TY - JOUR
T1 - A comparison of the ability of Leu8- And pro8-oxytocin to regulate intracellular Ca21 and Ca21-activated K1 channels at human and marmoset oxytocin receptors S
AU - Pierce, Marsha L.
AU - Mehrotra, Suneet
AU - Mustoe, Aaryn C.
AU - French, Jeffrey A.
AU - Murray, Thomas F.
N1 - Funding Information:
This work was supported by the National Institutes of Health Eunice Kennedy Shriver National Institute of Child Health and Human Development [Grant R01-HD089147].
PY - 2019/4
Y1 - 2019/4
N2 - The neurohypophyseal hormone oxytocin (OT) regulates biologic functions in both peripheral tissues and the central nervous system. In the central nervous system, OT influences social processes, including peer relationships, maternal-infant bonding, and affiliative social relationships. In mammals, the nonapeptide OT structure is highly conserved with leucine in the eighth position (Leu8-OT). In marmosets (Callithrix), a nonsynon-ymous nucleotide substitution in the OXT gene codes for proline in the eighth residue position (Pro8-OT). OT binds to its cognate G protein–coupled receptor (OTR) and exerts diverse effects, including stimulation (Gs) or inhibition (Gi/o) of adenylyl cyclase, stimulation of potassium channel currents (Gi), and activation of phospholipase C (Gq). Chinese hamster ovary cells expressing marmoset or human oxytocin receptors (mOTRs or hOTRs, respectively) were used to characterize OT signaling. At the mOTR, Pro8-OT was more efficacious than Leu8-OT in measures of Gq activation, with both peptides displaying subnanomolar potencies. At the hOTR, neither the potency nor efficacy of Pro8-OT and Leu8-OT differed with respect to Gq signaling. In both mOTR- and hOTR-expressing cells, Leu8-OT was more potent and modestly more efficacious than Pro8-OT in inducing hyperpolarization. In mOTR cells, Leu8-OT–induced hyperpolarization was modestly inhibited by pretreatment with pertussis toxin (PTX), consistent with a minor role for Gi/o activation; however, the Pro8-OT response in mOTR and hOTR cells was PTX insensitive. These findings are consistent with membrane hyperpolarization being largely mediated by a Gq signaling mechanism leading to Ca21-dependent activation of K1 channels. Evaluation of the influence of apamin, charybdotoxin, paxilline, and TRAM-34 demonstrated involvement of both intermediate and large conductance Ca21-activated K1 channels.
AB - The neurohypophyseal hormone oxytocin (OT) regulates biologic functions in both peripheral tissues and the central nervous system. In the central nervous system, OT influences social processes, including peer relationships, maternal-infant bonding, and affiliative social relationships. In mammals, the nonapeptide OT structure is highly conserved with leucine in the eighth position (Leu8-OT). In marmosets (Callithrix), a nonsynon-ymous nucleotide substitution in the OXT gene codes for proline in the eighth residue position (Pro8-OT). OT binds to its cognate G protein–coupled receptor (OTR) and exerts diverse effects, including stimulation (Gs) or inhibition (Gi/o) of adenylyl cyclase, stimulation of potassium channel currents (Gi), and activation of phospholipase C (Gq). Chinese hamster ovary cells expressing marmoset or human oxytocin receptors (mOTRs or hOTRs, respectively) were used to characterize OT signaling. At the mOTR, Pro8-OT was more efficacious than Leu8-OT in measures of Gq activation, with both peptides displaying subnanomolar potencies. At the hOTR, neither the potency nor efficacy of Pro8-OT and Leu8-OT differed with respect to Gq signaling. In both mOTR- and hOTR-expressing cells, Leu8-OT was more potent and modestly more efficacious than Pro8-OT in inducing hyperpolarization. In mOTR cells, Leu8-OT–induced hyperpolarization was modestly inhibited by pretreatment with pertussis toxin (PTX), consistent with a minor role for Gi/o activation; however, the Pro8-OT response in mOTR and hOTR cells was PTX insensitive. These findings are consistent with membrane hyperpolarization being largely mediated by a Gq signaling mechanism leading to Ca21-dependent activation of K1 channels. Evaluation of the influence of apamin, charybdotoxin, paxilline, and TRAM-34 demonstrated involvement of both intermediate and large conductance Ca21-activated K1 channels.
UR - http://www.scopus.com/inward/record.url?scp=85065313463&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85065313463&partnerID=8YFLogxK
U2 - 10.1124/mol.118.114744
DO - 10.1124/mol.118.114744
M3 - Article
C2 - 30739093
AN - SCOPUS:85065313463
VL - 95
SP - 376
EP - 385
JO - Molecular Pharmacology
JF - Molecular Pharmacology
SN - 0026-895X
IS - 4
ER -