Stephen J Publicover

University of Birmingham · School of Biosciences

Human spermatozoa interact with a complex biochemical environment in the female reproductive tract en route to the site of fertilisation. Ovarian follicular fluid contributes to this complex milieu and is known to contain steroids such as progesterone, whose effects on sperm physiology have been widely characterised. We have previously reported tha...

Background: Progesterone (P4) influences human sperm function by stimulating an elevation of intracellular calcium concentration [Ca2+]i. Assessment of the P4 response in sperm populations indicates an association between poor [Ca2+]i increase and reduced fertilisation capacity. Analysis of P4 sensitivity single donor sperm demonstrates heterogenei...

Background: CatSper is a multi-subunit sperm-specific calcium channel that mediates the progesterone-induced increase in intracellular calcium. Evidence from CatSper subunit knock-out mouse models implicates it as essential for sperm fertilisation competence. Similarly, impaired or absent P4 response in patient sperm is associated with poor or loss...

Several strands of evidence indicate the presence of marked similarities between human brain and testis. Understanding these similarities and their implications has become a topic of interest among the scientific community. Indeed, an association of intelligence with some semen quality parameters has been reported and a relation between dysfunction...

Lay summary A human sperm must swim to the egg to fertilise it. To do this the sperm uses different types of swimming (behaviours) as they are needed. When we watch sperm swimming we see that they regularly change behaviour, sometimes repeatedly switching between two different types. Calcium ions inside cells are crucial in controlling many cell fu...

STUDY QUESTION How are progesterone (P4)-induced repetitive intracellular Ca2+ concentration ([Ca2+]i) signals (oscillations) in human sperm generated? SUMMARY ANSWER P4-induced [Ca2+]i oscillations are generated in the flagellum by membrane potential (Vm)-sensitive Ca2+-influx through CatSper channels. WHAT IS KNOWN ALREADY A subset of human spe...

Objective: To design protein phosphatase 1 (PP1)-disrupting peptides covalently coupled to inert cell-penetrating peptides (CPPs) as sychnologically organized bioportide constructs as a strategy to modulate sperm motility. Design: Experimental study. Setting: Academic research laboratory. Patient(s)/animal(s): Normozoospermic men providing s...

Background: In attempting to formulate potential WHO guidelines for the diagnosis of male infertility, the Evidence Synthesis Group noted a paucity of high quality data on which to base key recommendations. As a result, a number of authors suggested that key areas of research/evidence gaps should be identified, so that appropriate funding and poli...

Background: Intensive research on sperm ion channels has identified members of several ion channel families in both mouse and human sperm. Gene knock-out studies have unequivocally demonstrated the importance of the calcium and potassium conductances in sperm for fertility. In both species, the calcium current is carried by the highly complex cati...

Human sperm show a variety of different behaviours (types of motility) that have different functional roles. Previous reports suggest that sperm may reversibly switch between these behaviours. We have recorded and analysed the behaviour of individual human sperm (180 cells in total), each cell monitored continuously for 3-3.5 min either under contr...

Study question: Does a man (patient 1) with a previously described deficiency in principle cation channel of sperm (CatSper) function have a mutation in the CatSper-epsilon (CATSPERE) and/or CatSper-zeta (CATSPERZ) gene? Summary answer: Patient 1 has a homozygous in-frame 6-bp deletion in exon 18 (c.2393_2398delCTATGG, rs761237686) of CATSPERE....

Study question: How do the alkaline pH, progesterone and 4-aminopyridine interact in their effects on human sperm? Summary answer: Behaviour of human sperm (proportion of hyperactivated cells and motility kinematics) were related directly to [Ca2+]i irrespective of pH or the agonist applied. What is known already?: CatSper channels of human sp...

The development of stimuli-responsive interfaces between synthetic materials and biological systems is providing the unprecedented ability to modulate biomolecular interactions for a diverse range of biotechnological and biomedical applications. Antibody-antigen binding interactions are at the heart of many biosensing platforms, but no attempts hav...

Background and purpose: Sperm from many species share the sperm-specific Ca2+ channel CatSper (cation channel of sperm) that controls the intracellular Ca2+ concentration and, thereby, the swimming behaviour. A growing body of evidence suggests that the mechanisms controlling CatSper activity and the role of the channel during fertilization differ...

Study question: What are the characteristics of progesterone-induced (CatSper-mediated) single cell [Ca2+]i signals in spermatozoa from sub-fertile men and how do they relate to fertilizing ability? Summary answer: Single cell analysis of progesterone-induced (CatSper-mediated) [Ca2+]i showed that reduced progesterone-sensitivity is a common fea...

Study question: Does progesterone in human follicular fluid (hFF) activate CatSper and do other components of hFF modulate this effect and/or contribute separately to hFF-induced Ca2+ signaling? Summary answer: hFF potently stimulates CatSper and increases [Ca2+]i, primarily due to high concentrations of progesterone, however, other components o...

This revised and updated second edition provides a comprehensive account of the human male gamete. Detailed overviews of human sperm production, maturation, and function - and how these processes affect and influence fertility, infertility, and assisted reproduction - are given. A wide range of new developments including proteomics, spermatogenesis...

STUDY QUESTION Are significant abnormalities in outward (K+) conductance and resting membrane potential (Vm) present in the spermatozoa of patients undertaking IVF and ICSI and if so, what is their functional effect on fertilization success?

STUDY QUESTION Are significant abnormalities of CatSper function present in IVF patients with normal sperm concentration and motility and if so what is their functional significance for fertilization success?

[Ca2 +]i signalling is a key regulatory mechanism in sperm function. In mammalian sperm the Ca2 +-permeable plasma membrane ion channel CatSper is central to [Ca2 +]i signalling, but there is good evidence that Ca2 + stored in intracellular organelles is also functionally important. Here we briefly review the current understanding of the diversity...

Previous work has provided evidence for involvement of store operated channels (SOCs) in [Ca(2+)]i signalling of human sperm, including a contribution to the transient [Ca(2+)]i elevation that occurs upon activation of CatSper, a sperm-specific cation channel localised to the flagellum, by progesterone . To further investigate the potential involve...

Whilst fertilizing capacity depends upon a K(+) conductance (GK) that allows the spermatozoon membrane potential (Vm) to be held at a negative value, the characteristics of this conductance in human sperm are virtually unknown. We therefore studied the biophysical / pharmacological properties of the K(+) conductance in spermatozoa from normal donor...

Is the environmental endocrine disruptor p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) able to induce non-genomic changes in human sperm and consequently affect functional sperm parameters? p,p'-DDE promoted Ca(2+) flux into human sperm by activating CatSper channels even at doses found in human reproductive fluids, ultimately compromising sperm...

Introduction Within the female tract sperm must use functionally different behaviours at different times. Motility is controlled primarily by intracellular Ca²⁺ concentration ([Ca²⁺]i), increased [Ca²⁺]i apparently switching sperm from linear swimming to more complex motility types. CatSper, which is expressed only in the flagellum of sperm, is bel...

STUDY QUESTION Do cell penetrating peptides (CPPs) translocate into spermatozoa and, if so, could they be utilized to deliver a much larger protein cargo?

Study question: What is the prevalence of defects in the Ca(2+)-signalling pathways mediating hyperactivation (calcium influx and store mobilization) among donors and sub-fertile patients and are they functionally significant, i.e. related to fertilization success at IVF? Summary answer: This study identifies, for the first time, the prevalence...

[Ca2+]i signaling regulates sperm motility, enabling switching between functionally different behaviors that the sperm must employ as it ascends the female tract and fertilizes the oocyte. We report that different behaviors in human sperm are recruited according to the Ca2+ signaling pathway used. Activation of CatSper (by raising pHi or stimulatin...

Objective: The goal of this study was to verify if 2,3,7,8-tetrachlorodibenzo-. p-dioxin (TCDD) could have any effect on male germ cells mitochondria and in this way add new insights in how male reproductive alterations observed in other studies occur. Methods: In vivo and in vitro approaches using rat testis and human sperm as models were employed...

Objective: To determine the mechanisms of spermicidal activity by cationic compounds. Design: In vitro study with human sperm. Setting: Academic research institute in collaboration with a university hospital. Patient(s): Normozoospermic men providing samples for routine analysis or assisted reproductive technologies. Intervention(s): In vi...

[Ca2+]i signalling is pivotal to sperm function. Progesterone, the best-characterised agonist of human sperm [Ca2+]i-signalling, stimulates a biphasic [Ca2+]i rise, comprising a transient and subsequent sustained phase. In accord with recent reports that progesterone directly activates CatSper, the [Ca2+]i transient was detectable in the anterior f...

A human sperm is a simple cell with a complex mission. From the vagina it must progress through the cervix and uterus to the oviduct, then ascend to the site of fertilisation, where it must find, recognise and interact successfully with the oocyte. This requires that the cell performs complex regulation of its motility, undergoes capacitation (a pr...

A sperm-specific cation channel (CatSper) facilitates the entry of calcium necessary for rapid changes in sperm motility allowing the cell to navigate the hurdles of the female reproductive tract and successfully to locate the egg. Brenker and colleagues show that CatSper is (directly) activated by a diverse range of small organic molecules that ar...

The hormone progesterone rapidly activates intracellular signalling in human sperm, regulating key aspects of their physiology. An ion channel unique to the sperm tail seems to relay progesterone's signal. See Letters p.382 & p.387

Cellular responses rely on signaling. In plant cells, cytosolic free calcium is a major second messenger, and ion channels play a key role in mediating physiological responses. Self-incompatibility (SI) is an important genetically controlled mechanism to prevent self-fertilization. It uses interaction of matching S-determinants from the pistil and...

Fluorescence microscopy of cells loaded with fluorescent, Ca(2+)-sensitive dyes is used for measurement of spatial and temporal aspects of Ca(2+) signaling in live cells. Here we describe the method used in our laboratories for loading suspensions of human sperm with Ca(2+)-reporting dyes and measuring the fluorescence signal during physiological s...

Sperm protein tyrosine phosphorylation. Spermatozoa double-stained for (A) protein Tyr-phosphorylation (green) and (B) acrosome (red) with the corresponding phase contrast image (C). The negative controls with normal serum from the respective species are shown in the insets. * A spermatozoon showing pattern “H” and an intact acrosome. (3.98 MB TIF)

Effect of specific inhibitors of the GC-cGMP-PKG pathway on sperm motility. Since chemotaxis determination can be affected by a decrease in sperm motility due to a secondly effect of the inhibitor, this parameter was additionally evaluated. A–C: Sperm velocity evaluated during the chemotactic assay towards 10 pM P and percentage of motile spermatoz...

Effect of specific inhibitors of calcium signaling on sperm motility. Since chemotaxis determination can be affected by a decrease in sperm motility due to a secondly effect of the inhibitor, this parameter was additionally evaluated. A–G: Sperm velocity evaluated during the chemotactic assay towards 10 pM P and percentage of motile spermatozoa aft...

Sequence of chemotactic signaling events. Molecules participating in sperm chemotaxis upstream or downstream the cAMP or cGMP involvement. (0.03 MB DOC)

Effect of specific inhibitors of the AC-cAMP-PKA pathway on sperm motility and acrosome reaction. Since chemotaxis determination can be affected by a decrease in sperm motility due to a secondly effect of the inhibitor, this parameter was additionally evaluated. A–C: Sperm velocity evaluated during the chemotactic assay towards 10 pM P and percenta...

Chemotactic signaling activation by cyclic nucleotides. A and B: Percentage of oriented spermatozoa (OS) towards (A) db-cAMP and (B) db-cGMP gradient. HAM and 10 pM P were assayed as a negative control and positive control, respectively. Data are expressed as the mean ± SEM. a Significant differences vs. HAM (p<0.05). (4.47 MB TIF)

Sperm chemotaxis is a chemical guiding mechanism that may orient spermatozoa to the egg surface. A picomolar concentration gradient of Progesterone (P), the main steroidal component secreted by the cumulus cells that surround the egg, attracts human spermatozoa. In order to elucidate the molecular mechanism of sperm chemotaxis mediated by P, we com...

Intracellular Ca2+ stores play a central role in the regulation of cellular [Ca2+](i) and the generation of complex [Ca2+] signals such as oscillations and waves. Ca2+ signalling is of particular significance in sperm cells, where it is a central regulator in many key activities (including capacitation, hyperactivation, chemotaxis and acrosome reac...

Epithelial sodium channels (ENaCs) are of immense importance, controlling Na(+) transport across epithelia and thus playing a central role in all aspects of fluid clearance as well as numerous other functions. Regulation of these channels is critical. Here, we show that haem, a regulator of Na(+) transport, directly influences ENaC activity, decrea...

v>There is evidence that intracellular Ca2+ concentration plays significant roles in sperm function such as motility and acrosome reaction. Many calcium channels have been identified in the plasma membrane of sperm. Progesterone (P4) stimulates Ca2+ influx and acrosome reaction in human spermatozoa. The effects of three multivalent calcium channel...

Generation of NO by nitric oxide synthase (NOS) is implicated in gamete interaction and fertilisation. Exposure of human spermatozoa to NO donors caused mobilisation of stored Ca(2+) by a mechanism that did not require activation of guanylate cyclase but was mimicked by S-nitroso-glutathione (GSNO; an S-nitrosylating agent). Application of dithioth...

An essential step in mammalian fertilisation is the sperm acrosome reaction (AR) - exocytosis of a single large vesicle (the acrosome) that surrounds the nucleus at the apical sperm head. The acrosomal and plasma membranes fuse, resulting in both the release of factors that might facilitate penetration of the zona pellucida (which invests the egg)...