Peptide Inhibitors of Sodium Channels

Abstract

The present invention relates to the ability of specialized non-naturally occurring peptides to bind to sodium channels and inhibit activation of the sodium channels. The invention further relates to methods for regulating of sodium absorption and fluid volume and treating disorders responsive to modulating sodium absorption by modulating the binding of specialized non-naturally occurring peptides to sodium channels.

1 . A peptide comprising the sequence:
 X 1 -X 2 -X 3 -X 4 -X 5 -X 6 -X 7 -X 8  (SEQ ID NO:116)   wherein:   X 1  is leucine or a conservative substitution with a natural or non-natural amino acid;   X 2  is proline or a conservative substitution with a natural or non-natural amino acid;   X 3  is valine or a conservative substitution with a natural or non-natural amino acid;   X 4  is proline or a conservative substitution with a natural or non-natural amino acid;   X 5  is leucine or a conservative substitution with a natural or non-natural amino acid;   X 6  is aspartic acid or a conservative substitution with a natural or non-natural amino acid;   X 7  is glutamine or a conservative substitution with a natural or non-natural amino acid; and   X 8  is threonine or a conservative substitution with a natural or non-natural amino acid;   or a functional fragment thereof.   
     
     
         2 . A peptide comprising the sequence:
 X 1 -X 2 -X 3 -X 4 -X 5 -X 6 -X 7 -X 8 -X 9 -X 10 -X 11 -X 12  (SEQ ID NO:117)   wherein:   X 1  is leucine, norleucine, or valine;   X 2  is proline, 4-hydroxyproline, (2R,5S)-5-phenyl-pyrrolidine-2-carboxylic acid, or 3,4-dehydro-L-proline;   X 3  is valine, leucine, norleucine, or N-methylvaline;   X 4  is proline, 4-hydroxyproline, (2R,5S)-5-phenyl-pyrrolidine-2-carboxylic acid, or 3,4-dehydro-L-proline;   X 5  is leucine, norleucine, or valine;   X 6  is aspartic acid or glutamic acid;   X 7  is glutamine or asparagine; and   X 8  is threonine, serine, or L-α-methylserine;   or a functional fragment thereof.   
     
     
         3 . The peptide of  claim 1 , comprising the sequence of any one of SEQ ID NOS:4-115. 
     
     
         4 . A peptide comprising the sequence:
 X 1 -X 2 -X 3 -X 4 -X 5 -X 6 -X 7 -X 8 -X 9 -X 10 -X 11 -X 12 -X 13 -X 14 -X 15  (SEQ ID NO:118)   wherein:   X 1  is leucine or a conservative substitution with a natural or non-natural amino acid;   X 2  is proline or a conservative substitution with a natural or non-natural amino acid;   X 3  is valine or a conservative substitution with a natural or non-natural amino acid;   X 4  is proline or a conservative substitution with a natural or non-natural amino acid;   X 5  is leucine or a conservative substitution with a natural or non-natural amino acid;   X 6  is aspartic acid or a conservative substitution with a natural or non-natural amino acid;   X 7  is glutamine or a conservative substitution with a natural or non-natural amino acid;   X 8  is threonine or a conservative substitution with a natural or non-natural amino acid;   X 9  is threonine or a conservative substitution with a natural or non-natural amino acid;   X 10  is leucine or a conservative substitution with a natural or non-natural amino acid;   X 11  is proline or a conservative substitution with a natural or non-natural amino acid;   X 12  is asparagine or a conservative substitution with a natural or non-natural amino acid;   X 13  is valine or a conservative substitution with a natural or non-natural amino acid;   X 14  is asparagine or a conservative substitution with a natural or non-natural amino acid; and   X 15  is proline or a conservative substitution with a natural or non-natural amino acid;   or a functional fragment thereof.   
     
     
         5 . The peptide of  claim 4 , comprising the sequence of SEQ ID NO:120. 
     
     
         6 . A peptide comprising the sequence of SEQ ID NO:127 or SEQ ID NO:128. 
     
     
         7 . The peptide of  claim 1 , wherein the N-terminus is acetylated and/or the C-terminus is amidated. 
     
     
         8 . The peptide of  claim 1 , wherein the peptide comprises at least one non-natural amino acid or at least one terminal modification. 
     
     
         9 . The peptide of  claim 1 , further comprising at least one D-alanine at the N-terminus and/or the C-terminus. 
     
     
         10 . A kit comprising the peptide of  claim 1 . 
     
     
         11 . A method of inhibiting the activation of a sodium channel, comprising contacting a sodium channel with the peptide of  claim 1 . 
     
     
         12 . The method of  claim 11 , wherein the sodium channel is an epithelial sodium channel (ENaC). 
     
     
         13 . The method of  claim 11 , wherein the sodium channel is present in an isolated cell. 
     
     
         14 . The method of  claim 13 , wherein the isolated cell is part of an epithelial cell culture. 
     
     
         15 . The method of  claim 11 , wherein the sodium channel is present in a cell in an animal. 
     
     
         16 . The method of  claim 15 , wherein the animal is a disease model. 
     
     
         17 . The method of  claim 11 , wherein contacting the sodium channel with the peptide comprises delivering the peptide to a cell comprising the sodium channel. 
     
     
         18 . The method of  claim 11 , wherein activation of the sodium channel is inhibited by at least 20%. 
     
     
         19 . The method of  claim 11 , wherein activation of the sodium channel is inhibited by at least 50%. 
     
     
         20 . The method of  claim 11 , wherein activation of the sodium channel is inhibited by at least 90%. 
     
     
         21 . A method of inhibiting sodium absorption through a sodium channel, comprising contacting the sodium channel with the peptide of  claim 1 . 
     
     
         22 . The method of  claim 21 , wherein the sodium channel is ENaC. 
     
     
         23 . A method of increasing the volume of fluid lining an epithelial mucosal surface, comprising contacting a sodium channel present on the epithelial mucosal surface with the peptide of  claim 1 . 
     
     
         24 . The method of  claim 23 , wherein the sodium channel is ENaC. 
     
     
         25 . A method of reducing the level of a sodium channel present on the surface of a cell, comprising contacting the sodium channel with the peptide of  claim 1 . 
     
     
         26 . The method of  claim 25 , wherein the sodium channel is ENaC. 
     
     
         27 . A method of treating a disorder responsive to inhibition of sodium absorption across an epithelial mucosal surface in a subject in need thereof, comprising delivering to the subject a therapeutically effective amount of the peptide of  claim 1 . 
     
     
         28 . The method of  claim 27 , wherein the sodium channel is ENaC. 
     
     
         29 . The method of  claim 27 , wherein said disorder is a lung disorder. 
     
     
         30 . The method of  claim 27 , wherein said lung disorder is cystic fibrosis. 
     
     
         31 . The method of  claim 27 , wherein said lung disorder is non-cystic fibrosis bronchiectasis. 
     
     
         32 . The method of  claim 27 , wherein said lung disorder is chronic obstructive pulmonary disease. 
     
     
         33 . The method of  claim 27 , wherein said lung disorder is acute or chronic bronchitis. 
     
     
         34 . The method of  claim 27 , wherein said lung disorder is asthma. 
     
     
         35 . The method of  claim 27 , wherein said disorder is a gastrointestinal disorder. 
     
     
         36 . The method of  claim 35 , wherein said gastrointestinal disorder is inflammatory bowel disease. 
     
     
         37 . The method of  claim 27 , wherein said disorder is a kidney disorder. 
     
     
         38 . A method of regulating salt balance, blood volume, and/or blood pressure in a subject in need thereof, comprising delivering to the subject a therapeutically effective amount of the peptide of  claim 1 . 
     
     
         39 . The method of  claim 27 , wherein delivering the peptide reduces the level of a sodium channel present on the surface of a cell in the subject. 
     
     
         40 . A method for treating a symptom of a lung disorder, a gastrointestinal disorder, a kidney disorder, or a cardiovascular disorder in a subject in need thereof, comprising administering to the subject a therapeutically effective amount of the peptide of  claim 1 . 
     
     
         41 . The method of  claim 40 , wherein the lung disorder is cystic fibrosis, non-cystic fibrosis bronchiectasis, chronic obstructive pulmonary disease, acute or chronic bronchitis, or asthma. 
     
     
         42 . The method of  claim 40 , wherein the gastrointestinal disorder is inflammatory bowel disease.