Crystal structure of the WFIKKN2 follistatin domain reveals insight into how it inhibits growth differentiation factor 8 (GDF8) and GDF11

J Biol Chem. 2019 Apr 19;294(16):6333-6343. doi: 10.1074/jbc.RA118.005831. Epub 2019 Feb 27.

Abstract

Growth differentiation factor 8 (GDF8; also known as myostatin) and GDF11 are closely related members of the transforming growth factor β (TGF-β) family. GDF8 strongly and negatively regulates skeletal muscle growth, and GDF11 has been implicated in various age-related pathologies such as cardiac hypertrophy. GDF8 and GDF11 signaling activities are controlled by the extracellular protein antagonists follistatin; follistatin-like 3 (FSTL3); and WAP, follistatin/kazal, immunoglobulin, Kunitz, and netrin domain-containing (WFIKKN). All of these proteins contain a follistatin domain (FSD) important for ligand binding and antagonism. Here, we investigated the structure and function of the FSD from murine WFIKKN2 and compared it with the FSDs of follistatin and FSTL3. Using native gel shift and surface plasmon resonance analyses, we determined that the WFIKKN2 FSD can interact with both GDF8 and GDF11 and block their interactions with the type II receptor activin A receptor type 2B (ActRIIB). Further, we solved the crystal structure of the WFIKKN2 FSD to 1.39 Å resolution and identified surface-exposed residues that, when substituted with alanine, reduce antagonism of GDF8 in full-length WFIKKN2. Comparison of the WFIKKN2 FSD with those of follistatin and FSTL3 revealed differences in both the FSD structure and position of residues within the domain that are important for ligand antagonism. Taken together, our results indicate that both WFIKKN and follistatin utilize their FSDs to block the type II receptor but do so via different binding interactions.

Keywords: GDF11; GDF8; WFIKKN; X-ray crystallography; antagonism; follistatin; inhibitor; muscle development; myostatin; protein structure; structural biology; tissue homeostasis; transforming growth factor beta (TGF-β).

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Activin Receptors, Type II / chemistry
  • Activin Receptors, Type II / metabolism
  • Animals
  • Bone Morphogenetic Proteins / antagonists & inhibitors*
  • Bone Morphogenetic Proteins / chemistry
  • Bone Morphogenetic Proteins / metabolism
  • Carrier Proteins / chemistry*
  • Carrier Proteins / metabolism
  • Crystallography, X-Ray
  • Follistatin-Related Proteins / chemistry
  • Follistatin-Related Proteins / metabolism
  • Growth Differentiation Factors / antagonists & inhibitors*
  • Growth Differentiation Factors / chemistry
  • Growth Differentiation Factors / metabolism
  • HEK293 Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins
  • Mice
  • Myostatin / antagonists & inhibitors*
  • Myostatin / chemistry
  • Myostatin / metabolism
  • Surface Plasmon Resonance

Substances

  • Bone Morphogenetic Proteins
  • Carrier Proteins
  • Follistatin-Related Proteins
  • Fstl3 protein, mouse
  • Gdf11 protein, mouse
  • Gprasp1 protein, mouse
  • Growth Differentiation Factors
  • Intracellular Signaling Peptides and Proteins
  • Mstn protein, mouse
  • Myostatin
  • Activin Receptors, Type II
  • activin receptor type II-B

Associated data

  • PDB/3HH2
  • PDB/6MAA