Rare Functional Variants of Podocin (NPHS2) Promoter in Patients With Nephrotic Syndrome
Podocin (NPHS2) is a component of the glomerular slit-diaphragm, with major regulatory functions in renal permeability of proteins. Loss of podocin and decrease in resynthesis may influence the outcome of proteinuric renal disease such as segmental glomerulosclerosis (FSGS), and promoter functionality plays a key role in this process. NPHS2 promoter variants with functional activity may be a part of the problem of podocin resynthesis. We sequenced NPHS2 promoter region from −628 to ATG in a large cohort of 260 nephrotic patients (161 with FSGS) who were presenting proteinuria from moderate to severe and were receiving or had received modular therapies according to their sensitivity to steroids and other immune modulators. Three sequence variants (−236C>T, −52C>G, −26C>G) were identified in our study population that gave an allele frequency below 1% (5 patients out of 520 alleles). Functional implications were shown for each variants that were most evident for −52C>G and −26C>G (−50% of luciferase expression compared to the wild-type sequence, p < 0.01). Consensus analysis for homology of the −52 region with regulatory factors revealed homology for USF1 and the sum of experiments with gel retardation and with cells silenced for USF1 confirmed that this factor regulates NPHS2 expression at this site. In conclusion, three functional variants in NPHS2 promoter have been identified in a large cohort of patients with nephrotic syndrome and FSGS that have a frequency <1%. One of these (i.e., −52C>G) is associated with a poor clinical outcome and evolution to end-stage renal failure. USF1 was identified as the transcriptional factor regulating NPHS2 at this site. Even if not sufficient to cause FSGS per se, these variants could represent modifiers for severity and/or progression of the disease.
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Focal segmental glomerulosclerosis;
Document Type: Review Article
Laboratory on Pathophysiology of Uremia, Istituto G. Gaslini, Genoa, Italy,
Laboratory on Pathophysiology of Uremia, Istituto G. Gaslini, Genoa, Italy
Department of Clinical Medicine, Nephrology and Health Sciences, University of Parma, Italy
Unit of Nephrology, Spedali Civili di Brescia, Italy
Department of Pediatrics, University of Padua, Italy
Nephrology Section, Ospedale Regina Margherita, Turin, Italy
Nephrology Section, Ospedale Bambin Gesù, Rome, Italy
Chair of Nephrology, University of Turin, Italy
Section of Nephrology, Istituto G. Gaslini, Genoa, Italy
Publication date: January 1, 2006
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Gene Expression, The Journal of Liver Research will publish articles in all aspects of hepatology. Hepatology, as a research discipline, has seen unprecedented growth especially in the cellular and molecular mechanisms of hepatic health and disease, which continues to have a major impact on understanding liver development, stem cells, carcinogenesis, tissue engineering, injury, repair, regeneration, immunology, metabolism, fibrosis, and transplantation. Continued research and improved understanding in these areas will have a meaningful impact on liver disease prevention, diagnosis, and treatment. The existing journal Gene Expression has expanded its focus to become Gene Expression, The Journal of Liver Research to meet this growing demand. In its revised and expanded scope, the journal will publish high-impact original articles, reviews, short but complete articles, and special articles (editorials, commentaries, opinions) on all aspects of hepatology, making it a unique and invaluable resource for readers interested in this field. The expanded team, led by an Editor-in-Chief who is uniquely qualified and a renowned expert, along with a dynamic and functional editorial board, is determined to make this a premier journal in the field of hepatology.