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J Histochem Cytochem. 2015 Jan;63(1):32-44. doi: 10.1369/0022155414558335. Epub 2014 Oct 15.

Insights into the renal pathogenesis in Schimke immuno-osseous dysplasia: A renal histological characterization and expression analysis.

Author information

1
Program in Pathology and Molecular Medicine, McMaster University, Hamilton, Canada (SS, AJ, FB, IA, BS, SC, DL, DB)
2
Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada (ABH, CFB)
3
Department of Medical Genetics, University of British Columbia, Vancouver, Canada (CFB)
4
Department of Pediatrics, Division of Nephrology, The Hospital for Sick Children, University of Toronto, Toronto, Canada (NDR)

Abstract

Schimke immuno-osseous dysplasia (SIOD) is a pleiotropic disorder caused by mutations in the SWI/SNF2-related, matrix-associated, actin-dependent regulator of chromatin, subfamily a-like-1 (SMARCAL1) gene, with multiple clinical features, notably end-stage renal disease. Here we characterize the renal pathology in SIOD patients. Our analysis of SIOD patient renal biopsies demonstrates the tip and collapsing variants of focal segmental glomerulosclerosis (FSGS). Additionally, electron microscopy revealed numerous glomerular abnormalities most notably in the podocyte and Bowman's capsule. To better understand the role of SMARCAL1 in the pathogenesis of FSGS, we defined SMARCAL1 expression in the developing and mature kidney. In the developing fetal kidney, SMARCAL1 is expressed in the ureteric epithelium, stroma, metanephric mesenchyme, and in all stages of the developing nephron, including the maturing glomerulus. In postnatal kidneys, SMARCAL1 expression is localized to epithelial tubules of the nephron, collecting ducts, and glomerulus (podocytes and endothelial cells). Interestingly, not all cells within the same lineage expressed SMARCAL1. In renal biopsies from SIOD patients, TUNEL analysis detected marked increases in DNA fragmentation. Our results highlight the cells that may contribute to the renal pathogenesis in SIOD. Further, we suggest that disruptions in genomic integrity during fetal kidney development contribute to the pathogenesis of FSGS in SIOD patients.

KEYWORDS:

DNA fragmentation; FSGS; SIOD; SMARCAL1; Schimke immuno-osseous dysplasia; focal segmental glomerulosclerosis; kidney; kidney pathology

PMID:
25319549
PMCID:
PMC4395996
DOI:
10.1369/0022155414558335
[Indexed for MEDLINE]
Free PMC Article

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