Regulation of the ovine MT1 melatonin receptor promoter: Interaction between multiple pituitary transcription factors at different phases of development

Expression of the MT(1) receptor in the ovine pituitary is influenced by the balance of transcription factors.

• The MT(1) receptor is primarily regulated by the transcription factors Pitx-1 and Egr-1.
• Nuclear protein from ovine pars tuberalis cells enhanced gene expression from the MT(1) promoter, indicating its functionality.
• Pitx-1 expression stimulated MT(1) promoter activity, while Egr-1 co-transfection led to promoter-specific effects, inhibiting MT(1) activity.
• Multiple E-boxes in the MT(1) promoter were present, but circadian clock genes Clock and Bmal1 did not regulate MT(1) promoter activity.
• The findings suggest that melatonin receptor expression is regulated by a developmental balance of stimulatory and inhibitory factors rather than direct clock gene action.

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