Differentiation of Colon Cells in Culture
Leonard H. Augenlicht in Cell and Molecular Biology of Colon Cancer, 2019
All those cell lines which express an integrated program of differentiation have some common characteristics. First, these lines form at confluency a monolayer of highly polarized cells. Second, the kinetic analysis of the development of the cell polarity and of the functional differentiation shows that the polarization is fully established and maintained only upon the formation of a continuous monolayer of cells. The coincidental timing of these events suggests that extensive cell-cell contact is an important factor in the development of cell polarity. Interestingly, this hypothesis is in line with the recent finding that cell-cell contacts in the epithelial MDCK cells initiate the formation of a stable, insoluble matrix of the membrane skeleton protein fodrin with preexisting proteins at the cell periphery.63 This matrix might result in the maintenance of membrane domains.
Factors Influencing Growth and Differentiation of Normal and Transformed Human Mammary Epithelial Cells in Culture
George E. Milo, Bruce C. Casto, Charles F. Shuler in Transformation of Human Epithelial Cells: Molecular and Oncogenetic Mechanisms, 2017
The above results led us to propose that the cells which display long-term growth in the serum-free medium represent a multipotent stem cell population initially present in the basal layer of the gland. With increasing time in culture, these cells show a partial differentiation toward the luminal phenotype. Based on phenotypic expression of keratins and other markers, a multipotent basal, stem cell population has also been proposed for the rodent mammary gland.23 However, we cannot be sure that culture conditions have not induced some artifactual phenotypic expression. In particular, growth of cells on impermeable plastic substrates prevents the normal cell-extracellular matrix contacts and precludes the normal development of cellular polarity. The lack of normal cell polarity may in turn affect the cells’ phenotypic expression in culture. Cells which are positive for keratins 5, 14, 8, and 18 are not commonly observed in vivo, although coexpression of keratin 8 and vimentin has been reported.17
Immune function of epithelial cells
Phillip D. Smith, Richard S. Blumberg, Thomas T. MacDonald in Principles of Mucosal Immunology, 2020
Intercellular junctions are under the control of a variety of different host, dietary, and microbial factors. Dietary factors such as glucose and amino acids increase permeability through the actin cytoskeleton by activating myosin light-chain kinase. A similar, though quantitatively greater myosin light-chain kinase activation is responsible for increases in leak pathway flux induced by tumor necrosis factor (TNF)-α or interleukin (IL)-1β. IL-13 and IL-6 also reduce barrier function by increasing claudin-2 expression and pore pathway flux. Microbial factors such as the Clostridium perfringens enterotoxin may reduce barrier function by binding to barrier-enhancing claudin proteins and directing their removal from the tight junction. Other microbial factors, including repeats in toxin (RTX) from Vibrio cholerae, cytokines, or cytolytic T cells, may increase intestinal permeability in a tight junction–independent manner by causing epithelial damage, e.g., apoptosis, that enhances flux across the so-called unrestricted pathway, which is normally sealed by the presence of an intact epithelium. Similar factors can also affect cell polarity and the endocytic and transcellular pathways of membrane and cargo transport. Thus, barrier permeability is under the control of microbial and immune factors.
Roles of membrane lipids in the organization of epithelial cells: Old and new problems
Published in Tissue Barriers, 2018
Examples of cell polarity are found in various cell types of diverse organisms. However, the mechanism by which cell membrane lipids plays a role in cell polarity as well as the mechanism that maintains the asymmetric distribution of cell membrane lipids is unknown in many cases. Furthermore, there are thousands of lipid species constituting the cell membrane. Although analytical methods for lipid composition using mass spectrometry have been established, the methodology for analyzing the lipid composition of specific cell membrane structures remains to be improved. In particular, tools to visualize the subcellular distribution of membrane lipids are currently limited. Therefore, elucidating the function of membrane lipids in the establishment of epithelial polarity and the associated formation of specific membrane structures awaits further development in this field.
Spatial profiling technologies and applications for brain cancers
Published in Expert Review of Molecular Diagnostics, 2021
Priyakshi Kalita-de Croft, Habib Sadeghi Rad, Harry Gasper, Ken O’Byrne, Sunil R Lakhani, Arutha Kulasinghe
Multiplexed error-robust fluorescence in situ hybridization (MERFISH) is a technique which uses direct imaging of individual RNA molecules in single cells. It utilizes the assignment of error-robust barcodes to individual RNA species followed by the labeling of RNA molecules with oligonucleotides representing each barcode and sequential single-molecule FISH imaging to read out these barcodes [58–60]. This not only provides quantitative measurements of RNA expression but also determines the spatial localization of individual RNAs on freshly frozen tissues, making it highly accurate and has a high detection efficiency [58,61]. These characteristics have led to new perspectives on biological processes, such as the establishment of cell polarity, cell migration, cell fate determination during cell division, and local translation [62]. Thus, using this technology, mapping, counting, and simultaneous imaging of thousands of RNA species in single cells are plausible, as well as enabling the delineation of regulatory networks and the in situ identification of cell types. However, currently, this is limited to 1001 mRNA molecules [58].
Lactobacillus rhamnosus GG prevents epithelial barrier dysfunction induced by interferon-gamma and fecal supernatants from irritable bowel syndrome patients in human intestinal enteroids and colonoids
Published in Gut Microbes, 2019
Xu Han, Allen Lee, Sha Huang, Jun Gao, Jason R. Spence, Chung Owyang
Previous models of host-microbe interactions have utilized human epithelial colorectal adenocarcinoma cell lines, such as Caco-2 and HT29. A key difference in our model is the use of enteroids and colonoids, which are three dimensional structures derived from LGR5+ intestinal stem cells isolated from the small intestine or colon crypts41 rather than cancer-derived cell lines that are not physiologically relevant models of human intestinal function and structure. The human enteroids and colonoids have a single layer of epithelial cells with structural and planar cell polarity which assemble into polarized monolayers that separate central apical lumens from basal submucosa.42 This system is physiologically active which enables functional studies of tight junction expression and intestinal barrier function.43 We have confirmed the unique ability of enteroids and colonoids to study the complex host-microbe interactions.