title: Expression of SPANX proteins in human-ejaculated spermatozoa and sperm precursors.
abstract: The sperm protein associated with nucleus in the X chromosome (SPANX) gene family is constituted by only a few members, clustered at Xq27, encoding small proteins which range from 15 to 20 kDa. These proteins have been shown to be present both in mature spermatozoa and in tumours, such as melanoma and some leukaemias. We developed polyclonal sera in order to study the distribution of the protein in human-ejaculated spermatozoa and their precursors. A synthetic peptide was designed from a domain common to the SPANX protein family and polyclonal sera were raised in mice. Seven healthy volunteer men with normal sperm parameters were recruited and the expression of SPANX proteins was evaluated in spermatozoa and ejaculated sperm precursors by immunocytochemistry and immunofluorescence analyses. SPANX proteins, present in a large fraction (96%) of mature spermatozoa, were localized in the sperm head (39.2%), midpiece (22.8%) or in both sites (34.4%). Spermatids also showed the presence of SPANX proteins in their cytoplasm, although a significantly higher number of spermatids were SPANX-negative compared with spermatozoa. In conclusion, SPANX proteins are expressed in an elevated percentage of spermatids and mature spermatozoa. In the latter, they are preferentially located in the sperm head. The greater number of SPANX-negative spermatids observed could relate to their easier exfoliation from the seminiferous tubules.
authors.affiliation: Section of Endocrinology, Andrology and Internal Medicine, Department of Biomedical Sciences, University of Catania, Catania, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Salemi
authors.forename: Aldo E
authors.initials: AE
authors.lastname: Calogero
authors.forename: Daniela
authors.initials: D
authors.lastname: Di Benedetto
authors.forename: Anna
authors.initials: A
authors.lastname: Cosentino
authors.forename: Nunziata
authors.initials: N
authors.lastname: Barone
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Rappazzo
authors.forename: Enzo
authors.initials: E
authors.lastname: Vicari
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D003593:Cytoplasm / Q000378:metabolism; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D018613:Microscopy, Confocal; D009363:Neoplasm Proteins / Q000737:chemistry / Q000378:metabolism*; D010455:Peptides / Q000138:chemical synthesis; D017434:Protein Structure, Tertiary; D013077:Sperm Head / Q000378:metabolism; D013087:Spermatids / Q000166:cytology / Q000378:metabolism*; D013094:Spermatozoa / Q000166:cytology / Q000378:metabolism*; D014960:X Chromosome
chemical_list: D009363:Neoplasm Proteins; D010455:Peptides; C403097:SPANXC protein, human