A Comparative Perspective on Extra-retinal Photoreception

Trends Endocrinol Metab. 2019 Jan;30(1):39-53. doi: 10.1016/j.tem.2018.10.005. Epub 2018 Dec 4.

Abstract

Ubiquitous in non-mammalian vertebrates, extra-retinal photoreceptors (ERPs) have been linked to an array of physiological, metabolic, behavioral, and morphological changes. However, the mechanisms and functional roles of ERPs remain one of the enduring questions of modern biology. In this review article, we use a comparative framework to identify conserved roles and distributions of ERPs, highlighting knowledge gaps. We conclude that ERP research can be divided into two largely unconnected categories: (i) identification and localization of photoreceptors and (ii) linkage of non-retinal light reception to behavioral and physiological processes, particularly endocrine systems. However, the emergence of novel gene editing and silencing techniques is enabling the unification of ERP research by allowing the bridging of this divide.

Keywords: OPN4; OPN5; VA-opsin; brain; extra-retinal photoreceptor.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Behavior, Animal / physiology*
  • Brain / cytology*
  • Brain / metabolism
  • Brain / physiology*
  • Opsins / metabolism
  • Opsins / physiology*
  • Photoperiod*
  • Photoreceptor Cells / classification
  • Photoreceptor Cells / cytology
  • Photoreceptor Cells / metabolism
  • Photoreceptor Cells / physiology*
  • Vertebrates / metabolism
  • Vertebrates / physiology*

Substances

  • Opsins