Methods for diagnosing osteoarthritis

Abstract

Methods are disclosed for assessing risk of developing osteoarthritis. Said methods comprise determining the cellular localizations, blood or synovial fluid concentrations, sumoylation states and post-translational modifications of pituitary homeobox transcription factor 1 (pitx-1) repressor proteins, identifying mutations in genes which encode said proteins and identifying any mutations or post-translational modifications causing the nuclear accumulation or retention of said proteins. Said proteins include prohibitin (PHB-I), prohibitone (PHB-2) and B cell lymphoma-6 transcriptional repressor interacting co-repressor (BCoR).

1 . A method comprising:
 determining the cellular localization of a pitx1 repressor protein or complex selected from the group consisting of prohibitin (PHB-1), prohibitone (PHB-2), B cell lymphoma-6 transcriptional repressor interacting co-repressor (BCoR), PHB-1-containing complex, PHB-2-containing complex and BCoR-containing complex, in a subject cell sample selected from the group consisting of an articular chondrocytes sample, a growth plate chondrocytes sample, an osteoblasts sample, a skeletal myoblasts sample and a synoviocytes sample.   
     
     
         2 . The method of  claim 1 , wherein said method further comprises determining whether the repressor protein or complex nuclear concentration is higher in the subject cell sample as compared to that in a control cell sample;
 wherein a higher repressor protein or complex nuclear concentration in the subject cell sample is indicative that the subject is at risk of developing osteoarthritis.   
     
     
         3 . A method comprising:
 (a) identifying a subject suspected of having osteoarthritis (OA); and   (b) detecting the blood concentration of a pitx1 repressor protein or complex in a blood sample of the subject.   
     
     
         4 . A method comprising:
 (a) identifying a subject suspected of having osteoarthritis (OA); and   (b) detecting the synovial fluid concentration of a pitx1 repressor protein or complex in a synovial fluid sample of the subject.   
     
     
         5 . The method of  claim 1 , wherein the osteoarthritis is selected from the group consisting of knee joint arthritis, hip joint arthritis and temporo-mandibular joints arthritis. 
     
     
         6 . The method of  claim 1 , wherein the osteoarthritis is knee joint arthritis. 
     
     
         7 . The method of  claim 1 , wherein the osteoarthritis is hip joint arthritis. 
     
     
         8 . A method of selecting a compound, said method comprising
 (a) contacting a test compound with a cell sample selected from the group consisting of an articular chondrocytes sample, a growth plate chondrocytes sample, an osteoblasts sample, a skeletal myoblasts sample and a synoviocytes sample; and   (b) determining a pitx1 repressor protein or complex nuclear localization in the cell sample;   wherein the test compound is selected if the pitx1 repressor protein or complex nuclear localization in the cell sample is decreased in the presence of the candidate compound as compared to in the absence thereof.   
     
     
         9 . A method of selecting a compound, said method comprising
 (a) contacting a test compound with a cell sample selected from the group consisting of an articular chondrocytes sample, a growth plate chondrocytes sample, an osteoblasts sample, a skeletal myoblasts sample and a synoviocytes sample; and   (b) assessing the sumoylation of a pitx1 repressor protein or complex in the cell sample;   wherein the test compound is selected if the sumoylation of the pitx1 repressor protein or complex in the cell sample is increased in the presence of the candidate compound as compared to in the absence thereof.   
     
     
         10 . The method of  claim 8 , wherein the selected test compound is potentially useful in preventing accumulation or retention of the pitx1 repressor protein or complex in cell nuclei or in promoting the pitx1 repressor protein or complex nuclear export. 
     
     
         11 . A method of selecting a compound, said method comprising the steps of
 (a) contacting a test compound with a cell sample selected from the group consisting of an articular chondrocytes sample, a growth plate chondrocytes sample, an osteoblasts sample, a skeletal myoblasts sample and a synoviocytes sample; and   (b) measuring the binding of a pitx1 repressor protein or complex on pitx1's E2F-like site in the cell sample,   wherein the test compound is selected if the binding of the pitx1 repressor protein or complex on pitx1's E2F-like site in the cell sample is decreased in the presence of the test compound as compared to in the absence thereof.   
     
     
         12 . The method of  claim 9 , wherein
 the selected test compound is potentially useful in the treatment of primary osteoarthritis.   
     
     
         13 . The method of  claim 1 , wherein the pitx1 repressor protein or complex comprises prohibitin (PHB-1). 
     
     
         14 . The method of  claim 1 , wherein the pitx1 repressor protein or complex comprises prohibitone (PHB-2). 
     
     
         15 . The method of  claims 1 , wherein the pitx1 repressor protein or complex comprises B cell lymphoma-6 transcriptional repressor interacting co-repressor (BCoR). 
     
     
         16 . The method of  claim 1 , wherein the pitx1 repressor protein is prohibitin (PHB-1). 
     
     
         17 . The method of  claim 1 , wherein the pitx1 repressor protein is prohibitone (PHB-2). 
     
     
         18 . The method of  claim 1 , wherein the pitx1 repressor protein is B cell lymphoma-6 transcriptional repressor interacting co-repressor (BCoR). 
     
     
         19 . The method of  claim 1 , wherein said cell sample is from a subject having osteoarthritis. 
     
     
         20 . The method of  claims 1 , wherein said cell sample is an articular chondrocytes sample. 
     
     
         21 . The method of  claim 20 , wherein said articular chondrocytes sample is from a subject having osteoarthritis in a knee joint. 
     
     
         22 . A method of identifying a mutation contributing to osteoarthritis, comprising comparing the nucleotide sequence of a gene selected from the group consisting of prohibitin (PHB-1) gene, prohibitone (PHB-2) gene, B cell lymphoma-6 transcriptional repressor interacting co-repressor (BCoR) gene or of any gene encoding a protein causing the nuclear accumulation or retention of PHB-1, PHB-2 or BCoR in articular chondrocytes of a subject having osteoarthritis with that of the corresponding gene in a control subject. 
     
     
         23 . The method of  claim 22 , wherein said gene is the PHB-1 gene. 
     
     
         24 . The method of  claim 22 , wherein said gene is the PHB-2 gene. 
     
     
         25 . The method of  claim 23 , wherein said mutation is one affecting PHB-1 or PHB-2 DNA-binding and/or its cellular localization. 
     
     
         26 . A method for predicting the risk of developing osteoarthritis comprising detecting in a subject the presence of a mutation directly or indirectly causing the nuclear accumulation or retention of prohibitin (PHB-1), prohibitone (PHB-2) or B cell lymphoma-6 transcriptional repressor interacting co-repressor (BCoR) in cells where PHB-1, PHB-2, BCoR or Pitx1 is normally expressed, wherein the presence of the mutation is an indication that the subject has or is at risk of developing osteoarthritis. 
     
     
         27 . The method of  claim 26 , wherein said method comprises detecting a mutation in CRM-1. 
     
     
         28 . A method of identifying a post-translational modification contributing to osteoarthritis, comprising comparing the post-translational modification of a protein selected from the group consisting of prohibitin (PHB-1) and prohibitone (PHB-2), B cell lymphoma-6 transcriptional repressor interacting co-repressor (BCoR) or of any protein causing the nuclear accumulation or retention of PHB-1, PHB-2 or BCoR in articular chondrocytes of a subject having osteoarthritis with that of the corresponding gene in a control subject. 
     
     
         29 . A method for predicting the risk of developing osteoarthritis comprising detecting in a subject, the presence of at least one post-translational modification directly or indirectly causing the nuclear accumulation or retention of prohibitin (PHB-1), prohibitone (PHB-2) or B cell lymphoma-6 transcriptional repressor interacting co-repressor (BCoR) in cells where PHB-1, PHB-2 or Pitx1 is normally expressed, wherein the presence of the at least one post-translational modification is an indication that the subject has or is at risk of developing osteoarthritis. 
     
     
         30 . A kit comprising an antibody specific to prohibitin (PHB-1) or to prohibitone (PHB-2) and an antibody specific to B cell lymphoma-6 transcriptional repressor interacting co-repressor (BCoR). 
     
     
         31 . The kit of  claim 30  further comprising instructions to use the antibodies to predict whether a subject is at risk for developing osteoarthritis. 
     
     
         32 . A purified repressor complex comprising B cell lymphoma-transcriptional repressor interacting co-repressor (BCoR) and at least one of prohibitin (PHB-1) and prohibitone (PHB-2). 
     
     
         33 . The repressor complex of  claim 32  comprising BCoR and PHB-1. 
     
     
         34 . The repressor complex of  claim 32  comprising BCoR and PHB-2. 
     
     
         35 . The repressor complex of  claim 32  comprising BCoR, PHB-1 and PHB-2. 
     
     
         36 . A method of using the repressor complex of  claim 32 , for binding to a E2F-site. 
     
     
         37 . The method of  claim 36 , wherein the E2F-site is that of pitx1 promoter.