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Parietal epithelial cells - Top 30 Publications

Alcohol exposure induces chick craniofacial bone defects by negatively affecting cranial neural crest development.

Excess alcohol consumption during pregnancy could lead to fetal alcohol syndrome (FAS). However, the molecular mechanism leading to craniofacial abnormality, a feature of FAS, is still poorly understood. The cranial neural crest cells (NCCs) contribute to the formation of the craniofacial bones. Therefore, NCCs exposed to ethanol was investigated - using chick embryos and in vitro explant culture as experimental models. We demonstrated that exposure to 2% ethanol induced craniofacial defects, which includes parietal defect, in the developing chick fetus. Immunofluorescent staining revealed that ethanol treatment downregulated Ap-2ɑ, Pax7 and HNK-1 expressions by cranial NCCs. Using double-immunofluorescent stainings for Ap-2ɑ/pHIS3 and Ap-2ɑ/c-Caspase3, we showed that ethanol treatment inhibited cranial NCC proliferation and increased NCC apoptosis, respectively. Moreover, ethanol treatment of the dorsal neuroepithelium increased Laminin, N-Cadherin and Cadherin 6B expressions while Cadherin 7 expression was repressed. In situ hybridization also revealed that ethanol treatment up-regulated Cadherin 6B expression but down-regulated slug, Msx1, FoxD3 and BMP4 expressions. In summary, our experimental results demonstrated that ethanol treatment interferes with the production of cranial NCCs by affecting the proliferation and apoptosis of these cells. In addition, ethanol affected the delamination, epithelial-mesenchymal transition (EMT) and cell migration of cranial NCCs, which may have contributed to the etiology of the craniofacial defects.

Urinary WT1-positive cells as a non-invasive biomarker of crescent formation.

The purpose of this study was to assess the relationship between urinary WT1-positive cells (podocytes and active parietal epithelial cells) and WT1-positive cells in renal biopsy to investigate whether urinary WT1-positive cells are useful for detection of crescent formation.

Therapeutic Mechanism of Glucocorticoids on Cellular Crescent Formation in Patients With Antiglomerular Basement Membrane Disease.

This study aimed to explore the therapeutic mechanism of glucocorticoids (GCs) in antiglomerular basement membrane disease.

Lrig1+ gastric isthmal progenitor cells restore normal gastric lineage cells during damage recovery in adult mouse stomach.

Lrig1 is a marker of proliferative and quiescent stem cells in the skin and intestine. We examined whether Lrig1-expressing cells are long-lived gastric progenitors in gastric glands in the mouse stomach. We also investigated how the Lrig1-expressing progenitor cells contribute to the regeneration of normal gastric mucosa by lineage commitment to parietal cells after acute gastric injury in mice.

The Role of Angiotensin II in Parietal Epithelial Cell Proliferation and Crescent Formation in Glomerular Diseases.

Crescentic glomerulonephritis (GN) is a devastating disease with rapidly progressive deterioration in kidney function, which, histologically, manifests as crescent formation in most glomeruli. We previously found that crescents derive from the aberrant proliferation and migration of parietal epithelial cells (PECs)/progenitor cells, and that the angiotensin (ang) II/ang II type-1 (AT1) receptor pathway may participate, together with the stromal cell-derived factor-1 (SDF-1)/C-X-C chemokine receptor 4 axis, in the development of those lesions. Herein, we elucidated sequential events and cellular and molecular interactions occurring during crescentic lesion onset and evolution. By analyzing kidney biopsy specimens of patients with extracapillary GN, divided according to the grade of glomerular lesions, we found that the accumulation of macrophages expressing matrix metallopeptidase-12 started manifesting in glomeruli affected by early-stage lesions, whereas AT1 receptor expression could not be detected. In glomeruli with advanced lesions, AT1 receptor expression increased markedly, and the up-regulation of SDF-1, and its receptor C-X-C chemokine receptor 7, was documented on podocytes and PECs, respectively. In vitro studies were instrumental to demonstrating the role of ang II in inducing podocyte SDF-1 production, which ultimately activates PECs. The present findings support the possibility that angiotensin-converting enzyme inhibitor treatment might limit PEC activation and reduce the frequency and extension of crescents in extracapillary GN.

Is CD44 in glomerular parietal epithelial cells a pathological marker of renal function deterioration in primary focal segmental glomerulosclerosis?

The search for risk factors for chronic kidney disease in children with focal segmental glomerulosclerosis (FSGS) is important in defining prognosis and individualized treatment. This study preliminarily investigated whether CD44 immunostaining in glomerular parietal epithelial cells (PECs) is a prognostic marker in pediatric FSGS.

Retinoic acid improves nephrotoxic serum-induced glomerulonephritis through activation of podocyte retinoic acid receptor α.

Proliferation of glomerular epithelial cells, including podocytes, is a key histologic feature of crescentic glomerulonephritis. We previously found that retinoic acid (RA) inhibits proliferation and induces differentiation of podocytes by activating RA receptor-α (RARα) in a murine model of HIV-associated nephropathy. Here, we examined whether RA would similarly protect podocytes against nephrotoxic serum-induced crescentic glomerulonephritis and whether this effect was mediated by podocyte RARα. RA treatment markedly improved renal function and reduced the number of crescentic lesions in nephritic wild-type mice, while this protection was largely lost in mice with podocyte-specific ablation of Rara (Pod-Rara knockout). At a cellular level, RA significantly restored the expression of podocyte differentiation markers in nephritic wild-type mice, but not in nephritic Pod-Rara knockout mice. Furthermore, RA suppressed the expression of cell injury, proliferation, and parietal epithelial cell markers in nephritic wild-type mice, all of which were significantly dampened in nephritic Pod-Rara knockout mice. Interestingly, RA treatment led to the coexpression of podocyte and parietal epithelial cell markers in a small subset of glomerular cells in nephritic mice, suggesting that RA may induce transdifferentiation of parietal epithelial cells toward a podocyte phenotype. In vitro, RA directly inhibited the proliferation of parietal epithelial cells and enhanced the expression of podocyte markers. In vivo lineage tracing of labeled parietal epithelial cells confirmed that RA increased the number of parietal epithelial cells expressing podocyte markers in nephritic glomeruli. Thus, RA attenuates crescentic glomerulonephritis primarily through RARα-mediated protection of podocytes and in part through the inhibition of parietal epithelial cell proliferation and induction of their transdifferentiation into podocytes.

Genetic ablation of carbonic anhydrase IX disrupts gastric barrier function via claudin-18 downregulation and acid backflux.

The study aims to explore the molecular mechanisms for the parietal cell loss and fundic hyperplasia observed in gastric mucosa of mice lacking the carbonic anhydrase 9 (CAIX).

Congenital lingual cyst: Expression of MUC protein and report of a new case.

Lingual congenital cysts are uncommon lesions that alter the functions of speech, swallowing and breathing when they have considerable dimension. They usually appear from birth and increase in size gradually in childhood and adolescence. While there are a considerable number of case reports, the nomenclature and origin of this lesion are controversial. Congenital lingual cysts are composed of an epithelial lining that can show heterogeneous histological features, such as globed, ciliated, squamous and parietal cells, while the wall presents mature connective tissue and eventually smooth muscle. In the present manuscript, we report a case of a congenital lingual cyst in a 13-year-old boy, as well as the immunoexpression of MUC family proteins (MUC-1 and MUC-5AC), hoping to provide data that will help to clarify the possible etiology of this lesion.

Caffeine induces gastric acid secretion via bitter taste signaling in gastric parietal cells.

Caffeine, generally known as a stimulant of gastric acid secretion (GAS), is a bitter-tasting compound that activates several taste type 2 bitter receptors (TAS2Rs). TAS2Rs are expressed in the mouth and in several extraoral sites, e.g., in the gastrointestinal tract, in which their functional role still needs to be clarified. We hypothesized that caffeine evokes effects on GAS by activation of oral and gastric TAS2Rs and demonstrate that caffeine, when administered encapsulated, stimulates GAS, whereas oral administration of a caffeine solution delays GAS in healthy human subjects. Correlation analysis of data obtained from ingestion of the caffeine solution revealed an association between the magnitude of the GAS response and the perceived bitterness, suggesting a functional role of oral TAS2Rs in GAS. Expression of TAS2Rs, including cognate TAS2Rs for caffeine, was shown in human gastric epithelial cells of the corpus/fundus and in HGT-1 cells, a model for the study of GAS. In HGT-1 cells, various bitter compounds as well as caffeine stimulated proton secretion, whereby the caffeine-evoked effect was (i) shown to depend on one of its cognate receptor, TAS2R43, and adenylyl cyclase; and (ii) reduced by homoeriodictyol (HED), a known inhibitor of caffeine's bitter taste. This inhibitory effect of HED on caffeine-induced GAS was verified in healthy human subjects. These findings (i) demonstrate that bitter taste receptors in the stomach and the oral cavity are involved in the regulation of GAS and (ii) suggest that bitter tastants and bitter-masking compounds could be potentially useful therapeutics to regulate gastric pH.

An In Vitro Model of Gastric Inflammation and Treatment with Cobalamin.

Pernicious anaemia (PA) is an autoimmune condition where antibodies target intrinsic factor and parietal cells, reducing the patient's ability to absorb cobalamin promoting atrophic gastritis. Treatment guidelines are based on excretion data of hydroxocobalamin from healthy individuals obtained 50 years ago. This manuscript describes the use of phorbol 12-myristate 13-acetate (PMA) to stimulate low grade inflammation in an epithelial colorectal cell line to assess the efficacy of methylcobalamin and hydroxocobalamin. Nitric oxide increased significantly in cells exposed to higher doses of PMA (100 ng/ml, 150 ng/ml, and 200 ng/ml) accompanied by a loss of the characteristic cobblestone morphology with no negative effect on cell activity or viability. A significant reduction in nitric oxide production was associated with the addition of 200 pg/ml hydroxocobalamin, alongside a return to the characteristic cobblestone morphology. This study highlights the use of PMA to promote low grade inflammation in human cell lines to model gastric inflammation associated with autoimmunity; furthermore it raises questions regarding the concentration of cobalamin administered clinically to restore cell functionality, feasibly allowing the patient to receive reduced quantity of the vitamin more regularly, providing the patient with levels which are akin to dietary intake.

PAX2 is dispensable for in vitro nephron formation from human induced pluripotent stem cells.

The kidney is formed by reciprocal interactions between the nephron progenitor and the ureteric bud, the former of which gives rise to the epithelia of nephrons consisting of glomeruli and renal tubules. The transcription factor PAX2 is essential for this mesenchymal-to-epithelial transition of nephron progenitors, as well as ureteric bud lineage development, in mice. PAX2 mutations in humans cause renal coloboma syndrome. We previously reported the induction of nephron progenitors and three-dimensional nephron structures from human induced pluripotent stem (iPS) cells. Here we generate iPS cells lacking PAX2, and address the role of PAX2 in our in vitro induction protocol. While PAX2-null human nephron progenitors were properly formed, they unexpectedly became epithelialised to form glomeruli and renal tubules. However, the mutant glomerular parietal epithelial cells failed to transit to the squamous morphology, retaining the shape and markers of columnar epithelia. Therefore, PAX2 is dispensable for mesenchymal-to-epithelial transition of nephron progenitors, but is required for morphological development of glomerular parietal epithelial cells, during nephron formation from human iPS cells in vitro.

Ischemia-induced glomerular parietal epithelial cells hyperplasia: Commonly misdiagnosed cellular crescent in renal biopsy.

Ischemic pseudo-cellular crescent (IPCC) that is induced by ischemia and composed of hyperplastic glomerular parietal epithelial cells resembles cellular crescent. In this study, we aimed to assess the clinical and pathological features of IPCC in renal biopsy to avoid over-diagnosis and to determine the diagnostic basis. 4 IPCC cases diagnosed over a 4-year period (2012-2015) were evaluated for the study. Meanwhile, 5 cases of ANCA-associated glomerulonephritis and 5 cases of lupus nephritis (LN) were selected as control. Appropriate clinical data, morphology, and immunohistochemical features of all cases were retrieved. Results showed that the basement membrane of glomerulus with IPCC appeared as a concentric twisted ball, and glomerular cells of the lesion were reduced even entirely absent, and the adjacent afferent arterioles showed sclerosis or luminal stenosis. Furthermore, immune globulin deposition, vasculitis, and fibrinous exudate have not been observed in IPCC. While the cellular crescents showed diverse characteristics in both morphology and immunostaining in the control group. Therefore, these results indicated that IPCC is a sort of ischemic reactive hyperplasia and associated with sclerosis, stenosis, or obstruction of adjacent afferent arterioles, which is clearly different from cellular crescents result from glomerulonephritis.

Lgr5-expressing chief cells drive epithelial regeneration and cancer in the oxyntic stomach.

The daily renewal of the corpus epithelium is fuelled by adult stem cells residing within tubular glands, but the identity of these stem cells remains controversial. Lgr5 marks homeostatic stem cells and 'reserve' stem cells in multiple tissues. Here, we report Lgr5 expression in a subpopulation of chief cells in mouse and human corpus glands. Using a non-variegated Lgr5-2A-CreERT2 mouse model, we show by lineage tracing that Lgr5-expressing chief cells do not behave as corpus stem cells during homeostasis, but are recruited to function as stem cells to effect epithelial renewal following injury by activating Wnt signalling. Ablation of Lgr5(+) cells severely impairs epithelial homeostasis in the corpus, indicating an essential role for these Lgr5(+) cells in maintaining the homeostatic stem cell pool. We additionally define Lgr5(+) chief cells as a major cell-of-origin of gastric cancer. These findings reveal clinically relevant insights into homeostasis, repair and cancer in the corpus.

Metaplasia in the Stomach Arises From Gastric Chief Cells.

The development of intestinal-type gastric cancer is preceded by loss of parietal cells (oxyntic atrophy) and the induction of metaplastic cell lineages in the gastric mucosa. For example, mouse models have shown that spasmolytic polypeptide-expressing metaplasia can develop following oxyntic atrophy through transdifferentiation of zymogen-secreting chief cells. Evolution of spasmolytic polypeptide-expressing metaplasia from chief cells occurs via a coordinated dismantling of their secretory apparatus and reprogramming of their transcriptome. Increasing evidence suggests that the process of chief cell reprogramming requires the influence of inflammatory cytokines and requires both zymogen granule autophagy and alterations in gene transcription. It is likely that spasmolytic polypeptide-expressing metaplasia is a physiological repair mechanism that is similar to those that occur in other tissues (eg, pancreas) for recruiting reparative progenitor cells in response to mucosal wounds. Chronic inflammation can induce a recurring pattern of persistent reprogramming/metaplasia that increases the risk for neoplasia.

Multiplex autoantibody detection for autoimmune liver diseases and autoimmune gastritis.

Autoantibody detection for autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC) and autoimmune gastritis (AIG) is traditionally performed by IIF on a combination of tissues. Multiplex line/dot blots (LIA/DIA) offer multiple advantages, i.e. automation, objective reading, no interfering reactivities, no coincidental findings. In the current study we evaluated automated DIA (D-Tek) for detecting autoantibodies related to autoimmune diseases of the gastrointestinal tract. We tested samples of the Dutch EQC program and compared the results with the consensus of the participating labs. For the autoimmune liver diseases and AIG, respectively, 64 and 36 samples were tested. For anti-mitochondrial and anti-smooth muscle antibodies a concordance rate of 97% and 88% was observed, respectively. The concordance rate for anti-parietal cell antibodies was 92% when samples without EQC consensus (n=15) were excluded. For antibodies against intrinsic factor a concordance of 96% was observed. For all these antibodies discrepancies were identified that relate to the different test characteristics and the preponderance of IIF utilizing labs in the EQC program. In conclusion, we observed good agreement of the tested DIA blots with the consensus results of the Dutch EQC program. Taken together with the logistic advantages these blots are a good alternative for autoantibody detection in the respective diseases. A large prospective multicenter study is warranted to position these novel tests further in the whole spectrum of assays for the detection of these antibodies in a routine autoimmune laboratory.

Characterization by Lectin Histochemistry of Two Subpopulations of Parietal Cells in the Rat Gastric Glands.

Parietal cells undergo a differentiation process while they move from the isthmus toward the pits and the base region of the gastric gland. The aim of this work was to analyze the rat gastric glands by lectin histochemistry to show the glycans expressed by upper (young) and lower (old) parietal cells. We used lectins recognizing the most frequent sugar moieties in mammals. Each lectin was assayed alone and in combination with several deglycosylation pretreatments: (1) β-elimination, which removes O-linked oligosaccharides; (2) incubation with Peptide-N-glycosidase F, to remove N-linked glycans; (3) acid hydrolysis, which removes terminal sialic acid moieties; (4) methylation-saponification, to remove sulfate groups from sugar residues; and (5) glucose oxidase, a technique carried out with the lectin concanavalin A to convert glucose into gluconic acid. The lectins from Helix pomatia, Dolichos biflorus (DBA), Glycine max (soybean), Maclura pomifera, Arachis hypogaea (peanut), Bandeiraea simplicifolia (lectin I-B4), and Datura stramonium showed a different glycan expression in the parietal cells throughout the gastric gland. This difference supports that parietal cells undergo a maturation/degeneration process while the cells descend along the gland. The role of DBA as a marker of parietal cells previously reported should be taken with caution because these cells showed different reactivity for the lectin, ranging from negative to strong labeling.

Expression of Adenosine A2B Receptor and Adenosine Deaminase in Rabbit Gastric Mucosa ECL Cells.

Adenosine is readily available to the glandular epithelium of the stomach. Formed continuously in intracellular and extracellular locations, it is notably produced from ATP released in enteric cotransmission. Adenosine analogs modulate chloride secretion in gastric glands and activate acid secretion in isolated parietal cells through A2B adenosine receptor (A2BR) binding. A functional link between surface A2BR and adenosine deaminase (ADA) was found in parietal cells, but whether this connection is a general feature of gastric mucosa cells is unknown. Here we examine whether A2BR is expressed at the membrane of histamine-producing enterochromaffin-like (ECL) cells, the major endocrine cell type in the oxyntic mucosa, and if so, whether it has a vicinity relationship with ADA. We used a highly homogeneous population of rabbit ECL cells (size 7.5-10 µm) after purification by elutriation centrifugation. The surface expression of A2BR and ADA proteins was assessed by flow cytometry and confocal microscopy. Our findings demonstrate that A2BR and ADA are partially coexpressed at the gastric ECL cell surface and that A2BR is functional, with regard to binding of adenosine analogs and adenylate cyclase activation. The physiological relevance of A2BR and ADA association in regulating histamine release is yet to be explained.

Gastrin induces parathyroid hormone-like hormone expression in gastric parietal cells.

Parietal cells play a fundamental role in stomach maintenance, not only by creating a pathogen-free environment through the production of gastric acid, but also by secreting growth factors important for homeostasis of the gastric epithelium. The gastrointestinal hormone gastrin is known to be a central regulator of both parietal cell function and gastric epithelial cell proliferation and differentiation. Our previous gene expression profiling studies of mouse stomach identified parathyroid hormone-like hormone (PTHLH) as a potential gastrin-regulated gastric growth factor. Although PTHLH is commonly overexpressed in gastric tumors, its normal expression, function, and regulation in the stomach are poorly understood. In this study we used pharmacologic and genetic mouse models as well as human gastric cancer cell lines to determine the cellular localization and regulation of this growth factor by the hormone gastrin. Analysis of Pthlh(LacZ/+) knock-in reporter mice localized Pthlh expression to parietal cells in the gastric corpus. Regulation by gastrin was demonstrated by increased Pthlh mRNA abundance after acute gastrin treatment in wild-type mice and reduced expression in gastrin-deficient mice. PTHLH transcripts were also observed in normal human stomach as well as in human gastric cancer cell lines. Gastrin treatment of AGS-E gastric cancer cells induced a rapid and robust increase in numerous PTHLH mRNA isoforms. This induction was largely due to increased transcriptional initiation, although analysis of mRNA half-life showed that gastrin treatment also extended the half-life of PTHLH mRNA, suggesting that gastrin regulates expression by both transcriptional and posttranscriptional mechanisms.NEW & NOTEWORTHY We show that the growth factor parathyroid hormone-like hormone (PTHLH) is expressed in acid-secreting parietal cells of the mouse stomach. We define the specific PTHLH mRNA isoforms expressed in human stomach and in human gastric cancer cell lines and show that gastrin induces PTHLH expression via transcription activation and mRNA stabilization. Our findings suggest that PTHLH is a gastrin-regulated growth factor that might contribute to gastric epithelial cell homeostasis.

What can target kidney fibrosis?

Fibrosis, a characteristic of all chronic kidney diseases, is now recognized to be an independent predictor of disease progression. Deposition of pathological matrix in the walls of glomerular capillaries, the interstitial space and around arterioles both predicts and contributes to functional demise of the nephron and its surrounding vasculature. Recent identification of the major cell populations of fibroblast precursors in the kidney interstitium as pericytes and tissue-resident mesenchymal stem cells, and in the glomerulus as podocytes, parietal epithelial and mesangial cells, has enabled the study of the fibrogenic process in much greater depth directly in the fibroblast precursors. These cells are not only matrix-producing cells, but are also important innate immune surveillance cells that regulate the inflammatory process, exacerbate tissue damage by release of radicals and cytokines, and contribute to parenchymal and microvascular dysfunction by aberrant wound-healing responses. Innate immune signaling in fibroblasts and their precursors is intimately intertwined with the process of fibrogenesis. In addition, genomic and genetic studies also point to defective responses in loci close to genes involved in solute transport, metabolism, autophagy, protein handling and vascular homeostasis, principally in the epithelium and endothelium, as upstream drivers of the fibrotic process, indicating that cellular crosstalk is vital for development of fibrosis. As we move beyond TGFβ inhibition as a central target for fibrosis, targeting innate immune signaling and metabolic dysfunction appear increasingly tenable alternative targets for novel therapies.

Comprehensive molecular screening strategy of OCLN in band-like calcification with simplified gyration and polymicrogyria.

Occludin (OCLN) is an important component of the tight junction complex, providing apical intercellular connections between adjacent cells in endothelial and epithelial tissue. In 2010 O'Driscoll et al reported mutations in OCLN to cause band-like calcification with simplified gyration and polymicrogyria (BLC-PMG). BLC-PMG is a rare autosomal recessive syndrome, characterized by early onset seizures, progressive microcephaly, severe developmental delay and deep cortical gray matter and basal ganglia calcification with symmetrical, predominantly fronto-parietal, polymicrogyria. Here we report 4 additional cases of BLC-PMG with novel OCLN mutations, and provide a summary of the published mutational spectrum. More generally, we describe a comprehensive molecular screening strategy taking into account the technical challenges associated with the genetic architecture of OCLN, which include the presence of a pseudo-gene and copy number variants.

Parietal cells-new perspectives in glomerular disease.

In normal glomeruli, parietal epithelial cells (PECs) line the inside of Bowman's capsule and form an inconspicuous sheet of flat epithelial cells in continuity with the proximal tubular epithelial cells (PTECs) at the urinary pole and with the podocytes at the vascular pole. PECs, PTECs and podocytes have a common mesenchymal origin and are the result of divergent differentiation during embryogenesis. Podocytes and PTECs are highly differentiated cells with well-established functions pertaining to the maintenance of the filtration barrier and transport, respectively. For PECs, no specific function other than a structural one has been known until recently. Possible important functions for PECs in the fate of the glomerulus in glomerular disease have now become apparent: (1) PECs may be involved in the replacement of lost podocytes; (2) PECs form the basis of extracapillary proliferative lesions and subsequent sclerosis in glomerular disease. In addition to the acknowledgement that PECs are crucial in glomerular disease, knowledge has been gained regarding the molecular processes driving the phenotypic changes and behavior of PECs. Understanding these molecular processes is important for the development of specific therapeutic approaches aimed at either stimulation of the regenerative function of PECs or inhibition of the pro-sclerotic action of PECs. In this review, we discuss recent advances pertaining to the role of PECs in glomerular regeneration and disease and address the major molecular processes involved.

Tracking the stochastic fate of cells of the renin lineage after podocyte depletion using multicolor reporters and intravital imaging.

Podocyte depletion plays a major role in focal segmental glomerular sclerosis (FSGS). Because cells of the renin lineage (CoRL) serve as adult podocyte and parietal epithelial cell (PEC) progenitor candidates, we generated Ren1cCre/R26R-ConfettiTG/WT and Ren1dCre/R26R-ConfettiTG/WT mice to determine CoRL clonality during podocyte replacement. Four CoRL reporters (GFP, YFP, RFP, CFP) were restricted to cells in the juxtaglomerular compartment (JGC) at baseline. Following abrupt podocyte depletion in experimental FSGS, all four CoRL reporters were detected in a subset of glomeruli at day 28, where they co-expressed de novo four podocyte proteins (podocin, nephrin, WT-1 and p57) and two glomerular parietal epithelial cell (PEC) proteins (claudin-1, PAX8). To monitor the precise migration of a subset of CoRL over a 2w period following podocyte depletion, intravital multiphoton microscopy was used. Our findings demonstrate direct visual support for the migration of single CoRL from the JGC to the parietal Bowman's capsule, early proximal tubule, mesangium and glomerular tuft. In summary, these results suggest that following podocyte depletion, multi-clonal CoRL migrate to the glomerulus and replace podocyte and PECs in experimental FSGS.

Can podocytes be regenerated in adults?

Podocytes are critical components of the nephron filtration barrier and are depleted in many kidney injuries and disease states. Terminally differentiated adult podocytes are highly specialized, postmitotic cells, raising the question of whether the body has any ability to regenerate lost podocytes. This timely question has recently been illuminated by a series of innovative studies. Here, we review recent progress on this topic of significant interest and debate.

MicroRNAs as Master Regulators of Glomerular Function in Health and Disease.

MicroRNAs (miRNAs) are important regulators of gene expression, and the dysregulation of miRNAs is a common feature of several diseases. More miRNAs are identified almost daily, revealing the complexity of these transcripts in eukaryotic cellular networks. The study of renal miRNAs, using genetically modified mice or by perturbing endogenous miRNA levels, has revealed the important biologic roles miRNAs have in the major cell lineages that compose the glomerulus. Here, we provide an overview of miRNA biogenesis and function in regulating key genes and cellular pathways in glomerular cells during development and homeostasis. Moreover, we focus on the emerging mechanisms through which miRNAs contribute to different diseases affecting the glomerulus, such as FSGS, IgA nephropathy, lupus nephritis, and diabetic nephropathy. In-depth knowledge of miRNA-based gene regulation has made it possible to unravel pathomechanisms, enabling the design of new therapeutic strategies for glomerular diseases for which available therapies are not fully efficacious.

Compound effects of aging and experimental FSGS on glomerular epithelial cells.

Advanced age portends a poorer prognosis in FSGS. To understand the impact of age on glomerular podocytes and parietal epithelial cells (PECs), experimental FSGS was induced in 3m-old mice (20-year old human age) and 27m-old mice (78-year old human age) by abruptly depleting podocytes with a cytopathic anti-podocyte antibody. Despite similar binding of the disease-inducing antibody, podocyte density was lower in aged FSGS mice compared to young FSGS mice. Activated PEC density was higher in aged versus young FSGS mice, as was the percentage of total activated PECs. Additionally, the percentage of glomeruli containing PECs with evidence of phosphorylated ERK and EMT was higher in aged FSGS mice. Extracellular matrix, measured by collagen IV and silver staining, was higher in aged FSGS mice along Bowman's capsule. However, collagen IV accumulation in the glomerular tufts alone and in glomeruli with both tuft and Bowman's capsule accumulation were similar in young FSGS and aged FSGS mice. Thus, the major difference in collagen IV staining in FSGS was along Bowman's capsule in aged mice. The significant differences in podocytes, PECs and extracellular matrix accumulation between young mice and old mice with FSGS might explain the differences in outcomes in FSGS based on age.

Silver nanoparticles alter the permeability of sheep pleura and of sheep and human pleural mesothelial cell monolayers.

Nanoparticles have been implicated in the development of pleural effusions in exposed factory workers while in experimental animal studies it has been shown that they induce inflammation, fibrosis and carcinogenesis in the pleura. The scope of this study was to investigate the direct effects of silver nanoparticles exposure on the membrane permeability of sheep parietal pleura, of primary sheep pleural cell monolayers and on a human mesothelial cell line. Our findings suggest that acute (30min) exposure increases the pleural permeability ex vivo, while longer (24h) exposure in vivo leads to late decrease of the pleural cell monolayers permeability.

Therapeutic Efficacy of Esomeprazole in Cotton Smoke-Induced Lung Injury Model.

Proton pump inhibitors (PPIs) are well-known antacid drugs developed to treat gastric disorders. Emerging studies demonstrate that PPIs possess biological activities that extend beyond inhibition of H(+)/K(+) ATPase (proton pumps) expressed in parietal cells of the stomach. Some of the extra-gastric activities of PPIs include modulation of epithelial, endothelial, and immune cell functions. Recently, we reported that PPIs suppress the expression of several proinflammatory and profibrotic molecules, as well as enhance antioxidant mechanisms in order to favorably regulate lung inflammation and fibrosis in an animal model of bleomycin-induced lung injury. In addition, several retrospective clinical studies report that the use of PPIs is associated with beneficial outcomes in chronic lung diseases including idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD). Based on these preclinical and clinical observations, we hypothesized that PPIs ameliorate smoke-induced lung injury. Accordingly, we evaluated the pharmacological efficacy of the PPI esomeprazole in a mouse model of cotton smoke-induced lung injury. The animals were exposed to cotton smoke for 3-weeks in the presence or absence of esomeprazole treatment. We found that therapeutic administration of esomeprazole significantly inhibited the progression of fibrosis throughout the lungs of the animals in this group compared to controls. In addition, esomeprazole also reduced circulating markers of inflammation and fibrosis. Overall, our work extends the emerging anti-inflammatory and antifibrotic potential of PPIs and their role in modulation of chronic lung diseases.

Beta-catenin participates in dialysate-induced peritoneal fibrosis via enhanced peritoneal cell epithelial-to-mesenchymal transition.

Long-term exposure to peritoneal dialysate with high glucose (HG) leads to peritoneal fibrosis and thus decreases dialysis efficiency. In this study, we explored the role of β-catenin in this process. C57BL/6 mice received daily intraperitoneal injection with 10% of the body weight of saline (control), 4.25% glucose peritoneal dialysis fluid (PDF), or PDF combined with 5 mg·kg(-1) of the β-catenin inhibitor ICG-001 (PDF+ICG) for 30 days. Also, mice peritoneal epithelial cells (mPECs) were cultured in 4.25% glucose (HG) or combined with 10 μm ICG-001 (HG+ICG) for 48 h. We found greater thickness of the parietal peritoneum in the PDF-treated mice. Additionally, lower expression of E-cadherin, higher expression of Vimentin, β-catenin, and Snail, and activation of β-catenin was observed in the mice and in HG-treated mPECs, all of which were reversed by ICG-001. The changes in E-cadherin and Vimentin indicated occurrence of the epithelial-to-mesenchymal transition (EMT). Thus, β-catenin signaling participates in the process of HG-induced peritoneal fibrosis, and the EMT of peritoneal epithelial cells is one of the underlying mechanisms of this pathological change.

A single transcription factor is sufficient to induce and maintain secretory cell architecture.

We hypothesized that basic helix-loop-helix (bHLH) MIST1 (BHLHA15) is a "scaling factor" that universally establishes secretory morphology in cells that perform regulated secretion. Here, we show that targeted deletion of MIST1 caused dismantling of the secretory apparatus of diverse exocrine cells. Parietal cells (PCs), whose function is to pump acid into the stomach, normally lack MIST1 and do not perform regulated secretion. Forced expression of MIST1 in PCs caused them to expand their apical cytoplasm, rearrange mitochondrial/lysosome trafficking, and generate large secretory granules. Mist1 induced a cohort of genes regulated by MIST1 in multiple organs but did not affect PC function. MIST1 bound CATATG/CAGCTG E boxes in the first intron of genes that regulate autophagosome/lysosomal degradation, mitochondrial trafficking, and amino acid metabolism. Similar alterations in cell architecture and gene expression were also caused by ectopically inducing MIST1 in vivo in hepatocytes. Thus, MIST1 is a scaling factor necessary and sufficient by itself to induce and maintain secretory cell architecture. Our results indicate that, whereas mature cell types in each organ may have unique developmental origins, cells performing similar physiological functions throughout the body share similar transcription factor-mediated architectural "blueprints."