Expression of the Otx2 homeobox gene in the developing mammalian brain: embryonic and adult expression in the pineal gland

• Published in: Journal of neurochemistry Vol. 97; no. 2; pp. 556 - 566
• Main Authors: Rath, Martin F., Muñoz, Estela, Ganguly, Surajit, Morin, Fabrice, Shi, Qiong, Klein, David C., Møller, Morten
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-04-2006; Blackwell
• Subjects: Adults; Age Factors; Animals; Animals, Newborn; Biochemistry and metabolism; Biological and medical sciences; Blotting, Northern - methods; Blotting, Western - methods; Brain; Brain - embryology; Brain - growth & development; Brain - metabolism; brain development; Central nervous system; Cloning, Molecular - methods; cone–rod homeobox; CRX protein; Embryo, Mammalian; Embryos; Fundamental and applied biological sciences. Psychology; Gene expression; Gene Expression Regulation, Developmental - physiology; Homeobox; Hormones and neuropeptides. Regulation; Hypothalamus. Hypophysis. Epiphysis. Urophysis; Immunohistochemistry - methods; Melatonin; mRNA; Neurosciences; Otx Transcription Factors - genetics; Otx Transcription Factors - metabolism; Otx2; Otx2 protein; Photoreceptors; Phototransduction; Pineal gland; Pineal Gland - embryology; Pineal Gland - growth & development; Pineal Gland - metabolism; Pinealocytes; Rats; Retina; Rodents; Sequence Analysis, DNA - methods; Vertebrates: endocrinology; Vertebrates: nervous system and sense organs; Rat; Central nervous system; Photoreceptor; Retina; homeobox; pineal gland; Encephalon; Eye; Visual system; Postnatal; Gene; Autonomic nervous system; Development; Otx2; Pineal hormone; brain development; Rod; Rodentia; cone-rod homeobox; Gene expression; Sympathetic nervous system; Protein; Vertebrata; Mammalia; Onset time; Temporal study
• ISSN: 0022-3042; 1471-4159
• DOI: 10.1111/j.1471-4159.2006.03773.x

Otx2 is a vertebrate homeobox gene, which has been found to be essential for the development of rostral brain regions and appears to play a role in the development of retinal photoreceptor cells and pinealocytes. In this study, the temporal expression pattern of Otx2 was revealed in the rat brain, with special emphasis on the pineal gland throughout late embryonic and postnatal stages. Widespread high expression of Otx2 in the embryonic brain becomes progressively restricted in the adult to the pineal gland. Crx (cone–rod homeobox), a downstream target gene of Otx2, showed a pineal expression pattern similar to that of Otx2, although there was a distinct lag in time of onset. Otx2 protein was identified in pineal extracts and found to be localized in pinealocytes. Total pineal Otx2 mRNA did not show day–night variation, nor was it influenced by removal of the sympathetic input, indicating that the level of Otx2 mRNA appears to be independent of the photoneural input to the gland. Our results are consistent with the view that pineal expression of Otx2 is required for development and we hypothesize that it plays a role in the adult in controlling the expression of the cluster of genes associated with phototransduction and melatonin synthesis.