Method of screening test substances for treating or preventing a disease mediated by plasma cells

Abstract

The present invention relates to a method of screening a compound for potential effectiveness in treating or preventing a mammalian disease mediated by plasma cells or a mammalian disease caused by virus infection of mammalian cells. Compounds are tested for their ability to inhibit IRE1-mediated processing of untranslatable XBP-1 mRNA into translatable XBP-1 mRNA. Drugs that are useful in treating or preventing a mammalian disease mediated by plasma cells and a method for detecting XBP-1 activity in living cells are also described.

1 . A method of screening a compound for potential effectiveness in treating a mammalian disease mediated by plasma cells, said method comprising:
 providing a test compound;   providing an assay system suitable for evaluating the test compound's ability to inhibit processing of unspliced XBP-1 mRNA to spliced XBP-1 mRNA said assay system-comprising:
 unspliced XBP-1 mRNA; 
 IRE1 protein; and 
 a system suitable to cut unspliced XBP-1 mRNA; 
   contacting the test compound with the assay system and providing a stimulus effective to activate cutting of unspliced XBP-1 mRNA with IRE1 present;   evaluating, with the assay system, the test compound's ability to inhibit IRE1-mediated cutting of unspliced XBP-1 mRNA by IRE1 by detecting whether cut XBP-1 mRNA is present in the assay system with and without the test compound; and   identifying test compounds which reduce cut XBP-1 mRNA or increase unspliced XBP-1 mRNA as having potential effectiveness in treating a mammalian disease mediated by plasma cells.   
     
     
         2 . The method according to  claim 1 , wherein said detecting comprises use of a polymerase chain reaction process to analyze whether unspliced XBP-1 mRNA and spliced XBP-1 mRNA are present. 
     
     
         3 . The method according to  claim 1 , wherein said mammalian disease is caused by pathogenic immunoglobulins secreted from said plasma cells. 
     
     
         4 . The method according to  claim 3 , wherein said mammalian disease is selected from the group consisting of Myasthenia Gravis, Pemphigus Vulgaris, Systemic Lupus Erythromatosus, Guillain Barré syndrome, proliferative glomerulonephritis, hemophilia with inhibitory antibodies to factor 8, hemophilia with inhibitory antibodies to factor 9, autoimmune thrombocytopenia, autoimmune hemolytic anemia, and paraneoplastic syndrome. 
     
     
         5 . The method according to  claim 1 , wherein said mammalian disease is a cancer caused by the abnormal proliferation of plasma cells. 
     
     
         6 . The method according to  claim 5 , wherein said cancer is Multiple Myeloma or plasma cell dyscrasia. 
     
     
         7 . A method of screening a compound for potential effectiveness in treating a mammalian disease caused by virus infection of mammalian cells, said method comprising:
 providing a test compound;   providing an assay system suitable for evaluating the test compound's ability to inhibit processing of unspliced XBP-1 mRNA to spliced XBP-1 mRNA said assay system-comprising:
 unspliced XBP-1 mRNA; 
 IRE1 protein; and 
 a system suitable to cut unspliced XBP-1 mRNA; 
   contacting the test compound with the assay system and providing a stimulus effective to activate cutting of unspliced XBP-1 mRNA with IRE1 present;   evaluating, with the assay system, the test compound's ability to inhibit IRE1-mediated cutting of unspliced XBP-1 mRNA by IRE1 by detecting whether cut XBP-1 mRNA is present in the assay system with and without the test compound; and   identifying test compounds which reduce cut XBP-1 mRNA or increase unspliced XBP-1 mRNA as having potential effectiveness in treating a mammalian disease caused by virus infection of mammalian cells.   
     
     
         8 . An isolated, spliced, human XBP-1 mRNA molecule comprising the RNA sequence of SEQ ID NO:2, wherein nucleotide 13 of SEQ ID NO:2 is spliced to nucleotide 40 of SEQ ID NO:2 and nucleotides 14-39 of SEQ ID NO:2 have been removed. 
     
     
         9 . An isolated, spliced, mouse XBP-1 mRNA molecule comprising the RNA sequence of SEQ ID NO:1, wherein nucleotide 13 of SEQ ID NO:1 is spliced to nucleotide 40 of SEQ ID NO:1 and nucleotides 14-39 of SEQ ID NO:1 have been removed. 
     
     
         10 . An isolated, spliced,  C. elegans  XBP-1 mRNA molecule comprising the RNA sequence of SEQ ID NO:3, wherein nucleotide 13 of SEQ ID NO:3 is spliced to nucleotide 37 of SEQ ID NO:3 and nucleotides 14-36 of SEQ ID NO:3 have been removed. 
     
     
         11 . An isolated, spliced, yeast XBP-1 mRNA molecule comprising the RNA sequence of SEQ ID NO:4, wherein nucleotide 13 of SEQ ID NO:4 is spliced to nucleotide 253 of SEQ ID NO:4 and nucleotides 14-252 of SEQ ID NO:4 have been removed.