Renal proximal tubule

BACKGROUND: A fructose high-salt (FHS) diet increases systolic blood pressure and Ang II (angiotensin II)-stimulated proximal tubule (PT) superoxide (O2 - ) production. These increases are prevented by scavenging O2 - or an Ang II type 1 receptor antagonist. SGLT4 (sodium glucose-linked cotransporters 4) and SGLT5 are implicated in PT fructose reabsorption, but their roles in fructose-induced hypertension are unclear. We hypothesized that PT fructose reabsorption by SGLT5 initiates a genetic program enhancing Ang II-stimulated oxidative stress in males and females, thereby causing fructose-induced salt-sensitive hypertension...

Cystinosis is an autosomal recessive lysosomal storage disorder, caused by mutations in the CTNS gene , resulting in an absent or altered cystinosin (CTNS) protein. Cystinosin exports cystine out of the lysosome, with a malfunction resulting in cystine accumulation and a defect in other cystinosin-mediated pathways. Cystinosis is a systemic disease, but the kidneys are the first and most severely affected organs. In the kidney, the disease initially manifests as a generalized dysfunction in the proximal tubules (also called renal Fanconi syndrome)...

BACKGROUND: Physiological PSMA expression in the cells of the proximal renal tubules and consecutive radiopharmaceutical binding and retention could potentially lead to radioligand-therapy-induced nephrotoxicity. Thus, patients with metastatic castration-resistant prostate cancer undergo 99m Tc-Mercaptoacetyltriglycine (MAG3) renal scintigraphy to assess kidney function and to exclude renal obstruction as part of their workup for PSMA-targeted radioligand therapy (RLT). 99m Tc-MAG-3 renal scintigraphy often requires an additional visit to the nuclear medicine department and patients spend 30-90 min in the department, which is inconvenient and takes up camera time...

Single-cell technologies such as flow cytometry and single-cell RNA sequencing (scRNAseq) have allowed for comprehensive characterisation of the kidney cellulome. However, there is disparity in the various protocols for preparing kidney single-cell suspensions. We aimed to address this limitation by characterising kidney cellular heterogeneity using three previously published single-cell preparation protocols. Single-cell suspensions were prepared from male and female C57BL/6 kidneys using the following kidney tissue dissociation protocols: (P1) a scRNAseq protocol; (P2) a multi-tissue digestion kit from Miltenyi Biotec ; and (P3) a protocol established in our laboratory...

Fanconi syndrome is a multi-factorial disorder that involves diffuse malfunction of the proximal convoluted tubule in the kidney. Renal wasting of potassium, glucose, bicarbonate, amino acids, and phosphorus characterize the condition. We report a case of a 57-year-old female who presented to our emergency department with cardiopulmonary arrest. After successful resuscitation, she had extensive workup to uncover the cause of her cardiac arrest. She had extensive negative workup but was found to have severely low potassium, prompting further evaluation...

BACKGROUND: Perfluorooctanoic acid (PFOA) is one of the major per- and polyfluoroalkyl substances. The role of ATP-binding cassette (ABC) transporters in PFOA toxicokinetics is unknown. METHODS: In this study, two ABC transporters, ABCB1 and ABCB4, were examined in mice with single intravenous PFOA administration (3.13 µmol/kg). To identify candidate renal PFOA transporters, we used a microarray approach to evaluate changes in gene expression of various kidney transporters in Abcb4 null mice...

Epigenetic regulations, including DNA methylation, are critical to the development and progression of kidney fibrosis, but the underlying mechanisms remain elusive. Here, we show that fibrosis of the mouse kidney was associated with the induction of DNA methyltransferases and increases in global DNA methylation and was alleviated by the DNA methyltransferase inhibitor 5-Aza-2'-deoxycytidine (5-Aza). Genome wide analysis demonstrated the hypermethylation of 94 genes in mouse unilateral ureteral obstruction kidneys, which was markedly reduced by 5-Aza...

OBJECTIVE: Hypertension is one of the cardiovascular diseases that causes the most mortality, and 95% of the causes are unknown. The aim of the study was to examine the possible correlation of nesfatin-1 levels, adropin levels, claudin-2 immunoreactivity (claudin-2 expression in the renal proximal tubule), and renalase immunoreactivity (renalase expression in the renal proximal tubule) with arterial blood pressure, kidney function, and kidney damage. METHODS: Adult male Sprague Dawley rats were divided into control and hypertension groups (8 per group)...

Renal cell carcinoma originates from the lining of the proximal convoluted renal tubule and represents the most common type of kidney cancer. Risk factors and comorbidities might be associated to renal cell carcinoma, while a small fraction of 2-3% emerges from patients with predisposing cancer syndromes, typically associated to hereditary mutations in VHL, folliculin, fumarate hydratase or MET genes. Here, we report a case of renal cell carcinoma in patient with concurrent germline mutations in BRCA1 and RAD51 genes...

The kidneys are crucial for maintaining Mg2+ homeostasis. Along the proximal tubule and thick ascending limb, Mg2+ is reabsorbed paracellularly, while along the distal convoluted tubule (DCT), Mg2+ is reabsorbed transcellularly via transient receptor potential melastatin 6 (TRPM6). TRPM6 and other renal transporter expressions are regulated by sex hormones. To investigate renal Mg2 handling, we have developed sex-specific computational models of electrolyte transport along rat superficial nephron. Model simulations indicated that along the proximal tubule and thick ascending limb, Mg2+ and Na+ transport occur parallelly, but they are dissociated along the DCT...

OBJECTIVES: Accumulative effects of heavy metals and polycyclic aromatic hydrocarbon could result in various toxicities. This study evaluated the effects of long-term exposure to low doses of nickel and benzo [a] anthracene on the kidney of rats, simulating human exposure through food. METHODS: Thirty-six (36) Male rats weighing between 80-100 g were assigned into six groups of 6 animals each; Group A (normal), Group B1 and B2 (fed nickel contaminated feed for 12 and 24 weeks), Group C1 and C2 (fed benzo [a] anthracene contaminated feed for 12 and 24 weeks)...

Candesartan is a common angiotensin-II receptor-1 blocker used for patients with cardiovascular and renal diseases. Angiotensin-converting enzyme 2 (ACE2) is a negative regulator of blood pressure (BP), and also a major receptor for coronaviruses. To determine whether and how candesartan upregulates ACE2, we examined BP and ACE2 in multi-organs from male and female C57BL/6J mice treated with candesartan (1 mg/kg, i.p.) for 7 days. Relative to the vehicle, candesartan lowered BP more in males than females; ACE2 protein abundances were increased in kidneys, not lungs, hearts, aorta, liver, spleen, brain, or serum, only from males...

Nicotinamide adenine dinucleotide (NAD+ ) is a pivotal coenzyme, essential for cellular reactions, metabolism, and mitochondrial function. Depletion of kidney NAD+ levels and reduced de novo NAD+ synthesis through the tryptophan-kynurenine pathway are linked to acute kidney injury (AKI), while augmenting NAD+ shows promise in reducing AKI. We investigated de novo NAD+ biosynthesis using in vitro, ex vivo and in vivo models to understand its role in AKI. 2D cultures of human primary renal proximal tubule epithelial cells (RPTECs) and HK-2 cells showed limited de novo NAD+ synthesis, likely due to low pathway enzyme gene expression...

The proximal convoluted tubule (PCT) of the kidney is a crucial functional segment responsible for reabsorption, secretion, and the maintenance of electrolyte and water balance within the renal tubule. However, there is a lack of a well-defined endogenous transgenic line for studying PCT morphogenesis. By analyzing single-cell transcriptome data from the adult zebrafish kidney, we have identified the expression of odd-skipped-related 2 ( osr2 , which encodes an odd-skipped zinc-finger transcription factor) in the PCT...

Lanthanide-doped upconverting nanoparticles (UCNPs) are ideal candidates for use in biomedicine. The interaction of nanomaterials with biological systems determines whether they are suitable for use in living cells. In-depth knowledge of the nano-bio interactions is therefore a pre-requisite for the development of biomedical applications. The current study evaluates fundamental aspects of the NP-cell interface for square bipyramidal UCNPs containing a LiYF4 :Yb3+ , Tm3+ core and two different silica surface coatings...

In the aftermath of acute kidney injury (AKI), surviving proximal tubule epithelia repopulate injured tubules to promote repair. However, a portion of cells fail to repair (termed Failed Repair Proximal Tubule Cells, FR-PTCs) and exert ongoing proinflammatory and profibrotic effects. To better understand the molecular drivers of the FR-PTC state, we reanalyzed a mouse ischemia-reperfusion injury single nucleus RNA-sequencing (snRNA-seq) atlas to identify Traf2 and Nck Interacting Kinase, Tnik, to be exclusively expressed in FR-PTCs, but not in healthy or acutely injured proximal tubules post AKI (2 and 6 weeks) in mice...

Chronic angiotensin II (AngII) infusion is an experimental model that induces hypertension in rodents. The natriuresis, diuresis, and blood pressure responses differ between males and females. This is perhaps not unexpected, given the rodent kidney, which plays a key role in blood pressure regulation, exhibit marked sex differences. Under normotensive conditions, compared to males, the female rat nephron exhibits lower Na+ /H+ exchanger 3 (NHE3) activity along the proximal tubule, but higher Na+ transporter activities along the distal segments...

Direct tubular injury caused by several medications, especially chemotherapeutic drugs, is a common cause of AKI. Inhibition or loss of cyclin-dependent kinase 12 (CDK12) triggers a transcriptional elongation defect that results in deficiencies in DNA damage repair, producing genomic instability in a variety of cancers. Notably, 10-25% of individuals developed AKI after treatment with a CDK12 inhibitor, and the potential mechanism is not well understood. Here, we found that CDK12 was downregulated in the renal tubular epithelial cells in both patients with AKI and murine AKI models...

The reabsorption of uric acid (UA) is mainly mediated by urate transporter 1 (URAT1) and glucose transporter 9 (GLUT9) in the kidneys. Dotinurad inhibits URAT1 but does not inhibit other UA transporters, such as GLUT9, ATP-binding cassette transporter G2 (ABCG2), and organic anion transporter 1/3 (OAT1/3). We found that dotinurad ameliorated the metabolic parameters and renal function in hyperuricemic patients. We consider the significance of the highly selective inhibition of URAT1 by dotinurad for metabolic syndrome, chronic kidney disease (CKD), and cardiovascular disease (CVD)...

Cisplatin (CDDP) stands out as an effective chemotherapeutic agent; however, its application is linked to the development of significant adverse effects, notably nephro- and ototoxicity. The human organic cation transporter 2 (hOCT2), found in abundance in the basolateral membrane domain of renal proximal tubules and the Corti organ, plays a crucial role in the initiation of nephro- and ototoxicity associated with CDDP by facilitating its uptake in kidney and ear cells. Given its limited presence in cancer cells, hOCT2 emerges as a potential druggable target for mitigating unwanted toxicities associated with CDDP...