TY - JOUR

T1 - The Calcium-Sensing Receptor Is Essential for Calcium and Bicarbonate Sensitivity in Human Spermatozoa

AU - Boisen, Ida Marie

AU - Rehfeld, Anders

AU - Mos, Iris

AU - Poulsen, Nadia Nicholine

AU - Nielsen, John Erik

AU - Schwarz, Peter

AU - Rejnmark, Lars

AU - Dissing, Steen

AU - Bach-Mortensen, Pernille

AU - Juul, Anders

AU - Bräuner-Osborne, Hans

AU - Lanske, Beate

AU - Blomberg Jensen, Martin

PY - 2021

Y1 - 2021

N2 - CONTEXT: The calcium-sensing receptor (CaSR) is essential to maintain a stable calcium concentration in serum. Spermatozoa are exposed to immense changes in concentrations of CaSR ligands such as calcium, magnesium, and spermine during epididymal maturation, in the ejaculate, and in the female reproductive environment. However, the role of CaSR in human spermatozoa is unknown.OBJECTIVE: This work aimed to investigate the role of CaSR in human spermatozoa.METHODS: We identified CaSR in human spermatozoa and characterized the response to CaSR agonists on intracellular calcium, acrosome reaction, and 3',5'-cyclic adenosine 5'-monophosphate (cAMP) in spermatozoa from men with either loss-of-function or gain-of-function mutations in CASR and healthy donors.RESULTS: CaSR is expressed in human spermatozoa and is essential for sensing extracellular free ionized calcium (Ca2+) and Mg2+. Activators of CaSR augmented the effect of sperm-activating signals such as the response to HCO3- and the acrosome reaction, whereas spermatozoa from men with a loss-of-function mutation in CASR had a diminished response to HCO3-, lower progesterone-mediated calcium influx, and were less likely to undergo the acrosome reaction in response to progesterone or Ca2+. CaSR activation increased cAMP through soluble adenylyl cyclase (sAC) activity and increased calcium influx through CatSper. Moreover, external Ca2+ or Mg2+ was indispensable for HCO3- activation of sAC. Two male patients with a CASR loss-of-function mutation in exon 3 presented with normal sperm counts and motility, whereas a patient with a loss-of-function mutation in exon 7 had low sperm count, motility, and morphology.CONCLUSION: CaSR is important for the sensing of Ca2+, Mg2+, and HCO3- in spermatozoa, and loss-of-function may impair male sperm function.

AB - CONTEXT: The calcium-sensing receptor (CaSR) is essential to maintain a stable calcium concentration in serum. Spermatozoa are exposed to immense changes in concentrations of CaSR ligands such as calcium, magnesium, and spermine during epididymal maturation, in the ejaculate, and in the female reproductive environment. However, the role of CaSR in human spermatozoa is unknown.OBJECTIVE: This work aimed to investigate the role of CaSR in human spermatozoa.METHODS: We identified CaSR in human spermatozoa and characterized the response to CaSR agonists on intracellular calcium, acrosome reaction, and 3',5'-cyclic adenosine 5'-monophosphate (cAMP) in spermatozoa from men with either loss-of-function or gain-of-function mutations in CASR and healthy donors.RESULTS: CaSR is expressed in human spermatozoa and is essential for sensing extracellular free ionized calcium (Ca2+) and Mg2+. Activators of CaSR augmented the effect of sperm-activating signals such as the response to HCO3- and the acrosome reaction, whereas spermatozoa from men with a loss-of-function mutation in CASR had a diminished response to HCO3-, lower progesterone-mediated calcium influx, and were less likely to undergo the acrosome reaction in response to progesterone or Ca2+. CaSR activation increased cAMP through soluble adenylyl cyclase (sAC) activity and increased calcium influx through CatSper. Moreover, external Ca2+ or Mg2+ was indispensable for HCO3- activation of sAC. Two male patients with a CASR loss-of-function mutation in exon 3 presented with normal sperm counts and motility, whereas a patient with a loss-of-function mutation in exon 7 had low sperm count, motility, and morphology.CONCLUSION: CaSR is important for the sensing of Ca2+, Mg2+, and HCO3- in spermatozoa, and loss-of-function may impair male sperm function.

U2 - 10.1210/clinem/dgaa937

DO - 10.1210/clinem/dgaa937

M3 - Journal article

C2 - 33340048

VL - 106

SP - e1775-e1792

JO - Journal of Clinical Endocrinology and Metabolism

JF - Journal of Clinical Endocrinology and Metabolism

SN - 0021-972X

IS - 4

ER -