Characterization of the chicken serotonin N-acetyltransferase gene. Activation via clock gene heterodimer/E box interaction.
The abundance of serotonin N-acetyltransferase (arylalkylamine N-acetyltransferase, AANAT) mRNA in the chicken pineal gland exhibits a circadian rhythm, which is translated into a circadian rhythm in melatonin production. Here we have started to elucidate the molecular basis of the circadian rhythm in chicken AANAT (cAANAT). The 5'-flanking region of the cAANAT gene was isolated and found to contain an E box DNA element that confers strong luciferase reporter activity. In transfection experiments using chicken pineal cells, an E box mutation dramatically decreased reporter activity. Northern blot analysis indicated that several putative clock genes (bmal1, Clock, and MOP4) are co-expressed in the chicken pineal gland. bmal1 mRNA is expressed in a rhythmic manner in the chicken pineal gland, with peak levels at early subjective night, coincident with the increase in cAANAT expression. Co-transfection experiments in COS cells demonstrated that chicken BMAL1/CLOCK and human BMAL1/MOP4 heterodimers bound the AANAT E box element and enhanced transcription. These observations suggest that binding of clock gene heterodimers to the cAANAT E box is a critical element in the expression of the cAANAT gene in vitro.
Chong
N W
NW
Section on Neuroendocrinology, Laboratory of Developmental Neurobiology, NICHD, National Institutes of Health, Bethesda, Maryland 20892, USA.
Bernard
M
M
Klein
D C
DC
D056930:ARNTL Transcription Factors; D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000235:genetics*; D001483:Base Sequence; D051792:Basic Helix-Loop-Helix Proteins; D056926:CLOCK Proteins; D019556:COS Cells; D002645:Chickens / Q000235:genetics*; D002940:Circadian Rhythm; D019281:Dimerization; D015971:Gene Expression Regulation, Enzymologic; D015723:Gene Library; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D008969:Molecular Sequence Data; D010870:Pineal Gland / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D015183:Restriction Mapping; D012160:Retina / Q000502:physiology; D017384:Sequence Deletion; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
D056930:ARNTL Transcription Factors; D001191:Arylamine N-Acetyltransferase; D051792:Basic Helix-Loop-Helix Proteins; D056926:CLOCK Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C538960:BMAL1 protein, human; C538943:CLOCK protein, human