title: Epithelial cell extrusion: Pathways and pathologies.
abstract: To remove dying or unwanted cells from an epithelium while preserving the barrier function of the layer, epithelia use a unique process called cell extrusion. To extrude, the cell fated to die emits the lipid Sphingosine 1 Phosphate (S1P), which binds the G-protein-coupled receptor Sphingosine 1 Phosphate receptor 2 (S1P2) in the neighboring cells that activates Rho-mediated contraction of an actomyosin ring circumferentially and basally. This contraction acts to squeeze the cell out apically while drawing together neighboring cells and preventing any gaps to the epithelial barrier. Epithelia can extrude out cells targeted to die by apoptotic stimuli to repair the barrier in the face of death or extrude live cells to promote cell death when epithelial cells become too crowded. Indeed, because epithelial cells naturally turn over by cell death and division at some of the highest rates in the body, epithelia depend on crowding-induced live cell extrusion to preserve constant cell numbers. If extrusion is defective, epithelial cells rapidly lose contact inhibition and form masses. Additionally, because epithelia act as the first line of defense in innate immunity, preservation of this barrier is critical for preventing pathogens from invading the body. Given its role in controlling constant cell numbers and maintaining barrier function, a number of different pathologies can result when extrusion is disrupted. Here, we review mechanisms and signaling pathways that control epithelial extrusion and discuss how defects in these mechanisms can lead to multiple diseases. We also discuss tactics pathogens have devised to hijack the extrusion process to infect and colonize epithelia.
authors.affiliation: Department of Oncological Sciences, Huntsman Cancer Institute, University Of Utah, 2000 Circle of Hope Drive, Salt Lake City, UT 84112, USA.
authors.forename: Swapna Aravind
authors.initials: SA
authors.lastname: Gudipaty
authors.affiliation: Department of Oncological Sciences, Huntsman Cancer Institute, University Of Utah, 2000 Circle of Hope Drive, Salt Lake City, UT 84112, USA. Electronic address: Jody.Rosenblatt@hci.utah.edu.
authors.forename: Jody
authors.initials: J
authors.lastname: Rosenblatt
mesh_terms: D011125:Adenomatous Polyposis Coli / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D025601:Adenomatous Polyposis Coli Protein / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis; D002465:Cell Movement; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism* / Q000473:pathology; D005786:Gene Expression Regulation; D006801:Humans; D008089:Listeria monocytogenes / Q000472:pathogenicity / Q000502:physiology; D008246:Lysophospholipids / Q000378:metabolism*; D051616:Neuronal Apoptosis-Inhibitory Protein / Q000235:genetics / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000378:metabolism; D049349:Receptors, Lysosphingolipid / Q000235:genetics / Q000378:metabolism*; D012486:Salmonella typhimurium / Q000472:pathogenicity / Q000502:physiology; D015398:Signal Transduction; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism; D000081025:Sphingosine-1-Phosphate Receptors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: C555337:APC protein, human; D025601:Adenomatous Polyposis Coli Protein; D004268:DNA-Binding Proteins; C117307:KRAS protein, human; D008246:Lysophospholipids; C496800:NAIP protein, human; D051616:Neuronal Apoptosis-Inhibitory Protein; D049349:Receptors, Lysosphingolipid; C477522:S1PR2 protein, human; C480633:SLC2A4RG protein, human; D000081025:Sphingosine-1-Phosphate Receptors; D014157:Transcription Factors; C060506:sphingosine 1-phosphate; D016283:Proto-Oncogene Proteins p21(ras); D013110:Sphingosine
keywords: Epithelial extrusion; Microtubules; Piezo1; Rho; Sphingosine-1-phosphate; Sphingosine-1-phosphate receptor 2