Specc1l deficiency leads to abnormal oocyte meiosis and reduced blastocyst development in mouse.

Proper oocyte maturation is important in early embryo development. This study provides evidence that abnormal meiotic maturation can impact the developmental competency of preimplantation embryos. This study aimed to investigate the potential role of the mouse SPECC1L (sperm antigen with calponin homology and coiled-coil domains 1 like), a microtubule and actin cytoskeleton-associated protein during oocyte meiotic maturation and its potential effects on preimplantation development. This study shows that the transcriptional levels of Specc1l did not significantly change from the germinal vesicle (GV) stage to the metaphase II (MII) stage, but maternal transcripts rapidly and gradually degraded after fertilization. SPECC1L was detected in both the cytoplasm and GV, but not in the nucleolus-like body in the GV intact oocyte. At the MII stages, SPECC1L was widely distributed in the cytoplasm but did not co-localize with chromatin. Knockdown of Specc1l expression in oocytes resulted in abnormal spindle morphology and misaligned chromosomes, as well as a decrease in the rate of polar body extrusion and a reduced developmental competence of oocytes, leading to decreased blastocyst formation rate. In conclusion, this study provides evidence that SPECC1L plays a critical role in mouse oocyte meiotic maturation and early embryo development, specifically in proper bipolar spindle assembly and extrusion of the first polar body.