Rax Retina and anterior neural fold homeobox (Rax) gene encodes a transcription factor essential for vertebrate eye development. Recent microarray studies indicate that Rax is expressed in the adult rat pineal gland and retina. The present study reveals that Rax expression levels in the rat change significantly during retinal development with a peak occurring at embryonic day 18, whereas Rax expression in the pineal is relatively delayed and not detectable until embryonic day 20. In both tissues, Rax is expressed throughout postnatal development into adulthood. In the mature rat pineal gland, the abundance of Rax transcripts increases 2-fold during the light period with a peak occurring at dusk. These findings are consistent with the evidence that Rax is of functional importance in eye development and suggest a role of Rax in the developing pineal gland. (From 1) Crx Cone-rod homeobox (Crx) encodes Crx, a transcription factor expressed selectively in retinal photoreceptors and pinealocytes, the major cell type of the pineal gland. In this study, the influence of Crx on the mammalian pineal gland was studied by light and electron microscopy and by use of microarray and qRTPCR technology, thereby extending previous studies on selected genes (Furukawa et al. 1999). Deletion of Crx was not found to alter pineal morphology, but was found to broadly modulate the mouse pineal transcriptome, characterized by a > 2-fold down-regulation of 543 genes and a > 2-fold up-regulation of 745 genes (p < 0.05). Of these, one of the most highly up-regulated (18-fold) was Hoxc4, a member of the Hox gene family, members of which are known to control gene expression cascades. During a 24-h period, a set of 51 genes exhibited differential day/night expression in pineal glands of wild-type animals;only eight of these were also day/night expressed in the Crx(-/-) pineal gland. However, in the Crx(-/-) pineal gland 41 genes exhibited differential night/day expression that was not seen in wild-type animals. These findings indicate that Crx broadly modulates the pineal transcriptome and also influences differential night/day gene expression in this tissue. Some effects of Crx deletion on the pineal transcriptome might be mediated by Hoxc4 up-regulation. (From 2). Evolution: Arylalkylamine N-acetyltransferase (AANAT) catalyzes the transfer of an acetyl group from acetyl coenzyme A (AcCoA) to arylalkylamines, including indolethylamines and phenylethylamines. Multiple aanats are present in teleost fish as a result of whole genome and gene duplications. Fish aanat1a and aanat2 paralogs display different patterns of tissue expression and encode proteins with different substrate preference: AANAT1a is expressed in the retina, and acetylates both indolethylamines and phenylethylamines;while AANAT2 is expressed in the pineal gland, and preferentially acetylates indolethylamines. The two enzymes are therefore thought to serve different roles. Here, the molecular changes that led to their specialization were studied by investigating the structure-function relationships of AANATs in the gilthead seabream (sb, Sperus aurata). Acetylation activity of reciprocal mutated enzymes pointed to specific residues that contribute to substrate specificity of the enzymes. Inhibition tests followed by complementary analyses of the predicted three-dimensional models of the enzymes, suggested that both phenylethylamines and indolethylamines bind to the catalytic pocket of both enzymes. These results suggest that substrate selectivity of AANAT1a and AANAT2 is determined by the positioning of the substrate within the catalytic pocket, and its accessibility to catalysis. This illustrates the evolutionary process by which enzymes encoded by duplicated genes acquire different activities and play different biological roles.(From 3) AANAT in subvertebrates: The arylalkylamine N-acetyltransferase (AANAT) family is divided into structurally distinct vertebrate and non-vertebrate groups. Expression of vertebrate AANATs is limited primarily to the pineal gland and retina, where it plays a role in controlling the circadian rhythm in melatonin synthesis. Based on the role melatonin plays in biological timing, AANAT has been given the moniker """"""""the Timezyme"""""""". Non-vertebrate AANATs, which occur in fungi and protists, are thought to play a role in detoxification and are not known to be associated with a specific tissue. We have found that the amphioxus genome contains seven AANATs, all having non-vertebrate type features. This and the absence of AANATs from the genomes of Hemichordates and Urochordates support the view that a major transition in the evolution of the AANATs may have occurred at the onset of vertebrate evolution. Analysis of the expression pattern of the two most structurally divergent AANATs in Branchiostoma lanceolatum (bl) revealed that they are expressed early in development and also in the adult at low levels throughout the body, possibly associated with the neural tube. Expression is clearly not exclusively associated with the proposed analogs of the pineal gland and retina. blAANAT activity is influenced by environmental lighting, but light/dark differences do not persist under constant light or constant dark conditions, indicating they are not circadian in nature. bfAANAT alpha and bfAANAT delta'have unusually alkaline (>9.0) optimal pH, more than two pH units higher than that of vertebrate AANATs. The substrate selectivity profiles of bfAANAT alpha and delta'are relatively broad, including alkylamines, arylalkylamines and diamines, in contrast to vertebrate forms, which selectively acetylate serotonin and other arylalkylamines. Based on these features, it appears that amphioxus AANATs could play several roles, including detoxification and biogenic amine inactivation. The presence of seven AANATs in amphioxus genome supports the view that arylalkylamine and polyamine acetylation is important to the biology of this organism and that these genes evolved in response to specific pressures related to requirements for amine acetylation (From 4)
| Yamazaki, Fumiyoshi; Møller, Morten; Fu, Cong et al. (2015) The Lhx9 homeobox gene controls pineal gland development and prevents postnatal hydrocephalus. Brain Struct Funct 220:1497-509 |
| Yamazaki, Fumiyoshi; Kim, Hyun Hee; Lau, Pierre et al. (2014) pY RNA1-s2: a highly retina-enriched small RNA that selectively binds to Matrin 3 (Matr3). PLoS One 9:e88217 |
| Falcón, Jack; Coon, Steven L; Besseau, Laurence et al. (2014) Drastic neofunctionalization associated with evolution of the timezyme AANAT 500 Mya. Proc Natl Acad Sci U S A 111:314-9 |
| Kucka, Marek; Bjelobaba, Ivana; Clokie, Samuel J H et al. (2013) Female-specific induction of rat pituitary dentin matrix protein-1 by GnRH. Mol Endocrinol 27:1840-55 |
| Matsuo, Masahiro; Coon, Steven L; Klein, David C (2013) RGS2 is a feedback inhibitor of melatonin production in the pineal gland. FEBS Lett 587:1392-8 |
| Rath, Martin F; Rohde, Kristian; Klein, David C et al. (2013) Homeobox genes in the rodent pineal gland: roles in development and phenotype maintenance. Neurochem Res 38:1100-12 |
| Ochocinska, Margaret J; Muñoz, Estela M; Veleri, Shobi et al. (2012) NeuroD1 is required for survival of photoreceptors but not pinealocytes: results from targeted gene deletion studies. J Neurochem 123:44-59 |
| Coon, Steven L; Munson, Peter J; Cherukuri, Praveen F et al. (2012) Circadian changes in long noncoding RNAs in the pineal gland. Proc Natl Acad Sci U S A 109:13319-24 |
| Rohde, Kristian; Klein, David C; Møller, Morten et al. (2011) Rax?: developmental and daily expression patterns in the rat pineal gland and retina. J Neurochem 118:999-1007 |
| Zilberman-Peled, Bina; Bransburg-Zabary, Sharron; Klein, David C et al. (2011) Molecular evolution of multiple arylalkylamine N-acetyltransferase (AANAT) in fish. Mar Drugs 9:906-21 |
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