Lysosome function in glomerular health and disease.
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ABSTRACT:
SUBMITTER: Meyer-Schwesinger C
PROVIDER: S-EPMC8523507 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Podocytes are highly differentiated glomerular epithelial cells that contribute to the glomerular barrier function of kidney. A role for autophagy has been proposed in maintenance of their cellular integrity, but the mechanisms controlling autophagy in podocytes are not clear. The present study tested whether CD38-mediated regulation of lysosome function contributes to autophagic flux or autophagy maturation in podocytes. Podocytes were found to exhibit a high constitutive level of LC3-II, a robust marker of autophagosomes (APs), suggesting a high basal level of autophagic activity. Treatment with the mTOR inhibitor, rapamycin, increased LC3-II and the content of both APs detected by Cyto-ID Green staining and autophagolysosomes (APLs) measured by acridine orange staining and colocalization of LC3 and Lamp1. Lysosome function inhibitor bafilomycin A1 increased APs, but decreased APLs content under both basal and rapamycin-induced conditions. Inhibition of CD38 activity by nicotinamide or silencing of CD38 gene produced the similar effects to that bafilomycin A1 did in podocytes. To explore the possibility that CD38 may control podocyte autophagy through its regulation of lysosome function, the fusion of APs with lysosomes in living podocytes was observed by co-transfection of GFP-LC3B and RFP-Lamp1 expression vectors. A colocalization of GFP-LC3B and RFP-Lamp1 upon stimulation of rapamycin became obvious in transfected podocytes, which could be substantially blocked by nicotinamide, CD38 shRNA, and bafilomycin. Moreover, blockade of the CD38-mediated regulation by PPADS completely abolished rapamycin-induced fusion of APs with lysosomes. These results indicate that CD38 importantly control lysosomal function and influence autophagy at the maturation step in podocytes.
| S-EPMC3914646 | biostudies-literature
Project description:This review focuses on the pathways that regulate lysosome biogenesis and that are implicated in numerous degenerative storage diseases, including lysosomal storage disorders and late-onset neurodegenerative diseases. Lysosomal proteins are synthesized in the endoplasmic reticulum and trafficked to the endolysosomal system through the secretory route. Several receptors have been characterized that execute post-Golgi trafficking of lysosomal proteins. Some of them recognize their cargo proteins based on specific amino acid signatures, others based on a particular glycan modification that is exclusively found on lysosomal proteins. Nearly all receptors serving lysosome biogenesis are under the transcriptional control of transcription factor EB (TFEB), a master regulator of the lysosomal system. TFEB coordinates the expression of lysosomal hydrolases, lysosomal membrane proteins, and autophagy proteins in response to pathways sensing lysosomal stress and the nutritional conditions of the cell among other stimuli. TFEB is primed for activation in lysosomal storage disorders but surprisingly its function is impaired in some late-onset neurodegenerative storage diseases like Alzheimer's and Parkinson's, because of specific detrimental interactions that limit TFEB expression or activation. Thus, disrupted TFEB function presumably plays a role in the pathogenesis of these diseases. Multiple studies in animal models of degenerative storage diseases have shown that exogenous expression of TFEB and pharmacological activation of endogenous TFEB attenuate disease phenotypes. These results highlight TFEB-mediated enhancement of lysosomal biogenesis and function as a candidate strategy to counteract the progression of these diseases. This article is part of the Special Issue "Lysosomal Storage Disorders".
| S-EPMC6368902 | biostudies-literature
Project description:Podocytes are visceral epithelial cells covering the outer surface of glomerular capillaries in the kidney. Blood is filtered through the slit diaphragm of podocytes to form urine. The functional and structural integrity of podocytes is essential for the normal function of the kidney. As a membrane-bound organelle, lysosomes are responsible for the degradation of molecules via hydrolytic enzymes. In addition to its degradative properties, recent studies have revealed that lysosomes may serve as a platform mediating cellular signaling in different types of cells. In the last decade, increasing evidence has revealed that the normal function of the lysosome is important for the maintenance of podocyte homeostasis. Podocytes have no ability to proliferate under most pathological conditions; therefore, lysosome-dependent autophagic flux is critical for podocyte survival. In addition, new insights into the pathogenic role of lysosome and associated signaling in podocyte injury and chronic kidney disease have recently emerged. Targeting lysosomal functions or signaling pathways are considered potential therapeutic strategies for some chronic glomerular diseases. This review briefly summarizes current evidence demonstrating the regulation of lysosomal function and signaling mechanisms as well as the canonical and noncanonical roles of podocyte lysosome dysfunction in the development of chronic glomerular diseases and associated therapeutic strategies.
| S-EPMC7084483 | biostudies-literature
Project description:There is scant literature describing the effect of glomerular disease on health-related quality of life (HRQOL). The Cure Glomerulonephropathy study (CureGN) is an international longitudinal cohort study of children and adults with four primary glomerular diseases (minimal change disease, focal segmental glomerulosclerosis, membranous nephropathy, and IgA nephropathy). HRQOL is systematically assessed using items from the Patient-Reported Outcomes Measurement Informative System (PROMIS). We assessed the relationship between HRQOL and demographic and clinical variables in 478 children and 1115 adults at the time of enrollment into CureGN. Domains measured by PROMIS items included global assessments of health, mobility, anxiety, fatigue, and sleep impairment, as well as a derived composite measure incorporating all measured domains. Multivariable models were created that explained 7 to 32% of variance in HRQOL. Patient-reported edema consistently had the strongest and most robust association with each measured domain of HRQOL in multivariable analysis (adjusted ? [95% CI] for composite PROMIS score in children, -5.2 [-7.1 to -3.4]; for composite PROMIS score in adults, -6.1 [-7.4 to -4.9]). Female sex, weight (particularly obesity), and estimated glomerular filtration rate were also associated with some, but not all, domains of HRQOL. Primary diagnosis, disease duration, and exposure to immunosuppression were not associated with HRQOL after adjustment. Sensitivity analyses and interaction testing demonstrated no significant association between disease duration or immunosuppression and any measured domain of HRQOL. Thus, patient-reported edema has a consistent negative association with HRQOL in patients with primary glomerular diseases, with substantially greater impact than other demographic and clinical variables.
| S-EPMC6743723 | biostudies-literature
Project description:Lysosomes are membrane-bound organelles responsible for the transport and degradation of intracellular and extracellular cargo. The intracellular motion of lysosomes is both diffusive and active, mediated by motor proteins moving lysosomes along microtubules. We sought to determine how lysosome diameter influences lysosome transport. We used osmotic swelling to double the diameter of lysosomes, creating a population of enlarged lysosomes. This allowed us to directly examine the intracellular transport of the same organelle as a function of diameter. Lysosome transport was measured using live cell fluorescence microscopy and single particle tracking. We find, as expected, the diffusive component of intracellular transport is decreased proportional to the increased lysosome diameter. Active transport of the enlarged lysosomes is not affected by the increased lysosome diameter.
| S-EPMC3908945 | biostudies-literature
Project description:Nlrp3 inflammasomes were shown to play a critical role in triggering obesity-associated early onsets of cardiovascular complications such as endothelial barrier dysfunction with endothelial hyperpermeability. Statins prevent endothelial dysfunction and decrease cardiovascular risk in patients with obesity and diabetes. However, it remains unclear whether statin treatment for obesity-induced endothelial barrier dysfunction is in part due to the blockade of Nlrp3 inflammasome signaling axis. The results showed that simvastatin, a clinically and widely used statin, prevented free fatty acid-induced endothelial hyperpermeability and disruption of ZO-1 and VE-cadherin junctions in mouse microvascular endothelial cells (MVECs). This protective effect of simvastatin was largely due to improved lysosome function that attenuated lysosome injury-mediated Nlrp3 inflammasome activation and subsequent release of high mobility group box protein-1 (HMGB1). Mechanistically, simvastatin induces autophagy that promotes removal of damaged lysosomes and also promotes lysosome regeneration that preserves lysosome function. Collectively, simvastatin treatment improves lysosome function via enhancing lysosome biogenesis and its autophagic turnover, which may be an important mechanism to suppress Nlrp3 inflammasome activation and prevents endothelial hyperpermeability in obesity.
| S-EPMC6812495 | biostudies-literature
Project description:Lysosomes are organelles responsible for the breakdown and recycling of cellular machinery. Dysfunctional lysosomes give rise to lysosomal storage disorders as well as common neurodegenerative diseases. Here, we use a DNA-based, fluorescent chloride reporter to measure lysosomal chloride in Caenorhabditis elegans as well as murine and human cell culture models of lysosomal diseases. We find that the lysosome is highly enriched in chloride, and that chloride reduction correlates directly with a loss in the degradative function of the lysosome. In nematodes and mammalian cell culture models of diverse lysosomal disorders, where previously only lysosomal pH dysregulation has been described, massive reduction of lumenal chloride is observed that is ~103 fold greater than the accompanying pH change. Reducing chloride within the lysosome impacts Ca2+ release from the lysosome and impedes the activity of specific lysosomal enzymes indicating a broader role for chloride in lysosomal function.
| S-EPMC5526669 | biostudies-literature
Project description:Background and objectivesDent disease is a rare X-linked disorder characterized by low molecular weight proteinuria and often considered a renal tubular disease. However, glomerulosclerosis was recently reported in several patients. Thus, Dent disease renal histopathologic features were characterized and assessed, and their association with kidney function was assessed.Design, setting, participants, & measurementsClinical renal pathology reports and slides (where available) were collected from 30 boys and men in eight countries who had undergone clinical renal biopsy between 1995 and 2014.ResultsMedian (25th, 75th percentiles) age at biopsy was 7.5 (5, 19) years with an eGFR of 69 (44, 94) ml/min per 1.73 m2 and a 24-hour urine protein of 2000 (1325, 2936) mg. A repeat biopsy for steroid-resistant proteinuria was performed in 13% (four of 30) of the patients. Prominent histologic findings included focal global glomerulosclerosis in 83% (25 of 30; affecting 16%±19% glomeruli), mild segmental foot process effacement in 57% (13 of 23), focal interstitial fibrosis in 60% (18 of 30), interstitial lymphocytic infiltration in 53% (16 of 30), and tubular damage in 70% (21 of 30). Higher percentages of globally sclerotic glomeruli, foot process effacement, and interstitial inflammation were associated with lower eGFR at biopsy, whereas foot process effacement was associated with steeper annual eGFR decline.ConclusionsThese associations suggest a potential role for glomerular pathology, specifically involving the podocyte, in disease progression, which deserves further study. Furthermore, Dent disease should be suspected in boys and men who have unexplained proteinuria with focal global glomerulosclerosis and segmental foot process effacement on renal biopsy.
| S-EPMC5142066 | biostudies-literature
Project description: Not available
| S-EPMC8016208 | biostudies-literature
Project description:Abnormalities of the endolysosomal and autophagy systems are found in Alzheimer's disease, but it is not clear whether defects in these systems are a cause or consequence of degenerative processes in the disease. In human neuronal models of monogenic Alzheimer's disease, APP and PSEN1 mutations disrupt lysosome function and autophagy, leading to impaired lysosomal proteolysis and defective autophagosome clearance. Processing of APP by ?-secretase is central to the pathogenic changes in the lysosome-autophagy system caused by PSEN1 and APP mutations: reducing production of C-terminal APP by inhibition of BACE1 rescued these phenotypes in both APP and PSEN1 mutant neurons, whereas inhibition of ?-secretase induced lysosomal and autophagic pathology in healthy neurons. Defects in lysosomes and autophagy due to PSEN1 mutations are rescued by CRISPR-knockout of APP. These data demonstrate a key role for proteolysis of the C-terminal of APP by ?-secretase in neuronal dysfunction in monogenic Alzheimer's disease.
| S-EPMC6315085 | biostudies-other