Orexin a enhances pro-opiomelanocortin transcription regulated by bmp-4 in mouse corticotrope att20 cells

Satoshi Fujisawa, Motoshi Komatsubara, Naoko Tsukamoto-Yamauchi, Nahoko Iwata, Takahiro Nada, Jun Wada, Fumio Otsuka

Research output: Contribution to journalArticlepeer-review

Abstract

Orexin is expressed mainly in the hypothalamus and is known to activate the hypothalamic– pituitary–adrenal (HPA) axis that is involved in various stress responses and its resilience. However, the effects of orexin on the endocrine function of pituitary corticotrope cells remain unclear. In this study, we investigated the roles of orexin A in pro-opiomelanocortin (POMC) transcription using mouse corticotrope AtT20 cells, focusing on the bone morphogenetic protein (BMP) system expressed in the pituitary. Regarding the receptors for orexin, type 2 (OXR2) rather than type 1 (OX1R) receptor mRNA was predominantly expressed in AtT20 cells. It was found that orexin A treatment enhanced POMC expression, induced by corticotropin-releasing hormone (CRH) stimulation through upregu-lation of CRH receptor type-1 (CRHR1). Orexin A had no direct effect on the POMC transcription suppressed by BMP-4 treatment, whereas it suppressed Smad1/5/9 phosphorylation and Id-1 mRNA expression induced by BMP-4. It was further revealed that orexin A had no significant effect on the expression levels of type I and II BMP receptors but upregulated inhibitory Smad6/7 mRNA and protein levels in AtT20 cells. The results demonstrated that orexin A upregulated CRHR signaling and downregulated BMP-Smad signaling, leading to an enhancement of POMC transcription by corticotrope cells.

Original languageEnglish
Article number4553
JournalInternational journal of molecular sciences
Volume22
Issue number9
DOIs
Publication statusPublished - May 1 2021

Keywords

  • Anterior pituitary
  • Bone morphogenetic protein (BMP)
  • Corticotrope
  • Orexin
  • Pro-opiomelanocortin (POMC)

ASJC Scopus subject areas

  • Catalysis
  • Molecular Biology
  • Spectroscopy
  • Computer Science Applications
  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

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