Analysis of circadian rhythm gene expression with reference to diurnal pattern of intraocular pressure in mice

Lauren A. Dalvin, Michael P Fautsch

Research output: Contribution to journalArticle

15 Scopus citations

Abstract

PURPOSE. To determine the expression of circadian rhythm clock genes in the iris–ciliary body complex of mice and their association with the diurnal pattern of intraocular pressure (IOP). METHODS. Thirty wild-type C57BL/6 mice were acclimated to a 12-hour light–dark cycle. Intraocular pressure was measured with a rebound tonometer at six time points daily (circadian time [CT] 2, 6, 10, 14, 18, and 22 hours) for five consecutive days. On day 6, mice were euthanized at CT 2, 6, 10, 14, 18, and 22. Eyes were flash-frozen or fixed in 4% phosphate-buffered paraformaldehyde. Total RNA was extracted from the iris–ciliary body complex, and RNA expression of circadian rhythm genes Bmal1, Clock, Cry1, Cry2, Per1, and Per2 was assessed by quantitative real-time PCR. Fixed eyes were paraffin embedded, and immunohistochemistry was performed to localize corresponding proteins (BMAL1, CLOCK, CRY1, CRY2, PER1, and PER2). Linear regression analysis was performed to correlate gene expression with IOP. RESULTS. Intraocular pressure demonstrated a consistent circadian pattern. The clock genes Bmal1, Clock, Cry1, Cry2, Per1, and Per2 showed a circadian pattern of expression in the iris–ciliary body complex of mice. Bmal1, Clock, Cry1, Per1, and Per2 gene expression demonstrated statistically significant correlations with diurnal variations of IOP. BMAL1, CLOCK, CRY1, CRY2, PER1, and PER2 proteins were found to be expressed locally in the nonpigmented epithelium of the ciliary body. CONCLUSIONS. Expression patterns of candidate circadian rhythm genes correlates with the diurnal pattern variation of IOP in mouse eyes, indicating a possible mechanism of IOP regulation through these genes.

Original languageEnglish (US)
Pages (from-to)2657-2663
Number of pages7
JournalInvestigative Ophthalmology and Visual Science
Volume56
Issue number4
DOIs
StatePublished - 2015

Keywords

  • Aqueous outflow
  • Circadian rhythm
  • Clock genes
  • Intraocular pressure
  • Iris–ciliary body complex

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

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