title: Quantification of CatSper1 expression in human spermatozoa and relation to functional parameters.
abstract: OBJECTIVE
  Is CatSper1 expression in human spermatozoa related to semen parameter values and sperm functions?
  
  
  CONCLUSIONS
  CatSper1 expression is positively related to progressive and hyperactivated (HA) motility, [Ca(2+)]i responsiveness to progesterone but not the acrosome reaction (AR).
  
  
  BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
  
  
  CONCLUSIONS
  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.
  
  
  BACKGROUND
  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.
authors.affiliation: Department of Biomedical Experimental and Clinical Sciences, Center of Excellence DENOthe, University of Florence, Viale Pieraccini 6, Florence I-50139, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Tamburrino
authors.affiliation: Department of Biomedical Experimental and Clinical Sciences, Center of Excellence DENOthe, University of Florence, Viale Pieraccini 6, Florence I-50139, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Marchiani
authors.affiliation: Fondazione Pasteur Cenci Bolognetti, Department of Anatomy, Histology, Forensic Medicine and Orthopedic, Section of Histology, Sapienza University of Rome, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Vicini
authors.affiliation: Fondazione Pasteur Cenci Bolognetti, Department of Anatomy, Histology, Forensic Medicine and Orthopedic, Section of Histology, Sapienza University of Rome, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Muciaccia
authors.affiliation: Department of Biomedical Experimental and Clinical Sciences, Center of Excellence DENOthe, University of Florence, Viale Pieraccini 6, Florence I-50139, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Cambi
authors.affiliation: Centro Procreazione Assistita 'Demetra' of Florence, Via Caccini 18, Florence I-50139, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Pellegrini
authors.affiliation: Department of Biomedical Experimental and Clinical Sciences, Center of Excellence DENOthe, University of Florence, Viale Pieraccini 6, Florence I-50139, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Forti
authors.affiliation: Department of Biomedical Experimental and Clinical Sciences, Center of Excellence DENOthe, University of Florence, Viale Pieraccini 6, Florence I-50139, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Muratori
authors.affiliation: Department of Biomedical Experimental and Clinical Sciences, Center of Excellence DENOthe, University of Florence, Viale Pieraccini 6, Florence I-50139, Italy elisabetta.baldi@unifi.it.
authors.forename: E
authors.initials: E
authors.lastname: Baldi
mesh_terms: D020101:Acrosome Reaction / Q000502:physiology; D000328:Adult; D053627:Asthenozoospermia / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011374:Progesterone / Q000494:pharmacology; D055101:Semen Analysis / Q000379:methods*; D013081:Sperm Motility / Q000502:physiology; D013094:Spermatozoa / Q000378:metabolism*
chemical_list: C438823:CATSPER1 protein, human; D015220:Calcium Channels; D011374:Progesterone
keywords: CatSper; asthenozoospermia; hyperactivation; sperm motility