Drosophila CRY Entrains Clocks in Body Tissues to Light and Maintains Passive Membrane Properties in a Non-clock Body Tissue Independent of Light

Curr Biol. 2017 Aug 21;27(16):2431-2441.e3. doi: 10.1016/j.cub.2017.06.064. Epub 2017 Aug 3.

Abstract

Circadian (∼24 hr) clocks regulate daily rhythms in physiology, metabolism, and behavior via cell-autonomous transcriptional feedback loops. In Drosophila, the blue-light photoreceptor CRYPTOCHROME (CRY) synchronizes these feedback loops to light:dark cycles by binding to and degrading TIMELESS (TIM) protein. CRY also acts independently of TIM in Drosophila to alter potassium channel conductance in arousal neurons after light exposure, and in many animals CRY acts independently of light to repress rhythmic transcription. CRY expression has been characterized in the Drosophila brain and eyes, but not in peripheral clock and non-clock tissues in the body. To investigate CRY expression and function in body tissues, we generated a GFP-tagged-cry transgene that rescues light-induced behavioral phase resetting in cry03 mutant flies and sensitively reports GFP-CRY expression. In bodies, CRY is detected in clock-containing tissues including Malpighian tubules, where it mediates both light-dependent TIM degradation and clock function. In larval salivary glands, which lack clock function but are amenable to electrophysiological recording, CRY prevents membrane input resistance from falling to low levels in a light-independent manner. The ability of CRY to maintain high input resistance in these non-excitable cells also requires the K+ channel subunits Hyperkinetic, Shaker, and ether-a-go-go. These findings for the first time define CRY expression in Drosophila peripheral tissues and reveal that CRY acts together with K+ channels to maintain passive membrane properties in a non-clock-containing peripheral tissue independent of light.

Keywords: Drosophila; Malpighian tubules; circadian clock; cryptochrome; larval salivary gland; passive membrane properties; peripheral tissues; photoreceptor; potassium channels.

MeSH terms

  • Animals
  • Circadian Clocks / genetics*
  • Cryptochromes / genetics*
  • Cryptochromes / metabolism
  • Drosophila Proteins / genetics*
  • Drosophila Proteins / metabolism
  • Drosophila melanogaster / genetics
  • Drosophila melanogaster / growth & development
  • Drosophila melanogaster / physiology*
  • Eye Proteins / genetics*
  • Eye Proteins / metabolism
  • Gene Expression Profiling
  • Green Fluorescent Proteins / genetics
  • Larva / genetics
  • Larva / growth & development
  • Larva / physiology
  • Light*
  • Transgenes / genetics

Substances

  • Cryptochromes
  • Drosophila Proteins
  • Eye Proteins
  • cry protein, Drosophila
  • Green Fluorescent Proteins