Oosp1, encoding mouse oocyte-secreted protein 1, is crucial for oocyte-somatic cell communication, an essential process for normal ovarian function [1]. It shares amino acid identity with placental-specific protein 1 (PLAC1). The Oosp1 gene in mice consists of 5 exons, spans over 16.4 kb, and localizes to chromosome 19, with synteny to human chromosome 11q12-11q13 [1].

In Sohlh2-deficient mice, where ovarian follicles are lacking, Oosp1 is misexpressed along with numerous other germ cell-and oocyte-specific genes, indicating Sohlh2's role in maintaining normal Oosp1 expression during early oogenesis [2]. In YY1-deficient oocytes, the level of Oosp1 is altered, suggesting YY1's involvement in folliculogenesis and ovarian function through its regulation of Oosp1 [3]. A Nuclease technology-mediated knockout of Oosp1, along with Oosp2 and Oosp3, showed that the triple KO mutant mice had decreased prolificacy but were not infertile, suggesting that Oosp1 may be dispensable for fertility [4].

In conclusion, Oosp1 is important for oocyte-somatic cell communication and ovarian function. Studies using gene-knockout mouse models, such as Sohlh2-deficient, YY1-deficient, and triple Oosp knockout mice, have revealed its role in early oogenesis, folliculogenesis, and fertility-related processes. Although the triple KO mice showed decreased prolificacy, the dispensability of Oosp1 for fertility provides new insights into female reproductive biology.

References:

1. Yan, C, Pendola, F L, Jacob, R, Eppig, J J, Matzuk, M M. . Oosp1 encodes a novel mouse oocyte-secreted protein. In Genesis (New York, N.Y. : 2000), 31, 105-10. doi:. https://pubmed.ncbi.nlm.nih.gov/11747200/

2. Choi, Youngsok, Yuan, Daniel, Rajkovic, Aleksandar. 2008. Germ cell-specific transcriptional regulator sohlh2 is essential for early mouse folliculogenesis and oocyte-specific gene expression. In Biology of reproduction, 79, 1176-82. doi:10.1095/biolreprod.108.071217. https://pubmed.ncbi.nlm.nih.gov/18753606/

3. Griffith, Gillian J, Trask, Mary C, Hiller, Jacob, Tremblay, Kimberly D, Mager, Jesse. 2010. Yin-yang1 is required in the mammalian oocyte for follicle expansion. In Biology of reproduction, 84, 654-63. doi:10.1095/biolreprod.110.087213. https://pubmed.ncbi.nlm.nih.gov/21123818/

4. Abbasi, Ferheen, Kodani, Mayo, Emori, Chihiro, Fujihara, Yoshitaka, Ikawa, Masahito. 2020. Nuclease technology-Mediated Genome Editing Reveals Oosp Family Genes are Dispensable for Female Fertility in Mice. In Cells, 9, . doi:10.3390/cells9040821. https://pubmed.ncbi.nlm.nih.gov/32231122/