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Expression of the blue-light receptor cryptochrome in the human retina

Carol L Thompson1, Catherine Bowes Rickman, Steven J Shaw

  • 1Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA.

Investigative Ophthalmology & Visual Science
|September 26, 2003
PubMed
Abstract

Insights

Human retinal cryptochromes CRY1 and CRY2 were analyzed. CRY2, abundant in the inner retina, suggests a role in blue-light photoreception and potentially non-circadian functions.

Area of Science:

  • Ophthalmology
  • Molecular Biology
  • Chronobiology

Background:

  • Cryptochromes (CRY1 and CRY2) are blue-light photoreceptors involved in circadian rhythms.
  • Their presence and function in the human retina, particularly nonvisual roles, require further investigation.

Purpose of the Study:

  • To analyze the expression patterns of CRY1 and CRY2 in the human retina.
  • To correlate their expression with nonvisual photoreceptor localization and potential functions.

Main Methods:

  • Quantitative RT-PCR was used to analyze CRY1 and CRY2 mRNA expression in human retinal macula and midperiphery.
  • Immunohistochemistry and immunoblot analysis were employed to examine CRY2 protein expression and subcellular localization.

Main Results:

  • CRY2 mRNA was significantly more abundant (11-fold) than CRY1 in adult human retina.
  • CRY2 protein was detected in the ganglion cell layer (GCL) and inner nuclear layer (INL), localized to both cytoplasm and nuclei.
  • Intracellular localization of CRY2 was confirmed in fractionated retinal extracts.

Conclusions:

  • The inner retina contains photopigments responsible for circadian photoreception.
  • The abundance and localization of CRY2 in the inner human retina support its role as a photoreceptor.
  • CRY2's cytoplasmic localization suggests functions beyond its known nuclear role in the molecular circadian clock.

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