Methods for diagnosing and treating alzheimer's disease and parkinson's disease

Abstract

The present invention relates to a method for diagnosing Alzheimer's disease and Parkinson's disease in a subject by analyzing the expression of Semaphorin 3 and downstream effectors. It also provides a method for identifying a substance useful in the prevention or treatment of Alzheimer's disease and Parkinson's disease, and a method of using such substance in the treatment of Alzheimer's disease and Parkinson's disease.

What is claimed:  
     
         1 . A method for early diagnosing Alzheimer's disease or Parkinson's disease in a subject, which method comprises assessing the level of expression or activity of Semaphorin 3 in a test subject and comparing it to the level of expression or activity of Semaphorin 3 in a control subject, wherein an increase of expression or activity of Semaphorin 3 in the test subject compared to the control subject is indicative of Alzheimer's disease in the test subject.  
     
     
         2 . The method according to  claim 1 , wherein the test subject is asymptomatic for Alzheimer's disease or Parkinson's disease.  
     
     
         3 . The method according to  claim 1 , wherein the Semaphorin 3 is Semaphorin 3A.  
     
     
         4 . The method according to  claim 1 , wherein the activity of Semaphorin 3 comprises detecting the level of expression or activity of an effector protein downstream the Semaphorin 3 pathway.  
     
     
         5 . The method according to  claim 4 , wherein the downstream effector protein is selected from the group consisting of microtubule assembly protein 1B (MAP1B), collapsing response mediator protein 2 (CRMP2), Neuropilin 1, Plexin A1, Plexin A2, p38 and Rac1.  
     
     
         6 . The method according to  claim 5 , wherein the downstream effector protein is phospho-MAP1B.  
     
     
         7 . The method according to  claim 5 , wherein the downstream effector protein is phospho-p38.  
     
     
         8 . The method according to  claim 1 , which is performed in vitro by assessing the level of expression or activity of Semaphorin 3 in a biological sample.  
     
     
         9 . The method of  claim 8 , wherein the biological sample is selected from the group consisting of cerebrospinal fluid (CSF), blood serum, and neuronal cells.  
     
     
         10 . The method of  claim 9 , wherein the neuronal cells are located within the hippocampus, substantia nigra, or thalamus.  
     
     
         11 . The method according to  claim 1 , wherein the level of expression of the Semaphorin 3 signaling complex member is assessed by determining the quantity of a Semaphorin 3 signaling complex member protein present in the biological sample.  
     
     
         12 . The method according to  claim 11 , wherein determining the quantity of Sepmaphorin 3 signaling complex member protein present in the biological sample is effected by an immunoassay using an antibody directed against a member of the Semaphorin 3 signaling complex.  
     
     
         13 . The method according to  claim 12 , wherein the immunoassay comprises the steps of: 
 (a) contacting the biological sample with a detectably labeled antibody which is directed against a member of the Semaphorin 3 signaling complex under conditions and time sufficient to allow the formation of complexes between the antibody and the member of the Semaphorin 3 signaling complex potentially present in the biological sample; and    (b) detecting and measuring the level of formation of these complexes.    
     
     
         14 . The method according to  claim 12 , wherein the immunoassay comprises the steps of: 
 (a) contacting the biological sample with a detectably labeled antibody which is directed against a member of the Semaphorin 3 signaling complex under conditions and time sufficient to allow the formation of complexes between the antibody and the member of the Semaphorin 3 signaling complex potentially present in the biological sample;    (b) contacting the complex from step (a) with a second antibody directed against a second member of the Semaphorin 3 signaling complex under conditions and time sufficient to allow the formation of complexes between the second antibody and the second member of the Semaphorin 3 signaling complex potentially present in the biological sample; and    (c) detecting and measuring the level of formation of complexes from step (b).    
     
     
         15 . The method of  claim 13 , wherein the member of the Semaphorin 3 signaling complex is Semaphorin 3A.  
     
     
         16 . The method of  claim 15 , wherein said antibody recognizes both processed and unprocessed forms of human Semaphorin 3A.  
     
     
         17 . The method of  claim 15 , wherein said antibody recognizes both dendritic and somatic forms of human Semaphorin 3A.  
     
     
         18 . The method of  claim 1 , wherein the level of expression of the member of the Semaphorin 3 signaling complex is assessed by assaying the quantity of mRNA which is present in the biological sample and encodes a member of the Semaphorin 3 signaling complex.  
     
     
         19 . A method for identifying a substance useful in the prevention or treatment of Alzheimer's disease or Parkinson's disease, which method comprises determining the effect of the substance on a biological activity Semaphorin 3, wherein an inhibitory effect is indicative of a substance useful in the prevention or treatment of Alzheimer's disease or Parkinson's disease.  
     
     
         20 . The method according to  claim 19 , wherein the member of the Semaphorin 3|signaling complex is Semaphorin 3A.  
     
     
         21 . The method according to  claim 20 , wherein the Semaphorin 3A is human Semaphorin 3A.  
     
     
         22 . The method according to  claim 19 , wherein determining the effect of the substance on the biological activity of Semaphorin 3 comprises: 
 (a) contacting a test cell with the substance and Semaphorin 3 under conditions wherein addition of Semaphorin 3A alone induces apoptosis of the cell; and    (b) observing the effect of addition of the substance and Semaphorin 3 on the cell, in comparison with the effect of addition of Semaphorin 3 alone to a control cell, wherein inhibition of apoptosis of the test cell compared to the control cell is indicative of a substance useful in the prevention or treatment of Alzheimer' disease or Parkinson's disease.    
     
     
         23 . The method according to  claim 22 , wherein the cell used in step (a) is a neuronal cell.  
     
     
         24 . The method according to  claim 23 , wherein the neuronal cell is located within the hippocampus, substantia nigra, or thalamus.  
     
     
         25 . A method for identifying a substance useful in the prevention or treatment of Alzheimer's disease, which method comprises determining the effect of the substance on a biological activity of the Semaphorin 3 signaling complex, wherein an inhibitory effect is indicative of a substance useful in the prevention or treatment of Alzheimer's disease or Parkinson's disease, and wherein determining the effect of the substance on the biological activity of Semaphorin 3 comprises: 
 (a) contacting a test neuronal cell with the substance and Semaphorin 3 under conditions wherein addition of Semaphorin 3 alone induces withdrawal of the nerve growth cone; and    (b) observing the effect of the addition of the substance and Semaphorin 3 on the test cell, in comparison with the effect of addition of Semaphorin 3 alone or to a control cell, wherein inhibition of withdrawal of the nerve growth cone in the test cell compared to the control cell is indicative of a substance useful in the prevention or treatment of Alzheimer's disease.    
     
     
         26 . The method according to  claim 19 , wherein determining the effect of the substance on the biological activity of Semaphorin 3 comprises determining the effect of the substance on the binding or activation of Semaphorin 3 receptor by Semaphorin 3, wherein an antagonist effect indicates that the substance is useful in the prevention or treatment of Alzheimer's disease or Parkinson's disease.  
     
     
         27 . The method according to  claim 19 , wherein the inhibitory effect of the substance is determined in vivo, by administering the substance to an animal that shows a level of Semaphorin 3 protein superior to a control animal.  
     
     
         28 . The method according to  claim 19 , wherein the animal is a transgenic animal that overexpresses Semaphorin 3.  
     
     
         29 . A method for the prevention or treatment of Alzheimer's disease or Parkinson's disease, which method comprises administering to a patient in need of such treatment an effective amount of a substance that inhibits Semaphorin 3 expression or activity, which a pharmaceutically acceptable carrier.  
     
     
         30 . The method according to  claim 29 , wherein the substance is an antibody directed against Semaphorin 3.  
     
     
         31 . The method according to  claim 29 , wherein the substance is an antisense nucleic acid specific for Semaphorin 3 mRNA.  
     
     
         32 . The method according to  claim 29 , wherein the Semaphorin 3 is human Semaphorin 3A.  
     
     
         33 . The method according to  claim 29 , wherein the activity of Semaphorin 3 comprises detecting the level of expression or activity of an effector protein downstream the Semaphorin 3 pathway.  
     
     
         34 . The method according to  claim 33 , wherein the downstream effector protein is selected from the group consisting of microtubule assembly (MAP1B), collapsing response mediator protein 2 (CRMP2), Neuropilin 1, Plexin A1, Plexin A2, p38 and Rac1.