In vivo, villin is required for Ca(2+)-dependent F-actin disruption in intestinal brush borders.
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.
Ferrary
E
E
Institut Curie, UMR 144, 75248 Paris, France.
Cohen-Tannoudji
M
M
Pehau-Arnaudet
G
G
Lapillonne
A
A
Athman
R
R
Ruiz
T
T
Boulouha
L
L
El Marjou
F
F
Doye
A
A
Fontaine
J J
JJ
Antony
C
C
Babinet
C
C
Louvard
D
D
Jaisser
F
F
Robine
S
S
D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D000199:Actins / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002217:Carbachol / Q000494:pharmacology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D003092:Colitis / Q000139:chemically induced / Q000473:pathology; D046508:Culture Techniques; D016264:Dextran Sulfate / Q000494:pharmacology; D005215:Fasting; D005260:Female; D017353:Gene Deletion; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D008871:Microvilli / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology / Q000648:ultrastructure; D011108:Polymers
D000199:Actins; D002352:Carrier Proteins; D008840:Microfilament Proteins; D011108:Polymers; C026615:villin; D002217:Carbachol; D016264:Dextran Sulfate; D002118:Calcium