Growing evidence suggests WT1 effects in the kidney development are modulated by Hsp70/NO interaction

Crocin improves the renal autophagy in rat experimental membranous nephropathy via regulating the SIRT1/Nrf2/HO-1 signaling pathway

Membranous nephropathy (MN) is a glomerular disease. Crocin is isolated from saffron and gardenia. Its antioxidant, anti-inflammatory, anti-hyperlipidemic, anti-atherosclerotic, anti-tumor, free-radical scavenging and neuroprotective activities have been well established. We investigated the biological functions of crocin and its related mechanisms in MN. We established an experimental passive Heymann nephritis (PHN) rat model induced by anti-Fx1A antiserum. The rats were divided into sham, sham + crocin, PHN, PHN + crocin, and PHN + enalapril groups. Blood samples and kidneys of rats were collected for estimation of biochemical parameters in serum and oxidative stress indicators in kidney tissues. Histopathological changes of renal tissues were evaluated by hematoxylin and eosin, periodic acid-Schiff (PAS) and Masson staining. The podocyte number was estimated by immunohistochemistry staining of Wilms tumor type 1 (WT1). The deposition of rat anti-rabbit IgG antibodies, complement C3 and C5b-9 was detected by immunofluorescence staining. Western blotting was performed to measure the levels of Sirtuin 1 (Sirt1), nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase 1 (HO-1) and apoptosis-related proteins. The total cholesterol, triglycerides, creatinine, blood urea nitrogen, urine volume and urine albumin of PMN rats were significantly reduced by crocin. Additionally, crocin attenuated the renal histopathological changes. Moreover, the oxidative stress damage and podocyte loss and immune injury were relieved by crocin in PHN rats. Mechanistically, crocin administration activated the Sirt1/Nrf2/HO-1 pathways. The results provide a scientific basis that crocin could alleviate MN by inhibiting immune injury and podocyte damage through activating the Sirt1/Nrf2/HO-1 pathways.

Immunoexpression Pattern of Autophagy Markers in Developing and Postnatal Kidneys of Dab1−/−(yotari) Mice

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.

Hypertension and renal disease programming: focus on the early postnatal period

The developmental origin of hypertension and renal disease is a concept highly supported by strong evidence coming from both human and animal studies. During development there are periods in which the organs are more vulnerable to stressors. Such periods of susceptibility are also called 'sensitive windows of exposure'. It was shown that as earlier an adverse event occurs; the greater are the consequences for health impairment. However, evidence show that the postnatal period is also quite important for hypertension and renal disease programming, especially in rodents because they complete nephrogenesis postnatally, and it is also important during preterm human birth. Considering that the developing kidney is vulnerable to early-life stressors, renal programming is a key element in the developmental programming of hypertension and renal disease. The purpose of this review is to highlight the great number of studies, most of them performed in animal models, showing the broad range of stressors involved in hypertension and renal disease programming, with a particular focus on the stressors that occur during the early postnatal period. These stressors mainly include undernutrition or specific nutritional deficits, chronic behavioral stress, exposure to environmental chemicals, and pharmacological treatments that affect some important factors involved in renal physiology. We also discuss the common molecular mechanisms that are activated by the mentioned stressors and that promote the appearance of these adult diseases, with a brief description on some reprogramming strategies, which is a relatively new and promising field to treat or to prevent these diseases.

Upregulation of HSP60 expression in the postnatal rat cochlea and rats with drug-induced hearing loss

Heat shock protein 60 (HSP60) is a highly conserved chaperone molecule that plays important roles in mediating some physiological and pathological functions. However, researchers have not yet determined whether HSP60 is expressed in the mammalian cochlea. This study constitutes the first investigation of the expression of HSP60 in the postnatal rat cochlea. We also examined the expression of HSP60 in rats with drug-induced hearing loss. Auditory thresholds were assessed by monitoring the auditory brainstem response (ABR) prior to and after drug injection. Expression levels of the HSP60 gene (Hsp60) and HSP60 protein in the rat cochlea were detected by quantitative real-time polymerase chain reaction and Western blotting, respectively. The distribution of HSP60 in the rat cochlea was further examined by immunofluorescence staining. We have demonstrated that HSP60 was expressed in the postnatal rat cochlea in an age-dependent and cell-specific manner. In addition, after drug exposure, the average hearing threshold of rats in the experimental group was significantly higher than that in the control group, with increased HSP60 expression level in response to kanamycin and furosemide treatments. HSP60 expression was observed in the supporting cells (SCs) within the organ of Corti in both the uninjured and the injured cochlea, but it was undetectable in the mechanosensory hair cells (HCs) and spiral ganglion neurons. Therefore, our research suggests that HSP60 may play an important role in auditory function.

Implications of the transcription factor WT1 linked to the pathologic cardiac remodeling post-myocardial infarction

New advances in the treatment of acute myocardial infarction involve novel signaling pathways and cellular progeny. In this sense, regeneration is a novel tool that would contribute to post-infarction physiological ventricular remodeling. More specifically, re-expression of the WT1 transcription factor in the myocardial wall by ischemia and infarction would be related to the invasion of cells with the capacity for regeneration. This mechanism seems not to be sufficient to restore muscle cells and lost vessels entirely. Of particular interest, the presence of the heat-shock response protein 70 (Hsp70) and its interaction with the vitamin D receptor would modulate the expression of WT1 positively. In this context, it is proposed that the activation of vitamin D receptors associated with Hsp70 could favor physiological cardiac remodeling and reduce the progression to heart failure.

Anandamide and endocannabinoid system: an attractive therapeutic approach for cardiovascular disease

Cardiovascular disease is currently not adequately managed and has become one of the main causes of morbidity and mortality worldwide. Current therapies are inadequate in terms of preventing its progression. There are several limitations, such as poor oral bioavailability, side effects, low adherence to treatment, and high dosage frequency of formulations due to the short half-life of the active ingredients used, among others. This review aims to highlight the most relevant aspects of the relationship between the cardiovascular system and the endocannabinoid system, with special attention to the possible translational effect of the use of anandamide in cardiovascular health. The deep and detailed knowledge of this interaction, not always beneficial, and that for years has gone unnoticed, is essential for the development of new therapies. We discuss the most recent and representative results obtained in the field of basic research, referring to the aforementioned subject, emphasizing fundamentally the main role of nitric oxide, renal physiology and its deregulation in pathological processes.

WT1 Is Necessary for the Proliferation and Migration of Cells of Renin Lineage Following Kidney Podocyte Depletion

Wilms' tumor suppressor 1 (WT1) plays an important role in cell proliferation and mesenchymal-epithelial balance in normal development and disease. Here, we show that following podocyte depletion in three experimental models, and in patients with focal segmental glomerulosclerosis (FSGS) and membranous nephropathy, WT1 increased significantly in cells of renin lineage (CoRL). In an animal model of FSGS in RenWt1^fl/fl reporter mice with inducible deletion of WT1 in CoRL, CoRL proliferation and migration to the glomerulus was reduced, and glomerular disease was worse compared with wild-type mice. To become podocytes, CoRL undergo mesenchymal-to-epithelial transformation (MET), typified by reduced staining for mesenchymal markers (MYH11, SM22, αSMA) and de novo expression of epithelial markers (E-cadherin and cytokeratin18). Evidence for changes in MET markers was barely detected in RenWt1^fl/fl mice. Our results show that following podocyte depletion, WT1 plays essential roles in CoRL proliferation and migration toward an adult podocyte fate.

Heat shock protein 70/nitric oxide effect on stretched tubular epithelial cells linked to WT-1 cytoprotection during neonatal obstructive nephropathy

BACKGROUND

Mechanical stress is a key pathogenic driver of apoptosis in the tubular epithelium in obstructive nephropathy. Heat shock protein 70 (Hsp70) and Wilms' tumor (WT-1) have been proposed to represent linked downstream effectors of the cytoprotective properties of NO. In the present study, we sought to evaluate whether the cytoprotective effects of L-arginine in neonatal obstructive nephropathy may be associated with NO-dependent increases in WT-1 and Hsp70 expression.

METHODS

Neonatal Wistar-Kyoto rats were submitted to complete unilateral ureteral obstruction (UUO) and treated thereafter with vehicle, L-NAME or L-arginine by daily gavage for 14 days to block or augment NO levels, respectively. Normal rat kidney epithelial cells by NRK-52E were exposed to mechanical stress in vitro in the presence or absence of L-NAME, L-arginine, sodium nitroprusside (SNP), L-arginine + SNP or L-arginine/L-NAME. Induction of apoptosis and the mRNA expression of WT-1 and Hsp70 genes were assessed.

RESULTS

WT-1 and Hsp70 genes expression decreased in the presence of L-NAME and following UUO coincident with increased tubular apoptosis. L-arginine treatment increased NO levels, reduced apoptosis and restored expression levels of WT-1 and Hsp70 to control levels. L-arginine treatment in vitro reduced basal apoptotic rates and prevented apoptosis in response to mechanical strain, an effect enhanced by SNP co-incubation. L-NAME increased apoptosis and prevented the anti-apoptotic action of L-arginine.

CONCLUSIONS

L-arginine treatment in experimental neonatal UUO reduces apoptosis coincident with restoration of WT-1 and Hsp70 expression levels and directly inhibits mechanical strain-induced apoptosis in an NO-dependent manner in vitro. This potentially implicates an NO-Hsp70-WT-1 axis in the cytoprotective effects of L-arginine.