scholarly journals Mitochondrial Dynamics of Proximal Tubular Epithelial Cells in Nephropathic Cystinosis

2019 ◽  
Vol 21 (1) ◽  
pp. 192 ◽  
Author(s):  
Domenico De Rasmo ◽  
Anna Signorile ◽  
Ester De Leo ◽  
Elena V. Polishchuk ◽  
Anna Ferretta ◽  
...  
Keyword(s):  
Fanconi Syndrome ◽  
Mitochondrial Dynamics ◽  
Proteolytic Processing ◽  
Nephropathic Cystinosis ◽  
Lysosomal Storage ◽  
Mitochondrial Fragmentation ◽  
Mitofusin 2 ◽  
Size Number ◽  
Proximal Tubular Epithelial Cells ◽  
Proximal Tubular

Nephropathic cystinosis is a rare lysosomal storage disorder caused by mutations in CTNS gene leading to Fanconi syndrome. Independent studies reported defective clearance of damaged mitochondria and mitochondrial fragmentation in cystinosis. Proteins involved in the mitochondrial dynamics and the mitochondrial ultrastructure were analyzed in CTNS−/− cells treated with cysteamine, the only drug currently used in the therapy for cystinosis but ineffective to treat Fanconi syndrome. CTNS−/− cells showed an overexpression of parkin associated with deregulation of ubiquitination of mitofusin 2 and fission 1 proteins, an altered proteolytic processing of optic atrophy 1 (OPA1), and a decreased OPA1 oligomerization. According to molecular findings, the analysis of electron microscopy images showed a decrease of mitochondrial cristae number and an increase of cristae lumen and cristae junction width. Cysteamine treatment restored the fission 1 ubiquitination, the mitochondrial size, number and lumen of cristae, but had no effect on cristae junction width, making CTNS−/− tubular cells more susceptible to apoptotic stimuli.

scholarly journals Cell-Based Phenotypic Drug Screening Identifies Luteolin as Candidate Therapeutic for Nephropathic Cystinosis

2020 ◽  
Vol 31 (7) ◽  
pp. 1522-1537
Author(s):  
Ester De Leo ◽  
Mohamed A. Elmonem ◽  
Sante Princiero Berlingerio ◽  
Marine Berquez ◽  
Beatrice Paola Festa ◽  
...  
Keyword(s):  
Safety Profile ◽  
High Throughput Screening ◽  
Fanconi Syndrome ◽  
Lysosomal Storage Diseases ◽  
Nephropathic Cystinosis ◽  
Lysosomal Storage ◽  
Renal Fanconi Syndrome ◽  
Cystine Transporter ◽  
Proximal Tubular Epithelial Cells ◽  
Proximal Tubular

BackgroundMutations in the gene that encodes the lysosomal cystine transporter cystinosin cause the lysosomal storage disease cystinosis. Defective cystine transport leads to intralysosomal accumulation and crystallization of cystine. The most severe phenotype, nephropathic cystinosis, manifests during the first months of life, as renal Fanconi syndrome. The cystine-depleting agent cysteamine significantly delays symptoms, but it cannot prevent progression to ESKD and does not treat Fanconi syndrome. This suggests the involvement of pathways in nephropathic cystinosis that are unrelated to lysosomal cystine accumulation. Recent data indicate that one such potential pathway, lysosome-mediated degradation of autophagy cargoes, is compromised in cystinosis.MethodsTo identify drugs that reduce levels of the autophagy-related protein p62/SQSTM1 in cystinotic proximal tubular epithelial cells, we performed a high-throughput screening on the basis of an in-cell ELISA assay. We then tested a promising candidate in cells derived from patients with, and mouse models of, cystinosis, and in preclinical studies in cystinotic zebrafish.ResultsOf 46 compounds identified as reducing p62/SQSTM1 levels in cystinotic cells, we selected luteolin on the basis of its efficacy, safety profile, and similarity to genistein, which we previously showed to ameliorate other lysosomal abnormalities of cystinotic cells. Our data show that luteolin improves the autophagy–lysosome degradative pathway, is a powerful antioxidant, and has antiapoptotic properties. Moreover, luteolin stimulates endocytosis and improves the expression of the endocytic receptor megalin.ConclusionsOur data show that luteolin improves defective pathways of cystinosis and has a good safety profile, and thus has potential as a treatment for nephropathic cystinosis and other renal lysosomal storage diseases.

scholarly journals miR-214 represses mitofusin-2 to promote renal tubular apoptosis in ischemic acute kidney injury

2020 ◽  
Vol 318 (4) ◽  
pp. F878-F887 ◽  
Author(s):  
Yu Yan ◽  
Zhengwei Ma ◽  
Jiefu Zhu ◽  
Mengru Zeng ◽  
Hong Liu ◽  
...  
Keyword(s):  
Mitochondrial Dynamics ◽  
Kidney Injury ◽  
Atp Depletion ◽  
Mitochondrial Fragmentation ◽  
Proximal Tubular Cells ◽  
Mitofusin 2 ◽  
Tubular Cells ◽  
Proximal Tubular ◽  
Renal Tubular ◽  
Kidney Proximal Tubular Cells

Disruption of mitochondrial dynamics is an important pathogenic event in both acute and chronic kidney diseases, but the underlying mechanism remains poorly understood. Here, we report the regulation of mitofusin-2 (Mfn2; a key mitochondrial fusion protein) by microRNA-214 (miR-214) in renal ischemia-reperfusion that contributes to mitochondrial fragmentation, renal tubular cell death, and ischemic acute kidney injury (AKI). miR-214 was induced, whereas Mfn2 expression was decreased, in mouse ischemic AKI and cultured rat kidney proximal tubular cells (RPTCs) following ATP depletion treatment. Overexpression of miR-214 decreased Mfn2. Conversely, inhibition of miR-214 with anti-miR-214 prevented Mfn2 downregulation in RPTCs following ATP depletion. Anti-miR-214 further ameliorated mitochondrial fragmentation and apoptosis, whereas overexpression of miR-214 increased apoptosis, in ATP-depleted RPTCs. To test regulation in vivo, we established a mouse model with miR-214 specifically deleted from kidney proximal tubular cells (PT- miR-214−/−). Compared with wild-type mice, PT- miR-214−/− mice had less severe tissue damage, fewer apoptotic cells, and better renal function after ischemic AKI. miR-214 induction in ischemic AKI was suppressed in PT- miR-214−/− mice, accompanied by partial preservation of Mfn2 in kidneys. These results unveil the miR-214/Mfn2 axis that contributes to the disruption of mitochondrial dynamics and tubular cell death in ischemic AKI, offering new therapeutic targets.

scholarly journals Protection of Cystinotic Mice by Kidney-Specific Megalin Ablation Supports an Endocytosis-Based Mechanism for Nephropathic Cystinosis Progression

2019 ◽  
Vol 30 (11) ◽  
pp. 2177-2190 ◽  
Author(s):  
Virginie Janssens ◽  
Héloïse P. Gaide Chevronnay ◽  
Sandrine Marie ◽  
Marie-Françoise Vincent ◽  
Patrick Van Der Smissen ◽  
...  
Keyword(s):  
Proximal Tubular Cell ◽  
Tubular Cell ◽  
Nephropathic Cystinosis ◽  
Lysosomal Storage ◽  
Proximal Tubular Cells ◽  
Renal Fanconi Syndrome ◽  
Crystal Deposition ◽  
Tubular Cells ◽  
Proximal Tubular ◽  
Kidney Proximal Tubular Cells

BackgroundDeletions or inactivating mutations of the cystinosin gene CTNS lead to cystine accumulation and crystals at acidic pH in patients with nephropathic cystinosis, a rare lysosomal storage disease and the main cause of hereditary renal Fanconi syndrome. Early use of oral cysteamine to prevent cystine accumulation slows progression of nephropathic cystinosis but it is a demanding treatment and not a cure. The source of cystine accumulating in kidney proximal tubular cells and cystine’s role in disease progression are unknown.MethodsTo investigate whether receptor-mediated endocytosis by the megalin/LRP2 pathway of ultrafiltrated, disulfide-rich plasma proteins could be a source of cystine in proximal tubular cells, we used a mouse model of cystinosis in which conditional excision of floxed megalin/LRP2 alleles in proximal tubular cells of cystinotic mice was achieved by a Cre-LoxP strategy using Wnt4-CRE. We evaluated mice aged 6–9 months for kidney cystine levels and crystals; histopathology, with emphasis on swan-neck lesions and proximal-tubular-cell apoptosis and proliferation (turnover); and proximal-tubular-cell expression of the major apical transporters sodium-phosphate cotransporter 2A (NaPi-IIa) and sodium-glucose cotransporter-2 (SGLT-2).ResultsWnt4-CRE–driven megalin/LRP2 ablation in cystinotic mice efficiently blocked kidney cystine accumulation, thereby preventing lysosomal deformations and crystal deposition in proximal tubular cells. Swan-neck lesions were largely prevented and proximal-tubular-cell turnover was normalized. Apical expression of the two cotransporters was also preserved.ConclusionsThese observations support a key role of the megalin/LRP2 pathway in the progression of nephropathic cystinosis and provide a proof of concept for the pathway as a therapeutic target.

scholarly journals Zika Virus-Induced Neuronal Apoptosis via Increased Mitochondrial Fragmentation

2020 ◽  
Vol 11 ◽  
Author(s):  
Shu Yang ◽  
Kirill Gorshkov ◽  
Emily M. Lee ◽  
Miao Xu ◽  
Yu-Shan Cheng ◽  
...  
Keyword(s):  
Cell Death ◽  
Zika Virus ◽  
Neuronal Apoptosis ◽  
Mitochondrial Dynamics ◽  
Neuronal Cell Death ◽  
Neuronal Cell ◽  
Mitochondrial Fragmentation ◽  
Zikv Infection ◽  
Mitofusin 2 ◽  
Infected Cells

The 2015 to 2016 outbreak of Zika virus (ZIKV) infections in the Americas coincided with a dramatic increase in neurodevelopmental abnormalities, including fetal microcephaly, in newborns born to infected women. In this study, we observed mitochondrial fragmentation and disrupted mitochondrial membrane potential after 24 h of ZIKV infection in human neural stem cells and the SNB-19 glioblastoma cell line. The severity of these changes correlated with the amount of ZIKV proteins expressed in infected cells. ZIKV infection also decreased the levels of mitofusin 2, which modulates mitochondria fusion. Mitochondrial division inhibitor 1 (Mdivi-1), a small molecule inhibiting mitochondria fission, ameliorated mitochondria disruptions and reduced cell death in ZIKV-infected cells. Collectively, this study suggests that abnormal mitochondrial fragmentation contributes to ZIKV-induced neuronal cell death; rebalancing mitochondrial dynamics of fission-fusion could be a therapeutic strategy for drug development to treat ZIKV-mediated neuronal apoptosis.

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