DEVELOPMENT OF ANIMAL MODELS OF ALZHEIMER'S DISEASE USING TRANSGENIC MICE

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The research proposed in this project is directed at developing a series of animals models for Alzheimer's disease using the technology of transgenic mouse production. The value of such a model is that it would allow various hypotheses concerning the biological and molecular bases of the disease to be tested in a reproducible, genetically uniform system. No such system exists at present and its introduction would speed the development of new diagnostic tools as well as novel therapeutic treatments. The specific mice to be created have been chosen based on evidence that points to the central role of the beta-amyloid precursor protein in the development of AD. Four types of mice will be produced. The first type will carry an artificial construct known as LC99 in which a truncated betaAPP cDNA (missing all coding sequences between the leader sequence and the last 99 amino acids) is driven by the cytomegalovirus promoter. Since CMV is a strong promoter with little tissue specificity, this construct should produce its amyloidogenic fragment promiscuously throughout the mouse. The specific cleavage products of LC99 have been well characterized in vitro and it will be informative to determine how the tissues of the live mouse deal with similar artificial peptides. The other three transgenic constructs will be driven by the Thy-1 promoter developed in our laboratory. This promoter drives expression of foreign genes in most CNS neurons and in a population of perivascular astrocytes. We will use this tissue specific pattern of expression to drive three different coding sequences: i) the LC99 sequences for comparison with the first experiment, ii) the val7l7 -> ile mutation of the betaAPP695 cDNA and iii) the wild-type form of betaAPP695. The second construct is identical to the mutation discovered by Hardy in association with a dominant form of familial Alzheimer's disease and should provide an increased likelihood of detecting neuropathological changes in the brains of the mice that carry it. The third construct is meant to serve as a control to the Hardy mutation lines, allowing us to assess the impact of the mutation itself. The analyses we will perform are biochemical and morphometric. Our goal is to thoroughly analyze, with rigorous quantitative methods, each transgenic line that we create in order to avoid missing lesions that might be subtle but important, and to prevent premature claims of a perfect animal model. The three co-investigators of this project have complementary areas of expertise that should ensure steady progress towards the goal of creating useful animal models of Alzheimer's disease.