scholarly journals The lysosomal V-ATPase B1 subunit in proximal tubule is linked to nephropathic cystinosis

2020 ◽  
Author(s):  
Amer Jamalpoor ◽  
Albertien M van Eerde ◽  
Marc R Lilien ◽  
Charlotte AGH van Gelder ◽  
Esther A Zaal ◽  
...  
Keyword(s):  
Metabolic Acidosis ◽  
Proximal Tubule ◽  
Renal Proximal Tubule ◽  
Nephropathic Cystinosis ◽  
Renal Fanconi Syndrome ◽  
Proximal Tubule Cells ◽  
Pathogenic Variants ◽  
Tubule Cells ◽  
Renal Proximal Tubule Cells ◽  
Renal Tubular

AbstractBackgroundRecently, a 23-month-old girl presented with increased granulocyte cystine levels, metabolic acidosis and symptoms of renal Fanconi syndrome. Cystinosis was suspected and treatment with electrolytes and cysteamine, a cystine depleting agent, was started that appeared effective. However, genetic testing did not detect any variants in CTNS (the gene affected in cystinosis) but instead revealed pathogenic variants in ATP6V1B1. ATP6V1B1 encodes the B1 subunit of the vacuolar H+-ATPase (V-ATPase), that is linked to autosomal recessive distal renal tubular acidosis, a metabolic disorder with an inappropriately alkaline urine and deafness. Here, the unknown link between ATP6V1B1 gene deficiency and proximal tubulopathy as well as a possible link to cystinosis pathophysiology was investigated.MethodsWe used CRISPR/Cas9 technology to selectively knockout the ATP6V1B1 or CTNS gene in human renal proximal tubule cells and compare their proteomic and metabolomic profile with isogenic wild type proximal tubule cells.ResultsATP6V1B1 was expressed along the human distal but also the proximal segments of the nephron. Consistent with the clinical data, loss of ATP6V1B1 in renal proximal tubule cells resulted in increased cystine levels with autophagy activation. Further, omics profiling showed that both ATP6V1B1-/- and CTNS-/- cells are in metabolic acidosis with impaired autophagy and signs of proximal tubular epithelial dysfunction.ConclusionWe identified the lysosomal V-ATPase B1 subunit to play an important role in proximal tubule function, regulating cystine transport and autophagy in human renal proximal tubule cells through its interaction with cystinosin and mTOR-signaling.

scholarly journals ATP induces PAD4 in renal proximal tubule cells via P2X7 receptor activation to exacerbate ischemic AKI

2018 ◽  
Vol 314 (2) ◽  
pp. F293-F305 ◽  
Author(s):  
May Rabadi ◽  
Mihwa Kim ◽  
Hongmei Li ◽  
Sang Jun Han ◽  
Yewoon Choi ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
P2x7 Receptor ◽  
Receptor Activation ◽  
Renal Proximal Tubule ◽  
Proximal Tubule Cells ◽  
Tubule Cells ◽  
Renal Proximal Tubule Cells ◽  
Renal Tubular ◽  
P2x7 Receptor Activation ◽  
Expression And Activity

We previously demonstrated that renal tubular peptidylarginine deiminase-4 (PAD4) is induced after ischemia-reperfusion (IR) injury and this induction of PAD4 exacerbates ischemic acute kidney injury (AKI) by promoting renal tubular inflammation and neutrophil infiltration. However, the mechanisms of renal tubular PAD4 induction after IR remain unknown. Here, we tested the hypothesis that ATP, a proinflammatory danger-associated molecular pattern (DAMP) ligand released from necrotic cells after IR injury, induces renal tubular PAD4 and exacerbates ischemic AKI via P2 purinergic receptor activation. ATP as well as ATPγS (a nonmetabolizable ATP analog) induced PAD4 mRNA, protein, and activity in human and mouse renal proximal tubule cells. Supporting the hypothesis that ATP induces renal tubular PAD4 via P2X7 receptor activation, A804598 (a selective P2X7 receptor antagonist) blocked the ATP-mediated induction of renal tubular PAD4 whereas BzATP (a selective P2X7 receptor agonist) mimicked the effects of ATP by inducing renal tubular PAD4 expression and activity. Moreover, ATP-mediated calcium influx in renal proximal tubule cells was blocked by A804598 and was mimicked by BzATP. P2X7 activation by BzATP also induced PAD4 expression and activity in mouse kidney in vivo. Finally, supporting a critical role for PAD4 in P2X7-mediated exacerbation of renal injury, BzATP exacerbated ischemic AKI in PAD4 wild-type mice but not in PAD4-deficient mice. Taken together, our studies show that ATP induces renal tubular PAD4 via P2X7 receptor activation to exacerbate renal tubular inflammation and injury after IR.

Effects of TCDD and estradiol-17β on the proliferation and Na+/glucose cotransporter in renal proximal tubule cells

2005 ◽  
Vol 19 (1) ◽  
pp. 21-30 ◽  
Author(s):  
Ho Jae Han ◽  
Min Jin Lim ◽  
Yun Jung Lee ◽  
Eun Jung Kim ◽  
Young Jin Jeon ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Renal Proximal Tubule ◽  
Proximal Tubule Cells ◽  
Tubule Cells ◽  
Renal Proximal Tubule Cells ◽  
Estradiol 17Β

Abstract P238: Regulation Of G Protein-coupled Receptor Kinase 4 Expression By Serum In Breast Cancer And Renal Proximal Tubule Cells

Hypertension ◽  
2021 ◽  
Vol 78 (Suppl_1) ◽  
Author(s):  
Wei Yue ◽  
Peng Xu ◽  
John J Gildea ◽  
Robin A Felder
Keyword(s):  
Breast Cancer ◽  
Protein Synthesis ◽  
Proximal Tubule ◽  
Cancer Cells ◽  
Breast Cancer Cells ◽  
Renal Proximal Tubule ◽  
Proximal Tubule Cells ◽  
Tubule Cells ◽  
Renal Proximal Tubule Cells ◽  
G Protein Coupled

G protein-coupled receptor kinase 4 (GRK4) is a member of the GRK family which play critical role in regulation of the function of G protein-coupled receptors. Our previous studies have shown that GRK4 not only plays a role in regulating sodium excretion in renal proximal tubule cells but also acts as a stimulator on proliferation of breast cancer cells. Uncontrolled proliferation is a characteristics of cancer cells and GRK4 is upregulated in breast cancer cells. We hypothesized that expression of GRK4 may be regulated differently in cancer and non-cancer cells. To test this hypothesis, expression of GRK4 in response to serum was compared in breast cancer cells and renal proximal tubule cells by Western analysis. In three breast cancer cell lines serum withdrawal caused rapid reduction in the levels of GRK4 which occurred as early as 15 min. GRK4 levels correlated with the concentrations of serum added to the culture media. To determine if growth factors were a critical element for maintaining GRK4 levels in the cells, EGF (10-20 ng/ml) was added to serum free medium for 24 h. There was no increase in GRK4 levels in the cells treated with EGF compared with the serum starvation control. Similarly, serum withdrawal (16 h) led to 40-80% decrease of GRK4 levels in renal proximal tubule cells even in the presence of EFG supplement. Serum feeding for 30 min after starvation dramatically increased the levels of GRK4 in both breast cancer cells and RPTC which exceeded the steady state levels. This rapid recovery of GRK4 protein do not need de novo protein synthesis because pretreatment of the cells with protein synthesis inhibitor, cycloheximide (10 μg/ml, 24 h), did not prevent this event. Expression of GRK2, another member of the GRK family, was not affected by serum starvation. Our results have shown that GRK4 is very sensitive to serum concentration in breast cancer cells as well as in RPTC. Preliminary studies suggest that rapid protein degradation rather than shutting down the protein synthesis plays a major role in this kind of GRK4 regulation. The biological significance of serum regulation of GRK4 in cancer and non-cancerous cells needs further investigation.

Primary cultures of renal proximal tubule cells derived from individuals with primary hyperoxaluria

2009 ◽  
Vol 37 (3) ◽  
pp. 127-132 ◽  
Author(s):  
Karen L. Price ◽  
Sally-Anne Hulton ◽  
William G. van’t Hoff ◽  
John R. Masters ◽  
Gill Rumsby
Keyword(s):  
Proximal Tubule ◽  
Primary Cultures ◽  
Primary Hyperoxaluria ◽  
Renal Proximal Tubule ◽  
Proximal Tubule Cells ◽  
Tubule Cells ◽  
Renal Proximal Tubule Cells

scholarly journals Signaling pathways utilized by PTH and dopamine to inhibit phosphate transport in mouse renal proximal tubule cells

2009 ◽  
Vol 296 (2) ◽  
pp. F355-F361 ◽  
Author(s):  
Rochelle Cunningham ◽  
Rajatsubhra Biswas ◽  
Marc Brazie ◽  
Deborah Steplock ◽  
Shirish Shenolikar ◽  
...  
Keyword(s):  
Proximal Tubule ◽  
Signaling Pathways ◽  
Phosphate Transport ◽  
Inhibitory Effect ◽  
Renal Proximal Tubule ◽  
Proximal Tubule Cells ◽  
Phosphate Cotransport ◽  
Tubule Cells ◽  
Renal Proximal Tubule Cells ◽  
Sodium Phosphate Cotransport

The present experiments were designed to detail factors regulating phosphate transport in cultured mouse proximal tubule cells by determining the response to parathyroid hormone (PTH), dopamine, and second messenger agonists and inhibitors. Both PTH and dopamine inhibited phosphate transport by over 30%. The inhibitory effect of PTH was completely abolished in the presence of chelerythrine, a PKC inhibitor, but not by Rp-cAMP, a PKA inhibitor. By contrast, both chelerythrine and Rp-cAMP blocked the inhibitory effect of dopamine. Chelerythrine inhibited PTH-mediated cAMP accumulation but also blocked the inhibitory effect of 8-bromo-cAMP on phosphate transport. On the other hand, Rp-cAMP had no effect on the ability of DOG, a PKC activator, to inhibit phosphate transport. PD98059, an inhibitor of MAPK, had no effect on PTH- or dopamine-mediated inhibition of sodium-phosphate cotransport. Finally, compared with 8-bromo-cAMP, 8-pCPT-2′- O-Me-cAMP, an activator of EPAC, had no effect on phosphate transport. These results outline significant differences in the signaling pathways utilized by PTH and dopamine to inhibit renal phosphate transport. Our results also suggest that activation of MAPK is not critically involved in PTH- or dopamine-mediated inhibition of phosphate transport in mouse renal proximal tubule cells in culture.

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