Single-cell analyses reveal that KISS1R-expressing cells undergo sustained kisspeptin-induced signaling that is dependent upon an influx of extracellular Ca2+.
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.
Children's Health Research Institute, The University of Western Ontario, London, Ontario, Canada N6C 2V5. ababwah@uwo.ca
Andy V
AV
Babwah
Macarena
M
Pampillo
Le
L
Min
Ursula B
UB
Kaiser
Moshmi
M
Bhattacharya
D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000737:chemistry / Q000378:metabolism*; D006224:Cricetinae; D057809:HEK293 Cells; D006801:Humans; D059648:Kisspeptins / Q000378:metabolism*; D018613:Microscopy, Confocal / Q000379:methods; D008954:Models, Biological; D009474:Neurons / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D043562:Receptors, G-Protein-Coupled / Q000096:biosynthesis*; D000074502:Receptors, Kisspeptin-1; D015398:Signal Transduction
C118688:KISS1R protein, human; D059648:Kisspeptins; D010455:Peptides; D043562:Receptors, G-Protein-Coupled; D000074502:Receptors, Kisspeptin-1; D002118:Calcium