NESFATIN-1 acts as a neuroendocrine hormone to suppress gonadotropin secretion in the female goldfish and to prevent germinal vesicle breakdown of oocytes in the zebrafish. However, the expression and function of NESFATIN-1 in meiotic maturation and development of porcine oocytes remains elusive. Genomic structure of porcine NESFATIN-1 precursor nucleobindin 2 (NUCB2) is first characterized in detail and an evolutionally closer relationship of NESFATIN-1 between pig and rat is shown by phylogenetic analysis of multiple species. Additionally, immunofluorescence analysis revealed that NESFATIN-1 is predominantly expressed and localizes on the membrane of both theca cells and granulosa cells, but not expressed in oocytes. Real-time quantitative polymerase chain reaction showed that the abundance of NESFATIN-1 transcripts in granulosa cells progressively decreases during the developmental transition from small follicles to large follicles. Correspondingly, NESFATIN-1 could significantly enhance both the cleavage and blastocyst rate of parthenogenetically activated oocytes from small follicles (p < 0.05), whereas it did not affect meiotic maturation and development of oocytes from large follicles. Interestingly, we found that NESFATIN-1 significantly improves meiotic maturation of oocytes cultured in chemically defined medium in the absence of pyruvate compared with the control group (p < 0.05), suggesting that the NESFATIN-1 as a substitute for pyruvate exerts beneficial effects on porcine oocyte maturation. In conclusion, these results demonstrate that NESFATIN-1 facilitates both meiotic maturation and development of porcine oocytes.
Keywords: NESFATIN-1; granulosa cells; meiotic maturation; oocytes; pig.
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