EPITHELIAL-CELL GROWTH AND DIFFERENTIATION .4. CONTROLLED SPATIOTEMPORAL EXPRESSION OF TRANSGENES - NEW TOOLS TO STUDY NORMAL AND PATHOLOGICAL STATES

The gut epithelium represents a dynamic, well-organized developmental system for examining self-renewal, differentiation, repair, and tumori genesis. The apical pole of the enterocytes, the brush border, is comp osed of an array of well-organized actin microfilaments that support t he plasma membrane. Villin, one actin-binding protein that contributes to the assembly and dynamics of the microvillus bundle, exhibits spec ial features such as restricted tissue specificity and early expressio n in the immature crypt cells. The regulatory elements of the villin g ene are suitable to control the expression of transgenes in intestinal cells. Engineering genetically modified animals by classic transgenes is using the villin promoter or by gene targeting in the villin locus will allow the establishment of animal models that may recapitulate hu man intestinal disorders.