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ANNALS HIGHLIGHTS view articles and original research papers that discuss the current understanding of the molecular constituents and mechanisms underlying tight junctions. The review articles span a range of topics related to junctional protein complexes and their components. These scholarly overviews include recent findings on the X-ray three dimensional crystal structures of claudins and discussed the insights provided into the intermolecular interactions that underlie how the proteins, assembled in the junction complex, provide barrier function. Another review discussed the mechanisms at the transcriptional level (when DNA is transcribed into RNA) that result in the coordinated assembly of tight junction complexes during the differentiation and development of epithelial sheets. Other reviews explored a number of further topics, including the degradation and recycling of tight junction proteins; the diverse roles of a tight junction protein called “zonulin 2”; the unique paracellular water pathway established by the protein “claudin-2”; and junctional structures in arthropod cells called “septate junctions,” which are analogous to vertebrate tight junctions. In the second half of Tight Junctions and Their Proteins I, several authors presented new, original research findings. For example, two papers discussed structural properties of tight junction proteins and their interactions; one explored the functional roles of specific amino acids in claudins during tight junction formation, while the other presented computer in silico modeling of the formation of pores (as opposed to barrier function) that form between cells. Three papers explored tricellular tight junctions, which are junctions, composed of the proteins “tricellulin” and “lipolysis-stimulated lipoprotein receptor”, that seal at the intersections of three individual cells. One of the papers explored the contribution of tricellular tight junctions to paracellular permeability, finding that tricellular tight junctions have different functions in different types of epithelial sheets — providing permeability in some but not others. Another paper presented data showing that tricellulin can be removed from cells by a process of targeted degradation through activity of another protein in cells called “Itch” (a ubiquitin ligase). The third paper demonstrated how the tensile force (the force between cells pulling them apart) across tight junction complexes determined the distribution of contact proteins between bicellular and tricellular junctions, depending on cell density. Finally, two somewhat more technical articles explored, in one, the use of a protein fragment from the Clostridium perfringens enterotoxin as a claudin-sensitive cancer biosensor and, in the other, use of a protein-based mimetic (based on a protein fragment of the claudin-5 protein) to modulate the permeability of the blood– brain barrier to improve drug delivery to the brain. A second volume exploring further intricacies of tight junction proteins will be published by the end of the calendar year. Special Issue: Tight Junctions and Their Proteins I Ann NY Acad Sci 1397 • September 2016

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Special Issue: The Year in Diabetes and Obesity Ann NY Acad Sci 1391: 1–100. March 2017

Special Issue: Addiction Reviews Ann NY Acad Sci 1394: 1–127. April 2017

Special Issue: The Year in Cognitive Neuroscience Ann NY Acad Sci 1396: 1–236. May 2017

Special Issue: The Year in Ecology and Conservation Biology Ann NY Acad Sci 1399: 1–115. July 2017

The New York Academy of Sciences Magazine • Fall 2017 27

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The New York Academy of Sciences Magazine, Fall 2017  

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