LDL receptor signaling pathways

Abstract

The invention provides methods and compositions for inducing and detecting signal transduction through LDL receptors, including specifically detecting a stress that alters a functional interaction of a low density lipoprotein (LDL) receptor binding polypeptide with an LDL receptor interaction domain, by (a) introducing a predetermined stress into a system which provides a physical interaction of an LDL receptor binding polypeptide with an LDL receptor intracellular binding polypeptide interaction domain, whereby the system provides a stress-biased interaction of the binding polypeptide and the interaction domain, wherein the absence of the stress, the system provides a unbiased interaction of the binding polypeptide and the interaction domain; and (b) detecting the stress-biased interaction of the binding polypeptide and the interaction domain, wherein the binding polypeptide is selected from SEMCAP-1, JIP-1, PSD-95, JIP-2, Talin, OMP25, CAPON, PIP4,5 kinase, Na channel brain 3, Mint1, ICAP-1 and APC subunit10.

1 . A method for identifying a candidate drug which may alter low density lipoprotein (LDL) receptor function by altering an interaction of the LDL receptor with a native intracellular LDL receptor binding polypeptide, the method comprising steps: 
 providing a system which comprises the binding polypeptide and a corresponding binding polypeptide interaction domain of the LDL receptor,    introducing a test compound into the system and detecting a resultant level of binding between the binding polypeptide and the interaction domain, wherein a difference in the level of binding as compared to that of the system without the test compound indicates that the compound is a candidate drug,    wherein the binding polypeptide is a c-Jun NH 2 -terminal kinase (JNK) interacting protein (JIP) selected from JIP1 and JIP2.    
     
     
         2 . A method according to  claim 1 , wherein the system is a two-hybrid assay.  
     
     
         3 . A method according to  claim 1 , wherein the system is a biochemical pull-down assay.  
     
     
         4 . A method according to  claim 1 , wherein the system is a high-throughput, in vitro fluorescent polarization assay.  
     
     
         5 . A method according to  claim 1 , wherein the system is a high-throughput, in vitro solid-phase binding assay.  
     
     
         6 . A method according to  claim 1 , wherein the system is a high-throughput, conformational sensor-solid-phase chemiluminescence assay.  
     
     
         7 . A method according to  claim 1 , wherein the system is a cell expressing both the binding polypeptide and the interaction domain.  
     
     
         8 . A method according to  claim 1 , wherein the system is an in vitro, cell-free mixture comprising a determined amount of the binding polypeptide and the interaction domain.  
     
     
         9 . A method according to  claim 1 , wherein the LDL receptor is selected from very low density lipoprotein receptor (VLDLR), apolipoprotein E receptor-2 (ApoER2), low density lipoprotein receptor (LDLR), low density lipoprotein receptor related protein (LRP), MEGF7 and Megalin.  
     
     
         10 . A method according to  claim 2 , wherein the LDL receptor is selected from very low density lipoprotein receptor (VLDLR), apolipoprotein E receptor-2 (ApoER2), low density lipoprotein receptor (LDLR), low density lipoprotein receptor related protein (LRP), MEGF7 and Megalin.  
     
     
         11 . A method according to  claim 3 , wherein the LDL receptor is selected from very low density lipoprotein receptor (VLDLR), apolipoprotein E receptor-2 (ApoER2), low density lipoprotein receptor (LDLR), low density lipoprotein receptor related protein (LRP), MEGF7 and Megalin.  
     
     
         12 . A method according to  claim 4 , wherein the LDL receptor is selected from very low density lipoprotein receptor (VLDLR), apolipoprotein E receptor-2 (ApoER2), low density lipoprotein receptor (LDLR), low density lipoprotein receptor related protein (LRP), MEGF7 and Megalin.  
     
     
         13 . A method according to  claim 5 , wherein the LDL receptor is selected from very low density lipoprotein receptor (VLDLR), apolipoprotein E receptor-2 (ApoER2), low density lipoprotein receptor (LDLR), low density lipoprotein receptor related protein (LRP), MEGF7 and Megalin.  
     
     
         14 . A method according to  claim 6 , wherein the LDL receptor is selected from very low density lipoprotein receptor (VLDLR), apolipoprotein E receptor-2 (ApoER2), low density lipoprotein receptor (LDLR), low density lipoprotein receptor related protein (LRP), MEGF7 and Megalin.  
     
     
         15 . A method according to  claim 7 , wherein the LDL receptor is selected from very low density lipoprotein receptor (VLDLR), apolipoprotein E receptor-2 (ApoER2), low density lipoprotein receptor (LDLR), low density lipoprotein receptor related protein (LRP), MEGF7 and Megalin.  
     
     
         16 . A method according to  claim 8 , wherein the LDL receptor is selected from very low density lipoprotein receptor (VLDLR), apolipoprotein E receptor-2 (ApoER2), low density lipoprotein receptor (LDLR), low density lipoprotein receptor related protein (LRP), MEGF7 and Megalin.