title: Diurnal expression of proteins in the retina of the blind cone-rod homeobox (Crx-/-) mouse and the 129/Sv mouse: a proteomic study.
abstract: OBJECTIVE
  The vertebrate retina contains a circadian clock participating in adaptations to day and night vision. This peripheral clock is independent of the master clock in the suprachiasmatic nucleus (SCN). The retinal clock is located in several cell types, including the photoreceptors. To investigate the role of the circadian clock of the photoreceptor cells in regulation of retinal protein rhythms, we analysed diurnal protein expression in the photoreceptor-deficient cone-rod homeobox knockout mouse (Crx-/-) and the 129/Sv mouse.
  
  
  METHODS
  2D gels were made from retinal homogenates of 129/Sv and Crx-/-mice killed at midday and midnight. Stained gels were analysed by use of PDQuest 2D gel analysis software. After trypsin digestion of differential expressed spots, the proteins were identified by LC-MS/MS using a nano-liquid chromatograph connected to a Q-TOF Premier mass spectrometer. These data were used to search the SWISS-PROT database.
  
  
  RESULTS
  Both the retinae of the control and the Crx-/-mice exhibited diurnal proteins rhythms. As expected, proteins involved in phototransduction were not detected in the Crx-/-mouse; in this phenotype, however, proteins from spots showing diurnal rhythms were specifically identified as enzymes involved in glucose metabolism, Krebs cycle, and mitochondrial enzymes. Data are available via ProteomeXchange with identifier PXD005556.
  
  
  CONCLUSIONS
  We show diurnal protein rhythms in the retina of a mouse lacking the rods and cones. The diurnal protein rhythms in this genotype, lacking the circadian clock of the photoreceptors, might be caused by a circadian clock in other retinal cell types or a direct light input to the retina.
authors.affiliation: Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Morten
authors.identifier: http://orcid.org/0000-0002-3263-7482
authors.initials: M
authors.lastname: Møller
authors.affiliation: Department of Neuroscience and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Martin Fredensborg
authors.initials: MF
authors.lastname: Rath
authors.affiliation: Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.|Department of Hematology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Maja
authors.initials: M
authors.lastname: Ludvigsen
authors.affiliation: Department of Biomedicine, Aarhus University, Aarhus, Denmark.
authors.forename: Bent
authors.initials: B
authors.lastname: Honoré
authors.affiliation: Department of Ophthalmology, Aalborg University Hospital, Aalborg, Denmark.|Department of Clinical Medicine, Aalborg University, Aalborg, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Vorum
mesh_terms: D000818:Animals; D001766:Blindness / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D002940:Circadian Rhythm; D004247:DNA / Q000235:genetics; D003623:Dark Adaptation; D005136:Eye Proteins / Q000096:biosynthesis*; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology*; D005838:Genotype; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D040901:Proteomics; D012160:Retina / Q000378:metabolism* / Q000473:pathology; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism*; D017948:Retinal Rod Photoreceptor Cells / Q000378:metabolism*; D053719:Tandem Mass Spectrometry; D015534:Trans-Activators / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D005136:Eye Proteins; D018398:Homeodomain Proteins; D015534:Trans-Activators; C109288:cone rod homeobox protein; D004247:DNA
keywords: blind; circadian; clock; mouse; retina