Localization of AKAP4 and tubulin proteins in sperm with reduced motility.
OBJECTIVE
To perform screening, related to A-kinase anchoring proteins 4 (AKAP4) and tubulin proteins, in spermatozoa with absent or severely reduced motility in order to detect the status of the fibrous sheath and the axonemal structure.


METHODS
An immunocytochemical study of tubulin, used as a positive control, and AKAP4 was carried out to detect the presence and the distribution of these proteins in different sperm samples. The morphological characteristics of sperm were studied by transmission electron microscope (TEM) and the results were elaborated using a formula reported in previous studies. PCR was carried out on DNA extracted from peripheral blood lymphocytes to analyse partial sequences of the Akap4 and Akap3 genes.


RESULTS
Immunolabelling of tubulin and AKAP4 showed different patterns, which led us to divide the patients into groups. In group I, the absence of AKAP4 and tubulin was revealed, although these patients did not show alterations in the Akap4/Akap3 binding site. TEM evaluation highlighted that a high presence of necrosis was associated with total sperm immotility. In group II, a regular AKAP4 and tubulin signal was present, although motility was reduced and TEM analysis revealed the presence of immaturity. In group III, in which a weak AKAP4 label associated with normal tubulin staining and reduced motility was observed, a severe disorganization of the fibrous sheath was highlighted by TEM.


CONCLUSIONS
While the role of AKAP4 in sperm motility is unclear, absent or weak AKAP4-labelling seems to be associated with absent or weak sperm motility.
Moretti
Elena
E
Department of General Surgery, Biology Section, University of Siena, Regional Referral Center for Male Infertility, Siena 53100, Italy.
Scapigliati
Giacomo
G
Pascarelli
Nicola Antonio
NA
Baccetti
Baccio
B
Collodel
Giulia
G
D054758:A Kinase Anchor Proteins; D006801:Humans; D007248:Infertility, Male / Q000235:genetics / Q000503:physiopathology*; D008297:Male; D008854:Microscopy, Electron; D016133:Polymerase Chain Reaction; D011498:Protein Precursors / Q000235:genetics* / Q000378:metabolism*; D012661:Semen / Q000502:physiology; D013081:Sperm Motility; D013094:Spermatozoa / Q000502:physiology* / Q000648:ultrastructure; D014404:Tubulin / Q000235:genetics / Q000378:metabolism*
D054758:A Kinase Anchor Proteins; C485480:AKAP4 protein, human; D011498:Protein Precursors; D014404:Tubulin