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. In addition, it would appear possible that Rax contributes to phenotype maintenance in the mature retina and pineal gland and may facilitate 24-h changes in the pineal transcriptome.(From Rhode et al., 2011). NeuroD: NeuroD1 encodes a basic helix-loop-helix transcription factor involved in the development of neural and endocrine structures, including the retina and pineal gland. To determine the effect of NeuroD1 knockout in these tissues, a Cre/loxP recombination strategy was used to target a NeuroD1 floxed gene and generate NeuroD1 conditional knockout (cKO) mice. Tissue specificity was conferred using Cre recombinase expressed under the control of the promoter of Crx, which is selectively expressed in the pineal gland and retina. At 2 months of age, NeuroD1 cKO retinas have a dramatic reduction in rod- and cone-driven electroretinograms and contain shortened and disorganized outer segments; by 4 months, NeuroD1 cKO retinas are devoid of photoreceptors. In contrast, the NeuroD1 cKO pineal gland appears histologically normal. Microarray analysis of 2-month-old NeuroD1 cKO retina and pineal gland identified a subset of genes that were affected 2-100-fold; in addition, a small group of genes exhibit altered differential night/day expression. Included in the down-regulated genes are Aipl1, which is necessary to prevent retinal degeneration, and Ankrd33, whose protein product is selectively expressed in the outer segments. These findings suggest that NeuroD1 may act through Aipl1 and other genes to maintain photoreceptor homeostasis. Molecular Evolution: ArylalkylamineN-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 Zilberman-Peled et al., 2011).
| 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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