TIMELESS mutation alters phase responsiveness and causes advanced sleep phase

Proc Natl Acad Sci U S A. 2019 Jun 11;116(24):12045-12053. doi: 10.1073/pnas.1819110116. Epub 2019 May 28.


Many components of the circadian molecular clock are conserved from flies to mammals; however, the role of mammalian Timeless remains ambiguous. Here, we report a mutation in the human TIMELESS (hTIM) gene that causes familial advanced sleep phase (FASP). Tim CRISPR mutant mice exhibit FASP with altered photic entrainment but normal circadian period. We demonstrate that the mutation prevents TIM accumulation in the nucleus and has altered affinity for CRY2, leading to destabilization of PER/CRY complex and a shortened period in nonmature mouse embryonic fibroblasts (MEFs). We conclude that TIM, when excluded from the nucleus, can destabilize the negative regulators of the circadian clock, alter light entrainment, and cause FASP.

Keywords: TIMELESS; familial advanced sleep phase; human genetics; mammalian circadian clock regulation.

Publication types

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

MeSH terms

  • Animals
  • Cell Cycle Proteins / genetics*
  • Cell Line
  • Circadian Clocks / genetics*
  • Circadian Rhythm / genetics*
  • Fibroblasts / physiology
  • HEK293 Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins / genetics*
  • Light
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mutation / genetics*
  • Sleep / genetics*


  • Cell Cycle Proteins
  • Intracellular Signaling Peptides and Proteins
  • TIMELESS protein, human
  • Timeless protein, mouse