Modulation of Aanat gene transcription in the rat pineal gland.
The main function of the rat pineal gland is to transform the circadian rhythm generated in the suprachiasmatic nucleus into a rhythmic signal of circulating melatonin characterized by a large nocturnal increase that closely reflects the duration of night period. This is achieved through the tight coupling between environmental lighting and the expression of arylalkylamine-N-acetyltransferase, the rhythm-controlling enzyme in melatonin synthesis. The initiation of Aanat transcription at night is controlled largely by the norepinephrine-stimulated phosphorylation of cAMP response element-binding protein by protein kinase A. However, to accurately reflect the duration of darkness, additional signaling mechanisms also participate to fine-tune the temporal profile of adrenergic-induced Aanat transcription. Here, we reviewed some of these signaling mechanisms, with emphasis on the more recent findings. These signaling mechanisms can be divided into two groups: those involving modification of constitutively expressed proteins and those requiring synthesis of new proteins. This review highlights the pineal gland as an excellent model system for studying neurotransmitter-regulated rhythmic gene expression.
Ho
Anthony K
AK
Department of Physiology, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada. anho@ualberta
Chik
Constance L
CL
D000818:Animals; D047068:Arylalkylamine N-Acetyltransferase / Q000235:genetics / Q000378:metabolism*; D064127:Aurora Kinases; D050882:CREB-Binding Protein / Q000378:metabolism; D002940:Circadian Rhythm / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology; D006657:Histones / Q000378:metabolism; D008550:Melatonin / Q000378:metabolism; D008954:Models, Biological; D010870:Pineal Gland / Q000187:drug effects / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
D006657:Histones; D050882:CREB-Binding Protein; C520223:Aanat protein, rat; D047068:Arylalkylamine N-Acetyltransferase; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases; D008550:Melatonin