A novel gene ACTRT3 mutations induce sperm malformations and fertilization failure via Acrosomal ultrastructural defects

Numerous actin-related proteins (ARPs) deficiencies have been confirmed to cause sperm acrosomal structural abnormalities, representing significant genetic factors in male infertility. We identified a patient with a missense mutation in ACTRT3, who presented with teratozoospermia and experienced embryonic developmental arrest following intracytoplasmic sperm injection (ICSI). Further analysis revealed ultrastructural abnormalities in the sperm acrosome. To validate these findings, we generated a conditional knockout transgenic mouse model. Male homozygous mutant mice recapitulated the human phenotype, exhibiting consistent acrosomal ultrastructural defects, infertility, and embryonic developmental arrest. To overcome this limitation, a dual-agonist artificial oocyte activation (AOA) protocol combining ionomycin and SrCl2 was developed. This strategy successfully rescued blastocyst formation in Actrt3-deficient mouse models and enabled embryos from the affected couple to develop to the blastocyst stage after ICSI, culminating in a successful pregnancy post-transfer. The combinatorial AOA approach outperformed monotherapy by synergistically restoring PLCZ1-associated calcium signaling defects, providing a tailored solution for infertility linked to actin-related protein deficiencies.