Comparative Analysis of ACTL7A Expression, Localization, and Sperm Functional Parameters in Fertile and Infertile...

Testis-specific actin-like 7A (ACTL7A) is an acrosome/perinuclear-theca-related protein implicated in male infertility. In this exploratory study, we assessed ACTL7A transcript levels in a clinical assisted reproductive technology (ART) setting and performed preliminary protein-level validation in a subset of samples, together with sperm chromatin integrity assays, to clarify potential associations with sperm quality.

For this preliminary case-control study, twenty-seven men were included: 11 infertile intracytoplasmic sperm injection (ICSI) candidates and 16 fertile preimplantation genetic testing (PGT) candidates. ACTL7A mRNA levels were quantified in all samples by quantitative real time polymerase chain reaction (qRTPCR). ACTL7A protein expression was evaluated by Western blot in a small feasibility-limited subset (n=3 per group) and interpreted as exploratory protein-level support for the mRNA findings. Localization was assessed by immunostaining. Classical semen parameters and sperm functional assays including DNA fragmentation (SCSA), histone retention (aniline blue), and protamine deficiency (CMA3) were performed. Clinical outcomes were also documented.

ACTL7A mRNA levels were significantly reduced in infertile men compared with fertile controls (qPCR: P=0.020). Preliminary Western blot analysis in the subset also suggested lower protein expression in the infertile group (P=0.010), providing supportive evidence for the transcript findings. Infertile men also showed lower sperm viability and poorer chromatin integrity (P=0.040 and P=0.020, respectively). ACTL7A expression positively correlated with sperm viability (r=0.40, P=0.040) and inversely correlated with DNA fragmentation (r=-0.43, P=0.020). Exploratory receiver operating characteristic (ROC) analysis showed a moderate discriminatory ability for ACTL7A expression [area under the curve-ROC (AUC-ROC=0.727, P=0.048], with 62.5% sensitivity and 81.8% specificity.

Reduced ACTL7A expression in human sperm is linked to impaired chromatin quality and decreased viability, supporting ACTL7A as a candidate research biomarker rather than a clinically validated predictor. Given the small cohort and limited protein-level testing, these findings are exploratory and emphasize the need for validation in larger independent populations to confirm clinical utility.