title: Inhibition of intracellular clusterin attenuates cell death in nephropathic cystinosis.
abstract: Nephropathic cystinosis, characterized by accumulation of cystine in the lysosomes, is caused by mutations in CTNS. The molecular and cellular mechanisms underlying proximal tubular dysfunction and progressive renal failure in nephropathic cystinosis are largely unclear, and increasing evidence supports the notion that cystine accumulation alone is not responsible for the end organ injury in cystinosis. We previously identified clusterin as potentially involved in nephropathic cystinosis. Here, we studied the expression of clusterin in renal proximal tubular epithelial cells obtained from patients with nephropathic cystinosis. The cytoprotective secretory form of clusterin, as evaluated by Western blot analysis, was low or absent in cystinosis cells compared with normal primary cells. Confocal microscopy revealed elevated levels of intracellular clusterin in cystinosis cells. Clusterin in cystinosis cells localized to the nucleus and cytoplasm and showed a filamentous and punctate aggresome-like pattern compared with diffuse cytoplasmic staining in normal cells. In kidney biopsy samples from patients with nephropathic cystinosis, clusterin protein expression was mainly limited to the proximal tubular cells. Furthermore, expression of clusterin overlapped with the expression of apoptotic proteins (apoptosis-inducing factor and cleaved caspase-3) and autophagy proteins (LC3 II and p62). Silencing of the clusterin gene resulted in a significant increase in cell viability and attenuation of apoptosis in cystinosis cells. Results of this study identify clusterin as a pivotal factor in the cell injury mechanism of nephropathic cystinosis and provide evidence linking cellular stress and injury to Fanconi syndrome and progressive renal injury in nephropathic cystinosis.
authors: California Pacific Medical Center Research Institute, San Francisco, California; poonam.sansanwal@gmail.com msarwal@psg.ucsf.edu.
authors: Poonam
authors: P
authors: Sansanwal
authors: Department of Genetics and Genomic Sciences, Mount Sinai School of Medicine, New York, New York; and.
authors: Li
authors: L
authors: Li
authors: California Pacific Medical Center Research Institute, San Francisco, California; Department of Surgery, Univeristy of California, San Francisco, School of Medicine, San Francisco, California poonam.sansanwal@gmail.com msarwal@psg.ucsf.edu.
authors: Minnie M
authors: MM
authors: Sarwal
mesh_terms: D000293:Adolescent; D051033:Apoptosis Inducing Factor / Q000378:metabolism; D001343:Autophagy; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D051152:Clusterin / Q000378:metabolism*; D003554:Cystinosis / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism; D020868:Gene Silencing; D006801:Humans; D007150:Immunohistochemistry; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D018613:Microscopy, Confocal; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism
chemical_list: C494829:AIFM1 protein, human; D051033:Apoptosis Inducing Factor; D051152:Clusterin; C477012:MAP1LC3A protein, human; D008869:Microtubule-Associated Proteins; C118585:P62 protein, human; D016601:RNA-Binding Proteins; D053148:Caspase 3
keywords: CKD; ESRD; apoptosis; disease; genetic renal; kidney disease; pediatric nephrology