Marker peptide for alzheimer's disease

Abstract

To provide a peptide obtainable by cleaving an N-terminal region and a C-terminal region of Alcadein α, Alcadein β, or Alcadein γ; and capable of being a diagnostic marker for Alzheimer's disease. It is possible to detect Alzheimer's disease at an early stage without burdening subjects to be tested by using the peptide as a diagnostic marker.

1 . A peptide capable of being a diagnostic marker for Alzheimer's disease, the peptide being obtained by cleaving an N-terminal region and a C-terminal region of Alcadein β. 
     
     
         2 . The peptide according to  claim 1 , wherein the N-terminal region to be cleaved is a portion of an extracellular domain of the N-terminal end of Alcadein β. 
     
     
         3 . The peptide according to  claim 1 , wherein the C-terminal region is cleaved by presenilin. 
     
     
         4 . The peptide according to  claim 1 , wherein the peptide is obtained by cleaving an N-terminal and a C-terminal region of Alcadein β; and the cleavage site of the N-terminal region is between amino acids 825 and 826 of the amino acid sequence represented by SEQ ID NO: 2. 
     
     
         5 . The peptide according to  claim 1 , wherein the peptide is obtained by cleaving an N-terminal and a C-terminal region of Alcadein β; and the cleavage site of the C-terminal region is between amino acids 875 and 876 of the amino acid sequence represented by SEQ ID NO: 2. 
     
     
         6 . An isolated peptide consisting of the amino acid sequence selected from the group consisting of SEQ ID NO:2. 
     
     
         7 . A method for diagnosing Alzheimer's disease, which comprises detecting or quantitatively determining the peptide according to any one of  claims 1  to  6  in body fluid or tissues taken from an animal. 
     
     
         8 . The method for diagnosing Alzheimer's disease according to  claim 7 , wherein the body fluid is blood or cerebrospinal fluid. 
     
     
         9 . The method for diagnosing Alzheimer's disease according to  claim 7 , wherein a ratio of a high-molecular-weight peptide to the detected or quantitatively determined peptide is used as an indicator for diagnosing Alzheimer's disease. 
     
     
         10 . A method for diagnosing Alzheimer's disease, which comprises:
 obtaining a sample of brain tissue taken from the subject, determining co-localization of the peptide according to  claim 6  with amyloid precursor protein (APP) present in said sample,   wherein Alzheimer's disease is indicated when the co-localization is detected as compared to the absence of said co-localization in a control non-Alzheimer's disease sample.   
     
     
         11 . A method for screening a therapeutic agent for Alzheimer's disease, which comprises contacting cells secreting the peptide according to any one of  claims 1  to  6  with an agent to be screened; and determining a change in the secreted amount of the peptide or a change in the molecular species of the secreted peptide. 
     
     
         12 . An antibody against the peptide according to any one of  claims 1  to  6 . 
     
     
         13 . A diagnostic reagent for Alzheimer's disease, the reagent comprising the antibody according to  claim 12 .