MKRN3 inhibits the reproductive axis through actions in kisspeptin-expressing neurons

J Clin Invest. 2020 Aug 3;130(8):4486-4500. doi: 10.1172/JCI136564.

Abstract

The identification of loss-of-function mutations in MKRN3 in patients with central precocious puberty in association with the decrease in MKRN3 expression in the medial basal hypothalamus of mice before the initiation of reproductive maturation suggests that MKRN3 is acting as a brake on gonadotropin-releasing hormone (GnRH) secretion during childhood. In the current study, we investigated the mechanism by which MKRN3 prevents premature manifestation of the pubertal process. We showed that, as in mice, MKRN3 expression is high in the hypothalamus of rats and nonhuman primates early in life, decreases as puberty approaches, and is independent of sex steroid hormones. We demonstrated that Mkrn3 is expressed in Kiss1 neurons of the mouse hypothalamic arcuate nucleus and that MKRN3 repressed promoter activity of human KISS1 and TAC3, 2 key stimulators of GnRH secretion. We further showed that MKRN3 has ubiquitinase activity, that this activity is reduced by MKRN3 mutations affecting the RING finger domain, and that these mutations compromised the ability of MKRN3 to repress KISS1 and TAC3 promoter activity. These results indicate that MKRN3 acts to prevent puberty initiation, at least in part, by repressing KISS1 and TAC3 transcription and that this action may involve an MKRN3-directed ubiquitination-mediated mechanism.

Keywords: Endocrinology; Sex hormones.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Arcuate Nucleus of Hypothalamus / metabolism
  • Arcuate Nucleus of Hypothalamus / pathology
  • Female
  • Gene Expression Regulation
  • Gonadotropin-Releasing Hormone / genetics
  • Gonadotropin-Releasing Hormone / metabolism
  • HEK293 Cells
  • Humans
  • Kisspeptins / biosynthesis*
  • Kisspeptins / genetics
  • Male
  • Mice
  • Neurokinin B / genetics
  • Neurokinin B / metabolism
  • Neurons / metabolism*
  • Neurons / pathology
  • Promoter Regions, Genetic
  • Puberty, Precocious / genetics
  • Puberty, Precocious / metabolism*
  • Puberty, Precocious / pathology
  • Rats, Sprague-Dawley
  • Transcription, Genetic
  • Ubiquitin-Protein Ligases / genetics
  • Ubiquitin-Protein Ligases / metabolism*

Substances

  • KISS1 protein, human
  • Kiss1 protein, mouse
  • Kiss1 protein, rat
  • Kisspeptins
  • TAC3 protein, human
  • Gonadotropin-Releasing Hormone
  • Neurokinin B
  • MKRN3 protein, human
  • Mkrn3 protein, mouse
  • Mkrn3 protein, rat
  • Ubiquitin-Protein Ligases