Tolloid cleavage activates latent GDF8 by priming the pro-complex for dissociation

EMBO J. 2018 Feb 1;37(3):384-397. doi: 10.15252/embj.201797931. Epub 2018 Jan 17.


Growth differentiation factor 8 (GDF8)/myostatin is a latent TGF-β family member that potently inhibits skeletal muscle growth. Here, we compared the conformation and dynamics of precursor, latent, and Tolloid-cleaved GDF8 pro-complexes to understand structural mechanisms underlying latency and activation of GDF8. Negative stain electron microscopy (EM) of precursor and latent pro-complexes reveals a V-shaped conformation that is unaltered by furin cleavage and sharply contrasts with the ring-like, cross-armed conformation of latent TGF-β1. Surprisingly, Tolloid-cleaved GDF8 does not immediately dissociate, but in EM exhibits structural heterogeneity consistent with partial dissociation. Hydrogen-deuterium exchange was not affected by furin cleavage. In contrast, Tolloid cleavage, in the absence of prodomain-growth factor dissociation, increased exchange in regions that correspond in pro-TGF-β1 to the α1-helix, latency lasso, and β1-strand in the prodomain and to the β6'- and β7'-strands in the growth factor. Thus, these regions are important in maintaining GDF8 latency. Our results show that Tolloid cleavage activates latent GDF8 by destabilizing specific prodomain-growth factor interfaces and primes the growth factor for release from the prodomain.

Keywords: TGF‐β; conformational dynamics; growth factor activation; myostatin; prodomain.

Publication types

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

MeSH terms

  • Animals
  • Cell Line
  • Deuterium Exchange Measurement
  • Drosophila
  • Enzyme Activation / physiology
  • Furin / metabolism
  • HEK293 Cells
  • Humans
  • Microscopy, Electron
  • Muscle, Skeletal / growth & development*
  • Myostatin / metabolism*
  • Protein Precursors / metabolism*
  • Tolloid-Like Metalloproteinases / metabolism
  • Transforming Growth Factor beta1 / metabolism*


  • MSTN protein, human
  • Myostatin
  • Protein Precursors
  • Transforming Growth Factor beta1
  • Tolloid-Like Metalloproteinases
  • Furin