Brush border structure defects in I-plastin deficient mice

Grimm-Günter, Eva-Maria S., Ramos, Sonia, Smyth, Neil, Celine, Revenu, Hurbain, Ilse, Raposo, Graca, Robine, Sylvie and Rivero, Francisco (2006) Brush border structure defects in I-plastin deficient mice. European Journal of Cell Biology, 85 (Supplement 1), p.22. (doi:10.1016/j.ejcb.2006.02.011).

Abstract

Plastin (or fimbrin) is an actin-bundling protein consisting of two actin-binding domains in tandem preceded by two calcium-binding EF-hands. In mammals three different isoforms are expressed in a cell-type specific manner. Iplastinis specifically expressed in the small intestine, colon and kidney, where it localizes in microvilli, specialized surface structures with highly ordered microfilament bundles. We have generated knockout mice lacking I-plastin. I-plastin deficient mice showed no overt phenotype at the whole animal level: growth rate, reproductive rate and litter size were normal. Antibodies specific for T- and L-plastin were used to demonstrate that lacking of I-plastin is not compensated by another plastin isoform. Transmission electron microscopy studies revealed morphological differences between wild type andI-plastin deficient mice in the microvilli. Brush border preparations of knockout mice are sensitive and seem to degrade easily. In immunofluorescence studies of intestinal mucosa cryosections decreased actin staining of the apical membrane was observed. Another abundant actin cross-linker of the brush border, villin, was found to be absent from the apical membrane. I-plastin seems to be an important regulator of the morphological structure and stability of microvilli.

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