Actriib-fc polynucleotides, polypeptides, and compositions

Abstract

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 neuron. The present invention also provides methods of screening compounds that modulate activity of an ActRII protein and/or an ActRII ligand. The compositions and methods provided herein are useful in treating diseases associated with abnormal activity of an ActRII protein and/or an ActRII ligand.

1 - 14 . (canceled) 
     
     
         15 . A soluble ActRIIB polypeptide comprising an extracellular domain of an ActRIIB polypeptide comprising an amino acid sequence that is at least 80% identical to SEQ ID NO: 2, a linker having the sequence TGGG, and an immunoglobulin Fc domain, wherein the immunoglobulin Fc domain is fused to the extracellular domain of the ActRIIB polypeptide by the linker, and wherein the extracellular domain of the ActRIIB polypeptide comprises one or more mutations at a residue selected from: L79, D80, and F82, using the amino acid numbering of SEQ ID NO:4. 
     
     
         16 . The soluble ActRIIB polypeptide of  claim 15 , Wherein the amino acid sequence of the extracellular domain of the ActRIIB polypeptide is at least 85% identical to SEQ ID NO:2. 
     
     
         17 . The soluble ActRIIB polypeptide of  claim 15 , wherein the one or more mutations in the extracellular domain of the ActRIIB polypeptide alter binding of an ActRIIB ligand to the soluble ActRIIB polypeptide. 
     
     
         18 . The soluble ActRIIB polypeptide of  claim 15 , wherein said soluble ActRIIB polypeptide 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. 
     
     
         19 . The soluble ActRIIB polypeptide of  claim 15 , wherein the soluble ActRIIB polypeptide has one or more of the following characteristics:
 i) binds to an ActRIIB ligand with a K d  of at least 10 −5 M; and   ii) inhibits ActRIIB signaling in a cell.   
     
     
         20 . The soluble ActRIIB polypeptide of  claim 15 , wherein the soluble ActRIIB polypeptide binds to an ActRIIB ligand with a K d  of less than 1 micromolar. 
     
     
         21 . The soluble ActRIIB polypeptide of  claim 17 , wherein the ActRIIB ligand is selected from: activin, BMP7, GDF8, GDF11, and Noda1. 
     
     
         22 . The soluble ActRIIB polypeptide of  claim 15 , wherein the polypeptide includes a A64R mutation, using the numbering of SEQ ID NO:4. 
     
     
         23 . A pharmaceutical preparation comprising:
 i) the soluble ActRIIB polypeptide of  claim 15 ; and   ii) a pharmaceutically acceptable carrier.   
     
     
         24 . The pharmaceutical preparation of  claim 23 , wherein said preparation is substantially pyrogen free. 
     
     
         25 . An isolated polynucleotide comprising a coding sequence for the soluble ActRIIB polypeptide of  claim 15 . 
     
     
         26 . A recombinant polynucleotide comprising a promoter sequence operably linked to the polynucleotide of  claim 25 . 
     
     
         27 . A cell comprising the recombinant polynucleotide of  claim 26 . 
     
     
         28 . The cell of  claim 27 , wherein the cell is a mammalian cell. 
     
     
         29 . The cell of  claim 28 , wherein the cell is a human cell.