Systemic Carnitine Deficiency Gene and Uses Thereof

Abstract

The gene responsible for systemic carnitine deficiency was found to be the OCTN2 gene involved in the transportation of organic cations. This invention enables tests for this disease by detecting whether or not the OCTN2 gene has a mutation. Furthermore, systemic carnitine deficiency can be treated using the normal OCTN2 gene and its protein.

1 . A method of screening for a compound that regulates OCTN2 gene expression, the method comprising:
 (a) contacting a test compound with (i) OCTN2 DNA encoding OCTN2; or (ii) a cell comprising said DNA; and   (b) measuring OCTN2 gene expression, wherein an increase or decrease in gene expression in the presence of the test compound, compared to in the absence of the test compound, is indicative of a compound that regulates OCTN2 gene expression.   
     
     
         2 . The method of  claim 1 , wherein the OCTN2 DNA comprises a promoter region or an enhancer region of the OCTN2 gene. 
     
     
         3 . The method of  claim 1 , wherein the OCTN2 DNA comprises the nucleotide sequence of SEQ ID NO:5. 
     
     
         4 . The method of  claim 1 , wherein the test compound is selected from among proteins, peptides, synthetic compounds, natural compounds, genes and gene products. 
     
     
         5 . The method of  claim 4 , wherein the test compound is a protein. 
     
     
         6 . The method of  claim 5 , wherein the protein is a transcription factor. 
     
     
         7 . A method of screening for a compound that regulates OCTN2 gene expression, the method comprising:
 (a) providing a vector comprising a reporter gene downstream of a promoter sequence from SEQ ID NO:5;   (b) contacting a test compound with the vector; and   (c) detecting expression of the reporter gene, wherein an increase or decrease in expression of the reporter gene in the presence of the test compound, compared to in the absence of the test compound, is indicative of a compound that regulates OCTN2 gene expression.   
     
     
         8 . The method of  claim 7 , wherein the test compound binds to the promoter. 
     
     
         9 . A method of screening for a compound that regulates OCTN2 gene expression, the method comprising:
 (a) providing an oligonucleotide DNA, wherein the oligonucleotide DNA comprises a regulatory sequence from SEQ ID NO:5 that is upstream of the OCTN2 coding sequence;   (b) contacting a test compound with the oligonucleotide DNA; and   (c) determining whether the test compound binds to the oligo DNA, wherein binding to the oligonucleotide DNA is an indication that the test compound is potentially able to regulate OCTN2 gene expression.   
     
     
         10 . The method of  claim 9 , wherein the regulatory sequence is a promoter region of the OCTN2 gene. 
     
     
         11 . A method of screening for a compound that regulates OCTN2 gene expression, the method comprising:
 (a) contacting a test compound with DNA that comprises a promoter region of the OCTN2 gene; and   (b) measuring binding of the test compound to the promoter, wherein a compound that binds to the promoter is indicative of a compound that regulates OCTN2 gene expression.   
     
     
         12 . The method of  claim 11 , wherein the DNA further comprises (i) OCTN2 genomic DNA (SEQ ID NO:5); (ii) a sequence that regulates transcription of SEQ ID NO:5; or (iii) DNA that encodes an OCTN2 protein comprising the amino acid sequence of SEQ ID NO:1. 
     
     
         13 . The method of  claim 11 , wherein the DNA is bound to a solid support. 
     
     
         14 . The method of  claim 13 , wherein the compound is purified by affinity chromatography. 
     
     
         15 . The method of  claim 11 , wherein the test compound is a protein. 
     
     
         16 . The method of  claim 15 , wherein the protein is a transcription factor. 
     
     
         17 . A method of screening for a compound that regulates OCTN2 gene expression, the method comprising:
 (a) providing a cell comprising a reporter gene downstream of DNA that comprises a promoter region of the OCTN2 gene; and   (b) detecting reporter gene activity in the cell, wherein an increase or decrease in reporter gene expression in the presence of the test compound, compared to in the absence of the test compound, is indicative of a compound that regulates OCTN2 gene expression.   
     
     
         18 . The method of  claim 17 , wherein the test compound is a protein. 
     
     
         19 . The method of  claim 18 , wherein the protein is a transcription factor. 
     
     
         20 . A method of screening for a compound that enhances the activity of the OCTN2 protein, the method comprising:
 (a) contacting a test compound with an OCTN2 protein comprising the amino acid sequence of SEQ ID NO: 1; and   (b) evaluating the activity of the protein, wherein an increase in activity in the presence of the test compound, compared to in the absence of the test compound, is indicative of a compound that enhances the activity of the OCTN2 protein.   
     
     
         21 . The method of  claim 20 , wherein the test compound is introduced into a cell comprising a vector that expresses the OCTN2 protein. 
     
     
         22 . The method of  claim 21 , wherein the activity of the OCTN2 protein is evaluated by measuring carnitine transport into the cell. 
     
     
         23 . A pharmaceutical composition comprising an isolated protein comprising the amino acid sequence of SEQ ID NO: 1 as an active ingredient, wherein the protein is in an amount effective to increase cellular uptake of carnitine. 
     
     
         24 . A method of testing whether an individual's genome carries a mutant OCTN2 allele that, in the homozygous state, may result in systemic carnitine deficiency, the method comprising
 (a) identifying an individual suspected of carrying the mutant allele; and   (b) analyzing a nucleic acid sample from the individual to determine the presence or absence of a mutation in (i) DNA encoding OCTN2 (SEQ ID NO: 1) or (ii) OCTN2 genomic DNA (SEQ ID NO:5) or (iii) a sequence that regulates expression of SEQ ID NO:5, wherein the presence of the mutation in (i) or (ii) or (iii) indicates that the individual carries a mutant OCTN2 allele that, in the homozygous state, may result in systemic carnitine deficiency.