Sperm-specific cation channel, catsper4, and uses therefor

Abstract

Nucleic acid and protein sequences relating to a cation channel which is sperm-specific (CatSper4) are disclosed. The CatSper4 protein is shown to be specifically expressed in sperm. Nucleic acids, vectors, transformed cells, transgenic animals, polypeptides, and antibodies relating to the CatSper4 gene and protein are disclosed. Also provided are methods of in vitro fertilization and contraception, methods of identifying modulators of CatSper4 activity, methods of genotyping subjects with respect to CatSper4, and methods of diagnosing and treating CatSper4-mediated disorders, including infertility. Related business methods are also disclosed.

We claim: 
     
         1 . A method of identifying a compound having potential contraceptive activity, the method comprising:
 (a) contacting a candidate compound with a cell expressing a CatSper4 protein;   (b) measuring an indicator of CatSper4 expression or activity in the cell;   (c) determining whether the candidate compound caused a decrease in the indicator relative to a reference level; and   (d) identifying the candidate compound as having potential contraceptive activity if a significant decrease is determined in (c).   
     
     
         2 . A method as in  claim 1 , wherein the indicator is an indicator of the level of mRNA encoding the CatSper4 protein. 
     
     
         3 . A method as in  claim 1 , wherein the indicator is an indicator of the level of CatSper4 protein. 
     
     
         4 . A method as in  claim 1 , wherein the indicator is an indicator of cation flux across a membrane of the cell. 
     
     
         5 . A method as in  claim 1 , wherein the indicator is an indicator of whole cell or channel currents of the cell. 
     
     
         6 . A method as in  claim 1 , wherein the cell has been transformed with a genetic construct capable of expressing a CatSper4 protein. 
     
     
         7 . A method as in  claim 1 , wherein the cell is a mature sperm cell and the indicator is a measure of sperm motility. 
     
     
         8 . A method as in  claim 1 , wherein the cell is a mature sperm cell and the indicator is a measure of egg penetrance. 
     
     
         9 . A method of identifying a compound having potential contraceptive activity, the method comprising:
 (a) contacting a candidate compound with a cell expressing a CatSper4 protein;   (b) measuring an indicator of CatSper4 expression or activity in the cell;   (c) determining whether the candidate compound caused a decrease in the indicator relative to a reference level;   (d) toxicity profiling the candidate compound; and   (e) identifying the candidate compound as having potential contraceptive activity if a significant decrease is determined in (c) and if acceptable toxicity and side-effects are determined in (d).   
     
     
         10 . A method as in  claim 9 , wherein toxicity profiling is performed in an animal. 
     
     
         11 . A method as in  claim 10 , wherein toxicity profiling is performed by monitoring the animal for adverse changes in at least one of immune function, kidney function, liver function, and cardiac function. 
     
     
         12 . A method as in  claim 9 , further comprising determining whether the candidate compound is pharmaceutically acceptable. 
     
     
         13 . A method as in  claim 9 , further comprising determining whether the candidate compound has sperm-specific activity. 
     
     
         14 . A method as in  claim 9 , further comprising determining whether the candidate compound has CatSper4-specific activity. 
     
     
         15 . A method as in  claim 9 , further comprising determining whether the candidate compound has testis-specific activity. 
     
     
         16 . A method of identifying a compound that inhibits sperm-specific protein, the method comprising:
 (a) contacting a candidate compound with a cell that has been transformed with a genetic construct capable of expressing a CatSper4 protein;   (b) measuring an indicator of CatSper4 expression or activity in the cell;   (c) determining whether the candidate compound caused a decrease in the indicator relative to a reference level; and   (d) identifying the candidate compound as inhibiting sperm-specific protein if a significant decrease is determined in (c).   
     
     
         17 . A method as in  claim 16 , wherein the indicator is selected from the group consisting of the level of mRNA encoding the CatSper4 protein, the level of CatSper4 protein, cation flux across a membrane of the cell, whole cell currents of the cell, and channel currents of the cell. 
     
     
         18 . A method as in  claim 16 , further comprising:
 (d) toxicity profiling the candidate compound; and   (e) identifying the candidate compound as inhibiting sperm-specific protein if a significant decrease is determined in (c) and if acceptable toxicity and side-effects are determined in (d).   
     
     
         19 . A method as in  claim 18 , further comprising:
 (f) testing the candidate compound identified as inhibiting sperm-specific protein in (e) in mature sperm cells for inhibition of an indicator of CatSper4 activity.   
     
     
         20 . A method as in  claim 19 , wherein the indicator of (f) is at least one of sperm motility and egg penetrance.