Modulation of Abeta levels by beta-secretase BACE2

Abstract

The present invention is based on the findings that BACE2, a homolog of β-secretase BACE, is able to stimulate processing of APP in a non-amyloidogenic pathway, thereby suppressing the level of Aβ. Accordingly, the present invention provides methods and means for the identification and use of modulators of this unique activity of BACE2 to suppress Aβ production. The compounds identified using the methods and means provided herein may be used as potential candidates for the treatment of Alzheimer's disease and other neurological diseases.

1 . A method for identifying a modulator of the enzymatic production of β-amyloid peptide (Aβ) from β-amyloid precursor protein (APP) or a fragment thereof, comprising: 
 providing a APP protease and BACE2 to a sample containing APP or an APP fragment;    contacting the APP or the APP fragment and BACE2 with a candidate compound; and    monitoring the effect of the candidate compound on the production of Aβ.    
     
     
         2 . The method of  claim 1 , wherein said modulator is an inhibitor of Aβ production.  
     
     
         3 . The method of  claim 1 , wherein the APP protease is a protease with α-secretase activity.  
     
     
         4 . The method of  claim 1 , wherein the APP protease is a protease with a γ-secretase activity.  
     
     
         5 . The method of  claim 1 , wherein the APP protease is a protease with a β-secretase activity other than BACE2.  
     
     
         6 . The method of  claim 5 , wherein said β-secretase activity is due to the presence of an enzyme having a pH optimum at about pH 6.5-7.0, and an estimated molecular weight of about 32-39 kDa as calculated from radiation inactivation analysis of HEK293 cell membrane extracts, or about 20-26 kDa as calculated from radiation inactivation analysis of human brain samples, with a candidate compound.  
     
     
         7 . The method of  claim 5 , wherein said β-secretase activity is due to the presence of a β-secretase enzyme having a pH optimum at about pH 4.5-5.0 and an estimated molecular weight of about 50-60 kDa as calculated from radiation inactivation analysis of HEK293 cell membrane extracts or human brain samples (BACE1).  
     
     
         8 . The method of  claim 1 , wherein the effect of the candidate compound on the production of Aβ is monitored by measuring the amount of Aβ formed.  
     
     
         9 . The method of  claim 8 , wherein the amount of Aβ formed is reduced by at least about 50%.  
     
     
         10 . The method of  claim 8 , wherein the amount of Aβ formed is reduced by at least about 75%.  
     
     
         11 . The method of  claim 8 , wherein the amount of Aβ formed is reduced by at least about 90%.  
     
     
         12 . The method of  claim 1 , further comprising the step of comparing the effect of the test compound on Aβ production with the effect of BACE2 in the absence of the test compound.  
     
     
         13 . The method of  claim 12 , wherein the test compound causes at least about 15% reduction in the amount of Aβ over the effect of BACE2 in the absence of the test compound.  
     
     
         14 . The method of  claim 13 , wherein said reduction is at least about 25%.  
     
     
         15 . The method of  claim 13 , wherein said reduction is at least about 50%.  
     
     
         16 . The method of  claim 13 , wherein said reduction is at least about 75%  
     
     
         17 . The method of  claim 1 , further comprising the step of comparing the effect of the test compound on Aβ production with Aβ production in the absence of BACE2.  
     
     
         18 . The method of  claim 1 , which is performed in a cell-free format.