Abstract
Recent studies have identified Ca(2+) stores in sperm cells; however, it is not clear whether these Ca(2+) stores are functional and how they are mobilized. Here, in vitro and in vivo, we determined that tripeptidyl peptidase II antagonists strongly activated the cAMP/PKA signaling pathway that drives sperm capacitation-associated protein tyrosine phosphorylation. We demonstrated that in the absence of Ca(2+), TPIII antagonists elevated the intracellular Ca(2+) levels in sperm, resulting in a marked improvement in sperm movement, capacitation, acrosome reaction, and the in vitro fertilizing ability. This antagonist-induced release of intracellular Ca(2+) could be blocked by the inhibitors of ryanodine receptors (RyRs) which are the main intracellular Ca(2+) channels responsible for releasing stored Ca(2+). Consistent with these results, indirect immunofluorescence assay using anti-RyR antibodies further validated the presence of RyR3 in the acrosomal region of mature sperm. Thus, TPPII can regulate sperm maturation by modulating intracellular Ca(2+) stores via the type 3 RyR.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Acrosome Reaction / physiology
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Amino Acid Chloromethyl Ketones / pharmacology
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Aminopeptidases / antagonists & inhibitors
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Aminopeptidases / metabolism*
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Animals
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Blotting, Western
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Calcium / metabolism*
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Cells, Cultured
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Cyclic AMP / metabolism
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Cyclic AMP-Dependent Protein Kinases / metabolism
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Dantrolene / pharmacology
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Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / antagonists & inhibitors
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Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / metabolism*
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Indoles / pharmacology
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Intracellular Space / drug effects
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Intracellular Space / metabolism
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Male
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Mice
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Mice, Inbred C57BL
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Muscle Relaxants, Central / pharmacology
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Phosphorylation / drug effects
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Ryanodine / pharmacology
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Ryanodine Receptor Calcium Release Channel / metabolism*
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Serine Endopeptidases / metabolism*
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Signal Transduction / drug effects
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Sperm Capacitation / physiology
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Spermatozoa / cytology
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Spermatozoa / physiology*
Substances
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Amino Acid Chloromethyl Ketones
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Indoles
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Muscle Relaxants, Central
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Ryanodine Receptor Calcium Release Channel
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butabindide
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alanyl-alanyl-phenylalanine chloromethyl ketone
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Ryanodine
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Cyclic AMP
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Cyclic AMP-Dependent Protein Kinases
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Aminopeptidases
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Dipeptidyl-Peptidases and Tripeptidyl-Peptidases
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tripeptidyl-peptidase 2
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Serine Endopeptidases
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Dantrolene
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Calcium
Grants and funding
This work was supported by grants from the National Key Basic Research Program (973 Program) (2009CB941701), the National Natural Science Foundation of China (30930053, 31171115 and 30971089), and the Chinese Academy of Sciences Knowledge Creative Program (No. KSCX2-EW-R-07). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.