Acetylated α-tubulin is reduced in individuals with poor sperm motility

Objective: To determine the status of alpha-tubulin acetylation and of testis-specific acetylable alpha-tubulin isoforms in asthenozoospermia. Design: Research study. Setting: Research institute and an infertility clinic. Patient(s): 50 men with normal sperm parameters, and 50 men with asthenozoospermia. Intervention(s): None. Main Outcome Measure(s): Western blot analyses of alpha-tubulin, acetylated alpha-tubulin, and isoforms TUBA3C, TUBA4A, and TUBA8 in Percoll separated sperm and flow cytometry, real-time reverse-transcription polymerase chain reaction, and immunofluorescent localization. Result(s): A statistically significant decrease in the expression of acetylated alpha-tubulin in asthenozoosperm was seen with Western blot analysis, double immunostaining by direct immunofluorescence, and flow cytometric analysis. The transcript and protein of testis-specific acetylable alpha-tubulin isoform TUBA3C was decreased and TUBA4A was statistically significantly increased in asthenozoosperm as compared with normal spermatozoa. TUBA8 was reduced in asthenozoosperm. Similar observations were noted by indirect immunofluorescent localization. The potential transcription factors involved in the differential expression of TUBA4A and TUBA3C have been identified. Conclusion(s): Data suggest an association of alpha-tubulin acetylation with asthenozoospermia. Ours is the first report to demonstrate a-tubulin isoforms in sperm, implicating their role in motility. The differential expression of TUBA3C and TUBA4A suggests that tubulin acetylation may be governed by the isoform of a-tubulin that is expressed or silenced and that this in turn is transcriptionally controlled. (Fertil Steril (R) 2014; 101: 95-104. (C) 2014 by American Society for Reproductive Medicine.)