Epithelial complexity

Cue D, Southern S, Southern P et al (2000) A non-peptide integrin antagonist can inhibit epithelial cell ingestion of streptococcus pyogenes by blocking a5 31 -fibronectin-Ml protein complexes. Proc Nat Acad Sci 97(6) 2858-2863... 

Bundles of parallel actin filaments with uniform polarity. The microvilli of intestinal epithelial cells (enterocytes) are packed with actin filaments that are attached to the overlying plasma membrane through a complex composed of a 110-kD protein and calmodulin. The actin filaments are attached to each other through fimbrin (68 kD) and villin (95 kD). The actin bundles that emerge out of the roots of microvilli disperse horizontally to form a filamentous complex, the terminal web, in which several cytoskeletal proteins, spectrin (fodrin), myosin, actinin, and tropomyosin are present. Actin in the terminal web also forms a peripheral ring, which is associated with the plasma membrane on the lateral surfaces of the enterocyte (see Figure 5, p. 24). 

The cytoskeleton is involved in the maintenance of cell shape and cytoplasmic processes (e.g., microvilli). In polarized epithelial cells, distinct cyto-cortical cytoskeletal complexes are associated with the apical and basal-lateral domains of the plasma membrane (Rodriguez-Boulan and Nelson, 1989 Mays et al., 1994). 

Nelson, W.J. Hammerton, R.W. (1989). A membrane-cytoskeletal complex containing Na, K -AT-Pase, ankyrin, and fodrin in Madin-Darby canine kidney (MDCK cells) Implications for the biogenesis of epithelial cell polarity. J. Cell Biol. 108, 893-902. 

Vitamin A is essential throughout life, including foetal development, but perhaps its most well researched role is that in vision where 11 -cis retinaldehyde is the initial part of the photoreceptor complex in rods and cones. Retinoic acid induces differentiation in epithelial cells and deficiency leads to... 

Plasminogen activator inhibitors have been shown to be present in a large variety of different cells and tissues. These inhibitors are thought to play an important role in regulating tissue fibrinolysis. One of these inhibitors has been purified from cultured bovine aortic epithelial cells. This inhibitor has been shown to be a serine protease inhibitor and inhibits the function of two proteolytic enzymes urokinase and tissue plasminogen activator, both of which cleave and activate plasminogen. The mechanism by which this inhibitor functions is very similar to that described above with a-l-PI. Thus, the inhibitor forms a binary complex with the proteolytic enzyme and thereby inhibits its activity. Again in a situation comparable to that with a-l-PI, it was found that when the purified bovine aortic epithelial inhibitor was exposed to Al-chlorosuccinimide,... 

Fig. 2.12 Vomeronasal complex Reptiles, TS Snake, (a) Drawing of Amphibolurus muricatus. skeletal elements in yellow (from Broom, 1895). (b) Generalised diagram of epithelial types L = lateral and M= medial (from Rehorek, 1998). (c) VNC, Primitive mammal junction of vomeronasal duct (VNd), with naso-palatine (Stenson s) duct (N-Pd) in Spiny Anteater (Short-nosed Echidna) brown = skeletal elements — septal and para-septal cartilages (from Broom, 1895).

Chia There is another experiment that is relevant to your question. If Pins is overexpressed in the epithelial cells in a Pins- mutant, there is no longer any apical Insc. But this distribution is bizarre it is in the cytoplasm, but it is preferentially in the apical cytoplasm, as if apical Baz were trying to recruit Insc. One might speculate that the transient Baz—Insc complex can t be stabilized in the absence of Pins, so Insc keeps falling off. In this situation you don t get spindle reorientation. 

JM Wilson, JA Whitney, MR Neutra. Biogenesis of the apical endosome-lysosome complex during differentiation of absorptive epithelial cells in rat ileum. J Cell Sci 100 133-143, 1991. 

Even if in vitro models can mimic only partially the complex responses in vivo, the behavior of lung epithelial cells in in vitro experiments resembles in some respects the pathological observations of in vivo experiments. First, the formation of... 

In summary, the in vivo protective effects of Tyv-specific antibodies, exclusion and immobility, can now be effectively studied using an in vitro model of the intestinal epithelium. Larvae are prevented from entering epithelial cells by caps of immune complexes or by binding of antibody to Tyv in the absence of immune complex formation. These effects would correlate with exclusion of larvae from epitheha observed in passively immunized rats. Larvae are encumbered as they migrate within epithelial monolayers, an effect that may correlate with immobility of larvae observed in vivo. It is reasonable to conclude that in the animal host the different effects work in combination, most iikeiy in cooperation with innate host defences, to cause nematode expuision from the intestine. 

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