cDNA Encoding a Gene Bog (B5T Over-Expressed Gene) and its Protein Product

Abstract

Nucleic acids that encode novel polypeptides, designated in the present application as “BOG” (B5T Over-expressed Gene) are provided. BOG binds to pRb and is over-expressed in a number transformed rat liver epithelial (RLE) cell lines resistant to the growth inhibitory effect of TGF-β1 as well as in primary liver tumors. Compositions including BOG chimeras, nucleic acids encoding BOG and antibodies to BOG are also provided. Methods of using BOG to modulate pRb-protein interactions and to alter cellular phenotype are further provided.

1 . An isolated polypeptide comprising a BOG polypeptide fragment, said BOG fragment comprising a pRb binding motif and a casein kinase II phosphorylation motif. 
     
     
         2 . The BOG polypeptide fragment of  claim 1 , wherein said BOG polypeptide fragment is a full length BOG polypeptide. 
     
     
         3 . The BOG polypeptide fragment of  claim 1 , comprising an amino acid sequence as shown in Table 1, 5 or 7. 
     
     
         4 . The BOG polypeptide fragment of  claim 1 , wherein said casein kinase II phosphorylation motif is located downstream of the pRb binding motif. 
     
     
         5 . The BOG polypeptide fragment of  claim 4 , further comprising a second casein kinase II phosphorylation motif, said second casein kinase II phosphorylation motif being located upstream of the pRb binding motif. 
     
     
         6 . The BOG polypeptide fragment of  claim 1  joined to a detectable label. 
     
     
         7 . The BOG polypeptide fragment of  claim 6 , wherein the detectable label includes a radioactive isotope, an enzyme, a chromophore or a mixture thereof. 
     
     
         8 . An isolated nucleic acid encoding a BOG polypeptide fragment. 
     
     
         9 . The nucleic acid of  claim 8 , comprising a nucleotide sequence coding for an amino acid sequence as shown in Table 1, Table 5 or Table 7. 
     
     
         10 . The nucleic acid of  claim 8 , wherein the nucleic acid sequence is codon optimized for a specific host cell. 
     
     
         11 . The nucleic acid of  claim 8  joined to a detectable label. 
     
     
         12 . A nucleic acid probe capable of hybridizing with the nucleic acid of  claim 8 . 
     
     
         13 . The nucleic acid of  claim 8 , wherein said nucleic acid is DNA. 
     
     
         14 . The nucleic acid of  claim 13 , wherein the DNA is cDNA. 
     
     
         15 . The nucleic acid of  claim 8 , wherein the nucleic acid is RNA. 
     
     
         16 . The nucleic acid of  claim 15 , wherein the RNA is mRNA. 
     
     
         17 . A vector comprising a polynucleotide encoding the BOG polypeptide fragment of  claim 1 . 
     
     
         18 . The vector of  claim 17 , wherein the nucleic acid is operably linked to at least one control sequence capable of being recognized by a host cell transformed with the vector. 
     
     
         19 . A host cell comprising the vector of  claim 18 . 
     
     
         20 . A process for producing BOG polypeptide fragments comprising culturing the host cell of  claim 19  under conditions such that the BOG polypeptide fragment is produced. 
     
     
         21 . A BOG polypeptide fragment produced by the method of  claim 20 . 
     
     
         22 . A BOG antisense oligonucleotide comprising a nucleotide sequence which is complimentary to an mRNA encoding a polypeptide comprising a BOG polypeptide fragment. 
     
     
         23 . A chimeric molecule comprising a BOG polypeptide fragment fused to a heterologous amino acid sequence. 
     
     
         24 . An isolated BOG specific polypeptide comprising an F ab  fragment from an antibody capable of specifically binding to a BOG polypeptide fragment. 
     
     
         25 . The isolated BOG specific polypeptide of  claim 24 , wherein said polypeptide comprises an isolated antibody. 
     
     
         26 . The BOG specific polypeptide of  claim 25 , wherein said antibody is a polyclonal, monoclonal or chimeric antibody. 
     
     
         27 . A method of assaying a sample for a polynucleotide encoding a BOG polypeptide fragment comprising detecting the presence or absence of said polynucleotide in said sample utilizing the nucleic acid probe of  claim 12 . 
     
     
         28 . A method of assaying a sample for a BOG polypeptide fragment comprising detecting the presence or absence of said BOG polypeptide fragment in said sample utilizing an isolated BOG specific polypeptide which includes a F ab  fragment from an antibody capable of specifically binding to the BOG polypeptide fragment. 
     
     
         29 . A method of reducing BOG polypeptide fragment expression in a cell comprising exposing the cell to an oligonucleotide of at least about 15 nucleotides which are complementary to a BOG mRNA. 
     
     
         30 . A method of inducing apoptosis in cells overexpressing BOG polypeptide fragments comprising exposing said cells to an effective amount of TGF-β and at least one BOG antisense oligonucleotide. 
     
     
         31 . A method for producing cell lines having an altered phenotype comprising:
 (i) transfecting in vitro mammalian cells with a DNA vector encoding a BOG polypeptide fragment;   (ii) expressing the BOG polypeptide fragment in said cells; and   (iii) selecting for cells having an altered phenotype.   
     
     
         32 . A method of inhibiting the interaction between a pRb A/B domain binding protein and a pRb family member comprising exposing the pRb family member to a BOG polypeptide fragment.