Melatonin synthesis pathway: circadian regulation of the genes encoding the key enzymes in the chicken pineal gland and retina.
The mRNAs encoding three enzymes of the melatonin synthesis pathway (tryptophan hydroxylase (TPH), arylalkylamine-N-acetyltransferase (AANAT) and hydroxyindole-O-methyl-transferase (HIOMT)) are expressed with a day/night rhythm in the chicken pineal gland and retina. TPH and AANAT mRNA levels reach their peak at night. HIOMT mRNA levels peak at night in the retina, but during the day in the pineal gland. In this tissue, the rhythm of TPH, AANAT and HIOMT mRNA levels persisted in constant darkness (DD), both in vivo and in vitro, indicating that the three genes are controlled by the circadian oscillator of the chicken pineal. In the retina, the rhythms of TPH and AANAT mRNA levels also persisted in DD in vivo, suggesting that they are driven by a circadian oscillator. In contrast, the rhythm of HIOMT mRNA in the retina appeared to be controlled only by light. The clones of chicken AANAT and HIOMT genes that we have isolated should help us to understand the molecular mechanisms of: 1) their transcriptional regulation by circadian oscillators and by light; 2) their tissue-specific expression in the pineal gland and the retina.
Bernard
M
M
Laboratoire de neuroendocrinologie, UMR CNRS 6558, Poitiers, France. neurobio@campus.univ-poitiers.fr
Guerlotté
J
J
Grève
P
P
Gréchez-Cassiau
A
A
Iuvone
M P
MP
Zatz
M
M
Chong
N W
NW
Klein
D C
DC
Voisin
P
P
D056930:ARNTL Transcription Factors; D000121:Acetylserotonin O-Methyltransferase / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D001191:Arylamine N-Acetyltransferase / Q000096:biosynthesis* / Q000235:genetics; D051792:Basic Helix-Loop-Helix Proteins; D056926:CLOCK Proteins; D002645:Chickens; D002940:Circadian Rhythm / Q000235:genetics*; D029721:Drosophila Proteins; D004790:Enzyme Induction / Q000528:radiation effects; D005136:Eye Proteins / Q000096:biosynthesis* / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000528:radiation effects; D019476:Insect Proteins / Q000096:biosynthesis / Q000235:genetics; D008027:Light; D008550:Melatonin / Q000096:biosynthesis*; D008954:Models, Biological; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000235:genetics; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics; D009928:Organ Specificity; D056950:Period Circadian Proteins; D017440:Photoperiod; D010870:Pineal Gland / Q000201:enzymology* / Q000294:innervation; D012333:RNA, Messenger / Q000096:biosynthesis; D012160:Retina / Q000201:enzymology* / Q000528:radiation effects; D013493:Suprachiasmatic Nucleus / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology; D015534:Trans-Activators / Q000502:physiology; D014157:Transcription Factors / Q000502:physiology; D014158:Transcription, Genetic; D014365:Tryptophan Hydroxylase / Q000096:biosynthesis* / Q000235:genetics
D056930:ARNTL Transcription Factors; D000121:Acetylserotonin O-Methyltransferase; D001191:Arylamine N-Acetyltransferase; D051792:Basic Helix-Loop-Helix Proteins; D056926:CLOCK Proteins; D029721:Drosophila Proteins; D005136:Eye Proteins; D019476:Insect Proteins; D008550:Melatonin; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D056950:Period Circadian Proteins; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors; D014365:Tryptophan Hydroxylase; C539040:PER protein, Drosophila; C096445:tim protein, Drosophila