In vivo, villin is required for Ca(2+)-dependent F-actin disruption in intestinal brush borders

• Published in: The Journal of cell biology 1999-08, Vol.146 (4), p.819
• Main Authors: Ferrary, E, Cohen-Tannoudji, M, Pehau-Arnaudet, G, Lapillonne, A, Athman, R, Ruiz, T, Boulouha, L, El Marjou, F, Doye, A, Fontaine, J J, Antony, C, Babinet, C, Louvard, D, Jaisser, F, Robine, S
• Format: Article
• Language: English
• Subjects: Actin Cytoskeleton - drug effects; Actin Cytoskeleton - metabolism; Actin Cytoskeleton - ultrastructure; Actins - metabolism; Animals; Calcium - metabolism; Carbachol - pharmacology; Carrier Proteins - genetics; Carrier Proteins - metabolism; Colitis - chemically induced; Colitis - pathology; Culture Techniques; Dextran Sulfate - pharmacology; Fasting; Female; Gene Deletion; Intestinal Mucosa - drug effects; Intestinal Mucosa - metabolism; Intestinal Mucosa - ultrastructure; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Microfilament Proteins - genetics; Microfilament Proteins - metabolism; Microvilli - drug effects; Microvilli - metabolism; Microvilli - pathology; Microvilli - ultrastructure; Polymers
• ISSN: 0021-9525
• DOI: 10.1083/jcb.146.4.819

Villin is an actin-binding protein localized in intestinal and kidney brush borders. In vitro, villin has been demonstrated to bundle and sever F-actin in a Ca(2+)-dependent manner. We generated knockout mice to study the role of villin in vivo. In villin-null mice, no noticeable changes were observed in the ultrastructure of the microvilli or in the localization and expression of the actin-binding and membrane proteins of the intestine. Interestingly, the response to elevated intracellular Ca(2+) differed significantly between mutant and normal mice. In wild-type animals, isolated brush borders were disrupted by the addition of Ca(2+), whereas Ca(2+) had no effect in villin-null isolates. Moreover, increase in intracellular Ca(2+) by serosal carbachol or mucosal Ca(2+) ionophore A23187 application abolished the F-actin labeling only in the brush border of wild-type animals. This F-actin disruption was also observed in physiological fasting/refeeding experiments. Oral administration of dextran sulfate sodium, an agent that causes colonic epithelial injury, induced large mucosal lesions resulting in a higher death probability in mice lacking villin, 36 +/- 9.6%, compared with wild-type mice, 70 +/- 8.8%, at day 13. These results suggest that in vivo, villin is not necessary for the bundling of F-actin microfilaments, whereas it is necessary for the reorganization elicited by various signals. We postulate that this property might be involved in cellular plasticity related to cell injury.