The ability of epithelial cells to organize through cell–cell adhesion into a functioning epithelium serves the purpose of a tight epithelial protective barrier. Contacts between adjacent cells are made up of tight junctions (TJ), adherens junctions (AJ), and desmosomes with unique cellular functions and a complex molecular composition. These proteins mediate firm mechanical stability, serves as a gatekeeper for the paracellular pathway, and helps in preserving tissue homeostasis. TJ proteins are involved in maintaining cell polarity, in establishing organ-specific apical domains and also in recruiting signaling proteins involved in the regulation of various important cellular functions including proliferation, differentiation, and migration. As a vital component of the epithelial barrier, TJs are under a constant threat from proinflammatory mediators, pathogenic viruses and bacteria, aiding inflammation and the development of disease. Inflammatory bowel disease (IBD) patients reveal loss of TJ barrier function, increased levels of proinflammatory cytokines, and immune dysregulation; yet, the relationship between these events is partly understood. Although TJ barrier defects are inadequate to cause experimental IBD, mucosal immune activation is changed in response to augmented epithelial permeability. Thus, the current studies suggest that altered barrier function may predispose or increase disease progression and therapies targeted to specifically restore the barrier function may provide a substitute or supplement to immunologic-based therapies. This review provides a brief introduction about the TJs, AJs, structure and function of TJ proteins. The link between TJ proteins and key signaling pathways in cell proliferation, transformation, and metastasis is discussed thoroughly. We also discuss the compromised intestinal TJ integrity under inflammatory conditions, and the signaling mechanisms involved that bridge inflammation and cancer.

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Claudins, a group of membrane proteins involved in the formation of tight junctions, are mainly found in endothelial or epithelial cells. These proteins have attracted much attention in recent years and have been implicated and studied in a multitude of diseases. Claudins not only regulate paracellular transepithelial/transendothelial transport but are also critical for cell growth and differentiation. Not only tissue-specific but the differential expression in malignant tumors is also the focus of claudin-related research. In addition to up- or down-regulation, claudin proteins also undergo delocalization, which plays a vital role in tumor invasion and aggressiveness. Claudin (CLDN)-1 is the most-studied claudin in cancers and to date, its role as either a tumor promoter or suppressor (or both) is not established. In some cancers, lower expression of CLDN-1 is shown to be associated with cancer progression and invasion, while in others, loss of CLDN-1 improves the patient survival. Another topic of discussion regarding the significance of CLDN-1 is its localization (nuclear or cytoplasmic vs perijunctional) in diseased states. This article reviews the evidence regarding CLDN-1 in cancers either as a tumor promoter or suppressor from the literature and we also review the literature regarding the pattern of CLDN-1 distribution in different cancers, focusing on whether this localization is associated with tumor aggressiveness. Furthermore, we utilized expression data from The Cancer Genome Atlas (TCGA) to investigate the association between CLDN-1 expression and overall survival (OS) in different cancer types. We also used TCGA data to compare CLDN-1 expression in normal and tumor tissues. Additionally, a pathway interaction analysis was performed to investigate the interaction of CLDN-1 with other proteins and as a future therapeutic target.

We have investigated the prevalence of mutations in the connexin 26 (GJB2) gene in Omani population using both PCR-RFLP and direct DNA sequencing methods. Two common GJB2 gene mutations (35delG and 167delT) were screened in 280 healthy controls and 95 deaf patients using two different PCR-RFLP methods. To investigate other GJB2 mutations, we have amplified and sequenced DNA from 51 unrelated deaf patients and 17 control subjects. None of the samples studied, either by RFLP or sequencing, revealed any deafness-associated mutations in the coding region of the GJB2 gene. These findings disagree with many reports on the GJB2 gene, describing various mutations as the cause of congenital recessive deafness. Although, an amino acid substitution (S86T) was identified by sequencing, we conclude that this change could not be associated with deafness since it was present in all the control and patient samples sequenced.

The I-B kinase (IKK) subunit NEMO/IKK␥ (NEMO) is an adapter molecule that is critical for canonical activation of NF-B, a pleiotropic transcription factor controlling immunity, differentiation, cell growth, tumorigenesis, and apoptosis. To explore the functional role of canonical NF-B signaling in thyroid gland differentiation and function, we have generated a murine strain bearing a genetic deletion of the NEMO locus in thyroid. Here we show that thyrocyte-specific NEMO knock-out mice gradually develop hypothyroidism after birth, which leads to reduced body weight and shortened life span. Histological and molecular analysis indicate that absence of NEMO in thyrocytes results in a dramatic loss of the thyroid gland cellularity, associated with down-regulation of thyroid differentiation markers and ongoing apoptosis. Thus, NEMO-dependent signaling is essential for normal thyroid physiology.

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Diet plays a major role in the body physiology and metabolism. The quantity, nature and stability of the macronutrients present in the diet have a major impact on the composition of gut microbiota. Gut microbiota plays a major role in the body metabolism and leads to obese or lean phenotype. Bacteriodetes, Firmicutes, Proteobacteria and Actinobacteria are the major microbes that inhabit in the region of the gut. We made an attempt to study the effects of Cafeteria (CAF) diets and normal chow diets on diet consumption, weight gain, metabolism and composition of gut microbiota in fecal and cecum samples from three weeks old Sprague Dawley (SD) rats (n = 18/group) using 16S rDNA high throughput sequencing. Results revealed that distinctive diet based phenotypical changes were observed in some of the Cafeteria diet fed rats. Interestingly, some weight gain resistant (WGR) animals in Cafeteria diet fed groups show similar trend like that of control normal chow fed rats. Fecal microbiome analysis indicates that the ratio of Bacteriodetes is higher than the Firmicutes in cecum samples of Cafeteria diet fed rats whereas no significant difference is found in fecal samples of Cafeteria diet fed rats and as well as in control rats. Further analysis of other taxa at the level of family and genus of microbial abundance are also discussed. Our study suggests that contribution of gut microbiota towards obesity is not at the phylum level, and microbiome composition even at the level of species or strain may exert impact on the metabolism of the Cafeteria diet.

Lafora epilepsy is characterized by starch formation in brain and skin and is diagnosed by skin biopsy or mutation detection. It has variable ages of onset (6-19 years) and death (18-32 years) even with the same mutation, likely due to extramutational factors. The authors identified 14 Lafora epilepsy patients in the genetic isolate of tribal Oman. The authors show that in this homogeneous environment and gene pool, the same mutation, EPM2B-c.468-469delAG, results in highly uniform ages of onset (14 years) and death (21 years). Biopsy, on the other hand, was not homogeneous (positive in 4/5 patients) and is, therefore, less sensitive than mutation testing.