Inflammation and fibrogenesis are the two determinants of the progression of renal fibrosis, the common pathway leading to end-stage renal disease. The p38 mitogen-activated protein kinase (MAPK) and transforming growth factor (TGF)-1/Smad signaling pathways play critical roles in inflammation and fibrogenesis, respectively. The present study examined the beneficial renoprotective effect of combination therapy using the p38 MAPK pathway inhibitor (SB203580) and a TGF- receptor I (ALK5) inhibitor (ALK5I) in a mouse model of adriamycin (ADR) nephrosis. The p38 MAPK and TGF-1/Smad2 signaling pathways were activated in ADR-induced nephropathy in a sequential time course manner. Two weeks after ADR injection, the combined administration of SB203580 (1 mg/kg/24 hours) and ALK5I (1 mg/kg/24 hours) markedly reduced p38 MAPK and Smad2 activities. Moreover, the co-administration of SB203580 and ALK5I to ADR-injected mice resulted in a down-regulation of total and active TGF-1 production, reduced myofibroblast accumulation, and decreased expression of collagen type IV and fibronectin. In these mice, retardation in the development of glomerulosclerosis and interstitial fibrosis was observed. In conclusion, although p38 MAPK and TGF-1/Smad signaling pathways are distinct they coordinate the progression of renal fibrosis in ADR nephrosis. The co-administration of a p38 MAPK inhibitor and an ALK5 inhibitor may have potential applications in the treatment of renal fibrosis. (Am J Pathol 2006, 169
SummaryGranulosa cells (GCs) are essential for proper oocyte, follicular development, and steroidogenesis in the ovary. Transforming growth factor b (TGF-b) superfamily members are critical in regulating GCs growth and differentiation. Smad3 is known to serve as a signaling intermediate for the TGF-b; however, the functions of Smad3 in the human GCs remain unidentified. In this study, the luteinized GCs collected from follicular aspirates from patients undergoing in vitro fertilization were cultured and engineered to overexpress and knockdown Smad3, which were validated by RT-PCR and Western blotting. Immunocytochemistry showed that Smad3 protein was strongly expressed in human ovarian luteinized GCs. EdU incorporation demonstrated that Smad3 promoted the proliferation of GCs, and the expression of PCNA was also enhanced by Smad3. ELISA analysis indicated that the secretion of both estradiol and progesterone was stimulated by Smad3. In addition, Smad3 upregulated the level of follicle-stimulating hormone receptor (FSHR), luteinizing hormone receptor (LHR), and protein kinase A (PKA) proteins. We subsequently added special PKA inhibitor H89 into the GCs and found that the stimulating effect on the growth of GCs by Smad3 was blocked partly. The morphology of cultured GCs was changed by Smad3, and the expression level of integrin b1 was enhanced by Smad3. Kindlin-2, an important cellular mediating molecule of integrin b signaling, was expressed in human ovarian luteinized GCs and was upregulated by Smad3. Our results indicated that Smad3 promoted the proliferation and steroidogenesis of human ovarian luteinized GCs, and these effects may be mediated by the FSHR/LHR-PKA signaling pathway. V C 2014 IUBMB Life, 66(6): [424][425][426][427][428][429][430][431][432][433][434][435][436][437] 2014
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