis in a YAP/TAZ- and Smad2/3-dependent manner. Interference with this YAP/TAZ and TGF-β/Smad crosstalk likely underlies the antifibrotic activity of verteporfin. Finally, through repurposing of a clinically used drug, we illustrate the therapeutic potential of a novel mechanointerference strategy that blocks TGF-β signaling and renal fibrogenesis.Item EP4 inhibition attenuates the development of diabetic and non-diabetic experimental kidney disease(Nature, 2017-06-13) Majumder, SyamantakThe therapeutic targeting of prostanoid subtype receptors may slow the development of chronic kidney disease (CKD) through mechanisms that are distinct from those of upstream COX inhibition. Here, employing multiple experimental models of CKD, we studied the effects of inhibition of the EP4 receptor, one of four receptor subtypes for the prostanoid prostaglandin E2. In streptozotocin-diabetic endothelial nitric oxide synthase knockout mice, EP4 inhibition attenuated the development of albuminuria, whereas the COX inhibitor indomethacin did not. In Type 2 diabetic db/db mice, EP4 inhibition lowered albuminuria to a level comparable with that of the ACE inhibitor captopril. However, unlike captopril, EP4 inhibition had no effect on blood pressure or hyperfiltration although it did attenuate mesangial matrix accumulation. Indicating a glucose-independent mechanism of action, EP4 inhibition also attenuated proteinuria development and glomerular scarring in non-diabetic rats subjected to surgical renal mass ablation. Finally, in vitro, EP4 inhibition prevented transforming growth factor-ß1 induced dedifferentiation of glomerular podocytes. In rodent models of diabetic and non-diabetic CKD, EP4 inhibition attenuated renal injury through mechanisms that were distinct from either broadspectrum COX inhibition or “standard of care” renin angiotensin system blockade. EP4 inhibition may represent a viable repurposing opportunity for the treatment of CKD.Item Shifts in podocyte histone H3K27me3 regulate mouse and human glomerular disease(PMC, 2018) Majumder, SyamantakHistone protein modifications control fate determination during normal development and dedifferentiation during disease. Here, we set out to determine the extent to which dynamic changes to histones affect the differentiated phenotype of ordinarily quiescent adult glomerular podocytes. To do this, we examined the consequences of shifting the balance of the repressive histone H3 lysine 27 trimethylation (H3K27me3) mark in podocytes. Adriamycin nephrotoxicity and subtotal nephrectomy (SNx) studies indicated that deletion of the histone methylating enzyme EZH2 from podocytes decreased H3K27me3 levels and sensitized mice to glomerular disease. H3K27me3 was enriched at the promoter region of the Notch ligand Jag1 in podocytes, and derepression of Jag1 by EZH2 inhibition or knockdown facilitated podocyte dedifferentiation. Conversely, inhibition of the Jumonji C domain–containing demethylases Jmjd3 and UTX increased the H3K27me3 content of podocytes and attenuated glomerular disease in adriamycin nephrotoxicity, SNx, and diabetes. Podocytes in glomeruli from humans with focal segmental glomerulosclerosis or diabetic nephropathy exhibited diminished H3K27me3 and heightened UTX content. Analogous to human disease, inhibition of Jmjd3 and UTX abated nephropathy progression in mice with established glomerular injury and reduced H3K27me3 levels. Together, these findings indicate that ostensibly stable chromatin modifications can be dynamically regulated in quiescent cells and that epigenetic reprogramming can improve outcomes in glomerular disease by repressing the reactivation of developmental pathways.