151
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Tresguerres M, Buck J, Levin LR. Physiological carbon dioxide, bicarbonate, and pH sensing. Pflugers Arch 2010; 460:953-64. [PMID: 20683624 DOI: 10.1007/s00424-010-0865-6] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Revised: 07/16/2010] [Accepted: 07/18/2010] [Indexed: 12/20/2022]
Abstract
In biological systems, carbon dioxide exists in equilibrium with bicarbonate and protons. The individual components of this equilibrium (i.e., CO₂, HCO₃⁻, and H(+)), which must be sensed to be able to maintain cellular and organismal pH, also function as signals to modulate multiple physiological functions. Yet, the molecular sensors for CO₂/HCO₃⁻/pH remained unknown until recently. Here, we review recent progress in delineating molecular and cellular mechanisms for sensing CO₂, HCO₃⁻, and pH.
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Affiliation(s)
- Martin Tresguerres
- Department of Pharmacology, Weill Cornell Medical College, Cornell University, New York, USA
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152
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Hermo L, Pelletier RM, Cyr DG, Smith CE. Surfing the wave, cycle, life history, and genes/proteins expressed by testicular germ cells. Part 3: developmental changes in spermatid flagellum and cytoplasmic droplet and interaction of sperm with the zona pellucida and egg plasma membrane. Microsc Res Tech 2010; 73:320-63. [PMID: 19941287 DOI: 10.1002/jemt.20784] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Spermiogenesis constitutes the steps involved in the metamorphosis of spermatids into spermatozoa. It involves modification of several organelles in addition to the formation of several structures including the flagellum and cytoplasmic droplet. The flagellum is composed of a neck region and middle, principal, and end pieces. The axoneme composed of nine outer microtubular doublets circularly arranged to form a cylinder around a central pair of microtubules is present throughout the flagellum. The middle and principal pieces each contain specific components such as the mitochondrial sheath and fibrous sheath, respectively, while outer dense fibers are common to both. A plethora of proteins are constituents of each of these structures, with each playing key roles in functions related to the fertility of spermatozoa. At the end of spermiogenesis, a portion of spermatid cytoplasm remains associated with the released spermatozoa, referred to as the cytoplasmic droplet. The latter has as its main feature Golgi saccules, which appear to modify the plasma membrane of spermatozoa as they move down the epididymal duct and hence may be partly involved in male gamete maturation. The end product of spermatogenesis is highly streamlined and motile spermatozoa having a condensed nucleus equipped with an acrosome. Spermatozoa move through the female reproductive tract and eventually penetrate the zona pellucida and bind to the egg plasma membrane. Many proteins have been implicated in the process of fertilization as well as a plethora of proteins involved in the development of spermatids and sperm, and these are high lighted in this review.
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Affiliation(s)
- Louis Hermo
- Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, Montreal, Quebec, Canada H3A 2B2.
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153
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Nixon B, Bielanowicz A, Anderson AL, Walsh A, Hall T, Mccloghry A, Aitken RJ. Elucidation of the signaling pathways that underpin capacitation-associated surface phosphotyrosine expression in mouse spermatozoa. J Cell Physiol 2010; 224:71-83. [PMID: 20232304 DOI: 10.1002/jcp.22090] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Recent studies from within our laboratory have demonstrated a causal relationship between capacitation-associated surface phosphotyrosine expression and the ability of mouse spermatozoa to recognize the oocyte and engage in sperm-zona pellucida interaction. In the studies described herein we have sought to investigate the signaling pathways that underpin the tyrosine phosphorylation of sperm surface protein targets and validate the physiological significance of these pathways in relation to sperm-zona pellucida adhesion. Through selective pharmacological inhibition we have demonstrated that surface phosphotyrosine expression is unlikely to be mediated by the canonical cAMP-dependent protein kinase A (PKA) signaling cascade that has been most widely studied in relation to sperm capacitation. Rather, it appears to be primarily driven by the extracellular signal-regulated kinase (ERK) module of the mitogen-activated protein kinase (MAPK) pathway. Consistent with this notion, the main components of the ERK module (RAS, RAF1, MEK, and ERK1/2) were localized to the periacrosomal region of the head of mature mouse spermatozoa and their phosphorylation status within this region of the cell was positively modulated by capacitation. Furthermore, inhibition of several elements of this pathway suppressed sperm surface phosphotyrosine expression and induced a concomitant reduction sperm-zona pellucida interaction. Collectively, these data highlight a previously unappreciated role of the ERK module in the modification of the sperm surface during capacitation to render these cells functionally competent to engage in the process of fertilization.
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Affiliation(s)
- Brett Nixon
- Reproductive Science Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, Australia.
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154
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Fraser LR. The "switching on" of mammalian spermatozoa: molecular events involved in promotion and regulation of capacitation. Mol Reprod Dev 2010; 77:197-208. [PMID: 19908247 DOI: 10.1002/mrd.21124] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Following the discovery of mammalian sperm capacitation and its fundamental importance for the acquisition of fertilizing potential, it has gradually become possible to identify some specific molecules and molecular events that play pivotal roles in the "switching on" of spermatozoa. These are discussed in the context of the promotion and regulation of capacitation, emphasizing differences between commonly used conditions in vitro and the environment in vivo where spermatozoa normally undergo capacitation. Although typical culture media used in vitro do support capacitation, they do not prevent capacitated cells from undergoing spontaneous acrosome reactions and so losing fertilizing potential. This is not a problem in vitro, but could be in vivo where few spermatozoa reach the site of fertilization. Several small molecules, known to be present in vivo, have been shown in vitro to bind to spermatozoa and to regulate capacitation, first accelerating capacitation and then inhibiting spontaneous acrosome reactions, by regulating cAMP production. Since spermatozoa would contact these molecules during and after ejaculation, it is plausible that they serve a similar function in vivo. The mechanisms whereby the presence or absence of decapacitation factors might alter plasma membrane architecture and so alter functionality of a number of membrane-associated enzymes involved in capacitation are also considered. Finally, several unresolved issues relating to events during capacitation are discussed.
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Affiliation(s)
- Lynn R Fraser
- Division of Reproduction and Endocrinology, School of Biomedical and Health Sciences, King's College London, London SE1 1UL, UK.
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155
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Chen MH, Chen H, Zhou Z, Ruan YC, Wong HY, Lu YC, Guo JH, Chung YW, Huang PB, Huang HF, Zhou WL, Chan HC. Involvement of CFTR in oviductal HCO3− secretion and its effect on soluble adenylate cyclase-dependent early embryo development. Hum Reprod 2010; 25:1744-54. [DOI: 10.1093/humrep/deq094] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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156
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Mariappa D, Aladakatti RH, Dasari SK, Sreekumar A, Wolkowicz M, van der Hoorn F, Seshagiri PB. Inhibition of tyrosine phosphorylation of sperm flagellar proteins, outer dense fiber protein-2 and tektin-2, is associated with impaired motility during capacitation of hamster spermatozoa. Mol Reprod Dev 2010; 77:182-93. [PMID: 19953638 DOI: 10.1002/mrd.21131] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In mammals, acquisition of fertilization competence of spermatozoa is dependent on the phenomenon of sperm capacitation. One of the critical molecular events of sperm capacitation is protein tyrosine phosphorylation. In a previous study, we demonstrated that a specific epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor, tyrphostin-A47, inhibited hamster sperm capacitation, accompanied by a reduced sperm protein tyrosine phosphorylation. Interestingly, a high percentage of tyrphostin-A47-treated spermatozoa exhibited circular motility, which was associated with a distinct hypo-tyrosine phosphorylation of flagellar proteins, predominantly of Mr 45,000-60,000. In this study, we provide evidence on the localization of capacitation-associated tyrosine-phosphorylated proteins to the nonmembranous, structural components of the sperm flagellum. Consistent with this, we show their ultrastructural localization in the outer dense fiber, axoneme, and fibrous sheath of spermatozoa. Among hypo-tyrosine phosphorylated major proteins of tyrphostin-A47-treated spermatozoa, we identified the 45 kDa protein as outer dense fiber protein-2 and the 51 kDa protein as tektin-2, components of the sperm outer dense fiber and axoneme, respectively. This study shows functional association of hypo-tyrosine-phosphorylation status of outer dense fiber protein-2 and tektin-2 with impaired flagellar bending of spermatozoa, following inhibition of EGFR-tyrosine kinase, thereby showing the critical importance of flagellar protein tyrosine phosphorylation during capacitation and hyperactivation of hamster spermatozoa.
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Affiliation(s)
- Daniel Mariappa
- Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science, Bangalore, Karnataka, India
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157
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Bragado MJ, Aparicio IM, Gil MC, Garcia-Marin LJ. Protein kinases A and C and phosphatidylinositol 3 kinase regulate glycogen synthase kinase-3A serine 21 phosphorylation in boar spermatozoa. J Cell Biochem 2010; 109:65-73. [PMID: 19911376 DOI: 10.1002/jcb.22393] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The cAMP-dependent protein kinase (PKA), protein kinase C (PKC) and phosphatidylinositol 3-kinase (PI3K) pathways control most relevant functions in male germ cells including motility. Recently we demonstrated that phosphorylation state of glycogen synthase kinase-3alpha (GSK3A) is also a key event in the control of boar spermatozoa motility. However, the upstream regulators of GSK3A serine phosphorylation (inhibition) in male germ cells remain largely unknown. This work investigates the involvement of PKA, PKC and PI3K pathways in GSK3A phosphorylation in boar spermatozoa. A capacitating medium (TCM) or the phosphodiesterase-resistant cell permeable cAMP analogue 8Br-cAMP cause a significant increase in Ser21 GSK3A phosphorylation associated with a simultaneous significant increase in boar spermatozoa motility. These effects are blocked after preincubation of spermatozoa with PKA inhibitor H89 or PKC inhibitor Ro-32-0432. The PI3K inhibitor LY294002 increases both spermatozoa motility parameters and the basal GSK3A phosphorylation, but does not affect either TCM- or 8Br-cAMP-stimulated GSK3A phosphorylation. PI3K inhibition effects are mediated by an increase in intracellular cAMP levels in boar spermatozoa and are suppressed by PKA inhibitor H89. In summary, we demonstrate that PKA, PKC and PI3K pathways crosstalk in porcine male germ cells to crucially regulate GSK3A phosphorylation which subsequently controls cell motility. In addition, our results suggest that PI3K is upstream of PKA which lies upstream of PKC in this regulatory cascade(s). Our findings contribute to elucidate the molecular mechanisms underlying the regulation of one of the most relevant male germ cell functions, motility.
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Affiliation(s)
- Maria J Bragado
- Research Team of Intracellular Signaling and Technology of Reproduction (SINTREP), Department of Biochemistry and Molecular Biology and Genetics, University of Extremadura, Cáceres 10071, Spain
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158
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Tate S, Nakamura K, Suzuki C, Noda T, Lee J, Harayama H. Evidence of the existence of adenylyl cyclase 10 (ADCY10) ortholog proteins in the heads and connecting pieces of boar spermatozoa. J Reprod Dev 2010; 56:271-8. [PMID: 20103986 DOI: 10.1262/jrd.09-180n] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The aim of this study is to provide evidence of the existence of the adenylyl cyclase 10 (ADCY10) ortholog proteins in boar spermatozoa. Experiments with RT-PCR techniques, nucleotide sequence analyses and Northern blot analyses revealed that boar testes exclusively express approximately 5.1-kbp RNA, the nucleotide sequence of which is highly similar to that of human ADCY10. Database analyses with CDART suggested that pig ADCY10 ortholog proteins conserve two catalytic domains of adenylyl cyclase. Western blot techniques and indirect immunofluorescence with a specific antiserum to pig recombinant ADCY10 ortholog proteins showed that 48-kDa and 70-kDa truncated forms of pig ADCY10 ortholog proteins are localized in the equatorial segments and connecting pieces of boar ejaculated spermatozoa. Finally, cell imaging techniques with fluo-3/AM indicated that incubation with sodium bicarbonate (an ADCY10 activator) can initiate the calcium influx in the boar sperm heads that is controlled via the cyclic AMP signaling cascades. These results are consistent with the suggestion that functional ADCY10 ortholog proteins exist in the heads of boar spermatozoa. This is the first direct evidence of the existence of ADCY10 proteins in the heads of mammalian spermatozoa.
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Affiliation(s)
- Shunsuke Tate
- Graduate School of Science and Technology, Kobe University, Kobe, Japan
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159
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Baker MA, Smith ND, Hetherington L, Taubman K, Graham ME, Robinson PJ, Aitken RJ. Label-Free Quantitation of Phosphopeptide Changes During Rat Sperm Capacitation. J Proteome Res 2010; 9:718-29. [DOI: 10.1021/pr900513d] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Mark A. Baker
- The ARC Centre of Excellence in Biotechnology and Development, Priority Research Centre in Reproductive Science, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, 2308, Australia, and Cell Signaling Unit, Childrens’ Medical Research Institute, The University of Sydney, Westmead, NSW, 2145, Australia
| | - Nathan D. Smith
- The ARC Centre of Excellence in Biotechnology and Development, Priority Research Centre in Reproductive Science, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, 2308, Australia, and Cell Signaling Unit, Childrens’ Medical Research Institute, The University of Sydney, Westmead, NSW, 2145, Australia
| | - Louise Hetherington
- The ARC Centre of Excellence in Biotechnology and Development, Priority Research Centre in Reproductive Science, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, 2308, Australia, and Cell Signaling Unit, Childrens’ Medical Research Institute, The University of Sydney, Westmead, NSW, 2145, Australia
| | - Kristy Taubman
- The ARC Centre of Excellence in Biotechnology and Development, Priority Research Centre in Reproductive Science, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, 2308, Australia, and Cell Signaling Unit, Childrens’ Medical Research Institute, The University of Sydney, Westmead, NSW, 2145, Australia
| | - Mark E. Graham
- The ARC Centre of Excellence in Biotechnology and Development, Priority Research Centre in Reproductive Science, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, 2308, Australia, and Cell Signaling Unit, Childrens’ Medical Research Institute, The University of Sydney, Westmead, NSW, 2145, Australia
| | - Phillip J. Robinson
- The ARC Centre of Excellence in Biotechnology and Development, Priority Research Centre in Reproductive Science, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, 2308, Australia, and Cell Signaling Unit, Childrens’ Medical Research Institute, The University of Sydney, Westmead, NSW, 2145, Australia
| | - R. John Aitken
- The ARC Centre of Excellence in Biotechnology and Development, Priority Research Centre in Reproductive Science, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW, 2308, Australia, and Cell Signaling Unit, Childrens’ Medical Research Institute, The University of Sydney, Westmead, NSW, 2145, Australia
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160
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Bicarbonate-sensing soluble adenylyl cyclase is an essential sensor for acid/base homeostasis. Proc Natl Acad Sci U S A 2009; 107:442-7. [PMID: 20018667 DOI: 10.1073/pnas.0911790107] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
pH homeostasis is essential for life, yet it remains unclear how animals sense their systemic acid/base (A/B) status. Soluble adenylyl cyclase (sAC) is an evolutionary conserved signaling enzyme that produces the second messenger cAMP in response to bicarbonate ions (HCO(3)(-)). We cloned the sAC ortholog from the dogfish, a shark that regulates blood A/B by absorbing and secreting protons (H(+)) and HCO(3)(-) at its gills. Similar to mammalian sAC, dogfish soluble adenylyl cyclase (dfsAC) is activated by HCO(3)(-) and can be inhibited by two structurally and mechanistically distinct small molecule inhibitors. dfsAC is expressed in the gill epithelium, where the subset of base-secreting cells resides. Injection of inhibitors into animals under alkaline stress confirmed that dfsAC is essential for maintaining systemic pH and HCO(3)(-) levels in the whole organism. One of the downstream effects of dfsAC is to promote the insertion of vacuolar proton pumps into the basolateral membrane to absorb H(+) into the blood. sAC orthologs are present throughout metazoans, and mammalian sAC is expressed in A/B regulatory organs, suggesting that systemic A/B sensing via sAC is widespread in the animal kingdom.
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161
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Baker MA, Reeves G, Hetherington L, Aitken RJ. Analysis of proteomic changes associated with sperm capacitation through the combined use of IPG-strip pre-fractionation followed by RP chromatography LC-MS/MS analysis. Proteomics 2009; 10:482-95. [DOI: 10.1002/pmic.200900574] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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162
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Carlson AE, Burnett LA, del Camino D, Quill TA, Hille B, Chong JA, Moran MM, Babcock DF. Pharmacological targeting of native CatSper channels reveals a required role in maintenance of sperm hyperactivation. PLoS One 2009; 4:e6844. [PMID: 19718436 PMCID: PMC2729922 DOI: 10.1371/journal.pone.0006844] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Accepted: 08/07/2009] [Indexed: 12/18/2022] Open
Abstract
The four sperm-specific CatSper ion channel proteins are required for hyperactivated motility and male fertility, and for Ca(2+) entry evoked by alkaline depolarization. In the absence of external Ca(2+), Na(+) carries current through CatSper channels in voltage-clamped sperm. Here we show that CatSper channel activity can be monitored optically with the [Na(+)](i)-reporting probe SBFI in populations of intact sperm. Removal of external Ca(2+) increases SBFI signals in wild-type but not CatSper2-null sperm. The rate of the indicated rise of [Na(+)](i) is greater for sperm alkalinized with NH(4)Cl than for sperm acidified with propionic acid, reflecting the alkaline-promoted signature property of CatSper currents. In contrast, the [Na(+)](i) rise is slowed by candidate CatSper blocker HC-056456 (IC(50) approximately 3 microM). HC-056456 similarly slows the rise of [Ca(2+)](i) that is evoked by alkaline depolarization and reported by fura-2. HC-056456 also selectively and reversibly decreased CatSper currents recorded from patch-clamped sperm. HC-056456 does not prevent activation of motility by HCO(3) (-) but does prevent the development of hyperactivated motility by capacitating incubations, thus producing a phenocopy of the CatSper-null sperm. When applied to hyperactivated sperm, HC-056456 causes a rapid, reversible loss of flagellar waveform asymmetry, similar to the loss that occurs when Ca(2+) entry through the CatSper channel is terminated by removal of external Ca(2+). Thus, open CatSper channels and entry of external Ca(2+) through them sustains hyperactivated motility. These results indicate that pharmacological targeting of the CatSper channel may impose a selective late-stage block to fertility, and that high-throughput screening with an optical reporter of CatSper channel activity may identify additional selective blockers with potential for male-directed contraception.
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Affiliation(s)
- Anne E. Carlson
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
| | - Lindsey A. Burnett
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
| | - Donato del Camino
- Hydra Biosciences Inc., Cambridge, Massachusetts, United States of America
| | - Timothy A. Quill
- Cecil H. and Ida Green Center for Reproductive Biology Sciences, Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Bertil Hille
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
| | - Jayhong A. Chong
- Hydra Biosciences Inc., Cambridge, Massachusetts, United States of America
| | - Magdalene M. Moran
- Hydra Biosciences Inc., Cambridge, Massachusetts, United States of America
| | - Donner F. Babcock
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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163
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Branham MT, Bustos MA, De Blas GA, Rehmann H, Zarelli VEP, Treviño CL, Darszon A, Mayorga LS, Tomes CN. Epac activates the small G proteins Rap1 and Rab3A to achieve exocytosis. J Biol Chem 2009; 284:24825-39. [PMID: 19546222 DOI: 10.1074/jbc.m109.015362] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Exocytosis of the acrosome (the acrosome reaction) relies on cAMP production, assembly of a proteinaceous fusion machinery, calcium influx from the extracellular medium, and mobilization from inositol 1,4,5-trisphosphate-sensitive intracellular stores. Addition of cAMP to human sperm suspensions bypasses some of these requirements and elicits exocytosis in a protein kinase A- and extracellular calcium-independent manner. The relevant cAMP target is Epac, a guanine nucleotide exchange factor for the small GTPase Rap. We show here that a soluble adenylyl cyclase synthesizes the cAMP required for the acrosome reaction. Epac stimulates the exchange of GDP for GTP on Rap1, upstream of a phospholipase C. The Epac-selective cAMP analogue 8-pCPT-2'-O-Me-cAMP induces a phospholipase C-dependent calcium mobilization in human sperm suspensions. In addition, our studies identify a novel connection between cAMP and Rab3A, a secretory granule-associated protein, revealing that the latter functions downstream of soluble adenylyl cyclase/cAMP/Epac but not of Rap1. Challenging sperm with calcium or 8-pCPT-2'-O-Me-cAMP boosts the exchange of GDP for GTP on Rab3A. Recombinant Epac does not release GDP from Rab3A in vitro, suggesting that the Rab3A-GEF activation by cAMP/Epac in vivo is indirect. We propose that Epac sits at a critical point during the exocytotic cascade after which the pathway splits into two limbs, one that assembles the fusion machinery into place and another that elicits intracellular calcium release.
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Affiliation(s)
- María T Branham
- Laboratorio de Biología Celular y Molecular, Instituto de Histología y Embriología-Consejo Nacional de Investigaciones Científicas y Técnicas, Facultad de Ciencias Médicas, CC 56, Universidad Nacional de Cuyo, 5500 Mendoza, Argentina
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164
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165
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Pierre S, Eschenhagen T, Geisslinger G, Scholich K. Capturing adenylyl cyclases as potential drug targets. Nat Rev Drug Discov 2009; 8:321-35. [PMID: 19337273 DOI: 10.1038/nrd2827] [Citation(s) in RCA: 181] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Cyclic AMP (cAMP) is an important intracellular signalling mediator. It is generated in mammals by nine membrane-bound and one soluble adenylyl cyclases (ACs), each with distinct regulation and expression patterns. Although many drugs inhibit or stimulate AC activity through the respective upstream G-protein coupled receptors (for example, opioid or beta-adrenergic receptors), ACs themselves have not been major drug targets. Over the past decade studies on the physiological functions of the different mammalian AC isoforms as well as advances in the development of isoform-selective AC inhibitors and activators suggest that ACs could be useful drug targets. Here we discuss the therapeutic potential of isoform-selective compounds in various clinical settings, including neuropathic pain, neurodegenerative disorders, congestive heart failure, asthma and male contraception.
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Affiliation(s)
- Sandra Pierre
- Pharmazentrum Frankfurt, ZAFES, Institut für Klinische Pharmakologie, Klinikum der Goethe-Universität Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany
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166
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Muratori M, Luconi M, Marchiani S, Forti G, Baldi E. Molecular markers of human sperm functions. ACTA ACUST UNITED AC 2009; 32:25-45. [DOI: 10.1111/j.1365-2605.2008.00875.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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167
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Functional expression of the olfactory signaling system in the kidney. Proc Natl Acad Sci U S A 2009; 106:2059-64. [PMID: 19174512 DOI: 10.1073/pnas.0812859106] [Citation(s) in RCA: 177] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Olfactory-like chemosensory signaling occurs outside of the olfactory epithelium. We find that major components of olfaction, including olfactory receptors (ORs), olfactory-related adenylate cyclase (AC3) and the olfactory G protein (G(olf)), are expressed in the kidney. AC3 and G(olf) colocalize in renal tubules and in macula densa (MD) cells which modulate glomerular filtration rate (GFR). GFR is significantly reduced in AC3(-/-) mice, suggesting that AC3 participates in GFR regulation. Although tubuloglomerular feedback is normal in these animals, they exhibit significantly reduced plasma renin levels despite up-regulation of COX-2 expression and nNOS activity in the MD. Furthermore, at least one member of the renal repertoire of ORs is expressed in a MD cell line. Thus, key components of olfaction are expressed in the renal distal nephron and may play a sensory role in the MD to modulate both renin secretion and GFR.
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168
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Tissue-specific PKA inhibition using a chemical genetic approach and its application to studies on sperm capacitation. Proc Natl Acad Sci U S A 2008; 105:20740-5. [PMID: 19074277 DOI: 10.1073/pnas.0810971105] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Studies on cAMP signaling and protein kinase A (PKA) function in vivo are limited by the lack of highly specific inhibitors that can be used in primary cell culture and whole animals. Previously we reported that a mutation in the ATP binding pocket of a catalytic subunit (Calpha) of PKA confers sensitivity to the pyrazolo[3,4-d]pyrimidine inhibitor, 1NM-PP1. We have now engineered the mouse Pkraca gene such that after Cre-mediated recombination in vivo, the CalphaM120A mutant protein is expressed and the wild-type Calpha is turned off. We demonstrate the utility of this approach by examining the requirement for PKA activity during capacitation of sperm from mice that express CalphaM120A mutant protein. For CalphaM120A sperm, 10 microM of 1NM-PP1 prevented PKA-dependent phosphorylation and the activation of motility that are both rapidly (<90 s) evoked by the HCO(3)(-) anion. A continuous (90 min) inhibition with 10 microM of 1NM-PP1 prevented the protein tyrosine phosphorylation of late-stage capacitation. Delayed application of 1NM-PP1 demonstrated that PKA activity was required for at least the initial 30 min of capacitation to produce subsequent protein tyrosine phosphorylation. Acute application of 1NM-PP1 rapidly slowed the accelerated beat of activated motility but did not affect the established waveform asymmetry of hyperactivated sperm. Our results demonstrate that PKA in CalphaM120A mutant sperm is rapidly and reversibly inhibited by 1NM-PP1 and that this blockade has selective and time-dependent effects on multiple aspects of capacitation. The conditional CalphaM120A-expressing mouse lines will be valuable tools for studying PKA function in vivo.
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169
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Townsend PD, Holliday PM, Fenyk S, Hess KC, Gray MA, Hodgson DRW, Cann MJ. Stimulation of mammalian G-protein-responsive adenylyl cyclases by carbon dioxide. J Biol Chem 2008; 284:784-91. [PMID: 19008230 PMCID: PMC2613629 DOI: 10.1074/jbc.m807239200] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Carbon dioxide is fundamental to the physiology of all organisms. There is
considerable interest in the precise molecular mechanisms that organisms use
to directly sense CO2. Here we demonstrate that a mammalian
recombinant G-protein-activated adenylyl cyclase and the related Rv1625c
adenylyl cyclase of Mycobacterium tuberculosis are specifically
stimulated by CO2. Stimulation occurred at physiological
concentrations of CO2 through increased kcat.
CO2 increased the affinity of enzyme for metal co-factor, but
contact with metal was not necessary as CO2 interacted directly
with apoenzyme. CO2 stimulated the activity of both
G-protein-regulated adenylyl cyclases and Rv1625c in vivo. Activation
of G-protein regulated adenylyl cyclases by CO2 gave a
corresponding increase in cAMP-response element-binding protein (CREB)
phosphorylation. Comparison of the responses of the G-protein regulated
adenylyl cyclases and the molecularly, and biochemically distinct mammalian
soluble adenylyl cyclase revealed that whereas G-protein-regulated enzymes are
responsive to CO2, the soluble adenylyl cyclase is responsive to
both CO2 and bicarbonate ion. We have, thus, identified a signaling
enzyme by which eukaryotes can directly detect and respond to fluctuating
CO2.
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Affiliation(s)
- Philip D Townsend
- School of Biological and Biomedical Sciences, Durham University, Durham, UK
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170
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Sadana R, Dessauer CW. Physiological roles for G protein-regulated adenylyl cyclase isoforms: insights from knockout and overexpression studies. Neurosignals 2008; 17:5-22. [PMID: 18948702 DOI: 10.1159/000166277] [Citation(s) in RCA: 275] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Accepted: 04/22/2008] [Indexed: 01/08/2023] Open
Abstract
Cyclic AMP is a universal second messenger, produced by a family of adenylyl cyclase (AC) enzymes. The last three decades have brought a wealth of new information about the regulation of cyclic AMP production by ACs. Nine hormone-sensitive, membrane-bound AC isoforms have been identified in addition to a tenth isoform that lacks membrane spans and more closely resembles the cyanobacterial AC enzymes. New model systems for purifying and characterizing the catalytic domains of AC have led to the crystal structure of these domains and the mapping of numerous interaction sites. However, big hurdles remain in unraveling the roles of individual AC isoforms and their regulation in physiological systems. In this review we explore the latest on AC knockout and overexpression studies to better understand the roles of G protein regulation of ACs in the brain, olfactory bulb, and heart.
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Affiliation(s)
- Rachna Sadana
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center at Houston, Houston, TX 77030, USA
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171
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O'Rand MG, Widgren EE, Beyler S, Richardson RT. Inhibition of human sperm motility by contraceptive anti-eppin antibodies from infertile male monkeys: effect on cyclic adenosine monophosphate. Biol Reprod 2008; 80:279-85. [PMID: 18945989 DOI: 10.1095/biolreprod.108.072942] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Epididymal protease inhibitor (eppin [official symbol, SPINLW1]) is of interest as a male contraceptive target because of its specificity and location on the human sperm surface. We have examined the effect of anti-eppin antibodies from infertile male monkeys and the effect of recombinant human semenogelin on human sperm motility. Anti-eppin antibodies significantly decreased the progressive motility of human spermatozoa as measured by decreased total distance traveled, decreased straight-line distance, and decreased velocity. Anti-eppin treatment of spermatozoa significantly increased the amount of cAMP present in nonprogressive spermatozoa; however, approximately 25% of antibody-treated spermatozoa could be rescued by the addition of cAMP-acetoxymethyl ester, indicating that anti-eppin-treated spermatozoa have a compromised ability to utilize cAMP. Addition of recombinant human semenogelin has a concentration-dependent inhibitory effect on progressive motility (increased tortuosity and decreased velocity). We tested the hypothesis that anti-eppin antibodies bound to eppin would subsequently block semenogelin binding to eppin. Anti-eppin antibodies from infertile monkeys inhibited eppin from binding to semenogelin. Addition of affinity-purified antibodies made to the dominant C-terminal epitope of eppin had an inhibitory effect on progressive motility (increased tortuosity, decreased velocity, and straight distance). Our results suggest that the eppin-semenogelin binding site is critical for the removal of semenogelin in vivo during semen liquefaction and for the initiation of progressive motility. We conclude that the eppin-semenogelin binding site on the surface of human spermatozoa is an ideal target for a nonsteroidal male contraceptive.
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Affiliation(s)
- Michael G O'Rand
- Department of Cell and Developmental Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
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172
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Farrell J, Ramos L, Tresguerres M, Kamenetsky M, Levin LR, Buck J. Somatic 'soluble' adenylyl cyclase isoforms are unaffected in Sacy tm1Lex/Sacy tm1Lex 'knockout' mice. PLoS One 2008; 3:e3251. [PMID: 18806876 PMCID: PMC2532759 DOI: 10.1371/journal.pone.0003251] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2008] [Accepted: 09/02/2008] [Indexed: 11/17/2022] Open
Abstract
Background Mammalian Soluble adenylyl cyclase (sAC, Adcy10, or Sacy) represents a source of the second messenger cAMP distinct from the widely studied, G protein-regulated transmembrane adenylyl cyclases. Genetic deletion of the second through fourth coding exons in Sacytm1Lex/Sacytm1Lex knockout mice results in a male sterile phenotype. The absence of any major somatic phenotype is inconsistent with the variety of somatic functions identified for sAC using pharmacological inhibitors and RNA interference. Principal Findings We now use immunological and molecular biological methods to demonstrate that somatic tissues express a previously unknown isoform of sAC, which utilizes a unique start site, and which ‘escapes’ the design of the Sacytm1Lex knockout allele. Conclusions/Significance These studies reveal increased complexity at the sAC locus, and they suggest that the known isoforms of sAC play a unique function in male germ cells.
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Affiliation(s)
- Jeanne Farrell
- Department of Pharmacology, Weill Medical College of Cornell University, New York, New York, USA
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173
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Harayama H, Nakamura K. Changes of PKA and PDK1 in the principal piece of boar spermatozoa treated with a cell-permeable cAMP analog to induce flagellar hyperactivation. Mol Reprod Dev 2008; 75:1396-407. [PMID: 18213679 DOI: 10.1002/mrd.20882] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A cAMP-induced protein tyrosine phosphorylation and flagellar hyperactivation are controlled via complicated signaling cascades in mammalian spermatozoa. For instance, these events seem to be regulated positively by the PKA-mediated signaling and negatively by the PI3K/PDK1-mediated signaling. In this article, we have shown molecular changes of PKA and PDK1 in cAMP analog (cBiMPS)-treated boar spermatozoa in order to disclose possible roles of these kinases in protein tyrosine phosphorylation and hyperactivation. Ejaculated spermatozoa were incubated with cBiMPS, and then they were used for biochemical analyses of sperm kinases by Western blotting and indirect immunofluorescence and for assessment of flagellar movement. The first 30-min incubation with cBiMPS highly activated PKA of the principal piece to the accompaniment of autophosphorylation on Thr-197 of catalytic subunits. However, protein tyrosine phosphorylation and hyperactivation were fully induced in the sperm samples after the 180-min incubation. A potentially active form of PDK1 (54/55-kDa phospho-PDK1) was detected in the principal piece of the spermatozoa during the 90-min incubation. Another potentially active form (59-kDa phospho-PDK1) gradually increased during the same incubation period. However, the PDK1 suddenly became inactive by the dephosphorylation after the 180-min incubation, namely coincidently with full induction of protein tyrosine phosphorylation and hyperactivation. Additionally, existence of PI3K-dependently suppressing mechanisms for protein tyrosine phosphorylation was confirmed in the principal piece by pharmacological experiments with LY294002 and biochemical analyses with anti-PI3K p85 antibodies. These findings suggest that dephosphorylation of PDK1 may be a molecular switch for enhancement of protein tyrosine phosphorylation and flagellar hyperactivation in boar spermatozoa.
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Affiliation(s)
- Hiroshi Harayama
- Department of Bioresource Science, Graduate School of Agricultural Science, Kobe University, Kobe, Japan. :
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174
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Hunnicutt GR, Koppel DE, Kwitny S, Cowan AE. Cyclic 3',5'-AMP causes ADAM1/ADAM2 to rapidly diffuse within the plasma membrane of guinea pig sperm. Biol Reprod 2008; 79:999-1007. [PMID: 18667756 DOI: 10.1095/biolreprod.107.067058] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Because sperm cannot synthesize new proteins as they journey to the egg, they use multiple mechanisms to modify the activity of existing proteins, including changes in the diffusion coefficient of some membrane proteins. Previously, we showed that during capacitation the guinea pig heterodimeric membrane protein ADAM1/ADAM2 (fertilin) transforms from a stationary state to one of rapid diffusion within the lipid bilayer. The cause for this biophysical change, however, was unknown. In this study we examined whether an increase in cAMP, such as occurs during capacitation, could trigger this change. We incubated guinea pig cauda sperm with the membrane-permeable cAMP analog dibutyryl cAMP (db-cAMP) and the phosphodiesterase inhibitor papaverine and first tested for indications of capacitation. We observed hypermotility and acrosome-reaction competence. We then used fluorescence redistribution after photobleaching (FRAP) to measure the lateral mobility of ADAM1/ADAM2 after the db-cAMP treatment. We observed that db-cAMP caused roughly a 12-fold increase in lateral mobility of ADAM1/ADAM2, yielding diffusion similar to that observed for sperm capacitated in vitro. When we repeated the FRAP on testicular sperm incubated in db-cAMP, we found only a modest increase in lateral mobility of ADAM1/ADAM2, which underwent little redistribution. Interestingly, testicular sperm also cannot be induced to undergo capacitation. Together, the data suggest that the release of ADAM1/ADAM2 from its diffusion constraints results from a cAMP-induced signaling pathway that, like others of capacitation, is established during epididymal sperm maturation.
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Affiliation(s)
- Gary R Hunnicutt
- population council, center for biomedical research, rockefeller university, new york, ny 10065, USA.
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175
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Abstract
BACKGROUND Sperm hyperactivation is critical to fertilization, because it is required for penetration of the zona pellucida. Hyperactivation may also facilitate release of sperm from the oviductal storage reservoir and may propel sperm through mucus in the oviductal lumen and the matrix of the cumulus oophorus. Hyperactivation is characterized by high amplitude, asymmetrical flagellar bending. METHODS This is a review of the original literature on the mechanisms that regulate hyperactivation, including physiological factors and signaling pathways. RESULTS Computer-assisted semen analysis systems can be used to identify hyperactivated sperm by setting minimum thresholds for curvilinear velocity (VSL) and lateral head movement and a maximum threshold for path linearity. Hyperactivation is triggered by a rise in flagellar Ca(2+) resulting from influx primarily through plasma membrane CatSper channels and possibly also by release of Ca(2+) from a store in the redundant nuclear envelope. It requires increased pH and ATP production. The physiological signals that trigger the rise in Ca(2+) remain elusive, but there is evidence that the increased Ca(2+) acts through a calmodulin/calmodulin kinase pathway. Hyperactivation is considered part of the capacitation process; however, the regulatory pathway that triggers hyperactivation can operate independently from that which prepares sperm to undergo the acrosome reaction. Hyperactivation may be modulated by chemotactic signals to turn sperm toward the oocyte. CONCLUSIONS Little is known about exactly what triggers hyperactivation in human sperm. This information could enable clinicians to develop reliable fertility assays to assess normal hyperactivation in human sperm samples.
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Affiliation(s)
- Susan S Suarez
- Department of Biomedical Sciences, T5-002B Veterinary Research Tower, Cornell University Ithaca, NY 14853, USA.
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176
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A polycystin-1 controls postcopulatory reproductive selection in mice. Proc Natl Acad Sci U S A 2008; 105:8661-6. [PMID: 18562295 DOI: 10.1073/pnas.0800603105] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Pkdrej, a member of the polycystin-1 gene family, is expressed only in the male germ line. Male mice that are homozygous for a targeted mutation in the Pkdrej allele (Pkdrej(tm/tm)) are fertile in unrestricted mating trials, but exhibit lower reproductive success when competing with wild-type males in sequential mating trials and in artificial insemination of mixed-sperm populations. Following mating, sperm from Pkdrej(tm/tm) mice require >2 h longer than those of wild-type males to be detected within the egg/cumulus complex in the oviduct. Sperm from mice of both genotypes are able to capacitate in vitro. However, one of the component processes of capacitation, the ability to undergo a zona pellucida-evoked acrosome reaction, develops more slowly in sperm from Pkdrej(tm/tm) animals than in sperm from wild-type males. In contrast, a second component process of capacitation, the transition to hyperactivated flagellar motility, develops with a similar time course in both genotypes. These two behavioral consequences of capacitation, exocytotic competence and altered motility, are therefore differentially regulated. These data suggest that Pkdrej controls the timing of fertilization in vivo through effects on sperm transport and exocytotic competence and is a factor in postcopulatory sexual selection.
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177
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Abstract
Despite significant advances in contraceptive options for women over the last 50 yr, world population continues to grow rapidly. Scientists and activists alike point to the devastating environmental impacts that population pressures have caused, including global warming from the developed world and hunger and disease in less developed areas. Moreover, almost half of all pregnancies are still unwanted or unplanned. Clearly, there is a need for expanded, reversible, contraceptive options. Multicultural surveys demonstrate the willingness of men to participate in contraception and their female partners to trust them to do so. Notwithstanding their paucity of options, male methods including vasectomy and condoms account for almost one third of contraceptive use in the United States and other countries. Recent international clinical research efforts have demonstrated high efficacy rates (90-95%) for hormonally based male contraceptives. Current barriers to expanded use include limited delivery methods and perceived regulatory obstacles, which stymie introduction to the marketplace. However, advances in oral and injectable androgen delivery are cause for optimism that these hurdles may be overcome. Nonhormonal methods, such as compounds that target sperm motility, are attractive in their theoretical promise of specificity for the reproductive tract. Gene and protein array technologies continue to identify potential targets for this approach. Such nonhormonal agents will likely reach clinical trials in the near future. Great strides have been made in understanding male reproductive physiology; the combined efforts of scientists, clinicians, industry and governmental funding agencies could make an effective, reversible, male contraceptive an option for family planning over the next decade.
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Affiliation(s)
- Stephanie T Page
- Center for Research in Reproduction and Contraception, Department of Medicine, University of Washington School of Medicine, Seattle, Washington 98195, USA.
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178
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Marquez B, Suarez SS. Soluble adenylyl cyclase is required for activation of sperm but does not have a direct effect on hyperactivation. Reprod Fertil Dev 2008; 20:247-52. [PMID: 18255013 DOI: 10.1071/rd07146] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2007] [Accepted: 10/12/2007] [Indexed: 01/24/2023] Open
Abstract
Soluble adenylyl cyclase (SACY) is an essential component of cAMP-signalling cascades that activate sperm motility and capacitate sperm. SACY activity is stimulated by HCO(3)(-) and Ca(2+). Sperm from Sacy(-/-) (null) mice were immotile or weakly motile, but cAMP analogues N(6),2'-O-dibutyryladenosine 3',5'-cyclic monophosphate (dbcAMP) and adenosine 3',5'-cyclic monophosphate acetoxymethyl ester (cAMP-AM) activated motility. Null sperm activated by dbcAMP quickly developed hairpin bends at the junction of the midpiece and principal piece, which could be prevented by omitting HCO(3)(-). Treating Sacy(-/-) sperm with thimerosal or NH(4)Cl to raise flagellar cytoplasmic Ca(2+) could not substitute for cAMP analogues in activating motility; however, sperm activated with cAMP-AM hyperactivated after thimerosal treatment. Treating activated wild-type sperm with SACY inhibitor KH7 did not prevent hyperactivation from developing during capacitation in vitro, although high doses impaired motility. These results indicate that, while the SACY/cAMP signalling pathway is required for motility activation, it is not directly involved in triggering hyperactivation.
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Affiliation(s)
- Becky Marquez
- Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
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179
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Da Ros VG, Maldera JA, Willis WD, Cohen DJ, Goulding EH, Gelman DM, Rubinstein M, Eddy EM, Cuasnicu PS. Impaired sperm fertilizing ability in mice lacking Cysteine-RIch Secretory Protein 1 (CRISP1). Dev Biol 2008; 320:12-8. [PMID: 18571638 DOI: 10.1016/j.ydbio.2008.03.015] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2007] [Revised: 03/12/2008] [Accepted: 03/13/2008] [Indexed: 11/18/2022]
Abstract
Mammalian fertilization is a complex multi-step process mediated by different molecules present on both gametes. Epididymal protein CRISP1, a member of the Cysteine-RIch Secretory Protein (CRISP) family, was identified by our laboratory and postulated to participate in both sperm-zona pellucida (ZP) interaction and gamete fusion by binding to egg-complementary sites. To elucidate the functional role of CRISP1 in vivo, we disrupted the Crisp1 gene and evaluated the effect on animal fertility and several sperm parameters. Male and female Crisp1(-/-) animals exhibited no differences in fertility compared to controls. Sperm motility and the ability to undergo a spontaneous or progesterone-induced acrosome reaction were neither affected in Crisp1(-/-) mice. However, the level of protein tyrosine phosphorylation during capacitation was clearly lower in mutant sperm than in controls. In vitro fertilization assays showed that Crisp1(-/-) sperm also exhibited a significantly reduced ability to penetrate both ZP-intact and ZP-free eggs. Moreover, when ZP-free eggs were simultaneously inseminated with Crisp1(+/+) and Crisp1(-/-) sperm in a competition assay, the mutant sperm exhibited a greater disadvantage in their fusion ability. Finally, the finding that the fusion ability of Crisp1(-/-) sperm was further inhibited by the presence of CRISP1 or CRISP2 during gamete co-incubation, supports that another CRISP cooperates with CRISP1 during fertilization and might compensate for its lack in the mutant mice. Together, these results indicate that CRISP proteins are players in the mammalian fertilization process. To our knowledge this is the first knockout mice generated for a CRISP protein. The information obtained might have important functional implications for other members of the widely distributed and evolutionarily conserved CRISP family.
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Affiliation(s)
- Vanina G Da Ros
- Instituto de Biología y Medicina Experimental (CONICET), Vuelta de Obligado 2490, Buenos Aires, 1428, Argentina
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180
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Mruk DD. New perspectives in non-hormonal male contraception. Trends Endocrinol Metab 2008; 19:57-64. [PMID: 18291665 DOI: 10.1016/j.tem.2007.11.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2007] [Revised: 11/03/2007] [Accepted: 11/05/2007] [Indexed: 02/06/2023]
Abstract
As the world's population continues to soar, contraception has become increasingly important. Recently, men have expressed willingness to share the burden of family planning. Thus, safe, effective and reversible male contraceptives would satisfy an urgent need among couples. Currently, there are several promising non-hormonal contraceptives at various stages of research and development. In addition, major advances in genomic and proteomic research have been instrumental in identifying and characterizing genes and proteins expressed uniquely in the testis or other male reproductive organs, which might become 'druggable' targets for non-hormonal male contraceptive development in the future. Through committed research, advocacy and support, male contraceptives are likely to become a valuable addition to the current choices of family planning.
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Affiliation(s)
- Dolores D Mruk
- Population Council, Center for Biomedical Research, 1230 York Avenue, New York, NY 10065, USA.
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181
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Affiliation(s)
- U. Benjamin Kaupp
- Forschungszentrum Jülich, Institut für Neurowissenschaften und Biophysik 1, D-52425 Jülich, Germany;
| | - Nachiket D. Kashikar
- Forschungszentrum Jülich, Institut für Neurowissenschaften und Biophysik 1, D-52425 Jülich, Germany;
| | - Ingo Weyand
- Forschungszentrum Jülich, Institut für Neurowissenschaften und Biophysik 1, D-52425 Jülich, Germany;
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182
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Mitchell LA, Nixon B, Baker MA, Aitken RJ. Investigation of the role of SRC in capacitation-associated tyrosine phosphorylation of human spermatozoa. ACTA ACUST UNITED AC 2008; 14:235-43. [DOI: 10.1093/molehr/gan007] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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183
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Carlson AE, Hille B, Babcock DF. External Ca2+ acts upstream of adenylyl cyclase SACY in the bicarbonate signaled activation of sperm motility. Dev Biol 2007; 312:183-92. [PMID: 17950270 PMCID: PMC2259292 DOI: 10.1016/j.ydbio.2007.09.017] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2007] [Revised: 09/06/2007] [Accepted: 09/10/2007] [Indexed: 12/18/2022]
Abstract
The HCO3(-) anion activates sperm motility, an important early step in capacitation, by increasing flagellar beat frequency through a pathway that requires the atypical adenylyl cyclase SACY and the sperm-specific C alpha2 catalytic subunit of PKA. Here we show that the accelerating action of HCO3(-) also requires the continued presence of external Ca2+ (EC50 approximately 0.5 mM), and find that Ca2+ can be replaced by Sr2+ but not by Mn2+. Ca2+ is required for HCO3(-) to elevate cAMP, but not for cAMP-AM to increase beat frequency, indicating that external Ca2+ acts before rather than after stimulation of SACY by HCO3(-). With external Ca2+ present, HCO3(-) does not alter cytosolic or near-membrane [Ca2+]. Removal of external Ca2+ initiates a slow decline in intracellular [Ca2+] and rapid block of the HCO3(-)-evoked acceleration that is not relieved upon increasing internal [Ca2+] by rapid photolysis of caged Ca2+. We also find that the rapid (t(1/2) approximately 10 s) accelerating action of HCO3(-) is slowed more than three-fold by the carbonic anhydrase inhibitor acetazolamide. It is unaltered by the broad spectrum anion transport inhibitor SITS, and is not accompanied by detectable changes in intracellular pH. We propose that external Ca2+ binds an unidentified extracellular protein that is required for HCO3(-) to engage cAMP-mediated activation of motility.
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Affiliation(s)
- Anne E. Carlson
- Department of Physiology and Biophysics, Box 357290, University of Washington, Seattle, WA 98195 USA
| | - Bertil Hille
- Department of Physiology and Biophysics, Box 357290, University of Washington, Seattle, WA 98195 USA
| | - Donner F. Babcock
- Department of Physiology and Biophysics, Box 357290, University of Washington, Seattle, WA 98195 USA
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184
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Beltrán C, Vacquier VD, Moy G, Chen Y, Buck J, Levin LR, Darszon A. Particulate and soluble adenylyl cyclases participate in the sperm acrosome reaction. Biochem Biophys Res Commun 2007; 358:1128-35. [PMID: 17524362 PMCID: PMC3644950 DOI: 10.1016/j.bbrc.2007.05.061] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2007] [Accepted: 05/10/2007] [Indexed: 12/01/2022]
Abstract
cAMP is important in sea urchin sperm signaling, yet the molecular nature of the adenylyl cyclases (ACs) involved remained unknown. These cells were recently shown to contain an ortholog of the mammalian soluble adenylyl cyclase (sAC). Here, we show that sAC is present in the sperm head and as in mammals is stimulated by bicarbonate. The acrosome reaction (AR), a process essential for fertilization, is influenced by the bicarbonate concentration in seawater. By using functional assays and immunofluorescence techniques we document that sea urchin sperm also express orthologs of multiple isoforms of transmembrane ACs (tmACs). Our findings employing selective inhibitors for each class of AC indicate that both sAC and tmACs participate in the sperm acrosome reaction.
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Affiliation(s)
- Carmen Beltrán
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos CP 62250, Mexico.
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185
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Florman HM, Jungnickel MK, Sutton KA. What can we learn about fertilization from cystic fibrosis? Proc Natl Acad Sci U S A 2007; 104:11123-4. [PMID: 17595298 PMCID: PMC2040861 DOI: 10.1073/pnas.0703626104] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Harvey M Florman
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
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186
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Wang D, Hu J, Bobulescu IA, Quill TA, McLeroy P, Moe OW, Garbers DL. A sperm-specific Na+/H+ exchanger (sNHE) is critical for expression and in vivo bicarbonate regulation of the soluble adenylyl cyclase (sAC). Proc Natl Acad Sci U S A 2007; 104:9325-30. [PMID: 17517652 PMCID: PMC1890493 DOI: 10.1073/pnas.0611296104] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2006] [Indexed: 02/04/2023] Open
Abstract
We previously identified a sperm-specific Na(+)/H(+) exchanger (sNHE) principally localized to the flagellum. Disruption of the sNHE gene in mice resulted in absolute male infertility associated with a complete loss of sperm motility. Here, we show that the sNHE-null spermatozoa fail to develop the cAMP-dependent protein tyrosine phosphorylation that coincides with the functional maturation occurring upon incubation in capacitating conditions in vitro. Both the sperm motility defect and the lack of induced protein tyrosine phosphorylation are rescued by the addition of cell-permeable cAMP analogs, suggesting that cAMP metabolism is impaired in spermatozoa lacking sNHE. Our analyses of the bicarbonate-dependent soluble adenylyl cyclase (sAC) signaling pathway in sNHE-null sperm cells reveal that sNHE is required for the expression of full-length sAC, and that it is important for the bicarbonate stimulation of sAC activity in spermatozoa. Furthermore, both codependent expression and coimmunoprecipitation experiments indicate that sNHE and sAC associate with each other. Thus, these two proteins appear to be components of a signaling complex at the sperm flagellar plasma membrane. We propose that the formation of this complex efficiently modulates intracellular pH and bicarbonate levels through the rapid and effective control of sAC and sNHE activities to facilitate sperm motility regulation.
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Affiliation(s)
- Dan Wang
- Cecil H. and Ida Green Center for Reproductive Biology Sciences, Department of Pharmacology, University of Texas Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390-9051, USA.
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187
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Affiliation(s)
- Donner F Babcock
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195-7290, USA.
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188
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Oberholzer M, Bregy P, Marti G, Minca M, Peier M, Seebeck T. Trypanosomes and mammalian sperm: one of a kind? Trends Parasitol 2006; 23:71-7. [PMID: 17174157 DOI: 10.1016/j.pt.2006.12.002] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2006] [Revised: 11/02/2006] [Accepted: 12/06/2006] [Indexed: 01/20/2023]
Abstract
Flagellar-mediated motility is an indispensable function for cell types as evolutionarily distant as mammalian sperm and kinetoplastid parasites, a large group of flagellated protozoa that includes several important human pathogens. Despite the obvious importance of flagellar motility, little is known about the signalling processes that direct the frequency and wave shape of the flagellar beat, or those that provide the motile cell with the necessary environmental cues that enable it to aim its movement. Similarly, the energetics of the flagellar beat and the problem of a sufficient ATP supply along the entire length of the beating flagellum remain to be explored. Recent proteome projects studying the flagella of mammalian sperm and kinetoplastid parasites have provided important information and have indicated a surprising degree of similarities between the flagella of these two cell types.
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Affiliation(s)
- Michael Oberholzer
- Institute of Cell Biology, University of Bern, CH-3012 Bern, Switzerland
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