ANKTM1, A Cold-Activated TRP-Like Channel Expressed in Nociceptive Neurons

Abstract

The methods and compositions of the invention are based on a method for measuring nociceptive responses in vertebrates, including humans and other mammals utilizing a newly discovered thermoreceptor belonging to the Transient Receptor Potential (TRP) family of non-selective cation channels that participates in thermosensation and pain. This receptor, designated ANKTM1, is associated with nociceptive pain, such as hyperalgesia. Accordingly, the invention provides isolated polypeptides and polynucleotides associated with nociception as well as methods for identifying or screening agents that modulate nociception.

1 . An isolated nucleic acid sequence encoding an ANKTM1-related polypeptide, characterized as
 encoding a temperature/pain sensitive non-selective cation channel protein that is activated by temperature below 20° C.;   being expressed in Calcitonin gene-related peptide- and substance P-positive neurons; and   comprising more than five ankyrin domains and a six transmembrane domain.   
     
     
         2 . (canceled) 
     
     
         3 . The isolated nucleic acid sequence of  claim 1 , wherein the ANKTM1-related polypeptide comprises the amino acid sequence of SEQ ID NO:1, or a conservation variation thereof. 
     
     
         4 . (canceled) 
     
     
         5 . A method for identifying an agent that modulates nociceptive response, the method comprising:
 (a) contacting an organism containing an ANKTM1-related polypeptide encoded by the sequence set forth in  claim 1  with an agent suspected of having nociceptive pain modulating activity under conditions that allow the agent and the polypeptide to interact;   (b) measuring a nociceptive response to administration of a nociceptive stimulus to the organism;   (c) and comparing the nociceptive response to a nociceptive response to the stimulus in the organism when not administered the agent,   wherein a change in the nociceptive response indicates an agent that modulates the nociceptive response.   
     
     
         6 . The method for  claim 5 , wherein the agent is selected from the group consisting of a peptide, a peptidomimetic, a chemical, and a nucleic acid sequence. 
     
     
         7 . The method for  claim 5 , wherein modulation of the nociceptive response is a decrease in pain and the change in the nociceptive response indicates that the agent decreases nociceptive pain. 
     
     
         8 . The method for  claim 5 , wherein the organism is selected from a non-human organism, a vertebrate, especially a murine species, and a mammal, especially a human. 
     
     
         9 . The method for  claim 8 , wherein the non-human organism is a mammalian cell. 
     
     
         10 . The method for  claim 9 , wherein stimulus is noxious cold and the response comprises a rise in [Ca 2+ ] i  or [Mg 2+ ] i  in the cell. 
     
     
         11 . A method for modulating nociceptive pain in an organism, the method comprising contacting a sentient organism containing a polypeptide sequence comprising an amino acid sequence selected from SEQ ID NO:1, SEQ ID NO:2 and SEQ ID NO:4, and conservative variations thereof, with an effective amount of an agent that modulates operation of the polypeptide under conditions that allow the agent and the polypeptide to interact, thereby modulating nociceptive pain in the organism. 
     
     
         12 . The method for  claim 11 , wherein the polypeptide contains an ion channel and the agent modifies operation of the ion channel. 
     
     
         13 . The method for  claim 11 , wherein the modulating is a decrease in the nociceptive pain. 
     
     
         14 . The method for  claim 11 , wherein the organism is a human. 
     
     
         15 . A method for identifying an agent that modulates nociceptive pain, the method comprising:
 (a) contacting an organism containing the polynucleotide sequence of  claim 1  with a candidate agent under conditions that allow the agent and the polynucleotide to interact;   (b) measuring a nociceptive response to administration of a nociceptive stimulus to the organism; and   (c) comparing the nociceptive response to a nociceptive response in the organism when not administered the nociceptive stimulus,   wherein a change in the nociceptive response indicates the agent modulates nociceptive pain.   
     
     
         16 . (canceled) 
     
     
         17 . A method for reducing nociceptive pain in an organism, the method comprising contacting an organism containing the polynucleotide sequence of  claim 1  with an effective amount of an agent that blocks function of the polynucleotide sequence under conditions that allow the agent and the polynucleotide to interact, thereby reducing nociceptive pain in the organism. 
     
     
         18 . The method of  claim 11  or  17 , wherein the agent is selected from the group consisting of a peptide, a peptidomimetic, a chemical, and a nucleic acid sequence. 
     
     
         19 . The method of  claim 11 , wherein the organism is a transgenic organism. 
     
     
         20 . The method for  claim 17 , wherein the organism is a mammal. 
     
     
         21 . An isolated polypeptide comprising an amino acid sequence selected from SEQ ID NO:1, SEQ ID NO:2 and conservative variations thereof. 
     
     
         22 . A binding molecule which is capable of binding to the polypeptide according to  claim 21  with a dissociation constant <1000 nM. 
     
     
         23 . The binding molecule according to  claim 22 , which is a chimeric or humanized monoclonal antibody.