Ho AK, Chik CL
Modulation of Aanat Gene Transcription in the Rat Pineal Gland. [JOURNAL ARTICLE]
J Neurochem 2009 Oct 27.
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 arylalkyl-N-acetyltransferase (AA-NAT), the rhythm-controlling enzyme in melatonin synthesis. The initiation of Aanat transcription at night is controlled largely by the norepinephrine-stimulated phosphorylation of cyclic AMP response element binding protein by protein kinase A. However, to accurate 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.
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