Calcium channels in chicken sperm regulate motility and the acrosome reaction

• Published in: The FEBS journal 2016-05, Vol.283 (10), p.1902-1920
• Main Authors: Nguyen, Thi Mong Diep, Duittoz, Anne, Praud, Christophe, Combarnous, Yves, Blesbois, Elisabeth
• Format: Article
• Language: English
• Subjects: Acrosome Reaction - physiology; Adenylate Kinase - metabolism; Animals; Calcium; Calcium - metabolism; calcium channels; Calcium Channels - physiology; chicken sperm; Chickens; Kinases; Life Sciences; Male; Motility; Other; Sperm; Sperm Motility - physiology
• ISSN: 1742-464X; 1742-4658
• DOI: 10.1111/febs.13710

Intracellular cytoplasmic calcium ([Ca2+]i) has an important regulatory role in gamete functions. However, the biochemical components involved in Ca2+ transport are still unknown in birds, an animal class that has lost functional sperm‐specific CatSper channels. Here, we provide evidence for the presence and expression of various Ca2+ channels in chicken sperm, including high voltage‐activated channels (L and R types), the store‐operated Ca2+ channel (SOC) component Orai1, the transient receptor potential channel (TRPC1) and inositol‐1,4,5–trisphosphate receptors (IP3R1). L‐ and R–type channels were mainly localized in the acrosome and the midpiece, and T–type channels were not detected in chicken sperm. Orai1 was found in all compartments, but with a weak, diffuse signal in the flagellum. TRCP1 was mainly localized in the acrosome and the midpiece, but a weak diffuse signal was also observed in the nucleus and the flagellum. IP3R1 was mainly detected in the nucleus. The L–type channel inhibitor nifedipine, the R–type channel inhibitor SNX–482 and the SOC inhibitors MRS–1845, 2–APB and YM–58483 decreased [Ca2+]i sperm motility and acrosome reaction capability, with the SOC inhibitors inhibiting these functions most efficiently. Furthermore, we showed that Ca2+‐mediated induction of AMP‐activated protein kinase (AMPK) phosphorylation was blocked by SOC inhibition. Our identification of important regulators of Ca2+ signaling in avian sperm suggests that SOCs play a predominant role in gamete function, whereas T–type channels may not be involved. In addition, Ca2+ entry via SOCs appears to be the most likely pathway for AMPK activation and energy‐requiring sperm functions such as motility and the acrosome reaction. We identified the presence of several Ca2+ channels (L‐type, R‐type, T‐type, TRPC1, Orai1 and IP3R) in chicken spermatozoa and investigated the role of store‐operated channels in AMPK activation. Ca2+ channels influence chicken spermatozoa functions that are required for fertilization such as motility and the acrosome reaction. Store‐operated channels also have a role in AMPK activation.