Search Results (33)

In this work, the utilization of calcium and strontium by the (Ca²⁺ + Mg²⁺)ATPase of the basolateral plasma membrane of renal proximal convoluted tubules were compared. [⁹⁰Sr]Sr²⁺ and [⁴⁵Ca]Ca²⁺ uptake by vesicles derived from this membrane were strictly dependent on ATP and Mg²⁺, and no other nucleotide was able to support the transport. Each cation inhibited the uptake of the other one in a purely competitive fashion (the same Vmax; increased K_0.5), without causing a significant change in the influx rate. These results indicate that both cations bind at the same transport site on the enzyme, facing the cytosolic surface of the cell. The K_0.5 for Sr²⁺ obtained for (Sr²⁺ + Mg²⁺)ATPase activity was 13.1 ± 0.2 µM and for Sr²⁺ uptake was 13.4 ± 0.1 µM. They were higher than K_0.5 for Ca²⁺ obtained for (Ca²⁺ + Mg²⁺)ATPase activity (0.42 ± 0.03 µM) and for Ca²⁺ uptake (0.28 ± 0.02 µM). It is postulated that the lower ATPase affinity for Sr²⁺ is associated with greater steric difficulties for the occupation by this cation of the binding and transport sites, as a consequence of its greater crystal ionic radius (1.13 Å for Sr²⁺ against 0.99 Å for Ca²⁺). Full article

The kidney plays an essential role in the proper homeostasis of glucose. In the kidney, glucose transport is carried out across cell membranes by two families of glucose transporters—facilitated diffusion glucose transporters (GLUTs) and Na(+)-dependent glucose co-transporters (SGLT family). Among the transporters, sodium-dependent glucose co-transporters play a major role in the kidney‘s ability to reabsorb glucose. Although the localization of glucose transporters has been extensively studied in mammals, there are still knowledge gaps regarding the localization of SGLTs in birds. The aim of this research was to conduct a comparative study of the immunolocalization of the sodium-dependent glucose co-transporters SGLT1 and SGLT2 in the kidneys of healthy and T-2-mycotoxicated chickens. Immunohistochemical staining was carried out using the polyclonal primary antibodies SGLT1 and SGLT2 (Abcam, UK) in kidney tissue derived from seven healthy and seven T-2-mycotoxicated 7-day-old female layer-type Ross chickens (Gallus gallus domesticus). The sections were stained using an immunohistochemistry kit (Abcam, UK). In the kidneys of the healthy birds, strong staining of SGLT1 and SGLT2 was observed in the cytoplasm of the epithelial cells of the proximal straight and convoluted tubules. In the kidneys of the birds of the T-2 toxin group, weak expression of SGLT1 and SGLT2 with morphological changes occurred, indicating reduced glucose transport in the urinary system during T-2 mycotoxicosis. Full article

Background: Etoricoxib is a widely used anti-inflammatory drug, but its safety profile concerning cardiovascular and renal health remains inadequately explored. This study aimed to assess the nephro- and cardiotoxic effects of etoricoxib in a murine model, with a focus on its impact on arachidonic acid-metabolizing enzymes and beta-adrenergic receptors associated with drug-induced toxicity. Methods: Thirty-five BALB/C mice were randomly assigned to five groups: control, low-dose etoricoxib, high-dose etoricoxib, low-dose celecoxib, and high-dose celecoxib (a well-known nephro- and cardiotoxic NSAID). The treatments were administered for 28 days, after which hearts and kidneys were excised for physical and histopathological analysis, and the expression of arachidonic acid-metabolizing enzymes (cytochrome P450s, lipoxygenases, cyclooxygenases) and beta-1 adrenergic receptor (adrb1) and angiotensin-converting enzyme (ace2) genes were quantified using quantitative reverse transcription PCR (qRT-PCR). Results: Etoricoxib administration resulted in dose-dependent nephro- and cardiotoxic effects. Renal histology revealed glomerular atrophy or hypertrophy and significant damage to the proximal and distal convoluted tubules, including epithelial flattening, cytoplasmic vacuolation, and luminal widening. Cardiac analysis showed disorganized muscle fibers and hyaline degeneration. These changes were associated with altered gene expression: the downregulation of cox2, cyp1a1, and cyp2c29 in the kidneys and the upregulation of cyp4a12, cox2, and adrb1, along with the downregulation of cyp2c29 and ace2 in the heart. Conclusions: Etoricoxib induces nephro- and cardiotoxicity, marked by alterations in arachidonic acid metabolism and beta-adrenergic signaling pathways. The drug affects the expression of arachidonic acid-metabolizing enzymes and adrb1 in the heart while downregulating cox2 and other related enzymes in the kidneys. These findings underscore the need for caution when prescribing etoricoxib, particularly in patients with pre-existing renal or cardiac conditions. Full article

The original UT-1 transporter gene was initially identified in the spiny dogfish (Squalus acanthias), but localization of the UT-1 protein was not determined. Subsequent UT-1 expression was shown to localize to the collecting tubule (CT) of the shark nephron in other shark species, with expression in a closely related chimaera species also located additionally at a lower level in the intermediate-I segment (IS-I) of the nephron. In spiny dogfish, two UT-1 splice variants are known (UT-1 long and short), and there was also a second UT-1 gene described (here termed Brain UT). In this study, a second splice variant of the second Brain UT gene was discovered. Expression profiles (mRNA) of UT-1 long and short and Brain UT were determined in a number of spiny dogfish tissues. Quantitative PCR in kidney samples showed that the level of the short variant of UT-1 was around 100 times higher than the long variant, which was itself expressed around 10 times higher than Brain UT cDNA/mRNA (in kidney). For the long variant, there was a significantly higher level of mRNA abundance in fish acclimatized to 75% seawater. Ultimately, three UT-1 antibodies were made that could bind to both the UT-1 short and long variant proteins. The first two of these showed bands of appropriate sizes on Western blots of around 52.5 and 46 kDa. The second antibody had some additional lower molecular weight bands. The third antibody was mainly bound to the 46 kDa band with faint 52.5 kDa staining. Both the 52.5 and 46 kDa bands were absent when the antibodies were pre-blocked with the peptide antigens used to make them. Across the three antibodies, there were many similarities in localization but differences in subcellular localization. Predominantly, antibody staining was greatest in the intermediate segment 1 (IS-I) and proximal (PIb) segments of the first sinus zone loop of the nephron, with reasonably strong expression also found at the start and middle of the late distal tubule (LDT; second sinus zone loop). While some expression in the collecting tubule (CT) could not be ruled out, the level of staining seemed to be low or non-existent in convoluted bundle zone nephron segments such as the CT. Hence, this suggests that spiny dogfish have a fundamentally different mode of urea absorption in comparison to that found in other shark species, potentially focused more on the nephron sinus zone loops than the CT. Full article

Autophagy is the primary intracellular degradation system, and it plays an important role in many biological and pathological processes. Studies of autophagy involvement in developmental processes are important for understanding various processes. Among them are fibrosis, degenerative diseases, cancer development, and metastasis formation. Diabetic kidney disease is one of the main causes of chronic kidney disease and end-stage renal failure. The aim of this study was to investigate the immunohistochemical expression patterns of LC3B, LAMP2A, and GRP78 during different developmental stages of early-developing human kidneys and in samples from patients with type II diabetes mellitus. During the 7/8th DW, moderate expression of LC3B and LAMP2A and strong expression of GRP78 were found in the mesonephric glomeruli and tubules. In the 9/10th DW, the expression of LC3B and LAMP2A was even more pronounced in the mesonephric tubules. LC3B, LAMP2A, and GRP78 immunoreactivity was also found in the paramesonephric and mesonephric ducts and was stronger in the 9/10th DW compared with the 7/8th DW. In addition, the expression of LC3B, LAMP2A, and GRP78 also appeared in the mesenchyme surrounding the paramesonephric duct in the 9/10th DW. In the 15/16th DW, the expression of LC3B in the glomeruli was weak, that of LAMP2A was moderate, and that of GRP78 was strong. In the tubuli, the expression of LC3B was moderate, while the expression of LAMP2A and GRP78 was strong. The strongest expression of LC3B, LAMP2A, and GRP78 was observed in the renal medullary structures, including developing blood vessels. In postnatal human kidneys, the most extensive LC3B, LAMP2A, and GRP78 expression in the cortex was found in the epithelium of the proximal convoluted tubules, with weak to moderate expression in the glomeruli. The medullary expression of LC3B was weak, but the expression of LAMP2A and GRP78 was the strongest in the medullary tubular structures. Significantly lower expression of LC3B was found in the glomeruli of the diabetic patients in comparison with the nondiabetic patients, but there was no difference in the expression of LC3B in the tubule–interstitial compartment. The expression of LAMP2A was significantly higher in the tubule–interstitial compartments of the diabetic patients in comparison with the nondiabetic patients, while its expression did not differ in the glomeruli. Extensive expression of GRP78 was found in the glomeruli and the tubule–interstitial compartments, but there was no difference in the expression between the two groups of patients. These data give us new information about the expression of LC3B, LAMP2A, and GRP78 during embryonic, fetal, and early postnatal development. The spatiotemporal expression of LC3B, LAMP2A, and GRP78 indicates the important role of autophagy during the early stages of renal development. In addition, our data suggest a disturbance in autophagy processes in the glomeruli and tubuli of diabetic kidneys as an important factor in the pathogenesis of diabetic kidney disease. Full article

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in reproductive-age women impacting their reproductive, mental, and metabolic health. Insulin resistance is a major driver of the pathophysiology of PCOS. There are several challenges with the management of this complex disorder including insufficient treatment options. Over the past 88 years, multiple hormonal and non-hormonal medications have been tried to treat the various components of this syndrome and there is no FDA (Food and Drug Administration)-approved medication specifically for PCOS yet. Sodium-glucose cotransporter-2 (SGLT-2) inhibitors have a unique mechanism of inhibiting the coupled reabsorption of sodium and glucose in renal proximal convoluted tubules. This review aims to examine the efficacy and side-effect profile of SGLT-2 inhibitors in patients with PCOS. In a limited number of studies, SGLT-2 inhibitors appear to be effective in improving menstrual frequency, reducing body weight and total fat mass, lowering total testosterone and DHEAS levels, and improving some glycemic indices in women with PCOS. SGLT2 inhibitors are generally well tolerated. With future research, it is possible that SGLT-2 inhibitors could become a key therapeutic option for PCOS. Full article

Calcium (Ca²⁺) and magnesium (Mg²⁺) are essential for cellular function. The kidneys play an important role in maintaining the homeostasis of these cations. Their reabsorption along the nephron is dependent on distinct trans- and paracellular pathways and is coupled to the transport of other electrolytes. Notably, sodium (Na⁺) transport establishes an electrochemical gradient to drive Ca²⁺ and Mg²⁺ reabsorption. Consequently, alterations in renal Na⁺ handling, under pathophysiological conditions or pharmacological manipulations, can have major effects on Ca²⁺ and Mg²⁺ transport. One such condition is the administration of diuretics, which are used to treat a large range of clinical conditions, but most commonly for the management of blood pressure and fluid balance. While the pharmacological targets of diuretics typically directly mediate Na⁺ transport, they also indirectly affect renal Ca²⁺ and Mg²⁺ handling through alterations in the electrochemical gradient. To investigate renal Ca²⁺ and Mg² handling and how those processes are affected by diuretic treatment, we have developed computational models of electrolyte transport along the nephrons. Model simulations indicate that along the proximal tubule and thick ascending limb, the transport of Ca²⁺ and Mg²⁺ occurs in parallel with Na⁺, but those processes are dissociated along the distal convoluted tubule. We also simulated the effects of acute administration of loop, thiazide, and K-sparing diuretics. The model predicted significantly increased Ca²⁺ and Mg²⁺ excretions and significantly decreased Ca²⁺ and Mg²⁺ excretions on treatment with loop and K-sparing diuretics, respectively. Treatment with thiazide diuretics significantly decreased Ca²⁺ excretion, but there was no significant alteration in Mg²⁺ excretion. The present models can be used to conduct in silico studies on how the kidney adapts to alterations in Ca²⁺ and Mg²⁺ homeostasis during various physiological and pathophysiological conditions, such as pregnancy, diabetes, and chronic kidney disease. Full article

This study aims to determine the protein expression patterns of acetylated α-tubulin, inversin, dishevelled-1, Wnt5a/b, and β-catenin in developing (E13.5 and E15.5) and early postnatal (P4 and P14) kidneys of Dab1^−/− (yotari) mice, their role in regulating the Wnt signaling pathway, and the possible relation to congenital anomalies of kidney and urinary tract (CAKUT). The analysis of target protein co-expression, observed in the renal vesicles/immature glomeruli, ampullae/collecting ducts, convoluted tubules, metanephric mesenchyme of developing kidneys, but proximal convoluted tubules, distal convoluted tubules and glomeruli of postnatal kidneys, was performed using double immunofluorescence and semi-quantitative methods. The overall expression of acetylated α-tubulin and inversin during normal kidney development increases with higher expression in yotari mice as the kidney acquires mature morphology. An increase in β-catenin and cytosolic DVL-1 levels, indicating a switch from non-canonical to canonical Wnt signaling, is found in the postnatal kidney of yotari mice. In contrast, healthy mouse kidney expresses inversin and Wnt5a/b in the postnatal period, thus activating non-canonical Wnt signaling. Target protein expression patterns in kidney development and the early postnatal period observed in this study could indicate that switching between canonical and non-canonical Wnt signaling is crucial for normal nephrogenesis, while the defective Dab1 gene product in yotari mice may promote CAKUT due to interfering with this process. Full article

The purpose of this study was to compare the immunofluorescence patterns of autophagic markers: Light chain 3 beta (LC3B), Glucose regulating protein 78 (GRP78), Heat shock cognate 71 (HSC70) and Lysosomal-associated membrane protein 2A (LAMP2A) in the developing and postnatal kidneys of Dab1^−/− (yotari) mice to those of wild-type samples. Embryos were obtained on gestation days 13.5 and 15.5 (E13.5 and E15.5), and adult animals were sacrificed at postnatal days 4, 11 and 14 (P4, P11, and P14). After fixation and dehydration, paraffin-embedded kidney tissues were sectioned and incubated with specific antibodies. Using an immunofluorescence microscope, sections were analyzed. For statistical analysis, a two-way ANOVA test and a Tukey’s multiple comparison test were performed with a probability level of p < 0.05. A significant increase in GRP78 and LAMP2A expression was observed in the renal vesicles and convoluted tubules of yotari in embryonic stages. In postnatal kidneys, all observed proteins showed higher signal intensities in proximal and distal convoluted tubules of yotari, while a higher percentage of LC3B-positive cells was also observed in glomeruli. Our findings suggest that all of the examined autophagic markers play an important role in normal kidney development, as well as the potential importance of these proteins in renal pathology, where they primarily serve a protective function and thus may be used as diagnostic and therapeutic targets. Full article

The use of silver nanoparticles (AgNPs) is expanding. This study evaluates the modulator effect of eugenol (Eug) on AgNP-induced nephrotoxicity in rats. Sixty male rats were separated into six groups: control, Eug, AgNPs low-dose, AgNPs high-dose, Eug + AgNPs low-dose, and Eug + AgNPs high-dose. After 30 days, kidney function, antioxidative and proinflammatory status, histopathological, histomorphometrical, and immunohistochemical assessments were performed. AgNPs markedly induced oxidative stress in renal tissues, characterized by increased levels of blood urea nitrogen, creatinine, uric acid, kidney injury molecule-1, the total oxidant capacity, malondialdehyde, tumor necrosis factor-alpha (TNF-α), and interleukin-6, as well as decreased levels of the total antioxidant capacity, superoxide dismutase, catalase, reduced glutathione, and glutathione peroxidase. Moreover, the normal renal architecture was destroyed, and the thickness of the renal capsules, cortex, and medulla, alongside the diameter and quantity of the normal Malpighian corpuscles and the proximal and distal convoluted tubules were decreased. Immunoreactivity for P53, caspase-3, and TNF-α reactive proteins were significantly increased; however, Bcl-2 immunoreactivity was decreased. Eug reversed most biochemical, histological, histomorphometrical, and immunohistochemical changes in AgNP-treated animals. This study demonstrated that nephrotoxicity in AgNP-treated rats was mitigated by an Eug supplementation. Eug’s antioxidant, antiapoptotic, and anti-inflammatory capabilities were the key in modulating AgNPs nephrotoxicity. Full article

Renal clear cell carcinoma (ccRCC) comprises over 75% of all renal tumors and arises in the epithelial cells of the proximal convoluted tubule. Molecularly ccRCC is characterized by copy number alterations (CNAs) such as the loss of chromosome 3p and VHL inactivation. Additional driver mutations (SETD2, PBRM1, BAP1, and others) promote genomic instability and tumor cell metastasis through the dysregulation of various metabolic and immune-response pathways. Many researchers identified mutation, gene expression, and proteomic signatures for early diagnosis and prognostics for ccRCC. Despite a tremendous influx of data regarding DNA alterations, gene expression, and protein expression, the incorporation of these analyses for diagnosis and prognosis of RCC into the clinical application has not been implemented yet. In this review, we focused on the molecular changes associated with ccRCC development, along with gene expression and protein signatures, to emphasize the utilization of these molecular profiles in clinical practice. These findings, in the context of machine learning and precision medicine, may help to overcome some of the barriers encountered for implementing molecular profiles of tumors into the diagnosis and treatment of ccRCC. Full article

The neurohypophysial hormone arginine vasotocin (avt) and its receptor (avtr) regulates ions in the osmoregulatory organs of euryhaline black porgy (Acanthopagrus schlegelii). The localization of avt and avtr transcripts in the osmoregulatory organs has yet to be demonstrated. Thus, in the present study, we performed an in situ hybridization analysis to determine the localization of avt and avtr in the gills, kidneys, and intestines of the black porgy. The avt and avtr transcripts were identified in the filament and lamellae region of the gills in the black porgy. However, the basal membrane of the filament contained more avt and avtr transcripts. Fluorescence double tagging analysis revealed that avt and avtr mRNAs were partially co-localized with α-Nka-ir cells in the gill filament. The proximal tubules, distal tubules, and collecting duct of the kidney all had positive hybridization signals for the avt and avtr transcripts. Unlike the α-Nka immunoreactive cells, the avt and avtr transcripts were found on the basolateral surface of the distal convoluted tubule and in the entire cells of the proximal convoluted tubules of the black porgy kidney. In the intestine, the avt and avtr transcripts were found in the basolateral membrane of the enterocytes. Collectively, this study provides a summary of evidence suggesting that the neuropeptides avt and avtr with α-Nka-ir cells may have functions in the gills, kidneys, and intestines via ionocytes. Full article

Background: The aim of this study was to determine the expression of epithelial to mesenchymal transition (EMT)-related transcription factors Snail, Wnt4, and Notch2 with key roles in renal fibrosis, in different renal areas of diabetic rats: glomeruli (G), proximal and distal convoluted tubules (PCT; DCT). Methods: Male Sprague Dawley rats were instilled with 55 mg/kg streptozotocin (diabetes mellitus type I model, DM group) or citrate buffer (control group). Kidney samples were collected 2 weeks and 2 months after DM induction and processed for immunohistochemistry. Results: Diabetic animals showed higher Wnt4 kidney expression both 2 weeks and 2 months post-DM induction, while Snail expression significantly increased only 2 weeks after DM initiation (p < 0.0001). We determined significantly higher expression of examined EMT-related genes in different kidney regions in diabetic animals compared with controls. The most substantial differences were observed in tubular epithelial cells in the period of 2 weeks after induction, with higher Snail and Wnt4 expression in PCT and increased Snail and Notch2 expression in DCT of diabetic animals (p < 0.0001; p < 0.001). Conclusion: The obtained results point to the EMT-related factors Snail, Wnt4, and Notch2 as a potential contributor to diabetic nephropathy development and progression. Changes in their expression, especially in PCT and DCT, could serve as diagnostic biomarkers for the early stages of DM and might be a promising novel therapeutic target in this condition. Full article

Diabetes mellitus (DM) is a chronic metabolic disorder characterized by hyperglycemia, which affects multiple tissues including kidneys. Soursop leaves (Annona muricata) are known to have antidiabetic potential, but their molecular and cellular effects are poorly characterized. We identified the bioactive compounds in soursop leaf ethanol extract (SLEE). The SLEE substances demonstrated the total alkaloid and total flavonoid contents. Twelve bioactive compounds profiles were identified in SLEE classified as alkaloid, flavonol glycoside, and monoterpenoid lactone derivatives. The SLEE treatments in mice were performed by dividing Swiss Webster mice into five groups, including negative and positive controls and three experimental groups provided with SLEE (doses 150, 300, and 600 mg/kg BW) for 14 days. The mice in the experimental groups were treated with alloxan to induce diabetes. The renal samples were stained for H&E for morphological changes. However, 600 mg/kg of SLEE showed a significant effect (p < 0.05) on the height of the Bowman’s space and prevented the tubularization of the left kidney’s glomerulus (p < 0.05). Altogether, we report no significant difference in the glomerular diameter, the thickness of the proximal convoluted tubules, the height of the Bowman’s space, and the glomerular tubularization after 14 days of treatment with SLEE. Full article

Sodium is reabsorbed all along the renal tubules. The positive impacts of sodium-glucose cotransporter-2 inhibitors (SGLT2i), angiotensin receptor neprilysin inhibitor (ARNI) and mineralocorticoid receptor antagonists (MRA) on hard renal and/or cardiac endpoints calls for the role of diuretics in nephroprotection and cardioprotection in patients with diabetes mellitus to be reviewed. Here, we review: (a) the mechanisms of action of the available natriuretics; (b) the physiological adaptations to chronic loop diuretic usage that lead to increased sodium reabsorption in the proximal and distal convoluted tubules; (c) the physiology of sodium retention in patients with diabetes mellitus; and (d) the mechanisms of aldosterone breakthrough. We show the rationale for combined diuretics to target not only the loop of Henle, but also the proximal and distal convoluted tubules. Indeed, higher residual proteinuria in patients treated with renin-angiotensin-aldosterone system (RAAS) blockers portends poorer renal and cardiovascular outcomes. Diuretics are known to optimize the reduction of proteinuria, in addition to RAAS blockers, but may favor aldosterone breakthrough in the absence of MRA. The aim of our study is to support a combined diuretics strategy to improve the management of patients with diabetes mellitus and chronic kidney disease or heart failure. Full article