The circadian E3 ligase complex SCFFBXL3+CRY targets TLK2

Sci Rep. 2019 Jan 17;9(1):198. doi: 10.1038/s41598-018-36618-3.


We recently demonstrated that the circadian clock component CRY2 is an essential cofactor in the SCFFBXL3-mediated ubiquitination of c-MYC. Because our demonstration that CRY2 recruits phosphorylated substrates to SCFFBXL3 was unexpected, we investigated the scope of this role by searching for additional substrates of FBXL3 that require CRY1 or CRY2 as cofactors. Here, we describe an affinity purification mass spectrometry (APMS) screen through which we identified more than one hundred potential substrates of SCFFBXL3+CRY1/2, including the cell cycle regulated Tousled-like kinase, TLK2. Both CRY1 and CRY2 recruit TLK2 to SCFFBXL3, and TLK2 kinase activity is required for this interaction. Overexpression or genetic deletion of CRY1 and/or CRY2 decreases or enhances TLK2 protein abundance, respectively. These findings reinforce the idea that CRYs function as co-factors for SCFFBXL3, provide a resource of potential substrates, and establish a molecular connection between the circadian and cell cycle oscillators via CRY-modulated turnover of TLK2.

Publication types

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

MeSH terms

  • Animals
  • Cells, Cultured
  • Circadian Clocks
  • Cryptochromes / genetics
  • Cryptochromes / metabolism*
  • F-Box Proteins / metabolism
  • Humans
  • Mice
  • Protein Serine-Threonine Kinases / drug effects
  • Protein Serine-Threonine Kinases / metabolism*
  • Stem Cell Factor / metabolism
  • Ubiquitin-Protein Ligase Complexes / metabolism*
  • Ubiquitin-Protein Ligases


  • Cry1 protein, mouse
  • Cry2 protein, mouse
  • Cryptochromes
  • F-Box Proteins
  • Fbxl3 protein, mouse
  • KITLG protein, human
  • Stem Cell Factor
  • Ubiquitin-Protein Ligase Complexes
  • Ubiquitin-Protein Ligases
  • Protein Serine-Threonine Kinases
  • Tlk2 protein, mouse