Peptides having reduced toxicity that stimulate cholesterol efflux
The present invention provides a family of non-naturally occurring polypeptides having cholesterol efflux activity that parallels that of full-length apolipoproteins (e.g., Apo AI and Apo E), and having high selectivity for ABCA1 that parallels that of full-length apolipoproteins. Further, the peptides of the invention have little or no toxicity when administered at therapeutic and higher doses. The invention also provides compositions comprising such polypeptides, methods of identifying, screening and synthesizing such polypeptides, and methods of treating, preventing or diagnosing diseases and disorders associated with dyslipidemia, hypercholesterolemia, or inflammation; or diseases involving abnormal glucose metabolism, e.g., diabetes, metabolic syndrome; or Alzheimer's Disease or frontotemporal dementia.
1. A method for mediating cholesterol efflux in a human patient diagnosed as having dementia or at risk of having dementia, and having at least one ApoE4 allele, said method comprising administering to said human a polypeptide having cholesterol efflux activity, wherein the polypeptide comprises an amino acid sequence that is an amphipathic α-helix that has a non-polar surface and a polar surface, wherein the polar surface comprises charged and uncharged amino acid residues at the lipid-water interface, wherein the amino acid sequence:
has at least 60% identity to SEQ ID NO:1; and
comprises a citrulline, or an uncharged analog of citrulline that has a modified R group or modified backbone, but retains the chemical structure of citrulline and maintains a salt-bridge configuration in the α-helix, at one of the three positions 3, 14, and 23 as determined with reference to SEQ ID NO:1; an uncharged amino acid residue at the second of the three positions 3, 14, and 23; and an uncharged amino acid residue or a positively charged residue at the third of the three positions 3, 14, and 23;
comprises an aliphatic amino acid at positions 2, 6, 10, 11, 12, 13, 16, 17, 20, 21, 22, and 24 as determined with reference to SEQ ID NO:1;
comprises a positively charged amino acid at position 5;
comprises a polar uncharged amino acid at position 4; and
comprises an acidic amino acid residue at positions 1, 7, 8, 15, 18, and 19 as determined with reference to SEQ ID NO:1.
2. The method of claim 1 , wherein the amino acid sequence comprises a citrulline at two of the three positions 3, 14, and 23; and an R or K at the third position.
3. The method of claim 1 , wherein the amino acid sequence comprises an uncharged amino acid residue at the and third of the three positions 3, 14, and 23.
4. The method of claim 1 , wherein the α-helix amino acid sequence is 24 amino acids in length and further comprises a position 25 and 26, wherein position 25 is K or N and position 26 is S or Y.
5. The method of claim 1 , wherein the amino acid sequence has Q, N, L, V, I, or A at at least one of the three position 3, 14, or 23.
6. The method of claim 5 , wherein the amino acid sequence has Q or N at at least one of the three position 3, 14, or 23.
7. The method of claim 1 , wherein the amino acid sequence comprises an amino acid residue at two of the three positions 3, 14, and 23 that are independently selected from Q, N, L, V, I, or A.
8. The method of claim 1 , wherein the amino acid sequence comprises R or K at one of the three positions 3, 14, and 23.
9. The method of claim 1 , wherein the amino acid sequence comprises a citrulline at positions 3 and 14 and an R or K at position 23.
10. The method of claim 9 , wherein the amino acid sequence comprises an aliphatic amino acid independently selected from the group consisting of L, I, and Vat positions 10, 13, 16, and 20.
11. The method of claim 1 , wherein the aliphatic amino acids at positions 2, 6, 10, 11, 12, 13, 16, 17, 20, 21, and 24 are independently selected from the group consisting of L, V, A, and I.
12. The method of claim 1 , wherein the amino acid sequence comprises SEQ ID NO:1 or SEQ ID NO:2.
13. The method of claim 1 , wherein the polypeptide further comprises a protecting group.