Variants derived from ActRIIB and uses therefor
In certain aspects, the present invention provides compositions and methods for modulating (promoting or inhibiting) growth of a tissue, such as bone, cartilage, muscle, fat, and/or neuronal tissue. The present invention also provides methods of screening compounds that modulate activity of an ActRIIB protein and/or an ActRIIB ligand. The compositions and methods provided herein are useful in treating diseases associated with abnormal activity of an ActRIIB protein and/or an ActRIIB ligand.
1. An ActRIIB fusion protein comprising an ActRIIB polypeptide and a heterologous polypeptide, wherein the ActRIIB polypeptide consists of amino acids 25-131 of SEQ ID NO:2, and wherein the ActRIIB fusion protein inhibits signaling by myostatin and/or GDF11 in a cell-based assay.
2. The ActRIIB fusion protein of claim 1 , wherein the ActRIIB fusion protein is a homodimer.
3. The ActRIIB fusion protein of claim 1 , wherein the heterologous polypeptide comprises a constant region from an IgG heavy chain.
4. The ActRIIB fusion protein of claim 3 , wherein the heterologous polypeptide comprises an Fc domain.
5. The ActRIIB fusion protein of claim 1 , wherein the ActRIIB fusion protein further comprises a linker domain positioned between the ActRIIB polypeptide and the heterologous polypeptide.
6. The ActRIIB fusion protein of claim 3 , wherein the ActRIIB fusion protein further comprises a linker domain positioned between the ActRIIB polypeptide and the IgG heavy chain.
7. The ActRIIB fusion protein of claim 4 , wherein the ActRIIB fusion protein further comprises a linker domain positioned between the ActRIIB polypeptide and the Fc domain.
8. The ActRIIB fusion protein of claim 1 , wherein the ActRIIB fusion protein includes one or more modified amino acid residues selected from: a glycosylated amino acid, a PEGylated amino acid, a farnesylated amino acid, an acetylated amino acid, a biotinylated amino acid, and an amino acid conjugated to a lipid moiety.
9. The ActRIIB fusion protein of claim 3 , wherein the ActRIIB fusion protein includes one or more modified amino acid residues selected from: a glycosylated amino acid, a PEGylated amino acid, a farnesylated amino acid, an acetylated amino acid, a biotinylated amino acid, and an amino acid conjugated to a lipid moiety.
10. The ActRIIB fusion protein of claim 4 , wherein the ActRIIB fusion protein includes one or more modified amino acid residues selected from: a glycosylated amino acid, a PEGylated amino acid, a farnesylated amino acid, an acetylated amino acid, a biotinylated amino acid, and an amino acid conjugated to a lipid moiety.
11. The ActRIIB fusion protein of claim 5 , wherein the ActRIIB fusion protein includes one or more modified amino acid residues selected from: a glycosylated amino acid, a PEGylated amino acid, a farnesylated amino acid, an acetylated amino acid, a biotinylated amino acid, and an amino acid conjugated to a lipid moiety.
12. The ActRIIB fusion protein of claim 6 , wherein the ActRIIB fusion protein includes one or more modified amino acid residues selected from: a glycosylated amino acid, a PEGylated amino acid, a farnesylated amino acid, an acetylated amino acid, a biotinylated amino acid, and an amino acid conjugated to a lipid moiety.
13. The ActRIIB fusion protein of claim 7 , wherein the ActRIIB fusion protein includes one or more modified amino acid residues selected from: a glycosylated amino acid, a PEGylated amino acid, a farnesylated amino acid, an acetylated amino acid, a biotinylated amino acid, and an amino acid conjugated to a lipid moiety.
14. The ActRIIB fusion protein of claim 1 , wherein the ActRIIB fusion protein further comprises a purification sequence selected from: an epitope tag, a FLAG tag, a polyhistidine sequence, and a GST fusion.
15. A pharmaceutical preparation comprising the fusion protein of any one of claims 1 , 2 - 3 , or 4 - 14 .