Human Male Infertility Caused by Mutations in the CATSPER1 Channel Protein

Department of Human Genetics, University of Michigan School of Medicine, Ann Arbor, MI 48109-0618, USA.
The American Journal of Human Genetics (Impact Factor: 10.93). 05/2009; 84(4):505-10. DOI: 10.1016/j.ajhg.2009.03.004
Source: PubMed


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.

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Available from: Nicole C Meyer, Jan 16, 2014
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    • "In previous studies genetic analysis has identified mutations in the genes coding for proteins of the CatSper channel. In humans, these abnormalities occur in association with other phenotypic abnormalities (Avidan et al., 2003; Avenarius et al., 2009; Hildebrand et al., 2010; Jaiswal et al., 2014). Analysis of CatSper currents has been undertaken in only one of these cases (Smith et al., 2013) where there was a 70 kb deletion which spans four loci, CATSPER2, Stereocilin, CKMT1 and KIAA0377 (Avidan et al., 2003). "
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    ABSTRACT: 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? Summary answer: Sperm with a near absence of CatSper current failed to respond to activation of CatSper by progesterone and there was fertilization failure at IVF. What is known already: In human spermatozoa, Ca(2+) influx induced by progesterone is mediated by CatSper, a sperm-specific Ca(2+) channel. A suboptimal Ca(2+) influx is significantly associated with, and more prevalent in, men with abnormal semen parameters, and is associated with reduced fertilizing capacity. However, abnormalities in CatSper current can only be assessed directly using electrophysiology. There is only one report of a CatSper-deficient man who showed no progesterone potentiated CatSper current. A CatSper 2 genetic abnormality was present but there was no information on the [Ca(2+)]i response to CatSper activation by progesterone. Additionally, the semen samples had indicating significant abnormalities (oligoasthenoteratozoospermia) multiple suboptimal functional responses in the spermatozoon. As such it cannot be concluded that impaired CatSper function alone causes infertility or that CatSper blockade is a potential safe target for contraception. Study design, size, duration: Spermatozoa were obtained from donors and subfertile IVF patients attending a hospital assisted reproductive techniques clinic between January 2013 and December 2014. In total 134 IVF patients, 28 normozoospermic donors and 10 patients recalled due to a history of failed/low fertilization at IVF took part in the study. Participants/materials, setting, methods: Samples were primarily screened using the Ca(2+) influx induced by progesterone and, if cell number was sufficient, samples were also assessed by hyperactivation and penetration into viscous media. A defective Ca(2+) response to progesterone was defined using the 99% confidence interval from the distribution of response amplitudes in normozoospermic donors. Samples showing a defective Ca(2+) response were further examined in order to characterize the potential CatSper abnormalities. In men where there was a consistent and robust failure of calcium signalling, a direct assessment of CatSper function was performed using electrophysiology (patch clamping), and a blood sample was obtained for genetic analysis. Main results and the role of chance: A total of 101/102 (99%) IVF patients and 22/23 (96%) donors exhibited a normal Ca(2+) response. The mean (±SD) normalized peak response did not differ between donors and IVF patients (2.57 ± 0.68 [n = 34 ejaculates from 23 different donors] versus 2.66 ± 0.68 [n = 102 IVF patients], P = 0.63). In recall patients, 9/10 (90%) showed a normal Ca(2+) response. Three men were initially identified with a defective Ca(2+) influx. However, only one (Patient 1) had a defective response in repeat semen samples. Electrophysiology experiments on sperm from Patient 1 showed a near absence of CatSper current and exon screening demonstrated no mutations in the coding regions of the CatSper complex. There was no increase in penetration of viscous media when the spermatozoa were stimulated with progesterone and importantly there was failed fertilization at IVF. Limitations, reasons for caution: A key limitation relates to working with a specific functional parameter (Ca(2+) influx induced by progesterone) in fresh sperm samples from donors and patients that have limited viability. Therefore, for practical, technical and logistical reasons, some men (∼22% of IVF patients) could not be screened. As such the incidence of significant Ca(2+) abnormalities induced by progesterone may be higher than the ∼1% observed here. Additionally, we used a strict definition of a defective Ca(2+) influx such that only substantial abnormalities were selected for further study. Furthermore, electrophysiology was only performed on one patient with a robust and repeatable defective calcium response. This man had negligible CatSper current but more subtle abnormalities (e.g. currents present but significantly smaller) may have been present in men with either normal or below normal Ca(2+) influx. Wider implications of the findings: These data add significantly to the understanding of the role of CatSper in human sperm function and its impact on male fertility. Remarkably, these findings provide the first direct evidence that CatSper is a suitable and specific target for human male contraception. Study funding/competing interests: Initial funding was from NHS Tayside, Infertility Research Trust, TENOVUS, Chief Scientist Office NRS Fellowship, the Wellcome Trust, University of Abertay. The majority of the data were obtained using funding from a MRC project grant (# 4190). The authors declare that there is no conflict of interest. Trial registration number: Not applicable.
    Human Reproduction 10/2015; DOI:10.1093/humrep/dev243 · 4.57 Impact Factor
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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). "
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    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:
    Human Reproduction 05/2015; 30(7). DOI:10.1093/humrep/dev103 · 4.57 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). "
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    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 · 10.43 Impact Factor
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