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Key points: Parkinson's disease (PD) is associated with respiratory dysfunction. In the 6‐OHDA rat model of PD this is seen as a reduction in respiratory frequency and minute ventilation during normoxia and hypercapnia stimulus.Respiratory dysfunction is caused by neuronal death of medullary respiratory nuclei in the 6‐OHDA model of PD.Oxidative stress can be considered a strong candidate for neurodegeneration via miR‐34c downregulation and pro‐apoptotic signalling in respiratory neurons, preceding the functional impairment observed in the 6‐OHDA model of PD. Parkinson's disease (PD) is a neurodegenerative disease caused by dopaminergic neuron death in the substantia nigra (SN). New evidence has revealed that this neurodegeneration is the result of complex interactions between genetic abnormalities, environmental toxins, mitochondrial dysfunction and disruption of the blood–brain barrier (BBB) in the SN. In addition to classic symptoms, PD patients also exhibit respiratory failure. Here, we investigated whether oxidative stress was associated with neurodegeneration in a respiratory group (RG) of 6‐OHDA‐treated rats, which act as a model of PD. We analysed how oxidative stress affected apoptotic signalling in the RG 30 days after 6‐OHDA treatment, shortly before commencement of breathing impairment (40 days). After 30 days, a dihydroethidium assay showed increased oxidative stress in the RG, anti‐apoptotic signalling, as shown by an increase in p‐Akt and BcL‐2 and a decrease in Bax in the caudal aspect of the nucleus of the solitary tract (cNTS), and a decrease in p‐p38 and Bax levels in the retrotrapezoid nucleus (RTN); pro‐apoptotic signalling was indicated by a decrease in p‐Akt and BcL‐2 and an increase in Bax in the rostral ventral respiratory group (rVRG) and pre‐Botzinger complex (preBotC). miR‐34c, a known oxidative stress protector, was downregulated in 6‐OHDA animals in the RC. After 40 days of 6‐OHDA, the NTS, rVRG, preBotC and RTN exhibited reduced NeuN immunoreactivity, no BBB disruption and an increase in thiobarbituric acid reactivity. We conclude that in the 6‐OHDA model of PD, oxidative stress contributes to neurodegeneration in medullary respiratory neurons. Key points: Parkinson's disease (PD) is associated with respiratory dysfunction. In the 6‐OHDA rat model of PD this is seen as a reduction in respiratory frequency and minute ventilation during normoxia and hypercapnia stimulus.Respiratory dysfunction is caused by neuronal death of medullary respiratory nuclei in the 6‐OHDA model of PD.Oxidative stress can be considered a strong candidate for neurodegeneration via miR‐34c downregulation and pro‐apoptotic signalling in respiratory neurons, preceding the functional impairment observed in the 6‐OHDA model of PD. [ABSTRACT FROM AUTHOR]

Blood glucose-lowering therapies can positively or negatively affect heart function in type 2 diabetes, or they can have neutral effects. Dipeptidyl peptidase 4 (DPP-4) inhibitors lower blood glucose by preventing the proteolytic inactivation of glucagon-like peptide 1 (GLP-1). However, GLP-1 is not the only peptide substrate of DPP-4. Here, we investigated the GLP-1-independent cardiac effects of DPP-4 substrates. Pointing to GLP-1 receptor (GLP-1R)-independent actions, DPP-4 inhibition prevented systolic dysfunction equally in pressure-overloaded wild-type and GLP-1R knockout mice. Likewise, DPP-4 inhibition or the DPP-4 substrates substance P or C-X-C motif chemokine ligand 12 (CXCL12) improved contractile recovery after no-flow ischemia in the hearts of otherwise healthy young adult mice. Either DPP-4 inhibition or CXCL12 increased phosphorylation of the Ca2+ regulatory protein phospholamban (PLN), and CXCL12 directly enhanced cardiomyocyte Ca2+ flux. In contrast, hearts of aged obese diabetic mice (which may better mimic the comorbid patient population) had diminished levels of PLN phosphorylation. In this setting, CXCL12 paradoxically impaired cardiac contractility in a phosphoinositide 3-kinase γ-dependent manner. These findings indicate that the cardiac effects of DPP-4 inhibition primarily occur through GLP-1R-independent processes and that ostensibly beneficial DPP-4 substrates can paradoxically worsen heart function in the presence of comorbid diabetes. [ABSTRACT FROM AUTHOR]

Histone protein modifications control fate determination during normal development and dedifferentiation during disease. Here, we set out to determine the extent to which dynamic changes to histones affect the differentiated phenotype of ordinarily quiescent adult glomerular podocytes. To do this, we examined the consequences of shifting the balance of the repressive histone H3 lysine 27 trimethylation (H3K27me3) mark in podocytes. Adriamycin nephrotoxicity and subtotal nephrectomy (SNx) studies indicated that deletion of the histone methylating enzyme EZH2 from podocytes decreased H3K27me3 levels and sensitized mice to glomerular disease. H3K27me3 was enriched at the promoter region of the Notch ligand Jag1 in podocytes, and derepression of Jag1 by EZH2 inhibition or knockdown facilitated podocyte dedifferentiation. Conversely, inhibition of the Jumonji C domain-containing demethylases Jmjd3 and UTX increased the H3K27me3 content of podocytes and attenuated glomerular disease in adriamycin nephrotoxicity, SNx, and diabetes. Podocytes in glomeruli from humans with focal segmental glomerulosclerosis or diabetic nephropathy exhibited diminished H3K27me3 and heightened UTX content. Analogous to human disease, inhibition of Jmjd3 and UTX abated nephropathy progression in mice with established glomerular injury and reduced H3K27me3 levels. Together, these findings indicate that ostensibly stable chromatin modifications can be dynamically regulated in quiescent cells and that epigenetic reprogramming can improve outcomes in glomerular disease by repressing the reactivation of developmental pathways. [ABSTRACT FROM AUTHOR]

Because of the paucity of information regarding metabolic effects of advanced glycation end products (AGEs) on liver, we evaluated effects of AGEs chronic administration in (1) insulin sensitivity; (2) hepatic expression of genes involved in AGEs, glucose and fat metabolism, oxidative stress and inflammation and; (3) hepatic morphology and glycogen content. Rats received intraperitoneally albumin modified (AlbAGE) or not by advanced glycation for 12 weeks. AlbAGE induced whole-body insulin resistance concomitantly with increased hepatic insulin sensitivity, evidenced by activation of AKT, inactivation of GSK3, increased hepatic glycogen content, and decreased expression of gluconeogenesis genes. Additionally there was reduction in hepatic fat content, in expression of lipogenic, pro-inflamatory and pro-oxidative genes and increase in reactive oxygen species and in nuclear expression of NRF2, a transcription factor essential to cytoprotective response. Although considered toxic, AGEs become protective when administered chronically, stimulating AKT signaling, which is involved in cellular defense and insulin sensitivity. [ABSTRACT FROM AUTHOR]

Aim: To assess the renal effects of chronic exposure to advanced glycation end-products (AGEs) in the absence of diabetes and the potential impact of concomitant treatment with the antioxidant N-acetyl cysteine (NAC). Methods: Wistar rats received intraperitoneally 20 mg/kg/day of albumin modified (AlbAGE) or not (AlbC) by advanced glycation for 12 weeks and oral NAC (600mg/L; AlbAGE+NAC and AlbC+NAC, respectively). Biochemical, urinary and renal morphological analyses; carboxymethyl-lysine (CML, an AGE), CD68 (macrophage infiltration), and 4-hydroxynonenal (4-HNE, marker of oxidative stress) immunostaining; intrarenal mRNA expression of genes belonging to pathways related to AGEs (Ager, Ddost, Nfkb1), renin-angiotensin system (Agt, Ren, Ace), fibrosis (Tgfb1, Col4a1), oxidative stress (Nox4, Txnip), and apoptosis (Bax, Bcl2); and reactive oxidative species (ROS) content were performed. Results: AlbAGE significantly increased urine protein-to-creatinine ratio; glomerular area; renal CML content and macrophage infiltration; expression of Ager, Nfkb1, Agt, Ren, Tgfb1, Col4a1, Txnip, Bax/Bcl2 ratio; and 4-HNE and ROS contents. Some of these effects were attenuated by NAC concomitant treatment. Conclusion: Because AGEs are highly consumed in modern diets and implicated in the progression of different kidney diseases, NAC could be a therapeutic intervention to decrease renal damage, considering that long-term restriction of dietary AGEs is difficult to achieve in practice. [ABSTRACT FROM AUTHOR]

Aim: To assess the renal effects of chronic exposure to advanced glycation end-products (AGEs) in the absence of diabetes and the potential impact of concomitant treatment with the antioxidant N-acetyl cysteine (NAC). Methods: Wistar rats received intraperitoneally 20 mg/ kg/day of albumin modified (AlbAGE) or not (AlbC) by advanced glycation for 12 weeks and oral NAC (600mg/L; AlbAGE+NAC and AlbC+NAC, respectively). Biochemical, urinary and renal morphological analyses; carboxymethyl-lysine (CML, an AGE), CD68 (macrophage infiltration), and 4-hydroxynonenal (4-HNE, marker of oxidative stress) immunostaining; intrarenal mRNA expression of genes belonging to pathways related to AGEs (Ager, Ddost, Nfkb1), reninangiotensin system (Agt, Ren, Ace), fibrosis (Tgfb1, Col4a1), oxidative stress (Nox4, Txnip), and apoptosis (Bax, Bcl2); and reactive oxidative species (ROS) content were performed. Results: AlbAGE significantly increased urine protein-to-creatinine ratio; glomerular area; renal CML content and macrophage infiltration; expression of Ager, Nfkb1, Agt, Ren, Tgfb1, Col4a1, Txnip, Bax/Bcl2 ratio; and 4-HNE and ROS contents. Some of these effects were attenuated by NAC concomitant treatment. Conclusion: Because AGEs are highly consumed in modern diets and implicated in the progression of different kidney diseases, NAC could be a therapeutic intervention to decrease renal damage, considering that long-term restriction of dietary AGEs is difficult to achieve in practice. [ABSTRACT FROM AUTHOR]

Chronic angiotensin II (ANG II) infusion for 1 or 2 wk leads to progressive hypertension and induces inward hypertrophic remodeling in preglomerular vessels, which is associated with increased renal vascular resistance (RVR) and decreased glomerular perfusion. Considering the ability of preglomerular vessels to exhibit adaptive responses, the present study was performed to evaluate glomerular perfusion and renal function after 6 wk of ANG II infusion. To address this study, male Wistar rats were submitted to sham surgery (control) or osmotic minipump insertion (ANG II 200 ng·kg-1·min-1, 42 days). A group of animals was treated or cotreated with losartan (10 mg·kg-1·day-1), an AT1 receptor antagonist, between days 28 and 42. Chronic ANG II infusion increased systolic blood pressure to 185 ± 4 compared with 108 ± 2 mmHg in control rats. Concomitantly, ANG II-induced hypertension increased intrarenal ANG II level and consequently, preglomerular and glomerular injury. Under this condition, ANG II enhanced the total renal plasma flow (RPF), glomerular filtration rate (GFR), urine flow and induced pressure natriuresis. These changes were accompanied by lower RVR and enlargement of the lumen of interlobular arteries and afferent arterioles, consistent with impairment of renal autoregulatory capability and outward preglomerular remodeling. The glomerular injury culminated with podocyte effacement, albuminuria, tubulointerstitial macrophage infiltration and intrarenal extracellular matrix accumulation. Losartan attenuated most of the effects of ANG II. Our findings provide new information regarding the contribution of ANG II infusion over 2 wk to renal hemodynamics and function via the AT1 receptor. [ABSTRACT FROM AUTHOR]

The role of hyperleptinemia in cardiovascular diseases is well known; however, in the renal tissue, the exact site of leptin’s action has not been established. This study was conducted to assess the effect of leptin treatment for 7 and 28 days on renal function and morphology and the participation of angiotensin II (Ang II), through its AT1 receptor. Rats were divided into four groups: sham, losartan (10 mg/kg/day, s.c.), leptin (0.5 mg/kg/day for the 7 days group and 0.25 mg/kg/day for the 28 days group) and leptin plus losartan. Plasma leptin, Ang II and endothelin 1 (ET-1) levels were measured using an enzymatic immuno assay. The systolic blood pressure (SBP) was evaluated using the tail-cuff method. The renal plasma flow (RPF) and the glomerular filtration rate (GFR) were determined by p-aminohippuric acid and inulin clearance, respectively. Urinary Na+ and K+ levels were also analyzed. Renal morphological analyses, desmin and ED-1 immunostaining were performed. Proteinuria was analyzed by silver staining. mRNA expression of renin-angiotensin system (RAS) components, TNF-α and collagen type III was analyzed by quantitative PCR. Our results showed that leptin treatment increased Ang II plasma levels and progressively increased the SBP, achieving a pre-hypertension state. Rats treated with leptin 7 days showed a normal RPF and GFR, but increased filtration fraction (FF) and natriuresis. However, rats treated with leptin for 28 showed a decrease in the RPF, an increase in the FF and no changes in the GFR or tubular function. Leptin treatment-induced renal injury was demonstrated by: glomerular hypertrophy, increased desmin staining, macrophage infiltration in the renal tissue, TNF-α and collagen type III mRNA expression and proteinuria. In conclusion, our study demonstrated the progressive renal morphological changes in experimental hyperleptinemia and the interaction between leptin and the RAS on these effects. [ABSTRACT FROM AUTHOR]

We examined the effect of Angiotensin II (Ang II) on the interaction between the Ca2+/CaM complex and hNHE1. Considering that calmodulin binds to NHE1 at two sites (A and B), amino acids at both sites were modified and two mutants were constructed: SA1K3R/4E and SB1K3R/4E. Wild type and mutants were transfected into PS120 cells and their activity was examined by H+ flux (JH+). The basal JH+ of wild type was 4.71 ± 0.57 (mM/min), and it was similar in both mutants. However, the mutations partially impaired the binding of CaM to hNHE1. Ang II (10-12 and 10-9 M) increased the JH+ in wild type and SB. Ang II (10-6 M) increased this parameter only in SA. Ang II (10-9 M) maintained the expression of calmodulin in wild type or mutants, and Ang II (10-6 M) decreased it in wild type or SA, but not in SB. Dimethyl-Bapta-AM (10-7 M), a calcium chelator, suppressed the effect of Ang II (10-9 M) in wild type. With Ang II (10-6 M), Bapta failed to affect wild type or SA, but it increased the JH+ in SB. W13 or calmidazolium chloride (10-5 M), two distinct calmodulin inhibitors, decreased the effect of Ang II (10-9 M) in wild type or SB. With Ang II (10-6 M), W13 or calmidazolium chloride decreased the JH+ in wild type or SA and increased it in SB. Thus, with Ang II (10-12 and 10-9 M), site A seems to be responsible for the stimulation of hNHE1 and with Ang II (10-6 M), site B is important to maintain its basal activity. Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

The effect of ANG II on intracellular pH (pHi) recovery rate and AT1 receptor translocation was investigated in transfected MDCK cells. The pHi recovery rate was evaluated by fluorescence microscopy using the fluorescent probe BCECF-AM. The human angiotensin II receptor isoform 1 (hAT1) translocation was analyzed by immunofluorescence and confocal microscope. Our data show that transfected cells in control situation have a pHi recovery rate of 0.219 ± 0.017 pH U/min (n = 11). This value was similar to nontransfected cells [0.211 ± 0.009 pH U/min (n = 12)]. Both values were significantly increased with ANG II (10-9 M) but not with ANG II (10-6 M). Losartan (10-7 M) and dimethyl-BAPTA-AM (10-7 M) decreased significantly the stimulatory effect of ANG II (10-9 M) and induced an increase in Na+/H+ exchanger 1 (NHE-1) activity with ANG II (10-6 M). Immunofluorescence studies indicated that in control situation, the hAT1 receptor was predominantly expressed in cytosol. However, it was translocated to plasma membrane with ANG II (10-9 M) and internalized with ANG II (10-6 M). Losartan (10-7 M) induced hAT1 translocation to plasma membrane in all studied groups. Dimethyl- BAPTA-AM (10-7 M) did not change the effect of ANG II (10-9 M) on the hAT1 receptor distribution but induced its accumulation at plasma membrane in cells treated with ANG II (10-6 M). With ionomycin (10-6 M), the receptor was accumulated in cytosol. The results indicate that, in MDCK cells, the effect of ANG II on NHE-1 activity is associated with ligand binding to AT1 receptor and intracellular signaling events related to AT1 translocation. [ABSTRACT FROM AUTHOR]

Advanced glycation end products (AGEs) play an important role in oxidative stress and inflammation, processes implicated in the development and progression of kidney dysfunction. In the present study, we investigated the participation of the pro-oxidant protein thioredoxin-interacting protein (TXNIP) and of epigenetic mechanisms on kidney tissue (in vivo , in non-diabetic rats) and on terminally differentiated glomerular podocytes (in vitro) chronically exposed to AGEs. AGEs induced total kidney and glomerular TXNIP expression and decreased H3K27me3 content. Concomitant treatment with the antioxidant N -acetyl-cysteine (NAC) reversed only the increased TXNIP expression. TXNIP expression positively correlated with proteinuria and negatively correlated with H3K27me3 content. In vitro studies in podocytes showed that 72 h exposure to AGEs decreased nephrin expression and increased Txnip , Nox4 , Col4a1 , and epithelial-to-mesenchymal transition (EMT) markers (Acta2 , Snail1 , and Tgfb1). Podocytes treatment with NAC reversed Nox4 , Col4a1 , Acta2 , and Tgfb1 increased expression but did not abrogate the reduced expression of nephrin. MiR-29a expression was downregulated by AGEs in vivo , but not in vitro. In conclusion, treatment of non-diabetic rats with AGEs induced TXNIP expression and decreased the contents of the repressive epigenetic mark H3K27me3 and of miR-29a, potentially driving injury to glomerular filtration barrier and podocytes dysfunction. • AGEs enhanced glomerular TNXIP and decreased H3K27me3 content in nondiabetic rats. • Proteinuria negatively correlated with nephrin expression and H3K27me3 content. • AGEs reduced total kidney miR-29a expression in non-diabetic rats. • AGEs reduced nephrin and increased mesenchymal markers expression in podocytes. [ABSTRACT FROM AUTHOR]

Obesity is an independent risk factor for the development of chronic kidney disease. The pathophysiology of the obesity-induced kidney injury is complex, but evidence suggests the involvement of reduced adiponectin levels and signaling. We investigated the extent by which adiponectin contributes to the establishment and progression of renal disease in wild type (WT) and adiponectin null (adipoKO) mice fed a control or a high-fat diet (HFD) for 16 weeks. HFD induced obesity, kidney hypertrophy, albuminuria, renal lipid accumulation and decreased nephrin expression in both mice genotypes. Notably, HFD in adipoKO mice exacerbated progression of albuminuria in comparison to WT mice. In addition, lack of adiponectin per se increased kidney weight, reduced nephrin levels, up-regulated Fabp4 expression, reduced Cpt1a expression and increased miR-130 levels in kidney. Our results demonstrate that lack of adiponectin combined with a HFD contributes to accelerated kidney dysfunction. • Lack of adiponectin reduces nephrin levels in kidney equally to obesity. • Lack of adiponectin induces kidney hyperthrophy. • Lack of adiponectin reduces fatty acid oxidation. • Higher levels of miR-130b are found in kidney of adipoKO mice compared to WT. • Adiponectin protects obese mice from accelerated progression of kidney disease. [ABSTRACT FROM AUTHOR]

As life expectancy continues to rise, age-related diseases are becoming more prevalent. For example, proteinuric glomerular diseases typified by podocyte injury have worse outcomes in the elderly compared with young patients. However, the reasons are not well understood. We hypothesized that injury to nonaged podocytes induces senescence, which in turn augments their aging processes. In primary cultured human podocytes, injury induced by a cytopathic antipodocyte antibody, adriamycin, or puromycin aminonucleoside increased the senescence-related genes CDKN2A (p16INK4a/p14ARF), CDKN2D (p19INK4d), and CDKN1A (p21). Podocyte injury in human kidney organoids was accompanied by increased expression of CDKN2A, CDKN2D, and CDKN1A. In young mice, experimental focal segmental glomerulosclerosis (FSGS) induced by adriamycin and antipodocyte antibody increased the glomerular expression of p16, p21, and senescence-associated β-galactosidase (SA-β-gal). To assess the long-term effects of early podocyte injury-induced senescence, we temporally followed young mice with experimental FSGS through adulthood (12 m of age) and middle age (18 m of age). p16 and Sudan blackstaining were higher at middle age in mice with earlier FSGS compared with age-matched mice that did not get FSGS when young. This was accompanied by lower podocyte density, reduced canonical podocyte protein expression, and increased glomerular scarring. These results are consistent with injury-induced senescence in young podocytes, leading to increased senescence of podocytes by middle age accompanied by lower podocyte lifespan and health span. [ABSTRACT FROM AUTHOR]

Extracting RNA from human urinary sediment is notoriously challenging because of cell paucity and hostile environment and column-based commercial kits using silica technology are commonly used. Nonetheless, in our experience, this methodology yields low amounts of total RNA and has low rates of success. We replaced the column-based commercial kit by a protocol using guanidine isothiocyanate-phenol-chloroform buffer (Trizol reagent) followed by addition of glycogen as a carrier and precipitation with isopropanol plus sodium acetate. This methodology was more affordable and efficient for urinary sediment total RNA isolation than silica technology, resulting in higher concentrations of total RNA of better quality. [ABSTRACT FROM AUTHOR]

Aims: Thioredoxin interacting protein (TXNIP), an inhibitor of antioxidant thioredoxin (Trx), is upregulated by hyperglycemia and implicated in pathogenesis of diabetes complications. We evaluated mRNA expressions of genes encoding TXNIP and Trx (TXN) in urinary sediment and peripheral blood mononuclear cells (PBMC) of type 1 diabetes (T1D) patients with different degrees of chronic complications.Methods: qPCR was employed to quantify target genes in urinary sediment (n = 55) and PBMC (n = 161) from patients sorted by presence or absence of diabetic nephropathy (DN), retinopathy, peripheral and cardiovascular neuropathy; 26 healthy controls and 13 patients presenting non-diabetic nephropathy (focal and segmental glomerulosclerosis, FSGS) were also included.Results: Regarding the urinary sediment,TXNIP(but notTXN) expression was higher in T1D (p = 0.0023) and FSGS (p = 0.0027) patientsversuscontrols. Expressions ofTXNIPandTXNwere higher, respectively, in T1D patients withversuswithout DN (p = 0.032) and in those with estimated glomerular filtration rate (eGFR) < 60versus ≥60 mL/min/1.73 m2(p = 0.008). eGFR negatively correlated withTXNIP(p = 0.04,r = −0.28) andTXN(p = 0.04,r = −0.30) expressions. T1D patients who lost ≥5 mL/min/1.73 m2yearly of eGFR presented higher basalTXNIPexpression than those who lost <5 mL/min/1.73 m2yearly after median follow-up of 24 months.TXNIP(p < 0.0001) andTXN(p = 0.002) expressions in PBMC of T1D patients were significantly higher than in controls but no differences were observed between patients with or without chronic complications.Conclusions:TXNIPandTXNare upregulated in urinary sediment of T1D patients with diabetic kidney disease (DKD), but onlyTXNIPexpression is associated with magnitude of eGFR decline. [ABSTRACT FROM AUTHOR]

Abstract: Angiotensin II (Ang II), acting via the AT1 receptor, induces an increase in intracellular calcium [Ca2+]i that then interacts with calmodulin (CaM). The Ca2+/CaM complex directly or indirectly activates sodium hydrogen exchanger 1 (NHE1) and phosphorylates calmodulin kinase II (CaMKII), which then regulates sodium hydrogen exchanger 3 (NHE3) activity. In this study, we investigated the cellular signaling pathways responsible for Ang II-mediated regulation of NHE1 and NHE3 in Madin–Darby canine kidney (MDCK) cells. The NHE1- and NHE3-dependent pHi recovery rates were evaluated by fluorescence microscopy using the fluorescent probe BCECF/AM, messenger RNA was evaluated with the reverse transcription polymerase chain reaction (RT-PCR), and protein expression was evaluated by immunoblot. We demonstrated that treatment with Ang II (1pM or 1nM) for 30min induced, via the AT1 but not the AT2 receptor, an equal increase in NHE1 and NHE3 activity that was reduced by the specific inhibitors HOE 694 and S3226, respectively. Ang II (1nM) did not change the total expression of NHE1, NHE3 or calmodulin, but it induced CaMKII, cRaf-1, Erk1/2 and p90RSK phosphorylation. The stimulatory effects of Ang II (1nM) on NHE1 or NHE3 activity or protein abundance was reduced by ophiobolin-A (CaM inhibitor), KN93 (CaMKII inhibitor) or PD98059 (Mek inhibitor). These results indicate that after 30min, Ang II treatment may activate G protein-dependent pathways, including the AT1/PLC/Ca2+/CaM pathway, which induces CaMKII phosphorylation to stimulate NHE3 and induces cRaf-1/Mek/Erk1/2/p90RSK activity to stimulate NHE1. [Copyright &y& Elsevier]

Chronic kidney disease (CKD) is a major public health concern and its prevalence and incidence are rising quickly. It is a non-communicable disease primarily caused by diabetes and/or hypertension and is associated with high morbidity and mortality. Despite decades of research efforts, the pathogenesis of CKD remains a puzzle with missing pieces. Understanding the cellular and molecular mechanisms that govern the loss of kidney function is crucial. Abrupt regulation of gene expression in kidney cells is apparent in CKD and shown to be responsible for disease onset and progression. Gene expression regulation extends beyond DNA sequence and involves epigenetic mechanisms including changes in DNA methylation and post-translational modifications of histones, driven by the activity of specific enzymes. Recent advances demonstrate the essential participation of epigenetics in kidney (patho)physiology, as its actions regulate both the integrity of cells but also triggers deleterious signaling pathways. Here, we review the known epigenetic processes regulating the complex filtration unit of the kidney, the glomeruli. The review will elaborate on novel insights into how epigenetics contributes to cell injury in the CKD setting majorly focusing on kidney glomerular cells: the glomerular endothelial cells, the mesangial cells, and the specialized and terminally differentiated podocyte cells. [ABSTRACT FROM AUTHOR]

Podocyte injury is closely related to proteinuria and the progression of chronic kidney disease (CKD). Currently, there is no conclusive understanding about the mechanisms involved in albumin overload and podocyte apoptosis response. In this study, we sought to explore the ways by which intracellular albumin can mediate podocyte apoptosis. Here, immortalized mouse podocytes were treated with bovine serum albumin (BSA) at different times and concentrations, in the presence or absence of SB203580 (0.1 µM, inhibitor of mitogen-activated-protein kinase - p38MAPK). Using immunofluorescence images, flow cytometry and immunoblotting, we observed a time-dependent intracellular accumulation of fluorescent albumin-FITC-BSA, followed by concentration-and time-dependent effect of intracellular albumin overload on podocyte apoptosis, which was mediated by increased expression of the chaperone glucose-regulated-protein 78 (GRP 78) and phosphorylated inositol-requiring enzyme 1 alpha (pIRE1-α), as well as protein kinase C delta (PKC-δ), p38MAPK and cleaved caspase 12 expression. SB203580 prevented the cleavage of caspase 12 and the albumin-mediated podocyte apoptosis. These results suggest that intracellular albumin overload is associated with endoplasmic reticulum (ER) stress and upregulation of PKC-δ/p38MAPK/caspase 12 pathway, which may be a target for future therapeutic of albumin-induced podocyte apoptosis. [ABSTRACT FROM AUTHOR]

Background/Aims: To assess the possible contribution of the β-adrenergic overstimulation in early stages of renal injury, the present study evaluated, in rats, the effects of the β-adrenoceptor agonist isoproterenol (ISO) on renal function and morphology, as well as the renal mRNA and protein expression of the NADPH oxidase isoform 4 (Nox 4) and subunit p22phox, endoplasmic reticulum (ER) stress, pro-inflammatory, pro-apoptotic and renin-angiotensin system (RAS) components. Methods: Wistar rats received ISO (0.3 mg.kg-1.day-1 s.c.) or vehicle (control) for eight days. At the end of the treatment, food and water intake, urine output and body weight gain were evaluated and renal function studies were performed. Renal tissue was used for the morphological, quantitative PCR and immunohistochemical studies. Results: ISO did not change metabolic parameters or urine output. However it induced a decrease in renal blood flow and an increase in the filtration fraction. These changes were accompanied by increased cortical mRNA and protein expression for the renal oxidative stress components including Nox 4 and p22phox; ER stress, pro-inflamatory, pro-apoptotic as well as RAS components. ISO also induced a significant increase in medullar renin protein expression. Conclusion: These findings support relevant information regarding the contribution of specific β-adrenergic hyperactivity in early stage of renal injury, indicating the reactive oxygen species, ER stress and intrarenal RAS as important factors in this process. [ABSTRACT FROM AUTHOR]