Dataset Information

Phenotypic and functional analysis of human SLC26A6 variants in patients with familial hyperoxaluria and calcium oxalate nephrolithiasis.

ABSTRACT:

Background

Urinary oxalate is a major risk factor for calcium oxalate stones. Marked hyperoxaluria arises from mutations in 2 separate loci, AGXT and GRHPR, the causes of primary hyperoxaluria (PH) types 1 (PH1) and 2 (PH2), respectively. Studies of null Slc26a6(-/-) mice have shown a phenotype of hyperoxaluria, hyperoxalemia, and calcium oxalate urolithiasis, leading to the hypothesis that SLC26A6 mutations may cause or modify hyperoxaluria in humans.

Study design

Cross-sectional case-control.

Setting & participants

Cases were recruited from the International Primary Hyperoxaluria Registry. Control DNA samples were from a pool of adult subjects who identified themselves as being in good health.

Predictor

PH1, PH2, and non-PH1/PH2 genotypes in cases.

Outcomes & measures

Homozygosity or compound heterozygosity for SLC26A6 variants. Functional expression of oxalate transport in Xenopus laevis oocytes.

Results

80 PH1, 6 PH2, 8 non-PH1/PH2, and 96 control samples were available for SLC26A6 screening. A rare variant, c.487C-->T (p.Pro163Ser), was detected solely in 1 non-PH1/PH2 pedigree, but this variant failed to segregate with hyperoxaluria, and functional studies of oxalate transport in Xenopus oocytes showed no transport defect. No other rare variant was identified specifically in non-PH1/PH2. Six additional missense variants were detected in controls and cases. Of these, c.616G-->A (p.Val206Met) was most common (11%) and showed a 30% reduction in oxalate transport. To test p.Val206Met as a potential modifier of hyperoxaluria, we extended screening to PH1 and PH2. Heterozygosity for this variant did not affect plasma or urine oxalate levels in this population.

Limitations

We did not have a sufficient number of cases to determine whether homozygosity for p.Val206Met might significantly affect urine oxalate.

Conclusions

SLC26A6 was effectively ruled out as the disease gene in this non-PH1/PH2 cohort. Taken together, our studies are the first to identify and characterize SLC26A6 variants in patients with hyperoxaluria. Phenotypic and functional analysis excluded a significant effect of identified variants on oxalate excretion.

SUBMITTER: Monico CG

PROVIDER: S-EPMC2710965 | biostudies-literature | 2008 Dec

REPOSITORIES: biostudies-literature

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Publications

Phenotypic and functional analysis of human SLC26A6 variants in patients with familial hyperoxaluria and calcium oxalate nephrolithiasis.

Monico Carla G CG Weinstein Adam A Jiang Zhirong Z Rohlinger Audrey L AL Cogal Andrea G AG Bjornson Beth B BB Olson Julie B JB Bergstralh Eric J EJ Milliner Dawn S DS Aronson Peter S PS

American journal of kidney diseases : the official journal of the National Kidney Foundation 20081031 6

<h4>Background</h4>Urinary oxalate is a major risk factor for calcium oxalate stones. Marked hyperoxaluria arises from mutations in 2 separate loci, AGXT and GRHPR, the causes of primary hyperoxaluria (PH) types 1 (PH1) and 2 (PH2), respectively. Studies of null Slc26a6(-/-) mice have shown a phenotype of hyperoxaluria, hyperoxalemia, and calcium oxalate urolithiasis, leading to the hypothesis that SLC26A6 mutations may cause or modify hyperoxaluria in humans.<h4>Study design</h4>Cross-sectional ...[more]

PMID: 18951670

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Project description:Oxidative stress, a well-known cause of stress-induced premature senescence (SIPS), is increased in patients with calcium oxalate (CaOx) kidney stones (KS). Oxalate and calcium oxalate monohydrate (COM) induce oxidative stress in renal tubular cells, but to our knowledge, their effect on SIPS has not yet been examined. Here, we examined whether oxalate, COM, or urine from patients with CaOx KS could induce SIPS and telomere shortening in human kidney (HK)-2 cells, a proximal tubular renal cell line. Urine from age- and sex-matched individuals without stones was used as a control. In sublethal amounts, H2O2, oxalate, COM, and urine from those with KS evoked oxidative stress in HK-2 cells, indicated by increased protein carbonyl content and decreased total antioxidant capacity, but urine from those without stones did not. The proportion of senescent HK-2 cells, as indicated by SA-βgal staining, increased after treatment with H2O2, oxalate, COM, and urine from those with KS. Expression of p16 was higher in HK-2 cells treated with H2O2, oxalate, COM, and urine from those with KS than it was in cells treated with urine from those without stones and untreated controls. p16 was upregulated in the SA-βgal positive cells. Relative telomere length was shorter in HK-2 cells treated with H2O2, oxalate, COM, and urine from those with KS than that in cells treated with urine from those without stones and untreated controls. Transcript expression of shelterin components (TRF1, TRF2 and POT1) was decreased in HK-2 cells treated with H2O2, oxalate, COM, and urine from those with KS, in which case the expression was highest. Urine from those without KS did not significantly alter TRF1, TRF2, and POT1 mRNA expression in HK-2 cells relative to untreated controls. In conclusion, oxalate, COM, and urine from patients with CaOx KS induced SIPS and telomere shortening in renal tubular cells. SIPS induced by a lithogenic milieu may result from upregulation of p16 and downregulation of shelterin components, specifically POT1, and might contribute, at least in part, to the development of CaOx KS.

Project description:Renal calcium oxalate (CaOx) stone is a common urologic disease with a high prevalence and recurrence rate. However, short-chain fatty acids (SCFAs) are less often reported in the prevention of urolithiasis. This study aimed to explore the effect of SCFAs on the renal CaOx stone formation and the underlying mechanisms. Ethylene glycol was used to induce renal CaOx crystals in rats. SCFAs (acetate, propionate, or butyrate) were added as supplements to the drinking water with or without antibiotics. Because intestinal oxalate transporters SLC26A6 and SLC26A3 regulate the excretion and absorption of oxalate in the intestine, we injected adeno-associated virus 9 (AAV9)-SLC26A6-shRNA (short hairpin RNA) and AAV9-SLC26A3 into the tail vein of rats to suppress SLC26A6 and overexpress SLC26A3 expression in the intestine, respectively, to explore the role of SLC26A3 and SLC26A6 (SLC26A3/6) in the reduction of renal CaOx crystals induced by SCFAs. Results showed that SCFAs reduced renal CaOx crystals and urinary oxalate levels but, however, increased the abundance of SCFA-producing bacteria and cecum SCFA levels. SCFA supplements still reduced renal crystals and urinary oxalate after gut microbiota depletion. Propionate and butyrate downregulated intestinal oxalate transporter SLC26A3 expression, while acetate and propionate upregulated SLC26A6 expression, both in vivo and in vitro. AAV9-SLC26A3 exerted a protective effect against renal crystals, while AAV9-SLC26A6-shRNA contributed to the renal crystal formation even though the SCFAs were supplemented. In conclusion, SCFAs could reduce urinary oxalate and renal CaOx stones through the oxalate transporter SLC26A6 in the intestine. SCFAs may be new supplements for preventing the formation of renal CaOx stones. IMPORTANCE Some studies found that the relative abundances of short-chain-fatty-acid (SCFA)-producing bacteria were lower in the gut microbiota of renal stone patients than healthy controls. Our previous study demonstrated that SCFAs could reduce the formation of renal calcium oxalate (CaOx) stones, but the mechanism is still unknown. In this study, we found that SCFAs (acetate, propionate, and butyrate) reduced the formation of renal calcium oxalate (CaOx) crystals and the level of urinary oxalate. Depleting gut microbiota increased the amount of renal crystals in model rats, and SCFA supplements reduced renal crystals and urinary oxalate after gut microbiota depletion. Intestinal oxalate transporter SLC26A6 was a direct target of SCFAs. Our findings suggested that SCFAs could reduce urinary oxalate and renal CaOx stones through the oxalate transporter SLC26A6 in the intestine. SCFAs may be new supplements for preventing the formation of renal CaOx stones.

Project description:BackgroundThe aim of this study was to use bioinformatics approaches to screen and identify the key genes of idiopathic calcium oxalate nephrolithiasis, and explore its potential molecular mechanism.MethodsThe GSE73680 kidney stone data set was downloaded from the Gene Expression Omnibus (GEO). R software (The R Foundation for Statistical Computing) was used to screen differentially expressed genes. GeneMANIA and Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) databases were used to analyze related genes interacting with crucial genes, and a protein-protein interaction (PPI) network was constructed. The differential genes were then subjected to the Gene Ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) signaling pathway enrichment analysis using the Database for Annotation, Visualization, and Integrated Discovery (DAVID) database. The clinical data of 156 patients who received percutaneous nephrolithotomy (PCNL) therapy at our facility between January 2013 and December 2017 were retrospectively analyzed. The various parameters associated with postoperative urogenous sepsis were identified using multivariable logistic regression analysis.ResultsThe study discovered one differentially expressed gene was nucleotide-binding oligomerization domain-containing protein 2 (NOD2). GO and KEGG analysis showed that NOD2 might affect the occurrence of idiopathic calcium oxalate kidney stones by affecting inflammation, receptor expression, immune environment, necrosis, apoptosis, and other pathways. The clinical parameter of patients who participated in the study, including preoperative urinary white blood cell (WBC) count, preoperative urinary nitrite, stone diameter, operation time, WBC count, and WBC D values, were statistically different between the systemic inflammatory response syndrome (SIRS) group and the urosepsis group. According to multivariate logistic regression analysis, the preoperative urine nitrite, calculus diameter, blood WBC, and NOD2 expression 3 hours after surgery were all independently associated with the urosepsis development.ConclusionsPreoperative urinary nitrite positive status, postoperative WBC count ≥2.98×109/L 3 hours after operation, stone diameter >6 cm, and low expression of NOD2 in renal papillary tissue are more likely to cause the urinary source of idiopathic calcium oxalate nephrolithiasis after PCNL urogenous sepsis. These parameters also offer a viable treatment paradigm for the perioperative management of PCNL in treating idiopathic calcium oxalate kidney stones.

Dataset Information

Phenotypic and functional analysis of human SLC26A6 variants in patients with familial hyperoxaluria and calcium oxalate nephrolithiasis.

Background

Study design

Setting & participants

Predictor

Outcomes & measures

Results

Limitations

Conclusions

Publications

Phenotypic and functional analysis of human SLC26A6 variants in patients with familial hyperoxaluria and calcium oxalate nephrolithiasis.

Similar Datasets

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