Development of gene silencer pyrrole-imidazole polyamides targeting GSK3ß for treatment of polycystic kidney diseases.

The cyclic adenosine monophosphate (cAMP)-response element binding protein (CREB)-glycogen synthase kinase 3ß (GSK3ß) signaling pathway was reported to be involved in the progression of autosomal dominant polycystic kidney diseases (ADPKD). We designed and synthesized pyrrole-imidazole (PI) polyamides as novel gene-silencers to prevent binding of CREB on the GSK3ß gene promoter and examined the effects of the PI polyamides on proliferation and cyst formation of mouse collecting duct M1 cells. The GSK3ß PI polyamides significantly inhibited expression of GSK3ß mRNA in M1 cells with forskolin. To obtain cells as collecting ducts from ADPKD, the PKD1 gene was knocked down by shRNA. Lower concentrations of forskolin significantly stimulated proliferation of PKD1 knock-down M1 cells, whereas GSK3ß PI polyamide significantly inhibited proliferation of PKD1 knock-down M1 cells with forskolin. Stimulation with forskolin for 5 days induced enlargement of cysts from PKD1 knock-down M1 cells. GSK3ß PI polyamides significantly suppressed the enlargement of cysts with forskolin stimulation in PKD1 knock-down M1 cells. Thus, the present study showed that transcriptional suppression of the GSK3ß gene by PI polyamides targeting the binding of CREB inhibited the proliferation and cyst formation of PKD1 knock-down M1 cells. The GSK3ß PI polyamides may potentially be novel medicines for ADPKD.

Transcriptional Suppression of Diabetic Nephropathy with Novel Gene Silencer Pyrrole-Imidazole Polyamides Preventing USF1 Binding to the TGF-ß1 Promoter.

Upstream stimulatory factor 1 (USF1) is a transcription factor that is increased in high-glucose conditions and activates the transforming growth factor (TGF)-ß1 promoter. We examined the effects of synthetic pyrrole-imidazole (PI) polyamides in preventing USF1 binding on the TGF-ß1 promoter in Wistar rats in which diabetic nephropathy was established by intravenous administration of streptozotocin (STZ). High glucose induced nuclear localization of USF1 in cultured mesangial cells (MCs). In MCs with high glucose, USF1 PI polyamide significantly inhibited increases in promoter activity of TGF-ß1 and expression of TGF-ß1 mRNA and protein, whereas it significantly decreased the expression of osteopontin and increased that of h-caldesmon mRNA. We also examined the effects of USF1 PI polyamide on diabetic nephropathy. Intraperitoneal injection of USF1 PI polyamide significantly suppressed urinary albumin excretion and decreased serum urea nitrogen in the STZ-diabetic rats. USF1 PI polyamide significantly decreased the glomerular injury score and tubular injury score in the STZ-diabetic rats. It also suppressed the immunostaining of TGF-ß1 in the glomerulus and proximal tubules and significantly decreased the expression of TGF-ß1 protein from kidney in these rats. These findings indicate that synthetic USF1 PI polyamide could potentially be a practical medicine for diabetic nephropathy.

Prevalence of Carnitine Deficiency and Decreased Carnitine Levels in Patients on Hemodialysis.

BACKGROUND: Patients on hemodialysis (HD) are known to be at risk of carnitine deficiency. The aims of this study were to investigate the prevalence of carnitine deficiency in patients on dialysis and to compare the likelihood of a reduction in the serum carnitine level on HD with that on hemodiafiltration (HDF). METHODS: The prevalence of carnitine deficiency, defined as a serum free carnitine level < 20 µmol/L, and that of carnitine insufficiency, defined as an acyl/free carnitine ratio > 0.4, was investigated in 150 patients on dialysis. The reduction rate of serum carnitine was then compared between HD and HDF. RESULTS: The prevalence of carnitine deficiency and that of carnitine insufficiency was 25.3 and 86.7%, respectively. Patients at high risk of carnitine deficiency accounted for 64.7%. Multivariate regression identified an association of duration of dialysis with the free serum carnitine level. The reduction rates of serum free carnitine in HD and HDF were 64 ± 4 and 75 ± 7%, respectively (p < 0.0001). CONCLUSION: The prevalence rates of carnitine deficiency and carnitine insufficiency were high in patients on dialysis. The serum carnitine reduction rate was greater with HDF than with HD.

Correlation between Aortic Calcification Score and Biochemical Parameters in Hemodialysis Patients.

BACKGROUND: The purpose of this study was to determine the correlation between aortic calcification and demographic and biochemical parameters in hemodialysis patients. SUMMARY: Calcification scores of the aortic arch and abdominal aorta were determined from multi-slice computed tomography scans and evaluated according to the Agatston score. The associations between demographic and biochemical parameters and aortic calcification score were determined. In total, 190 patients were included in the study. There was a significant positive correlation between aortic calcification scores and age, duration of hemodialysis, cardiothoracic ratio, normalized protein catabolic rate, brachial-ankle pulse wave velocity (baPWV), serum markers of mineral metabolism, and inflammation. A significant negative correlation was found between aortic calcification scores and platelet count. Multivariate analysis showed that age, duration of hemodialysis, baPWV, phosphate, calcium and phosphate (Ca×P) product, parathyroid hormone, and C-reactive protein levels were independent risk factors for calcification of the aortic arch, while baPWV and Ca×P product were independent risk factors for calcification of the abdominal aorta. Key Messages: Aortic calcification scores correlate with age, duration of hemodialysis, and several biochemical parameters of inflammation and mineral metabolism.