TGF-beta superfamily type I and type II receptor heteromultimers and uses thereof
In certain aspects, the disclosure provides soluble heteromeric polypeptide complexes comprising an extracellular domain of a type I serine/threonine kinase receptor of the TGF-beta family and an extracellular domain of a type II serine/threonine kinase receptor of the TGF-beta family. In some embodiments, the disclosure provides soluble polypeptide complexes comprising an extracellular domain of a type II receptor selected from: ActRIIA, ActRIIB, TGFBRII, BMPRII, and MISRII. In some embodiments, the disclosure provides soluble polypeptide complexes comprising an extracellular domain of a type I receptor selected from: ALK1, ALK2, ALK3, ALK4, ALK5, ALK6, and ALK7. Optionally the soluble complex is a heterodimer. In certain aspects, such soluble polypeptide complexes may be used to regulate (promote or inhibit) growth of tissues or cells including, for example, muscle, bone, cartilage, fat, neural tissue, tumors, cancerous cells, and/or cells of hematopoietic lineages, including red blood cells. In certain aspects, such soluble polypeptide complexes are can be used to improve muscle formation, bone formation, hematopoiesis, metabolic parameters, and disorders associated with these tissues, cellular networks, and endocrine systems.
1. A recombinant heteromultimer comprising an ALK7-Fc fusion protein and an ActRIIB-Fc fusion protein,
(a) wherein the ALK7-Fc fusion protein comprises:
(1) an ALK7 domain comprising an amino acid sequence that is at least 90% identical to amino acids 21-113 of SEQ ID NO: 38, and
(2) an Fc domain; wherein the Fc domain comprises a cysteine substitution at the position corresponding to S132 of SEQ ID NO: 3100 (S132C) and a tryptophan substitution at the position corresponding to T144 of SEQ ID NO: 3100 (T144W); and
(b) wherein the ActRIIB-Fc fusion protein comprises:
(1) an ActRIIB domain comprising an amino acid sequence that is at least 90% identical to amino acids 29-109 of SEQ ID NO: 1, and
(2) an Fc domain that is an IgG1 Fc domain, and wherein the IgG1 Fc domain comprises one or more amino acid modifications that alter the pI of the ActRIIB-Fc fusion protein; and
wherein the recombinant heteromultimer binds to one or more of activin B, activin C, and activin AC.
2. The heteromultimer of claim 1 , wherein the ALK7-Fc fusion protein and the ActRIIB-Fc fusion protein Fc domain is an IgG1 Fc domain comprising an amino acid sequence that is at least 90% identical to the amino acid sequence of SEQ ID NO: 3100.
3. The heteromultimer of claim 2 , wherein the ActRIIB-Fc fusion protein IgG1 Fc domain comprises a cysteine substitution at the position corresponding to Y127 of SEQ ID NO: 3100 (Y127C), a serine substitution at the position corresponding to T144 of SEQ ID NO: 3100 (T144S), an alanine substitution at the position corresponding to L146 of SEQ ID NO: 3100 (L146A), and a valine substitution at the position corresponding to Y185 of SEQ ID NO: 3100 (Y185V).
4. The heteromultimer of claim 2 , wherein the ActRIIB-Fc fusion protein IgG1 Fc domain comprises a cysteine substitution at the position corresponding to S132 of SEQ ID NO: 3100 (S132C) and a tryptophan substitution at the position corresponding to T144 of SEQ ID NO: 3100 (T144W).
5. The heteromultimer of claim 1 , wherein:
a) the ActRIIB-Fc fusion protein comprises one or more amino acid modifications that increase the pI of the ActRIIB-Fc fusion protein; and
b) the ALK7-Fc fusion protein comprises one or more amino acid modifications that decrease the pI of the ALK7-Fc fusion protein.
6. The heteromultimer of claim 1 , wherein the ALK7-Fc fusion protein comprises an ALK7 domain comprising an amino acid sequence that is at least 90% identical to an amino acid sequence selected from the group consisting of:
a) an amino acid sequence that:
i) begins at any one of amino acids 21-28 of SEQ ID NO: 305 or 309, and
ii) ends at any one of amino acids 92-113 of SEQ ID NO: 305 or 309;
b) an amino acid sequence comprising amino acids 28-92 of SEQ ID NOs: 38, 305, or 309;
c) an amino acid sequence comprising amino acids 21-113 of SEQ ID NOs: 305 or 309; or
d) an amino acid sequence comprising the amino acid sequence of any one of SEQ ID NOs: 38, 39, 301, 302, 305, 306, 309, 310, 313, 112, 114, 405, and 406.
7. The heteromultimer of claim 1 , wherein the ActRIIB-Fc fusion protein comprises an ActRIIB domain comprising an amino acid sequence that is at least 90% identical to an amino acid sequence selected from the group consisting of:
a) an amino acid sequence that:
i) begins at any one of amino acids of 20-29 SEQ ID NO: 1, and
ii) ends at any one of amino acids 109-134 of SEQ ID NO: 1;
b) an amino acid sequence comprising amino acids 20-134 of SEQ ID NO: 1;
d) an amino acid sequence comprising amino acids 25-131 of SEQ ID NO: 1; or
e) an amino acid sequence according to one of SEQ ID Nos: 1, 2, 3, 4, 5, 6, 100, 102, 401, and 402.
8. The heteromultimer of claim 1 , wherein the ALK7-Fc fusion protein further comprises a linker domain positioned between the ALK7 domain and the Fc domain; and wherein the ActRIIB-Fc fusion protein further comprises a linker domain positioned between the ActRIIB domain and the Fc domain.
9. The heteromultimer of claim 8 , wherein the linker domain is selected from: TGGG (SEQ ID NO: 62), TGGGG (SEQ ID NO: 60), SGGGG (SEQ ID NO: 61), GGGGS, GGG (SEQ ID NO: 58), GGGG (SEQ ID NO: 59), and SGGG (SEQ ID NO: 18).
10. The heteromultimer of claim 1 , wherein the heteromultimer is a heterodimer.
11. A pharmaceutical preparation comprising the heteromultimer of claim 1 , and a pharmaceutically acceptable carrier.