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The periphilin 1-like BFAR isoform 3 is highly expressed in transcriptionally silent oocytes and involved in RNA metabolism. Mrowiec K et al. (2021) The mouse 3110001I22Rik gene located in the first intron of Bfar is considered as a Bfar variant coding for the BFARv3 protein. However, it differs from other BFAR isoforms and resembles periphilin 1 (PPHLN1) due to its two (Lge1 and serine-rich) conserved domains. We identified the BFARv3/EGFP-interacting proteins by co-immunoprecipitation coupled to mass spectrometry, which revealed 40S ribosomal proteins (RPS3, RPS14, RPS19, RPS25, RPS27), histones (H1.2, H1.4, H3.3C), proteins involved in RNA processing and splicing (SFPQ, SNRPA1, HNRNPA3, NONO, KHDRBS3), calcium signaling (HPCAL1, PTK2B), as well as HSD17B4, GRB14, POSTN, and MYO10. Co-immunoprecipitation revealed that both Lge1 and Ser-rich domains of BFARv3 were necessary for binding to RNA-interacting factors NONO and SFPQ, known to be components of paraspeckles. Reciprocal co-immunoprecipitation and the proximity ligation assay confirmed that both BFARv3 and PPHLN1 could interact with NONO and SFPQ, suggesting a new function for PPHLN1 as well. BFARv3 and its Lge1 or Ser-rich-deficient mutants preferentially localize in the nucleus. We found an accumulation of BFARv3/EGFP (but not its mutated forms) in the nuclear granules, which was enhanced in response to arsenite treatment and ionizing radiation. Although Bfar v3 is expressed ubiquitously in mouse tissues, its expression is the highest in metaphase II oocytes. The BFARv3 interactome suggests its role in RNA metabolism, which is critical for the transcriptionally silent MII oocyte. Mouse BFARv3 has no ortholog in the human genome, thus it may contribute to the differences between these two species observed in oocyte maturation and early embryonic development.//////////////////
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Genomewide discovery and classification of candidate ovarian fertility genes in the mouse. Gallardo TD et al. Female infertility syndromes are among the most prevalent chronic health disorders in women, but their genetic basis remains unknown because of uncertainty regarding the number and identity of ovarian factors controlling the assembly, preservation, and maturation of ovarian follicles. To systematically discover ovarian fertility genes en masse, we employed a mouse model (Foxo3) in which follicles are assembled normally but then undergo synchronous activation. We developed a microarray-based approach for the systematic discovery of tissue-specific genes and, by applying it to Foxo3 ovaries and other samples, defined a surprisingly large set of ovarian factors (n = 348, approximately 1% of the mouse genome). This set included the vast majority of known ovarian factors, 44% of which when mutated produce female sterility phenotypes, but most were novel. Comparative profiling of other tissues, including microdissected oocytes and somatic cells, revealed distinct gene classes and provided new insights into oogenesis and ovarian function, demonstrating the utility of our approach for tissue-specific gene discovery. This study will thus facilitate comprehensive analyses of follicle development, ovarian function, and female infertility. This is an oocyte-specific gene.
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