Non-muscle myosin II deletion in the developing kidney causes ureter-bladder misconnection and apical extrusion of the nephric duct lineage epithelia.

In kidney development, connection of the nephric duct (ND) to the cloaca and subsequent sprouting of the ureteric bud (UB) from the ND are important for urinary exit tract formation. Although the roles of Ret signaling are well established, it remains unclear how intracellular cytoskeletal proteins regulate these morphogenetic processes. Myh9 and Myh10 encode two different non-muscle myosin II heavy chains, and Myh9 mutations in humans are implicated in congenital kidney diseases. Here we report that ND/UB lineage-specific deletion of Myh9/Myh10 in mice caused severe hydroureter/hydronephrosis at birth. At mid-gestation, the mutant ND/UB epithelia exhibited aberrant basal protrusion and ectopic UB formation, which likely led to misconnection of the ureter to the bladder. In addition, the mutant epithelia exhibited apical extrusion followed by massive apoptosis in the lumen, which could be explained by reduced apical constriction and intercellular adhesion mediated by E-cadherin. These phenotypes were not ameliorated by genetic reduction of the tyrosine kinase receptor Ret. In contrast, ERK was activated in the mutant cells and its chemical inhibition partially ameliorated the phenotypes. Thus, myosin II is essential for maintaining the apicobasal integrity of the developing kidney epithelia independently of Ret signaling.

Gene-Environment Interactions Target Mitogen-activated Protein 3 Kinase 1 (MAP3K1) Signaling in Eyelid Morphogenesis.

Gene-environment interactions determine the biological outcomes through mechanisms that are poorly understood. Mouse embryonic eyelid closure is a well defined model to study the genetic control of developmental programs. Using this model, we investigated how exposure to dioxin-like environmental pollutants modifies the genetic risk of developmental abnormalities. Our studies reveal that mitogen-activated protein 3 kinase 1 (MAP3K1) signaling is a focal point of gene-environment cross-talk. Dioxin exposure, acting through the aryl hydrocarbon receptor (AHR), blocked eyelid closure in genetic mutants in which MAP3K1 signaling was attenuated but did not disturb this developmental program in either wild type or mutant mice with attenuated epidermal growth factor receptor or WNT signaling. Exposure also markedly inhibited c-Jun phosphorylation in Map3k1(+/-) embryonic eyelid epithelium, suggesting that dioxin-induced AHR pathways can synergize with gene mutations to inhibit MAP3K1 signaling. Our studies uncover a novel mechanism through which the dioxin-AHR axis interacts with the MAP3K1 signaling pathways during fetal development and provide strong empirical evidence that specific gene alterations can increase the risk of developmental abnormalities driven by environmental pollutant exposure.

Increased nuclear ß-catenin expression in oral potentially malignant lesions: A marker of epithelial dysplasia.

BACKGROUND: Deregulation of ß-catenin is associated with malignant transformation; however, its relationship with potentially malignant and malignant oral processes is not fully understood. The aim of this study was to determine and compare the nuclear ß-catenin expression in oral dysplasia and oral squamous cell carcinoma (OSCC). MATERIAL AND METHODS: Cross sectional study. Immunodetection of ß-catenin was performed on 72 samples, with the following distribution: 21 mild dysplasia, 12 moderate dysplasia, severe dysplasia 3, 36 OSCC including 19 well differentiated, 15 moderately differentiated and 2 poorly differentiated. Through microscopic observation the number of positive cells per 1000 epithelial cells was counted. For the statistical analysis, the Kruskal Wallis test was used. RESULTS: Nuclear expression of ß-catenin was observed in all samples with severe and moderate dysplasia, with a median of 267.5, in comparison to mild dysplasia whose median was 103.75. Only 10 samples (27.7%) with OSCC showed nuclear expression, with statistically significant differences between groups (p < 0.05). CONCLUSIONS: Our results are consistent with most of the reports which show increased presence of ß-catenin in severe and moderate dysplasia compared to mild dysplasia; however the expression of nuclear ß-catenin decreased after starting the invasive neoplastic process. This suggests a role for this protein in the progression of dysplasia and early malignant transformation to OSCC. Immunodetection of ß-catenin could be a possible immune marker in the detection of oral dysplasia.

Abnormal WT1 expression in human fetuses with bilateral renal agenesis and cardiac malformations.

BACKGROUND: Bilateral renal agenesis has multiple etiologies. Animal models have provided useful information on possible causes of this condition, but its etiology in humans is less clear. We recently described autopsy findings of two human fetuses with bilateral renal agenesis and abnormal expression of WT1 (Wilms tumor 1) in liver mesothelium. METHODS: We have identified 14 additional fetuses with bilateral renal agenesis from autopsies performed in our institution over the past 10 years and subjected archival liver biopsy specimens from these cases to immunohistochemistry for WT1, as well as α-smooth muscle actin (α-SMA) and desmin to assess liver mesenchymal abnormalities. RESULTS: Six of seven fetuses with combined bilateral renal agenesis and cardiac anomalies showed abnormalities of WT1 expression in liver mesothelial cells, which was not seen in other fetuses with bilateral renal agenesis. Except in one case, the fetuses with renal agenesis and cardiac defects also showed liver mesenchymal anomalies (assessed by increased α-SMA expression), which was not present in other renal agenesis fetuses. CONCLUSIONS: WT1 is widely expressed in mesothelial cells during development, and we hypothesized that some of the defects are caused by abnormal function of mesenchyme derived from mesothelial cells, similar to the mesothelium-derived defects proposed in animal models. The methods we used are available to many laboratories and can be applied to archival paraffin tissue blocks. We suggest that future similar studies could help to expand the understanding of renal agenesis in humans and could help to subclassify this condition. This would be useful in patient management and counseling.

Case Series of Patients With Hereditary Benign Intraepithelial Dyskeratosis.

PURPOSE: The purpose of this retrospective case series was to compare the outcomes of different treatment options for patients diagnosed with hereditary benign intraepithelial dyskeratosis (HBID). METHODS: The study is designed as a single-institution retrospective chart review of patients who were clinically diagnosed with HBID during their care at the Duke Eye Center. Patient demographics were obtained, and disease course after different therapies was analyzed. RESULTS: Seventeen patients were diagnosed with HBID. 52.9% (9/17) of patients identified with HBID reported Native American ancestry. Medical therapy alone failed to reduce the size or number of corneal lesions in any patient identified in this study. Ten of the 17 patients required surgical intervention. Two eyes received corneal biopsies, 3 eyes received a full conjunctival lesion excision with amniotic membrane grafting, 12 eyes received superficial keratectomy with amniotic membrane grafting, and 1 eye received keratoprosthesis. Lesion recurrence was seen in 9 of the 10 patients treated with surgical excision with an average time to recurrence of 1.5 and 2 months for conjunctival excisions and superficial keratectomy, respectively, when excluding patients who missed scheduled postoperative follow-up appointments. CONCLUSIONS: Hereditary benign intraepithelial dyskeratosis is a rare and poorly understood disorder that predominantly affects people with Native American ancestry. Medical therapy only provides symptomatic relief, and patients who receive surgical excision almost always develop recurrence. As a result, we recommend future investigations focus on identifying the optimal surgical technique and timing to limit the morbidity of HBID and improve outcomes.

LET-413 is a basolateral protein required for the assembly of adherens junctions in Caenorhabditis elegans.

Epithelial cells are polarized, with apical and basal compartments demarcated by tight and adherens junctions. Proper establishment of these subapical junctions is critical for normal development and histogenesis. We report the characterization of the gene let-413 which has a critical role in assembling adherens junctions in Caenorhabditis elegans. In let-413 mutants, adherens junctions are abnormal and mislocalized to more basolateral positions, epithelial cell polarity is affected and the actin cytoskeleton is disorganized. The LET-413 protein contains one PDZ domain and 16 leucine-rich repeats with high homology to proteins known to interact with small GTPases. Strikingly, LET-413 localizes to the basolateral membrane. We suggest that LET-413 acts as an adaptor protein involved in polarizing protein trafficking in epithelial cells.

Gliotactin, a novel marker of tricellular junctions, is necessary for septate junction development in Drosophila.

Septate junctions (SJs), similar to tight junctions, function as transepithelial permeability barriers. Gliotactin (Gli) is a cholinesterase-like molecule that is necessary for blood-nerve barrier integrity, and may, therefore, contribute to SJ development or function. To address this hypothesis, we analyzed Gli expression and the Gli mutant phenotype in Drosophila epithelia. In Gli mutants, localization of SJ markers neurexin-IV, discs large, and coracle are disrupted. Furthermore, SJ barrier function is lost as determined by dye permeability assays. These data suggest that Gli is necessary for SJ formation. Surprisingly, Gli distribution only colocalizes with other SJ markers at tricellular junctions, suggesting that Gli has a unique function in SJ development. Ultrastructural analysis of Gli mutants supports this notion. In contrast to other SJ mutants in which septa are missing, septa are present in Gli mutants, but the junction has an immature morphology. We propose a model, whereby Gli acts at tricellular junctions to bind, anchor, or compact SJ strands apically during SJ development.

Combined loss of Hey1 and HeyL causes congenital heart defects because of impaired epithelial to mesenchymal transition.

Congenital heart defects affect almost 1% of human newborns. Recently, mutations in Notch ligands and receptors have been found to cause a variety of heart defects in rodents and humans. However, the molecular effects downstream of Notch are still poorly understood. Here we report that combined inactivation of Hey1 and HeyL, two primary target genes of Notch, causes severe heart malformations, including membranous ventricular septal defects and dysplastic atrioventricular and pulmonary valves. These defects lead to congestive cardiac failure with high lethality. We found both genes to be coexpressed with Notch1, Notch2 and the Notch ligand Jagged1 in the endocardium of the atrioventricular canal, representing the primary source of mesenchymal cells forming membraneous septum and valves. Atrioventricular explants from Hey1/HeyL deficient mice exhibited impaired epithelial to mesenchymal transition. Although epithelial to mesenchymal transition was initiated regularly, full transformation into mesenchymal cells failed. This was accompanied by reduced levels of matrix metalloproteinase-2 expression and reduced cell density in endocardial cushions in vivo. We further show that loss of Hey2 leads to very similar deficiencies, whereas a Notch1 null mutation completely abolishes epithelial to mesenchymal transition. Thus, the Hey gene family shows overlap in controlling Notch induced endocardial epithelial to mesenchymal transition, a process critical for valve and septum formation.

Thymic Epithelium Abnormalities in DiGeorge and Down Syndrome Patients Contribute to Dysregulation in T Cell Development.

The thymus plays a fundamental role in establishing and maintaining central and peripheral tolerance and defects in thymic architecture or AIRE expression result in the development of autoreactive lymphocytes. Patients with partial DiGeorge Syndrome (pDGS) and Down Syndrome (DS) present alterations in size and architecture of the thymus and higher risk to develop autoimmunity. We sought to evaluate thymic architecture and thymocyte development in DGS and DS patients and to determine the extent to which thymic defects result in immune dysregulation and T cell homeostasis perturbation in these patients. Thymi from pediatric patients and age-matched controls were obtained to evaluate cortex and medullary compartments, AIRE expression and thymocyte development. In the same patients we also characterized immunophenotype of peripheral T cells. Phenotypic and functional characterization of thymic and peripheral regulatory T (Treg) cells was finally assessed. Histologic analysis revealed peculiar alterations in thymic medulla size and maturation in DGS and DS patients. Perturbed distribution of thymocytes and altered thymic output was also observed. DGS patients showed lower mature CD4+ and CD8+ T cell frequency, associated with reduced proportion and function of Tregs both in thymus and peripheral blood. DS patients showed increased frequency of single positive (SP) thymocytes and thymic Treg cells. However, Tregs isolated both from thymus and peripheral blood of DS patients showed reduced suppressive ability. Our results provide novel insights on thymic defects associated with DGS and DS and their impact on peripheral immune dysregulation. Indeed, thymic abnormalities and defect in thymocyte development, in particular in Treg cell number and function could contribute in the pathogenesis of the immunodysregulation present in pDGS and in DS patients.

A dominant negative allele of the Drosophila leucine zipper protein Bunched blocks bunched function during tissue patterning.

The bunched (bun) gene encodes the Drosophila member of the TSC-22/GILZ family of leucine zipper transcriptional regulators. The bun locus encodes multiple BUN protein isoforms and has diverse roles during patterning of the eye, wing margin, dorsal notum and eggshell. Here we report the construction and activity of a dominant negative allele (BunDN) of the BUN-B isoform. In the ovary, BunDN expression in the follicle cells (FC) resulted in epithelial defects including aberrant accumulation of DE-cadherin and failure to rearrange into columnar FC cell shapes. BunDN expression in the posterior FC led to loss of epithelial integrity associated with extensive apoptosis. BunDN FC phenotypes collectively resemble loss-of-function bun mutant phenotypes. BunDN expression using tissue-specific imaginal disk drivers resulted in characteristic cuticular patterning defects that were enhanced by bun mutations and suppressed by co-expression of the BUN-B protein isoform. These data indicate that BunDN has dominant negative activity useful to identify bun functions and genetic interactions that occur during tissue patterning.

Cytogenic abnormalities in buccal cells during spinal deformities in children.

Evaluation of the incidence of nucleus abnormalities in buccal epithelium allows detecting the presence and intensity of the effect of various ecological conditions and pathologies of the musculoskeletal system. Two coefficients were used: mean number of NA per cell and ratio of cells with karyolysis to the total number of cells with NA. Coefficient of karyolysis decreases with increasing anthropogenic load In pupils of a special school in Moscow these coefficients were similar. Analysis of coefficients showed that karyolysis coefficient was reduced in mothers of children with spinal deformities.

Effect of folic acid in a modified experimental model of anorectal malformations adriamycin-induced in rats.

PURPOSE: To determine the effect of a single dose of adriamycin (ADR) to induce anorectal malformations (ARMs) and determine the effect of folic acid (FA) in this model. METHODS: Ten female Wistar rats were divided randomly in two groups. Group A - ADR; Group B - FA+ADR. Dams from group B received daily, since two weeks before the pregnancy to the end of pregnancy, FA (50mg/kg) by gavage. Dams from both groups received ADR (6mk/kg) by intraperitoneal injection on gestational day (GD) 8. Their fetuses were harvested by cesarean section on GD21 and were examined looking for ARMs. The thickness of anal stratified squamous epithelium (ASSE) and intestinal epithelium (IE) were analyzed. p≤0.05*. RESULTS: 81 fetuses were harvested. The number of fetuses; number of ARMs; mean (∆%) (± SD) were determined to be, respectively: ADR - 41[29;65%(±37%)] versus FA+ADR - 40[04;16%(±36%)] (p=0.05). AMRs were significantly lower in FA+ADR group than in ADR group (p=0.05). The thickness (µm) of ASSE (± SD) and IE (± SD) were measured, respectively: ADR - [25.98(±0.74) and 19.48(±1.68)] versus FA+ADR - [24.74(±0.91) and 24.80(±0.81)] (p<0.005). The thickness of IE was significantly enlarged when FA was given (p<0.005). CONCLUSIONS: Single dose of adriamycin on D8 was able to induce anorectal malformations. Folic acid reduces the number and enlarged the IE of ARMs ADR-induced.

Hereditary Benign Intraepithelial Dyskeratosis: Report of a Case and Re-examination of the Evidence for Locus Heterogeneity.

BACKGROUND: Hereditary benign intraepithelial dyskeratosis (HBID) is a rare autosomal-dominant disorder of the conjunctiva and oral mucosa first described in and predominantly affecting descendents of Haliwa-Saponi Native Americans. We report a spontaneous case of histopathologically-confirmed HBID affecting an individual not of Native American ancestry. MATERIALS AND METHODS: Report of a case with histopathologic examination of an excised conjunctival specimen as well as molecular and cytogenetic analysis. RESULTS: A Caucasian boy with a history of oral lesions and conjunctival injection from birth developed bilateral corneal opacities at age 5 and underwent penetrating keratoplasty, with recurrence of the corneal opacification shortly after surgery. Examination of a conjunctival biopsy specimen revealed features consistent with HBID. Copy number variant (CNV) analysis revealed a de novo 4q35 duplication that overlapped the duplication previously associated with HBID, although no genes were identified in the common interval. NLRP1 gene sequencing failed to reveal a presumed pathogenic variant. CONCLUSIONS: HBID may develop de novo in individuals who are not of Native American ancestry. The absence of coding regions in a duplicated region of 4q35 common to both the individual that we report and previously associated with HBID raises questions regarding the significance of this CNV in the pathogenesis of HBID.

Cell biology of normal and abnormal ciliogenesis in the ciliated epithelium.

Ciliogenesis is divided into four stages: (1) generation of centrioles, (2) migration of duplicated centrioles, (3) formation of the basal body-associated structures, and (4) elongation of cilia. The ultrastructural profile of ciliogenesis is fundamentally the same among various kinds of animal species. In acentriolar centriologenesis, centrioles are generated around deuterosomes by the use of fibrous granules. Components of the centriolar precursor structures, and genes that regulate the differentiation of ciliated cells, have been revealed. Ciliary abnormalities are classified into two categories: specific congenital defects of ciliary structure and acquired nonspecific anomalies of the ciliary apparatus. When ciliogenesis is disturbed, various nonspecific ciliary abnormalities develop in the cell. Inhibition of centriole migration results in the development of intracytoplasmic axonemes, cilia within periciliary sheaths, and intracellular ciliated vacuoles. Swollen cilia and the bulging type of compound cilia are formed during ciliary budding and elongation. Primary cilia can also develop from one of a pair of centrioles. They lack dynein arms and are immobile, but work as a mechanosensor and play a role during morphogenesis of the kidney. Abnormal function or structure of primary cilia results in the development of polycystic kidney disease. The axonemes of primary cilia or monocilia in the embryonic node cells are associated with dynein arms and move vortically. They have a role in determining the left-right (L-R) asymmetry of the fetus. This review also discusses the ciliogenesis of a primary cilium in the cell.

Effect of N'-nitrosonornicotine (NNN) on murine palatal fusion in vitro.

Maternal smoking has been linked to an increased risk for orofacial clefts. N'-nitrosonornicotine (NNN) is one of the tobacco-specific nitrosamines that has been shown to be linked to the deleterious effects of tobacco and could be linked to the formation of cleft palate birth defects. The effect of NNN on palatal fusion was examined using an in vitro organ culture model of palatal development. The organ cultures were exposed to NNN (0.01, 0.1, 1, 10 and 100 mM) and the effects on palatal development characterized at defined points. Palatal fusion was evaluated at embryonic day 13 (E13)+72 h by characterizing the remaining medial edge epithelium (MEE) and determining the extent of fusion compared to controls. The NNN-treated group (1 mM) had more MEE remaining in the palatal midline than the untreated group at E13+72 h (P<0.05). Changes in cell proliferation in the MEE resulting from NNN exposure were examined by BrdU incorporation in replicating DNA. Changes in the pattern of MEE cell death were examined by TUNEL. BrdU incorporation and TUNEL staining showed that the NNN (1 mM)-treated palates had more MEE cell proliferation and less apoptosis than the untreated-palates at E13+24 h (P<0.05). The mechanism altered by NNN was further evaluated by characterizations of extracellular signal-regulated kinase (ERK) 1/2, p38 and c-jun amino-terminal kinase (JNK). NNN at 1 mM induced ERK1/2 phosphorylation, but reduced p38 phosphorylation (P<0.05, P<0.01, respectively) in the MEE. The results suggest that NNN inhibited palatal fusion by effects on cell proliferation and MEE cell death.

Congenital lesions of epithelial origin.

Defects of embryologic development give rise to a variety of congenital lesions arising from the epithelium and are among the most common congenital lesions of the head and neck in the pediatric population. This article presents several congenital lesions of epithelial origin, including congenital midline cervical cleft, pilomatrixoma, dermoid, foregut duplication cysts, and preauricular sinuses and pits. In addition, the management of these lesions is reviewed.

Extension of the cleft lip phenotype: the subepithelial cleft.

We present a previously undescribed occult malformation of the upper lip manifest by discontinuity of the orbicularis oris muscle. The relationship of this defect to our current concept of abnormal maxillary process development is discussed along with a proposal to extend the cleft lip phenotype.

New clinical aspects of hereditary mucoepithelial dysplasia.

Hereditary mucoepithelial dysplasia (HMD) is a multiepithelial disorder. It is transmitted as an autosomal dominant trait (McKusick: Mendelian Inheritance in Man-Catalogs of Autosomal Dominant, Autosomal Recessive, and X-Linked Phenotypes, 8th edition. Baltimore: The Johns Hopkins University Press, pp 499, 1988). HMD is characterized by variable combinations of lesions of skin, hair, orificial mucosa, gingiva, eyes, and lungs. In some previously described patients, the corneal and pulmonary lesions were progressive and led to blindness, recurrent pneumonia, and/or premature death. On light microscopy, the lesion is characterized by dyskeratosis, and, on electron microscopy, by a paucity of gap junctions and desmosomes. Here, we describe a new 5-generation kindred in which affected individuals had the same histologic characteristics but a somewhat different clinical spectrum and a more benign course. HMD should be considered in the differential diagnosis of childhood alopecia, follicular hyperkeratosis, keratoconjunctivitis, juvenile cataracts, gingival hyperemia, restrictive lung disease, and esophageal stenosis or webs.

Bartsocas-Papas syndrome with internal anomalies: evidence for a more generalized epithelial defect or new syndrome?

We report on two Dutch sibs with external anomalies compatible with Bartsocas-Papas syndrome, who also had internal anomalies: bilateral renal agenesis in one, and esophageal atresia, hypoplastic diaphragma, unilateral renal agenesis, agenesis of the shaft of the penis, and anal atresia in the other patient. Several possible patterns for the pathogenesis of this combination of anomalies are discussed. We propose a generalized epithelial defect, affecting both epidermis and other lining epithelia, as the most probable cause in the present patients.

Incidence of ocular surface epithelial dysplasia in metropolitan Brisbane. A 10-year survey.

The ocular histologic records of all hospital and private pathologic laboratories in metropolitan Brisbane, Australia, were surveyed from 1980 through 1989. One hundred thirty-nine cases of histologically proven dysplasia, carcinoma in situ, and invasive carcinoma of the cornea and conjunctiva were identified. The incidence of these conditions in the area surveyed is estimated to be 1.9 per 100,000 per year averaged for 10 years.