Human Male Infertility Caused by Mutations in the CATSPER1 Channel Protein
ABSTRACT Male infertility, a common barrier that prevents successful conception, is a reproductive difficulty affecting 15% of couples. Heritable forms of nonsyndromic male infertility can arise from single-gene defects as well as chromosomal abnormalities. Although no CATSPER gene has been identified as causative for human male infertility, male mice deficient for members of the CatSper gene family are infertile. In this study, we used routine semen analysis to identify two consanguineous Iranian families segregating autosomal-recessive male infertility. Autozygosity by descent was demonstrated in both families for a approximately 11 cM region on chromosome 11q13.1, flanked by markers D11S1765 and D11S4139. This region contains the human CATSPER1 gene. Denaturing high-performance liquid chromatography (DHPLC) and bidirectional sequence analysis of CATSPER1 in affected family members revealed two separate insertion mutations (c.539-540insT and c.948-949insATGGC) that are predicted to lead to frameshifts and premature stop codons (p.Lys180LysfsX8 and p.Asp317MetfsX18). CATSPER1 is one of four members of the sperm-specific CATSPER voltage-gated calcium channel family known to be essential for normal male fertility in mice. These results suggest that CATSPER1 is also essential for normal male fertility in humans.
Full-textDOI: · Available from: Nicole C Meyer, Jan 16, 2014
- SourceAvailable from: Elisabetta Baldi
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- "Few men with CatSper1 or CatSper2 mutations that lead to a truncated protein have been described in the literature. These men show reduced or absent sperm motility and frequent oligozoospermia, although the two phenotypes are not severe or have not been evaluated or reported for all the subjects with the deletions (Avidan et al., 2003; Avenarius et al., 2009; Hildebrand et al., 2010; Jaiswal et al., 2014). "
ABSTRACT: Is CatSper1 expression in human spermatozoa related to semen parameter values and sperm functions? CatSper1 expression is positively related to progressive and hyperactivated (HA) motility, [Ca(2+)]i responsiveness to progesterone but not the acrosome reaction (AR). The role of cationic channel of sperm (CatSper) in sperm functions is clear in animal models but less defined in human sperm cells. Current knowledge is mostly based on low specificity CatSper inhibitors showing agonistic and toxic effects on human spermatozoa and is thus of little help in clarifying the role of the CatSper channel in human sperm functions. CatSper1 protein expression was evaluated in 115 men undergoing semen analysis for couple infertility. CatSper1 expression was related to routine semen parameters, motility kinematic parameters and basal and progesterone-stimulated [Ca(2+)]i and the AR. CatSper1 expression was evaluated (n = 85 normozoospermic, n = 30 asthenozoospermic patients) by immunofluorescence coupled to flow cytometry leading to quantitative measurement of the percentage of ejaculated sperm cells expressing the protein. Semen analysis was evaluated according to World Health Organization guidelines. Kinematic parameters were evaluated by a computer-aided sperm analysis system. [Ca(2+)]i was measured by a spectrofluorimetric method in fura-2-loaded spermatozoa. The AR was evaluated in live sperm cells by fluorescent-labeled lectin. CatSper1 protein expression in spermatozoa was reduced in asthenozoospermic men (mean ± SD: 53.0 ± 15.5%, n = 30 versus 67.9 ± 17.1% in normozoospermic, n = 85, P < 0.01) and was significantly correlated with progressive (r = 0.36, P < 0.001), total (r = 0.35, P < 0.001) and HA (r = 0.41, P < 0.005) motility. In addition to a higher percentage of spermatozoa not expressing CatSper1, asthenozoospermic men showed a large number of spermatozoa with immunofluorescent signal localized outside the principal piece compared with those in normozoospermia. A significant positive correlation was found between CatSper1 protein expression and the increase of [Ca(2+)]i in response to progesterone (r = 0.36, P < 0.05, n = 40) but not with basal [Ca(2+)]i. No correlation was found with the AR, either basal or in response to progesterone. The study is partly descriptive. Furthermore, we cannot rule out the possibility that some round cells remain after a single round of 40% density gradient centrifugation or that this step may have removed some defective or slow swimming sperm, and therefore this preparation may not be representative of the entire sperm sample. Although our data suggest that CatSper1 may be a useful marker for infertility, and a possible contraceptive target, any clinical application is limited without further research. Our results demonstrate an association of CatSper1 expression with human sperm progressive and HA motility and provide preliminary evidence that lack of expression or mislocalization of CatSper1 in spermatozoa may be involved in the pathogenesis of asthenozoospermia. However, mechanistic studies are needed to confirm that the correlations between CatSper1 expression and sperm functions are causative. Supported by grants from Ministry of University and Scientific Research (PRIN project to E.B. and FIRB project to S.M.) and by Regione Toscana (to G.F.). L.T. was recipient of a grant from Accademia dei Lincei (Rome, Italy). The authors have no conflicts of interest to declare. © The Author 2015. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: email@example.com.Human Reproduction 05/2015; 30(7). DOI:10.1093/humrep/dev103 · 4.59 Impact Factor
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- "Targeted disruption of CatSper in mice impairs sperm motility (Qi et al, 2007), and CatSper À/À sperm fail to traverse the oviduct (Ho et al, 2009; Miki & Clapham, 2013; Chung et al, 2014) and to penetrate the egg coat (Ren et al, 2001)—deficits that cause male infertility (Quill et al, 2001; Ren et al, 2001; Qi et al, 2007). Similarly, mutations in human CatSper genes cause infertility in men (Avenarius et al, 2009; Hildebrand et al, 2010). CatSper has been proposed to serve as a polymodal sensor that integrates diverse chemical and physical cues (Brenker et al, 2012; Miki & Clapham, 2013; Tavares et al, 2013; Schiffer et al, 2014): In general, CatSper is activated at depolarized membrane potentials (V m ) and at alkaline intracellular pH (pH i ) (Kirichok et al, 2006; Lishko et al, 2010, 2011; Strünker et al, 2011). "
ABSTRACT: Sperm guidance is controlled by chemical and physical cues. In many species, Ca(2+) bursts in the flagellum govern navigation to the egg. In Arbacia punctulata, a model system of sperm chemotaxis, a cGMP signaling pathway controls these Ca(2+) bursts. The underlying Ca(2+) channel and its mechanisms of activation are unknown. Here, we identify CatSper Ca(2+) channels in the flagellum of A. punctulata sperm. We show that CatSper mediates the chemoattractant-evoked Ca(2+) influx and controls chemotactic steering; a concomitant alkalization serves as a highly cooperative mechanism that enables CatSper to transduce periodic voltage changes into Ca(2+) bursts. Our results reveal intriguing phylogenetic commonalities but also variations between marine invertebrates and mammals regarding the function and control of CatSper. The variations probably reflect functional and mechanistic adaptations that evolved during the transition from external to internal fertilization. © 2014 The Authors.The EMBO Journal 12/2014; 34(3). DOI:10.15252/embj.201489376 · 10.75 Impact Factor
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- "In human, the role of CatSper channels in sperm motility is less clear. Mutations of CatSper1 and CatSper2 leading to deletion of the protein have occasionally been found in the population (Avidan et al., 2003; Avenarius et al., 2009) but the association between lack of CatSper1 or 2 and sperm motility in these subjects is not clear (Hildebrand et al., 2010). Although a recent study using the patch clamp technique has demonstrated the absence of CatSper currents in sperm from one man carrying CatSper2 mutations (Smith et al., 2013), the relationship between CatSper mutations and asthenozoospermia remains to be clarified, because the percentage of motile sperm in the ejaculates of subjects with mutations was variable and HA has not been evaluated (Hildebrand et al., 2010). "
ABSTRACT: Does CatSper have a role in the achievement of human sperm motility and in the Progesterone (P)-induced acrosome reaction (AR)? CatSper1 expression is associated with human sperm progressive motility and the P-induced AR; it may have a role in the pathogenesis of asthenozoospermia. Knockout mice for any of the Catsper family genes fail to acquire hyperactivated motility and are infertile. CatSper channels mediate P-induced Ca(2+) influx in human sperm. The role of CatSper in human sperm hyperactivated/activated motility and in asthenospermia is less clear. A few men with CatSper mutations have been described but the phenotype regarding sperm motility has not been well established. The effects of two Catsper inhibitors, NNC55-0396 (NNC, 10 and 20 µM) and Mibefradil (Mib, 30 and 40 µM), were tested on human sperm motility parameters and the P-induced AR. Catsper1 protein expression was evaluated in unselected and swim-up selected sperm samples and in sperm from normo- and astheno-zoospermic subjects. Semen sample kinematic parameters were analysed by a CASA system. A fluorescent-labelled lectin was used to evaluate P-induced AR in live sperm by fluorescence microscopy. CatSper1 protein expression was determined by western blot analysis and by flow cytometry. Intracellular calcium concentrations ([Ca(2+)]i) were evaluated by a spectrofluorimetric method following sperm loading with the calcium-sensitive probe fura 2/AM. CatSper1 protein was localized in the tail of human sperm. CatSperI expression was higher in swim up selected than unselected sperm both when measured by western blot or by flow cytometry (52.7 ± 15.8% versus 27.2 ± 9.01%, n = 7, P < 0.01). Basal and P-stimulated [Ca(2+)]i were significantly higher in swim-up selected compared with unselected sperm. CatSper1 expression (western blot analysis) was found to be decreased in sperm from asthenozoospermic (n = 10) compared with those from normozoospermic (n = 9) men (intensity values relative to β-actin: 244.4 ± 69.3 versus 385.8 ± 139.5, P < 0.01). A positive correlation was found between CatSper1 protein expression and the percentage of sperm with progressive motility (n = 19, r = 0.59, P = 0.007). NNC (10 µM) and Mib (30 µM) significantly reduced the percentage of sperm with progressive motility and several kinematic parameters but did not affect the percentage of hyperactivated sperm. Their effects were the same whether they were added to swim-up selected and capacitated sperm or were added to the swim-up medium. Mib was found to have a slight but significant effect on sperm viability at both concentrations tested. P-stimulated AR was significantly reduced by both inhibitors (P < 0.05). Overall, our results indicate that, in human sperm, CatSper channel expression and function are associated with progressive motility and may be involved in the pathogenesis of asthenozoospermia. In general, studies evaluating the effect of inhibitors have the limitation of the specificity of the molecules. We show here that Mib may have toxic effect on human sperm. Although most of the parameters have been evaluated in live sperm, the toxic effect could have contributed to the observed decreases. More studies are necessary to evaluate further the role of CatSper1 in asthenozoospermia. In view of the involvement in P-induced AR and of the evidence of a role in the pathogenesis of astenozoospermia, CatSper channels may represent a promising target for the development of new drugs for the treatment of male infertility and for non-hormonal contraception. This work was supported by grants from Ministry of University and Scientific Research (Prin project to E.B. and FIRB project to S.M) and Regione Toscana (to G.F.). The authors have no conflicts of interest to declare.Human Reproduction 01/2014; 29(3). DOI:10.1093/humrep/det454 · 4.59 Impact Factor