Translation initiation factor 4AIII, and methods of use thereof

Abstract

The present invention provides a vertebrate translation initiation factor (eIF-4AIII), that plays a role in the differentiation of an embryonic cell to an epidermal cell. This translation initiation factor interacts with BMP-4 in a positive regulatory loop. The nucleic acid and amino acid sequences are also disclosed. Also disclosed are methods of using the translation initiation factor, nucleic acids encoding the same, and corresponding antibodies and the like.

What is claimed is:  
     
         1 . An isolated nucleic acid encoding a vertebrate translation initiation factor 4AIII (eIF-4AIII) having an amino acid sequence substantially homologous to that of SEQ ID NO:2.  
     
     
         2 . The isolated nucleic acid of    claim 1    wherein the amino acid sequence is SEQ ID NO:2 or SEQ ID NO:2 with a conservative amino acid substitution.  
     
     
         3 . The isolated nucleic acid of    claim 2    wherein the nucleic acid contains the coding sequence of SEQ ID NO:1.  
     
     
         4 . The isolated nucleic acid of    claim 1    further comprising an heterologous nucleotide sequence.  
     
     
         5 . The isolated nucleic acid of    claim 4    wherein the heterologous nucleotide sequence encodes a fusion protein or fusion peptide.  
     
     
         6 . The isolated nucleic acid of    claim 1    operatively linked to an expression control sequence.  
     
     
         7 . A unicellular host transformed or transfected with the nucleic acid of    claim 6   .  
     
     
         8 . A method of expressing the eIF-4AIII comprising culturing the unicellular host of    claim 7    in an appropriate cell culture medium under conditions that provide for expression of the protein by the cell.  
     
     
         9 . The method of    claim 8    further comprising the step of purifying the eIF-4AIII.  
     
     
         10 . The purified form of the eIF-4AIII obtained by the method of    claim 9   .  
     
     
         11 . An isolated nucleic acid containing 15 or more nucleotides that hybridizes to SEQ ID NO:1 under standard hybridization conditions.  
     
     
         12 . The isolated nucleic acid of    claim 11    that hybridizes to nucleotides 1 to 90 of the coding region of SEQ ID NO:1 under standard hybridization conditions.  
     
     
         13 . An isolated vertebrate translation initiation factor 4AIII (eIF-4AIII) having an amino acid sequence substantially homologous to that of SEQ ID NO:2.  
     
     
         14 . The isolated eIF-4AIII-of    claim 13    having the amino acid sequence of SEQ ID NO:2 or SEQ ID NO:2 with a conservative amino acid substitution.  
     
     
         15 . The isolated eIF-4AIII of    claim 13    containing the amino acid sequence of SEQ ID NO:4.  
     
     
         16 . The isolated eIF-4AIII of    claim 13    having a detectable label.  
     
     
         17 . A proteolytic fragment of the isolated eIF-4AIII of    claim 13   .  
     
     
         18 . A chimeric protein comprising a fusion protein or peptide and the proteolytic fragment of    claim 17   .  
     
     
         19 . A chimeric protein comprising a fusion protein or peptide and an eIF-4AIII having an amino acid sequence substantially homologous to that of SEQ ID NO:2.  
     
     
         20 . An antibody to an isolated vertebrate translation initiation factor 4AIII (eIF-4AIII) having an amino acid sequence substantially homologous to that of SEQ ID NO:2.  
     
     
         21 . The antibody of    claim 20    that binds amino acids 1-30 of SEQ ID NO:2.  
     
     
         22 . The antibody of    claim 21    which is a monoclonal antibody.  
     
     
         23 . A method for identifying a potential drug that modulates the ability of the eIF-4AIII of    claim 13    to induce the transcription of epidermal markers comprising: 
 (a) injecting an mRNA encoding the eIF-4AIII into an animal pole of a 2-cell stage embryo in the presence of an agent;  
 (b) isolating the animal pole explant at the late blastula stage;  
 (c) culturing the animal pole explant until the midneurula stage;  
 (d) extracting the RNA from the animal pole explant;  
 (e) assaying for the transcription of an epidermal marker protein; and  
 (f) comparing the amount of transcription in the presence of the agent relative to in its absence; wherein an agent that enhances or diminishes said transcription relative to in its absence is identified as a potential drug that modulates the ability of the eIF-4AIII to induce the transcription of epidermal markers.  
 
     
     
         24 . The method of    claim 23    wherein said assaying the transcription of the epidermal marker is performed by reverse transcriptase polymerase chain reaction.  
     
     
         25 . The method of    claim 23    wherein the 2-cell stage embryo is a xenopus embryo.  
     
     
         26 . The method of    claim 23    wherein the animal pole explant is dissociated for 2-6 hours and then reaggregated prior to said culturing of step (c).