Open Access

ARTICLE

The regulatory role of melatonin in pituitary thyroid-stimulating hormone synthesis through casein kinase 1α

BINGJIE WANG¹, YEWEN ZHOU^1,2,3, TONGJUAN NIU¹, MENGQING YIN¹, SHENG CUI^1,2,3,*

1 College of Veterinary Medicine, Yangzhou University, Yangzhou, 225009, China
2 Institute of Reproduction and Metabolism, Yangzhou University, Yangzhou, 225009, China
3 Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, China

* Corresponding Author: SHENG CUI. Email:

(This article belongs to the Special Issue: Subcellular Organelles and Cellular Molecules: Localization, Detection, Prediction, and Diseases)

BIOCELL 2024, 48(2), 327-338. https://doi.org/10.32604/biocell.2023.044630

Received 04 August 2023; Accepted 26 October 2023; Issue published 23 February 2024

Abstract

Introduction: The regulation of thyroid-stimulating hormone (TSH) synthesis involves neurotransmitters, with melatonin being a subject of ongoing debate. TSH transcription, synthesis, and secretion from the pituitary pars distalis (PD) is primarily regulated in a photoperiodic manner by thyrotropin-releasing hormone (TRH). In contrast, in the pituitary pars tuberalis (PT), mRNA transcription and alpha/beta chain synthesis, but not secretion, of a TSH-like product is regulated by melatonin. Conversely, non-photoperiodic melatonin might also affect the secretion of a TSH-like product from the PT. Nevertheless, the impact of exogenous melatonin on the underlying PD-TSH synthesis remains unclear. Casein kinase 1α (CK1α) plays a negative regulatory role in TSH synthesis in the mouse pituitary. Objective: We investigated whether non-photoperiodic melatonin affects PD-TSH synthesis through its interaction with CK1α. Methods: Immunohistochemistry and immunofluorescence staining detected the colocalization of the melatonin receptor MT1 with CK1α and TSH-β in the PD. RT-qPCR, western blotting, and ELISA revealed the effect of melatonin on Tshb mRNA, MTNR1A mRNA, Csnk1a1 mRNA, CK1α protein, MT1 protein, and TSH levels. Results: Robust colocalization of the melatonin receptor MT1 with CK1α and TSH-β in the PD. Tshb mRNA and CK1α protein expression levels peaked at opposite phases of the 24-h light:dark cycle. Exogenous melatonin administration promoted pituitary TSH synthesis, while concurrently inhibiting CK1α activity. The upregulation of endogenous CK1α activity in primary pituitary cells significantly blunted the melatonin stimulatory impact on Tshb mRNA and TSH levels. Mechanistically, the CK1α agonist pyrvinium abrogated melatonin-induced activation of p-PKC and p-CREB expression in vitro. Conclusion: The CK1α/PKC signaling pathway mediates the regulation of melatonin in pituitary TSH synthesis. We demonstrate an important theoretical and experimental basis for understanding the mechanism of endocrine system diseases caused by abnormal TSH synthesis in the pituitary.

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