Transcriptional regulators in kidney disease: gatekeepers of renal homeostasis

Impacts of low birthweight on kidney development and intergenerational growth of the offspring

Low birthweight (LBW) increases the risk of adult-onset diseases, including kidney diseases, with intergenerational consequences; however, the underlying mechanisms and effective interventions are unclear. To examine the cross-generational effects of LBW, we established an LBW mouse model through reduced uterine perfusion pressure (RUPP) and investigated the therapeutic potential of tadalafil, a phosphodiesterase 5 inhibitor, on LBW-associated consequences. RUPP-pups (R1) had lower fetal and birth weights, delayed renal development, and fewer glomeruli than Sham-pups. In adulthood, R1 mice exhibited persistently fewer glomeruli and elevated blood pressure, while Tadalafil-R1 mice showed reduced hypertension in both sexes and improved renal pathological changes in males. Additionally, pregnant R1 mice displayed inadequate gestational liver hypertrophy, impaired hepatic purine metabolism, and diminished placental angiogenesis, resulting in fetal growth restriction in the subsequent generation. These findings underscore the lasting impact of LBW on adult health and future generations and suggest tadalafil's potential to mitigate LBW-associated risks.

The Impact of General Anesthesia on Redox Stability and Epigenetic Inflammation Pathways: Crosstalk on Perioperative Antioxidant Therapy

Worldwide, the prevalence of surgery under general anesthesia has significantly increased, both because of modern anesthetic and pain-control techniques and because of better diagnosis and the increased complexity of surgical techniques. Apart from developing new concepts in the surgical field, researchers and clinicians are now working on minimizing the impact of surgical trauma and offering minimal invasive procedures due to the recent discoveries in the field of cellular and molecular mechanisms that have revealed a systemic inflammatory and pro-oxidative impact not only in the perioperative period but also in the long term, contributing to more difficult recovery, increased morbidity and mortality, and a negative financial impact. Detailed molecular and cellular analysis has shown an overproduction of inflammatory and pro-oxidative species, responsible for augmenting the systemic inflammatory status and making postoperative recovery more difficult. Moreover, there are a series of changes in certain epigenetic structures, the most important being the microRNAs. This review describes the most important molecular and cellular mechanisms that impact the surgical patient undergoing general anesthesia, and it presents a series of antioxidant therapies that can reduce systemic inflammation.

Differential expression of microRNA miR-150-5p in IgA nephropathy as a potential mediator and marker of disease progression

Understanding why certain patients with IgA nephropathy progress to kidney failure while others maintain normal kidney function remains a major unanswered question. To help answer this, we performed miRNome profiling by next generation sequencing of kidney biopsies in order to identify microRNAs specifically associated with the risk of IgA nephropathy progression. Following sequencing and validation in independent cohorts, four microRNAs (-150-5p, -155-5p, -146b-5p, -135a-5p) were found to be differentially expressed in IgA nephropathy progressors compared to non-progressors, and patients with thin membrane nephropathy, lupus nephritis and membranous nephropathy, and correlated with estimated glomerular filtration rate, proteinuria, and the Oxford MEST-C scores (five histological features that are independent predictors of clinical outcome). Each individual microRNA increased the discrimination score of the International IgAN Prediction Tool, although due to the small number of samples the results did not reach statistical significance. miR-150-5p exhibited the largest amplitude of expression between cohorts and displayed the best discrimination between IgA nephropathy progressors and non-progressors by receiver operating curve analysis (AUC: 0.8). However, expression was similarly upregulated in kidneys with established fibrosis and low estimated glomerular filtration rates at the time of biopsy. Consistent with a more generic role in kidney fibrosis, in situ hybridization revealed that miR-150-5p was found in lymphoid infiltrates, and areas of proliferation and fibrosis consistent with the known drivers of progression. Thus, miR-150-5p may be a potential functional mediator of kidney fibrosis that may add value in predicting risk of progression in IgA nephropathy and other kidney diseases.

LINC00052 ameliorates acute kidney injury by sponging miR-532-3p and activating the Wnt signaling pathway

Acute kidney injury (AKI) is a complex renal disease. Long non-coding RNAs (lncRNAs) have frequently been associated with AKI. In the present study, we aimed to investigate the molecular mechanism(s) of LINC00052 in AKI. We found that LINC00052 expression was significantly decreased in AKI patient serum. In addition, in a hypoxic AKI cell model, LINC00052 expression was strongly elevated. In an I/R-triggered AKI rat model, the expression of TNF-α, IL-6 and IL-1β mRNA was strongly elevated. Moreover, we predicted miR-532-3p to be targeted by LINC00052 in AKI. Overexpression of LINC00052 increased hypoxia-induced inhibition of NRK-52E cell proliferation and reversed hypoxia-triggered apoptosis. Furthermore, we found that induction of TNF-α, IL-6 and IL-1β was repressed by overexpression of LINC00052. LINC00052 decreased hypoxia-induced ROS and MDA accumulation in vitro and increased SOD activity. Decreased levels of c-myc and cyclin D1 were observed in renal tissues of AKI rats. Lastly, Wnt/β-catenin signaling was inactivated in NRK-52E cells experiencing hypoxia, and LINC00052 upregulation reactivated Wnt/β-catenin signaling by sponging miR-532-3p. Taken together, these results suggest that LINC00052 ameliorates AKI by sponging miR-532-3p and activating Wnt signaling.

miR-214 ameliorates acute kidney injury via targeting DKK3 and activating of Wnt/β-catenin signaling pathway

Background

miR-214 was demonstrated to be upregulated in models of renal disease and promoted fibrosis in renal injury independent of TGF-β signaling in vivo. However, the detailed role of miR-214 in acute kidney injury (AKI) and its underlying mechanism are still largely unknown.

Methods

In this study, an I/R-induced rat AKI model and a hypoxia-induced NRK-52E cell model were used to study AKI. The concentrations of kidney injury markers serum creatinine, blood urea nitrogen, and kidney injury molecule-1 were measured. The expressions of miR-214, tumor necrosis factor-α, interleukin (IL)-1β, IL-6, were detected by RT-qPCR. The protein levels of Bcl-2, Bax, Dickkopf-related protein 3, β-catenin, c-myc, and cyclinD1 were determined by western blot. Cell apoptosis and caspase 3 activity were evaluated by flow cytometry analysis and caspase 3 activity assay, respectively. Luciferase reporter assay was used to confirm the interaction between miR-214 and Dkk3.

Results

miR-214 expression was induced in ischemia–reperfusion (I/R)-induced AKI rat and hypoxic incubation of NRK-52E cells. Overexpression of miR-214 alleviated hypoxia-induced NRK-52E cell apoptosis while inhibition of miR-214 expression exerted the opposite effect. Dkk3 was identified as a target of miR-214. Anti-miR-214 abolished the inhibitory effects of DKK3 knockdown on hypoxia-induced NRK-52E cell apoptosis by inactivation of Wnt/β-catenin signaling. Moreover, miR-214 ameliorated AKI in vivo by inhibiting apoptosis and fibrosis through targeting Dkk3 and activating Wnt/β-catenin pathway.

Conclusion

miR-214 ameliorates AKI by inhibiting apoptosis through targeting Dkk3 and activating Wnt/β-catenin signaling pathway, offering the possibility of miR-214 in the therapy of ischemic AKI.

Electronic supplementary material

The online version of this article (10.1186/s40659-018-0179-2) contains supplementary material, which is available to authorized users.

Clinical and mutational spectrum of hypoparathyroidism, deafness and renal dysplasia syndrome

Background

Hypoparathyroidism, deafness and renal dysplasia (HDR) syndrome is a rare autosomal dominant disorder, secondary to mutations in the GATA-3 gene. Due to its wide range of penetrance and expressivity, the disease may not always be recognized. We herein describe clinical and genetic features of patients with HDR syndrome, highlighting diagnostic clues.

Methods

Medical records of eight patients from five unrelated families exhibiting GATA-3 mutations were reviewed retrospectively, in conjunction with all previously reported cases.

Results

HDR syndrome was diagnosed in eight patients between the ages of 18 and 60 years. Sensorineural deafness was consistently diagnosed, ranging from clinical hearing loss since infancy in seven patients to deafness detected only by audiometry in adulthood in one single patient. Hypoparathyroidism was present in six patients (with hypocalcaemia and inaugural seizures in two out of six). Renal abnormalities observed in six patients were diverse and of dysplastic nature. Three patients displayed nephrotic-range proteinuria and reached end-stage renal disease (ESRD) between the ages of 19 and 61 years, whilst lesions of focal and segmental glomerulosclerosis were histologically demonstrated in one of them. Interestingly, phenotype severity differed significantly between a mother and son within one family. Five new mutations of GATA-3 were identified, including three missense mutations affecting zinc finger motifs [NM_001002295.1: c.856A>G (p.N286D) and c.1017C>G (p.C339W)] or the conserved linker region [c.896G>A (p.R299G)], and two splicing mutations (c.924+4_924+19del and c.1051-2A>G). Review of 115 previously reported cases of GATA-3 mutations showed hypoparathyroidism and deafness in 95% of patients, and renal abnormalities in only 60%. Overall, 10% of patients had reached ESRD.

Conclusions

We herein expand the clinical and mutational spectrum of HDR syndrome, illustrating considerable inter- and intrafamilial phenotypic variability. Diagnosis of HDR should be considered in any patient with hypoparathyroidism and deafness, whether associated with renal abnormalities or not. HDR diagnosis is established through identification of a mutation in the GATA-3 gene.

The Potential Role of Krüppel-Like Zinc-Finger Protein Glis3 in Genetic Diseases and Cancers

Gli-similar 3 (Glis3) belongs to a Glis subfamily of Krüppel-like zinc-finger transcription factors characterized to regulate a set of downstream targets essential for cellular functions, including pancreatic development, β-cell maturation and maintenance, and insulin production. Examination of the DNA-binding domain of Glis3 reveals that this domain contains a repeated cysteine 2/histidine 2 (Cys2/His2) zinc-finger motif in the central region where the recognized DNA sequence binds. The loss of the production of pancreatic hormones, such as insulin 1 and 2, is linked to the down-regulation of β cells-related genes and promotes the apoptotic death of β cells found in mutant Glis3. Although accumulating studies converge on the Glis3 functioning in β cells, recently, there have been developments in the field of Glis3 using knockdown/mutant mice to better understand the role of Glis3 in diseases. The Glis3 mutant mice have been characterized for their propensity to develop congenital hypothyroidism, polycystic kidney disease, and some types of cancer. In this review, we attempt to comprehensively summarize the knowledge of Glis3, including its structure and general function in cells. We also collected and organized the academic achievements related to the possible mechanisms of Glis3-related diseases.

Improper hydration induces global gene expression changes associated with renal development in infant mice

BACKGROUND

The kidney is a major organ in which fluid balance and waste excretion is regulated. For the kidney to achieve maturity with functions, normal renal developmental processes need to occur. Comprehensive genetic programs underlying renal development during the prenatal period have been widely studied. However, postnatal renal development, from infancy to the juvenile period, has not been studied yet. Here, we investigated whether structural and functional kidney development was still ongoing in early life by analyzing the renal transcriptional networks of infant (4 weeks old) and juvenile (7 weeks old) mice. We further examined the effects of dehydration on kidney development to unravel the mechanistic bases underlying deteriorative impact of pediatric dehydration on renal development.

METHODS

3-week-old infant mice that just finished weaning period were provided limited access to a water for fifteen minutes per day for one week (RES 1W) and four weeks (RES 4W) to induce dehydration while control group consumed water ad libitum with free access to the water bottle. Transcriptome analysis was conducted to understand physiological changes during postnatal renal development and dehydration.

RESULTS

Kidneys in 4-week- and 7-week-old mice showed significantly distinctive functional gene networks. Gene sets related to cell cycle regulators, fetal kidney patterning molecules, and immature basement membrane integrity were upregulated in infantile kidneys while heightened expressions of genes associated with ion transport and drug metabolism were observed in juvenile kidneys. Dehydration during infancy suppressed renal growth by interrupting the SHH signaling pathway, which targets cell cycle regulators. Importantly, it is likely that disruption of the developmental program ultimately led to a decline in gene expression associated with basement membrane integrity.

CONCLUSIONS

Altogether, we demonstrate transcriptional events during renal development in infancy and show that the impacts of inadequate water intake in the early postnatal state heavily rely on the impairment of normal renal development. Here, we provide a meaningful perspective of renal development in infancy with a molecular and physiological explanation of why infants are more vulnerable to dehydration than adults. These results provide new insights into the molecular effects of dehydration on renal physiology and indicate that optimal nutritional interventions are necessary for pediatric renal development.

Gata3 Hypomorphic Mutant Mice Rescued with a Yeast Artificial Chromosome Transgene Suffer a Glomerular Mesangial Cell Defect

GATA3 is a zinc finger transcription factor that plays a crucial role in embryonic kidney development, while its precise functions in the adult kidney remain largely unexplored. Here, we demonstrate that GATA3 is specifically expressed in glomerular mesangial cells and plays a critical role in the maintenance of renal glomerular function. Newly generated Gata3 hypomorphic mutant mice exhibited neonatal lethality associated with severe renal hypoplasia. Normal kidney size was restored by breeding the hypomorphic mutant with a rescuing transgenic mouse line bearing a 662-kb Gata3 yeast artificial chromosome (YAC), and these animals (termed G3YR mice) survived to adulthood. However, most of the G3YR mice showed degenerative changes in glomerular mesangial cells, which deteriorated progressively during postnatal development. Consequently, the G3YR adult mice suffered severe renal failure. We found that the 662-kb Gata3 YAC transgene recapitulated Gata3 expression in the renal tubules but failed to direct sufficient GATA3 activity to mesangial cells. Renal glomeruli of the G3YR mice had significantly reduced amounts of platelet-derived growth factor receptor (PDGFR), which is known to participate in the development and maintenance of glomerular mesangial cells. These results demonstrate a critical role for GATA3 in the maintenance of mesangial cells and its absolute requirement for prevention of glomerular disease.

Downregulation of renal tubular Wnt/β-catenin signaling by Dickkopf-3 induces tubular cell death in proteinuric nephropathy

Studies on the role of Wnt/β-catenin signaling in different forms of kidney disease have yielded discrepant results. Here, we report the biphasic change of renal β-catenin expression in mice with overload proteinuria in which β-catenin was upregulated at the early stage (4 weeks after disease induction) but abrogated at the late phase (8 weeks). Acute albuminuria was observed at 1 week after bovine serum albumin injection, followed by partial remission at 4 weeks that coincided with overexpression of renal tubular β-catenin. Interestingly, a rebound in albuminuria at 8 weeks was accompanied by downregulated tubular β-catenin expression and heightened tubular apoptosis. In addition, there was an inverse relationship between Dickkopf-3 (Dkk-3) and renal tubular β-catenin expression at these time points. In vitro, a similar trend in β-catenin expression was observed in human kidney-2 (HK-2) cells with acute (upregulation) and prolonged (downregulation) exposure to albumin. Induction of a proapoptotic phenotype by albumin was significantly enhanced by silencing β-catenin in HK-2 cells. Finally, Dkk-3 expression and secretion was increased after prolonged exposure to albumin, leading to the suppression of intracellular β-catenin signaling pathway. The effect of Dkk-3 on β-catenin signaling was confirmed by incubation with exogenous Dkk-3 in HK-2 cells. Taken together, these data suggest that downregulation of tubular β-catenin signaling induced by Dkk-3 has a detrimental role in chronic proteinuria, partially through the increase in apoptosis.

Stem cells and fluid flow drive cyst formation in an invertebrate excretory organ

Cystic kidney diseases (CKDs) affect millions of people worldwide. The defining pathological features are fluid-filled cysts developing from nephric tubules due to defective flow sensing, cell proliferation and differentiation. The underlying molecular mechanisms, however, remain poorly understood, and the derived excretory systems of established invertebrate models (Caenorhabditis elegans and Drosophila melanogaster) are unsuitable to model CKDs. Systematic structure/function comparisons revealed that the combination of ultrafiltration and flow-associated filtrate modification that is central to CKD etiology is remarkably conserved between the planarian excretory system and the vertebrate nephron. Consistently, both RNA-mediated genetic interference (RNAi) of planarian orthologues of human CKD genes and inhibition of tubule flow led to tubular cystogenesis that share many features with vertebrate CKDs, suggesting deep mechanistic conservation. Our results demonstrate a common evolutionary origin of animal excretory systems and establish planarians as a novel and experimentally accessible invertebrate model for the study of human kidney pathologies.

Hepatocyte nuclear factor-1β: A regulator of kidney development and cystogenesis

The understanding of the genomics of the renal tissue has gathered a considerable interest and is making rapid progress. The molecular mechanisms as well as the precise function of the associated molecular components toward renal pathophysiology have recently been realized. For the cystic kidney disease, the regulation of gene expression affecting epithelial cells proliferation, apoptosis as well as process of differentiation/de-differentiation represent key molecular targets. For the cystic disorders, molecular targets have been identified, which besides lending heterogeneity to cysts may also provide tools to unravel their functional importance to understand the renal tissue homeostasis. This review focuses on providing comprehensive information about the transcriptional regulatory role of hepatocyte nuclear factor-1β, a homeoprotein, as well as its interacting partners in renal tissue development and pathophysiology.

The impact of maternal cigarette smoke exposure in a rodent model on renal development in the offspring

This study aimed to investigate whether maternal cigarette smoke exposure can disrupt fetal kidney development by changing the expression of growth and transcription factors essential for renal development, and thereafter predispose the offspring to chronic kidney disease later in life. Female Balb/c mice (6 weeks) were exposed either to cigarette smoke or air under identical conditions, 6 weeks prior to mating, during gestation and during lactation. Male offspring were sacrificed at three time points, postnatal day (P)1, P20 (weaning age), and 13 weeks (mature age). Blood, urine, and kidneys were collected for analysis. At P1, the developmental genes fibroblast growth factor 2, glial cell-line derived neurotrophic factor and paired box 2 were upregulated at mRNA and protein levels; whilst fibroblast growth factor (FGF) 7 and FGF10 were downregulated. At P20, mRNA expression of FGF2, FGF10 and Wingless-type 4 was upregulated by maternal smoke exposure. These changes were normalised in adulthood. Nephron development was delayed, with fewer nephron numbers from P1 persisted to adulthood; while glomerular volume was increased at P20 but reduced in adulthood. Pro-inflammatory marker monocyte chemoatractant protein 1 (MCP1) was increased in the kidney by maternal smoke exposure. These changes were accompanied by an increased albumin/creatinine ratio in adulthood, suggesting reduced renal dysfunction. In conclusion maternal cigarette smoke exposure prior to and during pregnancy, as well as lactation leads to significant renal underdevelopment and functional abnormalities in adulthood. This study confirms the hypothesis that maternal smoking predisposes offspring to chronic kidney disorders.

Epigenetics of progression of chronic kidney disease: fact or fantasy?

Epigenetic modifications are important in the normal functioning of the cell, from regulating dynamic expression of essential genes and associated proteins to repressing those that are unneeded. Epigenetic changes are essential for development and functioning of the kidney, and aberrant methylation, histone modifications, and expression of microRNA could lead to chronic kidney disease (CKD). Here, epigenetic modifications modulate transforming growth factor β signaling, inflammation, profibrotic genes, and the epithelial-to-mesenchymal transition, promoting renal fibrosis and progression of CKD. Identification of these epigenetic changes is important because they are potentially reversible and may serve as therapeutic targets in the future to prevent subsequent renal fibrosis and CKD. In this review we discuss the different types of epigenetic control, methods to study epigenetic modifications, and how epigenetics promotes progression of CKD.

DNA methylation profile associated with rapid decline in kidney function: findings from the CRIC study

BACKGROUND

Epigenetic mechanisms may be important in the progression of chronic kidney disease (CKD).

METHODS

We studied the genome-wide DNA methylation pattern associated with rapid loss of kidney function using the Infinium HumanMethylation 450 K BeadChip in 40 Chronic Renal Insufficiency (CRIC) study participants (n = 3939) with the highest and lowest rates of decline in estimated glomerular filtration rate.

RESULTS

The mean eGFR slope was 2.2 (1.4) and -5.1 (1.2) mL/min/1.73 m(2) in the stable kidney function group and the rapid progression group, respectively. CpG islands in NPHP4, IQSEC1 and TCF3 were hypermethylated to a larger extent in subjects with stable kidney function (P-values of 7.8E-05 to 9.5E-05). These genes are involved in pathways known to promote the epithelial to mesenchymal transition and renal fibrosis. Other CKD-related genes that were differentially methylated are NOS3, NFKBIL2, CLU, NFKBIB, TGFB3 and TGFBI, which are involved in oxidative stress and inflammatory pathways (P-values of 4.5E-03 to 0.046). Pathway analysis using Ingenuity Pathway Analysis showed that gene networks related to cell signaling, carbohydrate metabolism and human behavior are epigenetically regulated in CKD.

CONCLUSIONS

Epigenetic modifications may be important in determining the rate of loss of kidney function in patients with established CKD.

Scrutinizing ciliopathies by unraveling ciliary interaction networks

Research of cilia has gained significant momentum in the last 15 years, as an increasing number of human genetic diseases were found to be caused by disruption of a protein that localizes to cilia. These ciliopathies are as diverse as the functions of the associated proteins, covering a spectrum of overlapping phenotypes that ranges from relatively mild characteristics in isolated tissues with a late onset, to severe defects of multiple tissues with an onset early in embryogenesis that is incompatible with life. As cilia harbour many receptors and components of key signaling cascades, such as Hedgehog, Wnt, Notch and Hippo signaling, disruption of ciliary function has severe consequences. Recent (affinity) proteomics studies have focused on the composition and dynamics of ciliary protein interaction networks. This has unveiled important knowledge about the highly ordered, interconnected but very dynamic nature of the cilium as a molecular machine. Disruption of the members of the same functional modules of this machine leads to similar phenotypes, and detailed analyses of the binding repertoire, the biochemical properties and the biological functions of these modules have yielded new ciliopathy genes as well as new insights into the pathogenic mechanisms underlying ciliopathies.

Primary cilia are decreased in breast cancer: analysis of a collection of human breast cancer cell lines and tissues

Primary cilia (PC) are solitary, sensory organelles that are critical for several signaling pathways. PC were detected by immunofluorescence of cultured cells and breast tissues. After growth for 7 days in vitro, PC were detected in ∼70% of breast fibroblasts and in 7-19% of epithelial cells derived from benign breast (184A1 and MCF10A). In 11 breast cancer cell lines, PC were present at a low frequency in four (from 0.3% to 4% of cells), but were absent in the remainder. The cancer cell lines with PC were all of the basal B subtype, which is analogous to the clinical triple-negative breast cancer subtype. Furthermore, the frequency of PC decreased with increasing degree of transformation/progression in the MCF10 and MDA-MB-435/LCC6 isogenic models of cancer progression. In histologically normal breast tissues, PC were frequent in fibroblasts and myoepithelial cells and less common in luminal epithelial cells. Of 26 breast cancers examined, rare PC were identified in cancer epithelial cells of only one cancer, which was of the triple-negative subtype. These data indicate a decrease or loss of PC in breast cancer and an association of PC with the basal B subtype. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.

Cell regulation: determined to signal discrete cooperation

Do kinases cascade? How well is cell regulation understood? What are the best ways to model regulatory systems? Attempts to answer such questions can have bearings on the way in which research is conducted. Fortunately there are recurring themes in regulatory processes from many different cellular contexts, which might provide useful guidance. Three principles seem to be almost universal: regulatory interactions are cooperative; regulatory decisions are made by large dynamic protein complexes; and regulation is intricately networked. A fourth principle, although not universal, is remarkably common: regulatory proteins are actively placed where they are needed. Here, I argue that the true nature of cell signalling and our perceptions of it are in a state of discord. This raises the question: Are our misconceptions detrimental to progress in biomedical science?

Compound ion salt, a novel low-sodium salt substitute: from animal study to community-based population trial

BACKGROUND

Salt restriction, an important approach for primary and secondary prevention of hypertension, is undermined by unsatisfactory adherence. A salt-restriction study tested the efficacy and safety of a compound ion salt (CISalt) with low sodium content in an animal model and in a community-based population.

METHODS

In part 1, 8-week-old male spontaneously hypertensive rats (SHRs) were fed 1% CISalt in the study group and 8% or 1% normal salt (NSalt) in controls (n = 10 each) for 12 weeks. Blood pressure (BP) and urinary electrolytes were measured every 3 weeks. After 12 weeks, collagen deposition in the heart and kidney and the levels of angiotensin II (Ang II) and nitric oxide (NO) in plasma and renal cortex were measured. In part 2, a single-blind, randomized, 6-month controlled trial with CISalt was conducted in 248 persons (age >or=65 years) in 10 rural communities. Plasma renin activity and Ang II were included in blood and urinary measures at baseline and 6 months.

RESULTS

Reduced BP urinary protein excretion and reduced collagen in the heart and kidneys were significantly different in animals fed CISalt compared to controls. In human studies, at 6 months, mean systolic BP (SBP) was decreased by 9.6 mm Hg (95% confidence interval (CI): 13.1 to 6.1, P < 0.001) and diastolic BP (DBP) by 5.3 mm Hg (95% CI: 7.9 to 2.6, P < 0.001), respectively, compared to controls; urinary sodium excretion also decreased by 67.4 mmol/24 h (95% CI: 84.8 to 50.0, P < 0.001), and plasma renin activity was slightly increased by 0.19 ng/ml/h (95% CI: 0.04-0.33, P = 0.013). No adverse cardiovascular events were reported.

CONCLUSIONS

In these studies, CISalt lowered BP and showed end-organ protection in hypertensive animals and BP reduction in humans. CISalt appears to be a safe and acceptable strategy to reduce BP.

Multipotent stem cells in the Malpighian tubules of adult Drosophila melanogaster

Excretion is an essential process of an organism's removal of the waste products of metabolism to maintain a constant chemical composition of the body fluids despite changes in the external environment. Excretion is performed by the kidneys in vertebrates and by Malpighian tubules (MTs) in Drosophila. The kidney serves as an excellent model organ to investigate the cellular and molecular mechanisms underlying organogenesis. Mammals and Drosophila share common principles of renal development. Tissue homeostasis, which is accomplished through self-renewal or differentiation of stem cells, is critical for the maintenance of adult tissues throughout the lifetime of an animal. Growing evidence suggests that stem cell self-renewal and differentiation is controlled by both intrinsic and extrinsic factors. Deregulation of stem cell behavior results in cancer formation, tissue degeneration, and premature aging. The mammalian kidney has a low rate of cellular turnover but has a great capacity for tissue regeneration following an ischemic injury. However, there is an ongoing controversy about the source of regenerating cells in the adult kidney that repopulate injured renal tissues. Recently, we identified multipotent stem cells in the MTs of adult Drosophila and found that these stem cells are able to proliferate and differentiate in several types of cells in MTs. Furthermore, we demonstrated that an autocrine JAK-STAT (Janus kinase-signal transducers and activators of transcription) signaling regulates stem cell self-renewal or differentiation of renal stem cells. The Drosophila MTs provide an excellent in vivo system for studying the renal stem cells at cellular and molecular levels. Understanding the molecular mechanisms governing stem cell self-renewal or differentiation in vivo is not only crucial to using stem cells for future regenerative medicine and gene therapy, but it also will increase our understanding of the mechanisms underlying cancer formation, aging and degenerative diseases. Identifying and understanding the cellular processes underlying the development and repair of the mammalian kidney may enable more effective, targeted therapies for acute and chronic kidney diseases in humans.

Glis3 is associated with primary cilia and Wwtr1/TAZ and implicated in polycystic kidney disease

In this study, we describe the generation and partial characterization of Krüppel-like zinc finger protein Glis3 mutant (Glis3(zf/zf)) mice. These mice display abnormalities very similar to those of patients with neonatal diabetes and hypothyroidism syndrome, including the development of diabetes and polycystic kidney disease. We demonstrate that Glis3 localizes to the primary cilium, suggesting that Glis3 is part of a cilium-associated signaling pathway. Although Glis3(zf/zf) mice form normal primary cilia, renal cysts contain relatively fewer cells with a primary cilium. We further show that Glis3 interacts with the transcriptional modulator Wwtr1/TAZ, which itself has been implicated in glomerulocystic kidney disease. Wwtr1 recognizes a P/LPXY motif in the C terminus of Glis3 and enhances Glis3-mediated transcriptional activation, indicating that Wwtr1 functions as a coactivator of Glis3. Mutations in the P/LPXY motif abrogate the interaction with Wwtr1 and the transcriptional activity of Glis3, indicating that this motif is part of the transcription activation domain of Glis3. Our study demonstrates that dysfunction of Glis3 leads to the development of cystic renal disease, suggesting that Glis3 plays a critical role in maintaining normal renal functions. We propose that localization to the primary cilium and interaction with Wwtr1 are key elements of the Glis3 signaling pathway.