LDL Receptor-Related Proteins 1 and 2 and Treatment of Bone or Cartilage Conditions

Abstract

LDL receptor-related proteins 1 and 2 (LRP-1 and LRP-2) and interaction between lactoferrin and LRP-1, LRP-2, or p42/44 MAP kinase in diagnosis and treatment of disorders such as bone or cartilage disorders. Also disclosed are methods of screening for related therapeutic compounds.

1 . A method of determining whether a patient is suffering from or at risk for developing a bone condition, the method comprising:
 providing a test sample from a patient suspected of suffering from or being at risk for developing a bone condition, and   quantifying an expression level of an LRP-1 gene,   
     wherein the expression level of the LRP-1 gene in the test sample, if different from that in a normal sample, indicates that the patient is suffering from or at risk for developing a bone condition. 
   
   
       2 . The method of  claim 1 , wherein the test sample is prepared from a bone tissue. 
   
   
       3 . A method of determining whether a patient is suffering from or at risk for developing a bone condition, the method comprising:
 providing a test sample from a patient suspected of suffering from or being at risk for developing a bone condition, and   quantifying an activity of an LRP-1 protein,   
     wherein the activity of the LRP-1 protein in the test sample, if different from that in a normal sample, indicates that the patient is suffering from or at risk for developing a bone condition. 
   
   
       4 . The method of  claim 3 , wherein the test sample is prepared from a bone tissue. 
   
   
       5 . A method of identifying a candidate compound for treating a bone condition, the method comprising:
 contacting a compound with a cell expressing an LRP-1 gene, and   quantifying an expression level of the LRP-1 gene in the cell,   
     wherein the expression level of the LRP-1 gene in the presence of the compound, if different from that in the absence of the compound, indicates that the compound is a candidate for treating a bone condition. 
   
   
       6 . The method of  claim 5 , wherein the cell is an osteoblast cell, osteoblast-like cell, or osteocyte. 
   
   
       7 . The method of  claim 6 , wherein the cell is a SaOS-2 cell. 
   
   
       8 . The method of  claim 5 , wherein the cell is an osteoclast cell. 
   
   
       9 . A method of identifying a candidate compound for treating a bone condition, the method comprising:
 contacting a compound with a cell expressing an LRP-1 gene encoding an LRP-1 protein, and   quantifying an activity of the LRP-1 protein in the cell,   
     wherein the activity of the LRP-1 protein in the presence of the compound, if different from that in the absence of the compound, indicates that the compound is a candidate for treating a bone condition. 
   
   
       10 . The method of  claim 9 , wherein the cell is an osteoblast cell, osteoblast-like cell, or osteocyte. 
   
   
       11 . The method of  claim 10 , wherein the cell is a SaOS-2 cell. 
   
   
       12 . The method of  claim 9 , wherein the cell is an osteoclast cell. 
   
   
       13 . A method of treating a bone condition, the method comprising modulating a level of an LRP-1 protein in bone cells. 
   
   
       14 . The method of  claim 13 , wherein the level of the LRP-1 protein is modulated by providing and expressing a nucleic acid encoding an LRP-1 protein. 
   
   
       15 . The method of  claim 14 , wherein the nucleic acid is expressed in the bone cells. 
   
   
       16 . The method of  claim 13 , wherein the level of the LRP-1 protein is modulated by providing an LRP-1 protein. 
   
   
       17 . The method of  claim 16 , wherein the LRP-1 protein is introduced into the bone cells. 
   
   
       18 . The method of  claim 13 , wherein the level of the LRP-1 protein is modulated by providing and expressing a nucleic acid complementary to a sequence encoding an LRP-1 protein. 
   
   
       19 . The method of  claim 18 , wherein the nucleic acid is expressed in the bone cells. 
   
   
       20 . A method of treating a bone condition, the method comprising modulating an activity of an LRP-1 protein in bone cells. 
   
   
       21 . The method of  claim 20 , wherein the activity of the LRP-1 protein is modulated by providing an agonist of the LRP-1 protein. 
   
   
       22 . The method of  claim 21 , wherein the agonist is introduced into the bone cells. 
   
   
       23 . The method of  claim 20 , wherein the activity of the LRP-1 protein is modulated by providing an antagonist of the LRP-1 protein. 
   
   
       24 . The method of  claim 23 , wherein the antagonist is introduced into the bone cells. 
   
   
       25 . The method of  claim 20 , wherein the activity of the LRP-1 protein is modulated by providing an antibody against the LRP-1 protein. 
   
   
       26 . The method of  claim 25 , wherein the antibody is introduced into the bone cells. 
   
   
       27 . A method of determining whether a patient is suffering from or at risk for developing a bone condition, the method comprising:
 providing a test sample from a bone tissue of a patient suspected of suffering from or being at risk for developing a bone condition, and   quantifying an expression level of an LRP-2 gene,   
     wherein the expression level of the LRP-2 gene in the test sample, if different from that in a normal sample, indicates that the patient is suffering from or at risk for developing a bone condition. 
   
   
       28 . A method of determining whether a patient is suffering from or at risk for developing a bone condition, the method comprising:
 providing a test sample from a bone tissue of a patient suspected of suffering from or being at risk for developing a bone condition, and   quantifying an activity of an LRP-2 protein,   
     wherein the activity of the LRP-2 protein in the test sample, if different from that in a normal sample, indicates that the patient is suffering from or at risk for developing a bone condition. 
   
   
       29 . A method of identifying a candidate compound for treating a bone condition, the method comprising:
 contacting a compound with a bone cell expressing an LRP-2 gene, and   quantifying an expression level of the LRP-2 gene in the cell,   
     wherein the expression level of the LRP-2 gene in the presence of the compound, if different from that in the absence of the compound, indicates that the compound is a candidate for treating a bone condition. 
   
   
       30 . The method of  claim 29 , wherein the cell is an osteoblast cell, osteoblast-like cell, or osteocyte. 
   
   
       31 . The method of  claim 30 , wherein the cell is a SaOS-2 cell. 
   
   
       32 . The method of  claim 29 , wherein the cell is an osteoclast cell. 
   
   
       33 . A method of identifying a candidate compound for treating a bone condition, the method comprising:
 contacting a compound with a bone cell expressing an LRP-2 gene encoding an LRP-2 protein, and   quantifying an activity of the LRP-2 protein in the cell,   
     wherein the activity of the LRP-2 protein in the presence of the compound, if different from that in the absence of the compound, indicates that the compound is a candidate for treating a bone condition. 
   
   
       34 . The method of  claim 33 , wherein the cell is an osteoblast cell, osteoblast-like cell, or osteocyte. 
   
   
       35 . The method of  claim 34 , wherein the cell is a SaOS-2 cell. 
   
   
       36 . The method of  claim 33 , wherein the cell is an osteoclast cell. 
   
   
       37 . A method of treating a bone condition, the method comprising modulating a level of an LRP-2 protein in bone cells. 
   
   
       38 . The method of  claim 37 , wherein the level of the LRP-2 protein is modulated by introducing into and expressing in the bone cells a nucleic acid encoding an LRP-2 protein. 
   
   
       39 . The method of  claim 37 , wherein the level of the LRP-2 protein is modulated by introducing into the bone cells an LRP-2 protein. 
   
   
       40 . The method of  claim 37 , wherein the level of the LRP-2 protein is modulated by introducing into and expressing in the bone cells a nucleic acid complementary to a sequence encoding an LRP-2 protein. 
   
   
       41 . A method of treating a bone condition, the method comprising modulating an activity of an LRP-2 protein in bone cells. 
   
   
       42 . The method of  claim 41 , wherein the activity of the LRP-2 protein is modulated by introducing into the bone cells an agonist of the LRP-2 protein. 
   
   
       43 . The method of  claim 41 , wherein the activity of the LRP-2 protein is modulated by introducing into the bone cells an antagonist of the LRP-2 protein. 
   
   
       44 . The method of  claim 41 , wherein the activity of the LRP-2 protein is modulated by introducing into the bone cells an antibody against the LRP-2 protein. 
   
   
       45 . A method of determining whether a subject is suffering from or at risk for developing a bone or cartilage condition, the method comprising:
 providing a test sample from a subject, and   determining a level of interaction between a lactoferrin polypeptide and an LRP-1 or LRP-2 protein in the test sample,   
     wherein the level of the interaction between the lactoferrin polypeptide and the LRP-1 or LRP-2 protein in the test sample, if different from that in a normal sample, indicates that the subject is suffering from or at risk for developing a bone or cartilage condition. 
   
   
       46 . The method of  claim 45 , wherein the test sample is prepared from a bone or cartilage tissue. 
   
   
       47 . A method of identifying a candidate compound for treating a bone or cartilage condition, the method comprising:
 introducing a compound to a system containing a lactoferrin polypeptide and an LRP-1 or LRP-2 protein, and   determining a level of interaction between the lactoferrin polypeptide and the LRP-1 or LRP-2 protein,   
     wherein the level of the interaction between the lactoferrin polypeptide and the LRP-1 or LRP-2 protein in the presence of the compound, if different from that in the absence of the compound, indicates that the compound is a candidate for treating a bone or cartilage condition. 
   
   
       48 . The method of  claim 47 , wherein the sample contains an osteoblastic, osteoclastic or fibroblastic cell, or a chondrocyte. 
   
   
       49 . A method of treating a bone or cartilage condition, the method comprising modulating interaction between a lactoferrin polypeptide and an LRP-1 or LRP-2 protein in bone or cartilage cells. 
   
   
       50 . The method of  claim 49 , wherein the interaction between the lactoferrin polypeptide and the LRP-1 or LRP-2 protein is modulated by providing an agonist of the LRP-1 or LRP-2 protein. 
   
   
       51 . The method of  claim 50 , wherein the agonist is introduced into the bone or cartilage cells. 
   
   
       52 . The method of  claim 50 , wherein the agonist is an exogenous lactoferrin polypeptide. 
   
   
       53 . The method of  claim 52 , wherein the exogenous lactoferrin polypeptide is introduced into the bone or cartilage cells. 
   
   
       54 . The method of  claim 49 , wherein the interaction between the lactoferrin polypeptide and the LRP-1 or LRP-2 protein is modulated by providing an antagonist of the LRP-1 or LRP-2 protein. 
   
   
       55 . The method of  claim 54 , wherein the antagonist is introduced into the bone or cartilage cells. 
   
   
       56 . The method of  claim 54 , wherein the antagonist is a receptor-associated protein. 
   
   
       57 . The method of  claim 56 , wherein the receptor-associated protein is introduced into the bone or cartilage cells. 
   
   
       58 . A method of determining whether a subject is suffering from or at risk for developing a bone or cartilage condition, the method comprising:
 providing a test sample from a subject, and   determining a level of interaction between a lactoferrin polypeptide and a p42/44 MAP kinase in the test sample,   
     wherein the level of the interaction between the lactoferrin polypeptide and the p42/44 MAP kinase in the test sample, if different from that in a normal sample, indicates that the subject is suffering from or at risk for developing a bone or cartilage condition. 
   
   
       59 . The method of  claim 58 , wherein the test sample is prepared from a bone or cartilage tissue. 
   
   
       60 . A method of identifying a candidate compound for treating a bone or cartilage condition, the method comprising:
 introducing a compound with a system containing a lactoferrin polypeptide and a p42/44 MAP kinase, and   determining a level of interaction between the lactoferrin polypeptide and the p42/44 MAP kinase,   
     wherein the level of the interaction between the lactoferrin polypeptide and the p42/44 MAP kinase in the presence of the compound, if different from that in the absence of the compound, indicates that the compound is a candidate for treating a bone or cartilage condition. 
   
   
       61 . The method of  claim 60 , wherein the sample contains an osteoblastic, osteoclastic or fibroblastic cell, or a chondrocyte. 
   
   
       62 . A method of treating a bone or cartilage condition, the method comprising modulating interaction between a lactoferrin polypeptide and a p42/44 MAP kinase in bone or cartilage cells. 
   
   
       63 . The method of  claim 62 , wherein the interaction between the lactoferrin polypeptide and the p42/44 MAP kinase is modulated by providing an agonist of the p42/44 MAP kinase. 
   
   
       64 . The method of  claim 63 , wherein the agonist is introduced into the bone or cartilage cells. 
   
   
       65 . The method of  claim 63 , wherein the agonist is an exogenous lactoferrin polypeptide. 
   
   
       66 . The method of  claim 65 , wherein the exogenous lactoferrin polypeptide is introduced into the bone or cartilage cells. 
   
   
       67 . The method of  claim 62 , wherein the interaction between the lactoferrin polypeptide and the p42/44 MAP kinase is modulated by providing an antagonist of the p42/44 MAP kinase. 
   
   
       68 . The method of  claim 67 , wherein the antagonist is introduced into the bone or cartilage cells. 
   
   
       69 . The method of  claim 67 , wherein the antagonist is an inhibitor of a p42/44 MAP kinase. 
   
   
       70 . The method of  claim 69 , wherein the inhibitor of the p42/44 MAP kinase is introduced into the bone or cartilage cells.