Endoplasmic HDAC activity assay reticulum (ER) stress has been postulated as one contributor during the development of renal fibrosis. The present study investigated the anti-fibrotic

effects through the attenuation of ER stress, exerted by sodium 4-phenylbutyrate (4-PBA), a chemical chaperon of ER, and mechanisms of underlying these effects. Methods: Anti-fibrotic effects in vivo were assayed in a rat model of renal fibrosis [the unilateral ureteral obstruction (UUO) model]. A rat tubular epithelial cell line (NRK-52E) was stimulated by transforming growth factor-β1 (TGF-β1) and treated with 4-PBA to explore possible mechanisms of these anti-fibrotic effects. Protein expression was analyzed by Western blotting. Transcriptional regulation was investigated using luciferase activity driven by a connective tissue growth factor (CTGF) promoter. Results: The 4-PBAsignificantly

attenuated UUO-induced overwhelming ER stress-related protein expressions, and restored adaptive ER response, splicing X-box-binding protein 1 expression. 4-PBA also attenuated apoptosis, renal fibrosis and tubulointerstitial injury, which is accompanied by attenuating α-smooth muscle actin and CTGF protein expressions ADP ribosylation factor in the rat UUO kidney. 4-PBA also inhibited TGF-β-induced ER stress-associated proapoptotic molecules, profibrotic H 89 molecular weight factors, and CTGF-luciferase activities in renal tubular cells. Conclusion: 4-PBA, acts as an ER chaperone, amelorites ER stess and protects against renal tubular cell apoptosis and renal fibrosis. 4-PBA may become a therapeutic agent to prevent renal fibrosis. TAGUCHI ATSUHIRO, NISHINAKAMURA RYUICHI Department of Kidney Development, Institute of Molecular Embryology and Genetics,

Kumamoto University Introduction: Generation of the kidney in vitro is a challenge for developmental biology and regenerative medicine, because reconstitution of the three-dimensional structures including glomeruli and nephric tubules is a prerequisite for the kidney functions. Adult kidney derives from embryonic metanephros which develops by the reciprocal interaction of the metanephric mesenchyme (MM) and the ureteric bud (UB). Most kidney components are derived from metanephric nephron progenitors in the MM. However, the developmental process how the MM is formed in vivo is largely unknown, resulting in the unsuccessful reconstitution of kidney from pluripotent stem cells (PSCs) in vitro.

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