Identification of genes involved in Alzheimer's disease using Drosophila melanogaster

Abstract

Transgenic flies displaying altered phenotypes due to expression of the Abeta and C 99 portions of the human APP gene are disclosed. Use of these flies in a method to identify Drosophila genes and the human homologs of these Drosophila genes, that are potentially involved in Alzheimer's Disease, is also disclosed. The use of said human homologs as drug targets for the development of therapeutics to treat Alzheimer's Disease and other conditions associated with defects in the APP pathway, as well as pharmaceutical compositions comprising substances directed to these genes, are also disclosed.

1 . A transgenic fly whose genome comprises a DNA sequence encoding a polypeptide comprising the Abeta portion of human APP wherein said DNA sequence encodes Abeta40 (SEQ ID NO:1) or Abeta42 (SEQ ID NO: 2), fused to a signal sequence, said DNA sequence operably linked to a tissue-specific expression control sequence; and expressing said DNA sequence, wherein expression of said DNA sequence results in said fly displaying an altered phenotype.  
     
     
         2 . A transgenic fly whose genome comprises a DNA sequence encoding a polypeptide comprising the wild type C99 portion of human APP (SEQ. ID NO:3) or C99 portion of human APP with the London Mutation (SEQ ID NO:4), fused to a signal sequence, said DNA sequence operably linked to a tissue-specific expression control sequence; and expressing said DNA sequence, wherein expression of said DNA sequence results in said fly displaying an altered phenotype.  
     
     
         3 . The transgenic fly of  claim 2 , wherein said DNA sequence encodes wild type C99, and wherein said tissue-specific expression control sequence comprises the UAS control element activated by Gal4 protein produced in the brain by the 7B-Gal4 transgene.  
     
     
         4 . The transgenic fly of  claim 3  wherein said expression of said DNA sequence results in said fly displaying a phenotype characterized as a locomotory defect.  
     
     
         5 . The transgenic fly of  claim 2 , wherein said DNA sequence encodes either wild type C99 or C99 portion of human APP with the London Mutation, and wherein said tissue-specific expression control sequence is the UAS control element activated by Gal4 protein produced by the apterous-Gal4 transgene.  
     
     
         6 . The transgenic fly of  claim 5  wherein said expression of said DNA sequence results in said fly displaying the “concave wing” phenotype.  
     
     
         7 . A method to identify genetic modifiers of the APP pathway, said method comprising: 
 (a) providing a transgenic fly whose genome comprises a DNA sequence encoding a polypeptide comprising the Abeta portion of human APP wherein said DNA sequence encodes Abeta40 (SEQ. ID NO:1) or Abeta42 (SEQ ID NO: 2), fused to a signal sequence, said DNA sequence operably linked to a tissue-specific expression control sequence; and expressing said DNA sequence, wherein expression of said DNA sequence results in said fly displaying an altered phenotype;    (b) crossing said transgenic fly with a fly containing a mutation in a known or predicted gene; and    (c) screening progeny of said crosses for flies that carry said DNA sequence and said mutation and display modified expression of the transgenic phenotype as compared to controls.    
     
     
         8 . The method of  claim 6  wherein said genetic modifier and/or its human homolog is a gene that affects the course of Alzheimer's Disease.  
     
     
         9 . The method of  claim 8  wherein said DNA sequence encodes Abeta42, and wherein said tissue specific expression control sequence comprises the eye-specific promoter GMR.  
     
     
         10 . The method of  claim 8  wherein said expression of said DNA sequence results in said fly displaying the “rough eye” phenotype.