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GnRH Stimulates Peptidylarginine Deiminase Catalyzed Histone Citrullination in Gonadotrope Cells.

Authors
  • Khan, Shaihla A1
  • Edwards, Brian S1
  • Muth, Aaron1
  • Thompson, Paul R1
  • Cherrington, Brian D1
  • Navratil, Amy M1
  • 1 Department of Zoology and Physiology (S.A.K., B.S.E., B.D.C., A.M.N.), University of Wyoming, Laramie, Wyoming 82071; and Department of Biochemistry and Molecular Pharmacology (A.M., P.R.T.), University of Massachusetts Medical School, Worcester, Massachusetts 01605.
Type
Published Article
Journal
Molecular Endocrinology
Publisher
The Endocrine Society
Publication Date
Oct 01, 2016
Volume
30
Issue
10
Pages
1081–1091
Identifiers
PMID: 27603413
Source
Medline
License
Unknown

Abstract

Peptidylarginine deiminase (PAD) enzymes convert histone tail arginine residues to citrulline resulting in chromatin decondensation. Our previous work found that PAD isoforms are expressed in female reproductive tissues in an estrous cycle-dependent fashion, but their role in the anterior pituitary gland is unknown. Thus, we investigated PAD expression and function in gonadotrope cells. The gonadotrope-derived LβT2 cell line strongly expresses PAD2 at the protein level compared with other PAD isoforms. Consistent with this, PAD2 protein expression is highest during the estrous phase of the estrous cycle and colocalizes with the LH β-subunit in the mouse pituitary. Using the GnRH agonist buserelin (GnRHa), studies in LβT2 and mouse primary gonadotrope cells revealed that 30 minutes of stimulation caused distinct puncta of PAD2 to localize in the nucleus. Once in the nucleus, GnRHa stimulated PAD2 citrullinates histone H3 tail arginine residues at sites 2, 8, and 17 within 30 minutes; however, this effect and PAD2 nuclear localization was blunted by incubation of the cells with the pan-PAD inhibitor, biphenyl-benzimidazole-Cl-amidine. Given that PAD2 citrullinates histones in gonadotropes, we next analyzed the functional consequence of PAD2 inhibition on gene expression. Our results show that GnRHa stimulates an increase in LHβ and FSHβ mRNA and that this response is significantly reduced in the presence of the PAD inhibitor biphenyl-benzimidazole-Cl-amidine. Overall, our data suggest that GnRHa stimulates PAD2-catalyzed histone citrullination in gonadotropes to epigenetically regulate gonadotropin gene expression.

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