Single-cell analyses reveal that KISS1R-expressing cells undergo sustained kisspeptin-induced signaling that is dependent upon an influx of extracellular Ca2+

Endocrinology. 2012 Dec;153(12):5875-87. doi: 10.1210/en.2012-1747. Epub 2012 Oct 15.

Abstract

The kisspeptin receptor (KISS1R) is a Gα(q/11)-coupled seven-transmembrane receptor activated by a group of peptides referred to as kisspeptins (Kps). The Kp/KISS1R signaling system is a powerful regulator of GnRH secretion, and inactivating mutations in this system are associated with hypogonadotropic hypogonadism. A recent study revealed that Kp triggers prolonged signaling; not from the inability of the receptor to undergo rapid desensitization, but instead from the maintenance of a dynamic and active pool of KISS1R at the cell surface. To investigate this further, we hypothesized that if a dynamic pool of receptor is maintained at the cell surface for a protracted period, chronic Kp-10 treatment would trigger the sustained activation of Gα(q/11) as evidenced through the prolonged activation of phospholipase C, protein kinase C, and prolonged mobilization of intracellular Ca(2+). Through single-cell analyses, we tested our hypothesis in human embryonic kidney (HEK) 293 cells and found that was indeed the case. We subsequently determined that prolonged KISS1R signaling was not a phenomenon specific to HEK 293 cells but is likely a conserved property of KISS1R-expressing cells because evidence of sustained KISS1R signaling was also observed in the GT1-7 GnRH neuronal and Chinese hamster ovary cell lines. While exploring the regulation of prolonged KISS1R signaling, we identified a critical role for extracellular Ca(2+). We found that although free intracellular Ca(2+), primarily derived from intracellular stores, was sufficient to trigger the acute activation of a major KISS1R secondary effector, protein kinase C, it was insufficient to sustain chronic KISS1R signaling; instead extracellular Ca(2+) was absolutely required for this.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CHO Cells
  • Calcium / chemistry
  • Calcium / metabolism*
  • Cricetinae
  • HEK293 Cells
  • Humans
  • Kisspeptins / metabolism*
  • Microscopy, Confocal / methods
  • Models, Biological
  • Neurons / metabolism
  • Peptides / chemistry
  • Receptors, G-Protein-Coupled / biosynthesis*
  • Receptors, Kisspeptin-1
  • Signal Transduction

Substances

  • KISS1R protein, human
  • Kisspeptins
  • Peptides
  • Receptors, G-Protein-Coupled
  • Receptors, Kisspeptin-1
  • Calcium