Expression of cell adhesion molecules in the adriamycin-induced esophageal atresia rat model

Role of JNK during buccopharyngeal membrane perforation, the last step of embryonic mouth formation

BACKGROUND

The buccopharyngeal membrane is a thin layer of cells covering the embryonic mouth. The perforation of this structure creates an opening connecting the external and the digestive tube which is essential for oral cavity formation. In humans, persistence of the buccopharyngeal membrane can lead to orofacial defects such as choanal atresia, oral synechiaes, and cleft palate. Little is known about the causes of a persistent buccopharyngeal membrane and, importantly, how this structure ruptures.

RESULTS

We have determined, using antisense and pharmacological approaches, that Xenopus embryos deficient c-Jun N-terminal kinase (JNK) signaling have a persistent buccopharyngeal membrane. JNK deficient embryos have decreased cell division and increased cellular stress and apoptosis. However, altering these processes independently of JNK did not affect buccopharyngeal membrane perforation. JNK deficient embryos also have increased intercellular adhesion and defects in e-cadherin localization. Conversely, embryos with overactive JNK have epidermal fragility, increased E-cadherin internalization, and increased membrane localized clathrin. In the buccopharyngeal membrane, clathrin is colocalized with active JNK. Furthermore, inhibition of endocytosis results in a persistent buccopharyngeal membrane, mimicking the JNK deficient phenotype.

CONCLUSIONS

The results of this study suggest that JNK has a role in the disassembly adherens junctions by means of endocytosis that is required during buccopharyngeal membrane perforation. Developmental Dynamics 246:100-115, 2017. © 2016 Wiley Periodicals, Inc.

The effects of adriamycin on E-cadherin mediated cell-cell adhesion and apoptosis during early kidney development

Adriamycin (ADR) is strongly teratogenic. We investigated the effects of ADR on apoptosis and the intensity of E-cadherin expression in developing kidneys. An experimental group of rats was given 2 mg/kg/day ADR on days 6-9 of gestation and a control group was given saline on the same schedule. Embryos were decapitated on days 13, 15, 17 and 19 of gestation, and processed and embedded in paraffin for routine light microscopy. Kidney specimens were stained with hematoxylin and eosin or periodic acid-Schiff, or immunostained for E-cadherin. Apoptosis was assessed using the TUNEL method. Weight loss and developmental deficiency were determined in embryos of the experimental group. ADR damaged or destroyed tubule epithelial cells, which caused apparent dilatation of the tubule lumen. Also, the brush borders of proximal tubules were damaged and glomerular spaces were dilated. ADR caused apoptosis of kidney tissue by days 15, 17 and 19 of development and E-cadherin expression was up-regulated during kidney development compared to controls. We found that ADR can cause apoptosis and increased E-cadherin expression in the developing rat kidney. E-cadherin expression and apoptosis may contribute to the development of ADR nephrotoxicity.

Adriamycin-Induced Models of VACTERL Association

Animal models are of great importance for medical research. They have enabled analysis of the aetiology and pathogenesis of complex congenital malformations and have also led to major advances in the surgical and therapeutic management of these conditions. Animal models allow us to comprehend the morphological and molecular basis of disease and consequently to discover novel approaches for both surgical and medical therapy. The anthracycline antibiotic adriamycin was incidentally found to have teratogenic effects on rats, producing a range of defects remarkably similar to the VACTERL association of congenital anomalies in humans, providing a reproducible animal model of this condition. VACTERL association is a spectrum of birth defects which includes vertebral, anal, cardiovascular, tracheo-oesophageal, renal and limb anomalies. In recent years, adriamycin rodent models of VACTERL have provided valuable insights into the pathogenesis of this complex association, particularly in relation to tracheo-oesophageal malformations. The adriamycin rat model and adriamycin mouse model are now well established in the investigation of the morphology of faulty organogenesis and the regulation of gene expression in tracheo-oesophageal anomalies.