Regulation of the Mel 1a melatonin receptor mRNA and protein levels in the ovine pars tuberalis

Evidence for a cyclic adenosine 3',5'-monophosphate-independent Mel 1a receptor coupling and an autoregulatory mechanism expression

Perry Barrett, A MacLean, G Davidson, Peter John Morgan

Research output: Contribution to journalArticle

77 Citations (Scopus)

Abstract

The Mel la receptor gene has recently been cloned and sequenced, and its product has been found to represent a new class of the G protein-coupled receptor superfamily. A unique aspect of its endogenous hormonal ligand, melatonin, is the prolonged duration (16 h) required to initiate appropriate photoperiodic responses in the animal. This study provides the first data on the transcriptional and translational regulation of this receptor in primary cultures of its native tissue, the pars tuberalis of the ovine pituitary. Using RNAse protection assays we show Mel la mRNA expression is rapidly induced through changes in intracellular cAMP levels. Forskolin enhances Mel la mRNA expression, whereas melatonin reverses this effect. RNA stability is also a factor, as Mel la mRNA expression decreases rapidly in the presence of actinomycin D. Although the expression of receptor protein is sensitive to forskolin stimulation, the lag between induction of mRNA and protein suggests that other factors (e.g. RNA splicing) contribute to functional receptor expression. Furthermore we observed that both mRNA and receptor protein levels increase spontaneously during primary culture, and these rises could be blocked by melatonin. A spontaneous rise in Mel la mRNA can also occur in serum-depleted cultures. In the absence of corresponding changes in cAMP, these results suggest not only that the Mel la receptor can autoregulate its own expression by an undefined pathway, but also they provide the first evidence that melatonin can act via a cAMP-independent signal transduction pathway to repress transcription in this tissue.

Original languageEnglish
Pages (from-to)892-902
Number of pages11
JournalMolecular Endocrinology
Volume10
Issue number7
DOIs
Publication statusPublished - Jul 1996

Keywords

  • hamster phodopus-sungorus
  • messenger-RNA
  • binding-sites
  • rat pituitary
  • gene
  • amp
  • transcription
  • photoperiod
  • inhibition
  • duration

Cite this

@article{1cc9df6d81584678befa36fe00c21533,
title = "Regulation of the Mel 1a melatonin receptor mRNA and protein levels in the ovine pars tuberalis: Evidence for a cyclic adenosine 3',5'-monophosphate-independent Mel 1a receptor coupling and an autoregulatory mechanism expression",
abstract = "The Mel la receptor gene has recently been cloned and sequenced, and its product has been found to represent a new class of the G protein-coupled receptor superfamily. A unique aspect of its endogenous hormonal ligand, melatonin, is the prolonged duration (16 h) required to initiate appropriate photoperiodic responses in the animal. This study provides the first data on the transcriptional and translational regulation of this receptor in primary cultures of its native tissue, the pars tuberalis of the ovine pituitary. Using RNAse protection assays we show Mel la mRNA expression is rapidly induced through changes in intracellular cAMP levels. Forskolin enhances Mel la mRNA expression, whereas melatonin reverses this effect. RNA stability is also a factor, as Mel la mRNA expression decreases rapidly in the presence of actinomycin D. Although the expression of receptor protein is sensitive to forskolin stimulation, the lag between induction of mRNA and protein suggests that other factors (e.g. RNA splicing) contribute to functional receptor expression. Furthermore we observed that both mRNA and receptor protein levels increase spontaneously during primary culture, and these rises could be blocked by melatonin. A spontaneous rise in Mel la mRNA can also occur in serum-depleted cultures. In the absence of corresponding changes in cAMP, these results suggest not only that the Mel la receptor can autoregulate its own expression by an undefined pathway, but also they provide the first evidence that melatonin can act via a cAMP-independent signal transduction pathway to repress transcription in this tissue.",
keywords = "hamster phodopus-sungorus, messenger-RNA, binding-sites, rat pituitary, gene, amp, transcription, photoperiod, inhibition, duration",
author = "Perry Barrett and A MacLean and G Davidson and Morgan, {Peter John}",
year = "1996",
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TY - JOUR

T1 - Regulation of the Mel 1a melatonin receptor mRNA and protein levels in the ovine pars tuberalis

T2 - Evidence for a cyclic adenosine 3',5'-monophosphate-independent Mel 1a receptor coupling and an autoregulatory mechanism expression

AU - Barrett, Perry

AU - MacLean, A

AU - Davidson, G

AU - Morgan, Peter John

PY - 1996/7

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N2 - The Mel la receptor gene has recently been cloned and sequenced, and its product has been found to represent a new class of the G protein-coupled receptor superfamily. A unique aspect of its endogenous hormonal ligand, melatonin, is the prolonged duration (16 h) required to initiate appropriate photoperiodic responses in the animal. This study provides the first data on the transcriptional and translational regulation of this receptor in primary cultures of its native tissue, the pars tuberalis of the ovine pituitary. Using RNAse protection assays we show Mel la mRNA expression is rapidly induced through changes in intracellular cAMP levels. Forskolin enhances Mel la mRNA expression, whereas melatonin reverses this effect. RNA stability is also a factor, as Mel la mRNA expression decreases rapidly in the presence of actinomycin D. Although the expression of receptor protein is sensitive to forskolin stimulation, the lag between induction of mRNA and protein suggests that other factors (e.g. RNA splicing) contribute to functional receptor expression. Furthermore we observed that both mRNA and receptor protein levels increase spontaneously during primary culture, and these rises could be blocked by melatonin. A spontaneous rise in Mel la mRNA can also occur in serum-depleted cultures. In the absence of corresponding changes in cAMP, these results suggest not only that the Mel la receptor can autoregulate its own expression by an undefined pathway, but also they provide the first evidence that melatonin can act via a cAMP-independent signal transduction pathway to repress transcription in this tissue.

AB - The Mel la receptor gene has recently been cloned and sequenced, and its product has been found to represent a new class of the G protein-coupled receptor superfamily. A unique aspect of its endogenous hormonal ligand, melatonin, is the prolonged duration (16 h) required to initiate appropriate photoperiodic responses in the animal. This study provides the first data on the transcriptional and translational regulation of this receptor in primary cultures of its native tissue, the pars tuberalis of the ovine pituitary. Using RNAse protection assays we show Mel la mRNA expression is rapidly induced through changes in intracellular cAMP levels. Forskolin enhances Mel la mRNA expression, whereas melatonin reverses this effect. RNA stability is also a factor, as Mel la mRNA expression decreases rapidly in the presence of actinomycin D. Although the expression of receptor protein is sensitive to forskolin stimulation, the lag between induction of mRNA and protein suggests that other factors (e.g. RNA splicing) contribute to functional receptor expression. Furthermore we observed that both mRNA and receptor protein levels increase spontaneously during primary culture, and these rises could be blocked by melatonin. A spontaneous rise in Mel la mRNA can also occur in serum-depleted cultures. In the absence of corresponding changes in cAMP, these results suggest not only that the Mel la receptor can autoregulate its own expression by an undefined pathway, but also they provide the first evidence that melatonin can act via a cAMP-independent signal transduction pathway to repress transcription in this tissue.

KW - hamster phodopus-sungorus

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KW - rat pituitary

KW - gene

KW - amp

KW - transcription

KW - photoperiod

KW - inhibition

KW - duration

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