title: Further evidence for the role of cryptochromes in retinohypothalamic photoreception/phototransduction.
abstract: Cryptochrome is a blue-light absorbing photopigment that has been proposed to act as a photoreceptor for a variety of nonvisual light-responsive tasks. While mouse models have suggested an important role for cryptochrome in nonvisual photoreception, there are no biochemical data demonstrating the functional photoreceptive capability of cryptochrome in mice. There are two models that describe the effect of cryptochrome on light responsive events: (1) cryptochrome is a photoreceptor or (2) cryptochrome is required for either normal phototransduction from the retina to the brain or for normal transcriptional regulation in the brain, irrespective of light. To differentiate between these two models, we have examined the integrity of the regulatory mechanism of c-fos in cryptochromeless cell lines and in the suprachiasmatic nucleus (SCN) of cryptochromeless mice. Photoinduction of c-fos mRNA in the SCN can be used as a marker for circadian photoreception/phototransduction and it is drastically reduced in mice lacking cryptochromes. Our results indicate that light-independent transcription regulatory system of c-fos is normal in cryptochromeless mice and that the reduced c-fos light responsiveness in the absence of cryptochromes is due to a loss of photoreceptor function.
authors.affiliation: Department of Biochemistry and Biophysics CB#7260, School of Medicine, University of North Carolina, Chapel Hill, NC 27599-7260, USA.
authors.forename: Carol L
authors.initials: CL
authors.lastname: Thompson
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Selby
authors.forename: Carrie L
authors.initials: CL
authors.lastname: Partch
authors.forename: David T
authors.initials: DT
authors.lastname: Plante
authors.forename: Randy J
authors.initials: RJ
authors.lastname: Thresher
authors.forename: Francisco
authors.initials: F
authors.lastname: Araujo
authors.forename: Aziz
authors.initials: A
authors.lastname: Sancar
mesh_terms: D000818:Animals; D001683:Biological Clocks / Q000235:genetics; D002460:Cell Line; D002940:Circadian Rhythm / Q000235:genetics*; D056931:Cryptochromes; D003580:Cytochromes / Q000172:deficiency / Q000235:genetics*; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins / Q000235:genetics; D005786:Gene Expression Regulation / Q000235:genetics; D055537:Light Signal Transduction / Q000235:genetics*; D051379:Mice; D018345:Mice, Knockout; D023421:Models, Animal; D009434:Neural Pathways / Q000166:cytology / Q000378:metabolism*; D017956:Photoreceptor Cells, Invertebrate; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled; D012160:Retina / Q000166:cytology / Q000378:metabolism*; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000378:metabolism*
chemical_list: D056931:Cryptochromes; D003580:Cytochromes; D029721:Drosophila Proteins; D005136:Eye Proteins; D005420:Flavoproteins; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D043562:Receptors, G-Protein-Coupled; C119828:cry protein, Drosophila