Cis and trans regulatory elements in NPHS2 promoter: Implications in proteinuria and progression of renal diseases

• Published in: Kidney international Vol. 70; no. 7; pp. 1332 - 1341
• Main Authors: Di Duca, M., Oleggini, R., Sanna-Cherchi, S., Pasquali, L., Di Donato, A., Parodi, S., Bertelli, R., Caridi, G., Frasca, G., Cerullo, G., Amoroso, A., Schena, F.P., Scolari, F., Ghiggeri, G.M., The European IgA Nephropathy Consortium
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.10.2006; Nature Publishing; Elsevier Limited
• Subjects: Adolescent; Adult; Aged; Animals; Biological and medical sciences; Cell Line; Child; Child, Preschool; Chronic Disease; Cohort Studies; Creatinine - blood; Data Interpretation, Statistical; Disease Progression; Female; focal segmental glomerulosclerosis; Follow-Up Studies; Gene Expression Regulation; Gene Frequency; Genetic Variation; Glomerulonephritis; Glomerulonephritis, IGA - genetics; Glomerulosclerosis, Focal Segmental - genetics; haplotype analysis; Haplotypes; Humans; IgA nephropathy; Infant; Intracellular Signaling Peptides and Proteins - genetics; Kidney Diseases - genetics; Luciferases - genetics; Male; Medical sciences; Membrane Proteins - genetics; Middle Aged; Nephrology. Urinary tract diseases; Nephropathies. Renovascular diseases. Renal failure; Nephrotic Syndrome - genetics; podocin expression; Podocytes - metabolism; Polymorphism, Single Nucleotide; progression of renal diseases; Promoter Regions, Genetic; Proteinuria - genetics; Sequence Analysis, DNA; Time Factors; trans-acting elements; Urinary system involvement in other diseases. Miscellaneous; Urinary tract. Prostate gland; haplotype analysis; IgA nephropathy; podocin expression; focal segmental glomerulosclerosis; trans-acting elements; progression of renal diseases; Glomerulonephritis; Kidney disease; Immunopathology; Nephrology; Urinary system disease; Prognosis; Urology; Promoter; Renal failure; Evolution; IgA glomerular nephropathy; Nephrotic syndrome with focal glomerular sclerosis; Regulatory sequence; Haplotype; Proteinuria
• ISSN: 0085-2538; 1523-1755
• DOI: 10.1038/sj.ki.5001767

Podocin (NPHS2) expression in podocytes is associated with variable degrees of proteinuria and progression to renal failure in different glomerular diseases that suggests different expression profiles in NPHS2 promoter. Three functional polymorphisms in NPHS2 promoter (-51T, −116T, and −535 insCTTTTTT3) were found determining strong downregulation (-73, −59, and −82%, respectively) of the reporter gene expression when transfected in podocytes. Electrophoretic mobility shift assay experiments showed that all wild-type variants (-51G, −116C, and −535 insCTTTTTT2) formed specific DNA–protein complexes with podocyte nuclear extracts that were abolished by the presence of the rare forms (-51T, −116T, and −535 insCTTTTTT3). In the case of −51G, upstream stimulatory factor-1 (USF1) was identified as the specific trans element in accord to binding inhibition experiments and USF1 RNAi silencing. Haplotype analysis of 204 normal controls and 545 patients with renal diseases (308 immunoglobulin (Ig)A nephropathy and 237 focal segmental glomerulosclerosis) evidenced that −116/−51 and −535/P2OL formed two blocks in strong linkage disequilibrium in both normal and pathological cohorts. The high NPHS2 promoter profile −116C/−51G haplotype was more frequent in patients with IgA nephropathy (P−value=0.005) and was associated with a better clinical outcome in terms of proteinuria and creatinine levels. Overall our study describes functional variants of NPHS2 promoter and characterizes trans-acting elements that modulate podocin expression in the kidney. High producer NPHS2 promoter haplotypes seem protective in patients with chronic glomerular diseases.