Zebrafish serotonin-N-acetyltransferase-2 gene regulation: pineal-restrictive downstream module contains a functional E-box and three photoreceptor conserved elements.
Pineal function is defined by a set of very narrowly expressed genes that encode proteins required for photoperiodic transduction and rhythmic melatonin secretion. One of these proteins is serotonin N-acetyltransferase (arylalkylamine N-acetyltransferase, AANAT), which controls the daily rhythm in melatonin production. Here, pineal-specific expression of the zebrafish aanat-2 (zfaanat-2) was studied using in vivo transient expression analyses of promoter-reporter constructs; this revealed that specificity is determined by two regions located 12 kb away from each other. One is the 5'-flanking region, and the other is a 257-bp sequence, located 6 kb downstream of the transcribed region. This 3'-sequence, designated pineal-restrictive downstream module (PRDM), has a dual function: enhancement of pineal expression and inhibition of extrapineal expression. The former is an autonomic property of PRDM whereas the later function requires interaction with the upstream regulatory region of zfaanat-2. Functional analyses of the PRDM sequence revealed that three photoreceptor conserved elements (TAATC) and a single perfect E-box (CACGTG) are crucial for the dual function of PRDM. These results indicate that pineal specificity of zfaanat-2 is determined by the dual functionality of the PRDM and the interaction between upstream regulatory region and downstream photoreceptor conserved elements and E-box element.
Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
Lior
L
Appelbaum
Reiko
R
Toyama
Igor B
IB
Dawid
David C
DC
Klein
Ruben
R
Baler
Yoav
Y
Gothilf
D000818:Animals; D047068:Arylalkylamine N-Acetyltransferase / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002940:Circadian Rhythm / Q000502:physiology*; D003001:Cloning, Molecular; D004625:Embryo, Nonmammalian / Q000201:enzymology; D008550:Melatonin / Q000378:metabolism*; D008969:Molecular Sequence Data; D010786:Photoreceptor Cells / Q000378:metabolism; D010870:Pineal Gland / Q000201:enzymology*; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D015027:Zebrafish / Q000196:embryology / Q000235:genetics*
D047068:Arylalkylamine N-Acetyltransferase; D008550:Melatonin