Evolutionary Conservation of Mammalian Sperm Proteins Associates with Overall, not Tyrosine, Phosphorylation in Human Spermatozoa

The presence of a novel functional estrogen receptor on the human sperm surface has been demonstrated by using different experimental approaches. Ligand blot analysis of sperm lysates, using peroxidase-conjugated estradiol as probe, identified a specific estradiol-binding protein of approximately 29-kDa apparent molecular mass. The same protein band was also revealed by using αH222 antibody, which is directed against the steroid binding domain of the genomic estrogen receptor. The biological effects of estrogen receptor were investigated by analyzing calcium fluxes, tyrosine phosphorylation, and acrosome reaction (AR) in response to 17β-estradiol (17βE2) and by measuring the steroid influence on calcium and AR in responses to progesterone (P), a well-known physiological stimulus for human spermatozoa. Our results demonstrate that 17βE2 induces a rapid and sustained increase of intracellular calcium concentrations ([Ca2+]i). This effect is totally dependent on the presence of extracellular calcium, because it is completely abolished in a calcium-depleted medium. The dose-response curve for calcium increase to 17βE2 is biphasic with a first component in the nanomolar range (effective concentration 50 = 0.60 ± 0.12 nmol/L) and a second component in the micromolar range (EC50 = 3.80 ± 0.26 μmol/L). 17βE2 stimulates tyrosine phosphorylation of several sperm proteins, including the 29-kDa protein band, and determines a reduction of calcium response to P, finally resulting in inhibition of P-stimulated sperm AR. Conversely, no direct effect of 17βE2 is observed on AR. 17βE2 effects on calcium are clearly mediated by a membrane receptor, because they are reproduced by the membrane-impermeable conjugate of the hormone BSA-E2 and reduced by sperm preincubation with αH222 antibody. Taken together, our results clearly show the presence of a functional surface estrogen receptor, of 29 kDa, on human spermatozoa. This receptor may play a role in the modulation of nongenomic action of P in these cells during the process of fertilization.

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Stimulation of protein tyrosine phosphorylation by platelet-activating factor and progesterone in human spermatozoa

Molecular and Cellular Endocrinology ◽

10.1016/0303-7207(95)92576-a ◽

1995 ◽

Vol 108 (1-2) ◽

pp. 35-42 ◽

Cited By ~ 56

Author(s):

Michaela Luconi ◽

Lorella Bonaccorsi ◽

Csilla Krausz ◽

Ginetta Gervasi ◽

Gianni Forti ◽

...

Keyword(s):

Tyrosine Phosphorylation ◽

Platelet Activating Factor ◽

Human Spermatozoa ◽

Protein Tyrosine Phosphorylation ◽

Protein Tyrosine ◽

Stimulation Of

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Effects of the environmental endocrine disruptors di-2-ethylhexyl phthalate and mono-2-ethylhexyl phthalate on human sperm function in vitro

Reproduction Fertility and Development ◽

10.1071/rd19164 ◽

2020 ◽

Vol 32 (6) ◽

pp. 629

Author(s):

Xinyi Sun ◽

Wenqiong Chen ◽

Shiqi Weng ◽

Tingting Pan ◽

Xiaonian Hu ◽

...

Keyword(s):

Tyrosine Phosphorylation ◽

Membrane Integrity ◽

Human Sperm ◽

Male Reproduction ◽

Human Spermatozoa ◽

Mitochondrial Activity ◽

Sperm Function ◽

Endocrine Disrupting Chemical ◽

Ethylhexyl Phthalate

Di-2-ethylhexyl phthalate (DEHP), a plastic-derived, endocrine-disrupting chemical, has been shown to exhibit male reproductive toxicity. However, its effects on human mature spermatozoa are largely unknown. In this study we investigated the invitro effects of DEHP and mono-2-ethylhexyl phthalate (MEHP; the main metabolite of DEHP) on sperm function and the mechanisms involved. Human spermatozoa were exposed to phthalates invitro at the doses that cover the concentrations detected in human semen: 20nM–8 μM DEHP, 1nM–20 μM MEHP or a mixture of 20nM–8 μM DEHP and 1nM–20 μM MEHP. DEHP and MEHP, alone or in combination, had no effect on the viability, membrane integrity, motility, homeostasis of reactive oxygen species or mitochondrial activity of human spermatozoa. Interestingly, 1nM–20 μM MEHP and combinations of 20nM–8 μM DEHP and 1nM–20 μM MEHP enhanced penetration ability, hyperactivation and the spontaneous acrosome reaction of human spermatozoa, and increased intracellular free Ca2+ concentrations ([Ca2+]i) and tyrosine phosphorylation, two key signalling pathways that regulate sperm function. The findings of this study suggest that invitro exposure to MEHP metabolised from DEHP affects human sperm function by inducing increases in sperm [Ca2+]i and tyrosine phosphorylation, which adds to our understanding of the effects of DEHP on male reproduction.

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A caged progesterone analog alters intracellular Ca2+ and flagellar bending in human sperm

Reproduction ◽

10.1530/rep-11-0268 ◽

2012 ◽

Vol 144 (1) ◽

pp. 101-109 ◽

Cited By ~ 22

Author(s):

M Rocio Servin-Vences ◽

Yoshiro Tatsu ◽

Hisanori Ando ◽

Adán Guerrero ◽

Noboru Yumoto ◽

...

Keyword(s):

Time Lag ◽

Human Sperm ◽

Human Spermatozoa ◽

Mammalian Sperm ◽

Intracellular Ca ◽

Stroboscopic Illumination ◽

Initial Action ◽

Principal Piece ◽

Short Time ◽

First Time

Progesterone is a physiological agonist for mammalian sperm, modulating its flagellar movement and facilitating the acrosome reaction. To study the initial action of progesterone, we developed a caged analog with a photosensitive group: nitrophenylethanediol, at position 20. Using this compound combined with stroboscopic illumination, we performed Ca2+imaging of human spermatozoa and analyzed the effects of progesterone on the intracellular Ca2+concentration ([Ca2+]i) of beating flagella for the first time. We observed a transient [Ca2+]iincrease in the head and the flagellum upon photolysis of the caged progesterone and an increase in flagellar curvature. Detailed kinetic analysis revealed that progesterone elicits an increase in the [Ca2+]iimmediately in the flagellum (mid-piece and principal piece), thereafter in the head with a short time lag. This observation is different from the progesterone-induced Ca2+mobilization in mouse spermatozoa, where the Ca2+rise initiates at the base of the sperm head. Our finding is mostly consistent with the recent discovery that progesterone activates CatSper channels in human spermatozoa, but not in mouse spermatozoa.

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Cyclic nucleotide phosphodiesterase inhibition increases tyrosine phosphorylation and hyper motility in normal and pathological human spermatozoa

BIOCELL ◽

10.32604/biocell.2005.29.287 ◽

2005 ◽

Vol 29 (3) ◽

pp. 287-293 ◽

Cited By ~ 6

Author(s):

ROBERTO YUNES ◽

PEDRO FERN罭DEZ ◽

GUSTAVO F. DONCEL ◽

AN虰AL A. ACOSTA

Keyword(s):

Tyrosine Phosphorylation ◽

Cyclic Nucleotide ◽

Human Spermatozoa ◽

Cyclic Nucleotide Phosphodiesterase ◽

Phosphodiesterase Inhibition

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A novel signal transduction cascade in capacitating human spermatozoa characterised by a redox-regulated, cAMP-mediated induction of tyrosine phosphorylation

Journal of Cell Science ◽

10.1242/jcs.111.5.645 ◽

1998 ◽

Vol 111 (5) ◽

pp. 645-656 ◽

Cited By ~ 7

Author(s):

R.J. Aitken ◽

D. Harkiss ◽

W. Knox ◽

M. Paterson ◽

D.S. Irvine

Keyword(s):

Reactive Oxygen Species ◽

Signal Transduction ◽

Protein Kinase ◽

Protein Kinase A ◽

Tyrosine Phosphorylation ◽

Reactive Oxygen ◽

Human Spermatozoa ◽

Oxygen Species ◽

Signal Transduction Cascade ◽

Kinase A

Capacitation is a priming event that renders mammalian spermatozoa responsive to signals originating from the cumulus-oocyte complex. The attainment of a capacitated state is dependent upon an increase in tyrosine phosphorylation and results in the acquisition of responsiveness to physiological agonists such as progesterone and ZP3. In this study we have shown that this capacitation-dependent increase in tyrosine phosphorylation is controlled by a unique redox-regulated, cAMP-mediated, signal transduction cascade. Either stimulation of reactive oxygen species generation or elevation of intracellular cAMP induced increases in phosphotyrosine expression by human spermatozoa and enhanced their responsiveness to progesterone. Ultimate convergence of the redox- and cAMP-regulated pathways was indicated by the ability of the protein kinase A inhibitor, H89, to block both modes of signal transduction. Furthermore, the fact that the redox-regulated pathway could be silenced by catalase, while this enzyme had no effect on the cAMP-mediated response, indicated that oxidant generation must lie upstream from cAMP in the reaction sequence. In keeping with this conclusion, a functional association was demonstrated between the redox status of human spermatozoa and their cAMP content. The continuous production of reactive oxygen species was also shown to be necessary for the protein kinase A-tyrosine phosphorylation axis to remain functional. If the generation of oxidising conditions during capacitation was prevented with 2-mercaptoethanol, 2-deoxyglucose or the flavoprotein inhibitor, diphenylene iodonium, then cAMP could no longer trigger tyrosine phosphorylation. These data support a model for human sperm capacitation as a redox-regulated process, involving a unique sequence of interactive events including reactive oxygen species production, elevation of intracellular cAMP, stimulation of protein kinase A and the induction of tyrosine phosphorylation. This is the first report of such a signal transduction cascade and may have implications for the functional significance of reactive oxygen metabolites in other cell types.

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