Product Reference
Two Distinct Ca2+ Signaling Pathways Modulate Sperm Flagellar Beating Patterns in Mice.
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| Author |
Chang H, Suarez SS |
| Citation Information |
Biol Reprod, : (2011) |
| Related Products |
AB1603 |
| Pub Med ID |
21389347 |
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Abstract
Hyperactivation, a swimming pattern of mammalian sperm in the oviduct, is essential for fertilization. It is characterized by asymmetrical flagellar beating and an increase of cytoplasmic Ca(2+). We observed that some mouse sperm swimming in the oviduct produce high-amplitude pro-hook bends (bends in the direction of the hook on the head), while other sperm produce high-amplitude anti-hook bends. Switching direction of the major bends could serve to re-direct sperm toward oocytes. We hypothesized that different Ca(2+) signaling pathways produce high-amplitude pro-hook and anti-hook bends. In vitro, sperm that hyperactivated during capacitation, which is due to activation of CATSPER plasma membrane Ca(2+) channels, developed high-amplitude pro-hook bends. CATSPER activators procaine and 4-aminopyridine (4-AP) also induced high-amplitude pro-hook bends. Thimerosal, which triggers a Ca(2+) release from internal stores, induced high-amplitude anti-hook bends. Activation of CATSPER channels is facilitated by a pH rise, so both Ca(2+) and pH responses to treatments with 4-AP and thimerosal were monitored. Thimerosal triggered a Ca(2+) increase that initiated at the base of the flagellum, whereas 4-AP initiated a rise in the proximal principal piece. Only 4-AP triggered a flagellar pH rise. Proteins were extracted from sperm for examination of phosphorylation patterns induced by Ca(2+) signaling. Procaine and 4-AP induced phosphorylation of proteins on threonine and serine, while thimerosal primarily induced dephosphorylation of proteins. Tyrosine phosphorylation was unaffected. We concluded that hyperactivation, which is associated with capacitation, can be modulated by release of Ca(2+) from intracellular stores to reverse the direction of the dominant flagellar bend and thus re-direct sperm.
