Phosphorylation of Ci/Gli by Fused Family Kinases Promotes Hedgehog Signaling

Dev Cell. 2019 Sep 9;50(5):610-626.e4. doi: 10.1016/j.devcel.2019.06.008. Epub 2019 Jul 3.

Abstract

Hedgehog (Hh) signaling culminates in the conversion of the latent transcription factor Cubitus interruptus (Ci)/Gli into its activator form (CiA/GliA), but the underlying mechanism remains poorly understood. Here, we demonstrate that Hh stimulates the phosphorylation of Ci by the Ser/Thr kinase Fused (Fu) and that Fu-mediated phosphorylation of Ci promotes its activation. We find that Fu directly phosphorylates Ci on Ser218 and Ser1230, which primes its further phosphorylation by CK1 on adjacent sties. These phosphorylation events alter Ci binding to the pathway inhibitor Suppressor of fused (Sufu) and facilitate the recruitment of Transportion and the transcriptional coactivator CBP. Furthermore, we provide evidence that Sonic hedgehog (Shh) activates Gli2 by stimulating its phosphorylation on conserved sites through the Fu-family kinases ULK3 and mFu/STK36 in a manner depending on Gli2 ciliary localization. Hence, Fu-family kinase-mediated phosphorylation of Ci/Gli serves as a conserved mechanism that activates the Hh pathway transcription factor.

Keywords: Ci; Fu; Gli2; Hedgehog; Shh; Sufu; ULK1; ULK3; medulloblastoma.

Publication types

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

MeSH terms

  • 3T3 Cells
  • Animals
  • Autophagy-Related Protein-1 Homolog / metabolism
  • Cell Line, Tumor
  • Cells, Cultured
  • DNA-Binding Proteins / metabolism*
  • Drosophila Proteins / metabolism*
  • Drosophila melanogaster
  • HEK293 Cells
  • Hedgehog Proteins / metabolism*
  • Humans
  • Mice
  • Phosphorylation
  • Protein-Serine-Threonine Kinases / metabolism*
  • Repressor Proteins / metabolism
  • Sf9 Cells
  • Signal Transduction*
  • Spodoptera
  • Transcription Factors / metabolism*
  • Zinc Finger Protein Gli2 / metabolism*

Substances

  • DNA-Binding Proteins
  • Drosophila Proteins
  • Hedgehog Proteins
  • Repressor Proteins
  • SUFU protein, human
  • Transcription Factors
  • Zinc Finger Protein Gli2
  • ci protein, Drosophila
  • fu protein, Drosophila
  • Autophagy-Related Protein-1 Homolog
  • Protein-Serine-Threonine Kinases
  • STK36 protein, human