Rfpl4, encoding a RING finger-like protein with a B30.2 domain, is a member of the Ret Finger Protein-Like gene family. It is a putative E3 ubiquitin-protein ligase and is involved in the ubiquitin-proteasome degradation pathway, which is crucial for oocyte meiosis, early embryonic mitotic divisions, gametogenesis, and the maternal-to-zygotic transition [1,2].

Immunohistochemistry and immunofluorescence showed that RFPL4 accumulates in growing oocytes and disappears during early embryonic cleavage. Yeast two-hybrid and co-immunoprecipitation assays demonstrated that RFPL4 interacts with components of the ubiquitin-proteasome system like the E2 ubiquitin-conjugating enzyme HR6A, proteasome subunit beta type 1, ubiquitin B, and cyclin B1, suggesting it targets cyclin B1 for proteasomal degradation, an important aspect of oocyte cell cycle control [1]. Knockout studies of Rfpl4 in mice, generating Rfpl4a/b double KO mice, led to the birth of healthy offspring, indicating that Rfpl4 is not essential for mouse development [3].

In conclusion, Rfpl4 is involved in the ubiquitin-proteasome degradation pathway, specifically in regulating oocyte cell cycle through targeting cyclin B1 for degradation. The Rfpl4 KO mouse model has shown that despite its role in oocyte-related processes, it is not essential for overall mouse development, which may provide insights into understanding the redundancy or compensatory mechanisms in early mammalian development.

References:

1. Suzumori, Nobuhiro, Burns, Kathleen H, Yan, Wei, Matzuk, Martin M. 2003. RFPL4 interacts with oocyte proteins of the ubiquitin-proteasome degradation pathway. In Proceedings of the National Academy of Sciences of the United States of America, 100, 550-5. doi:. https://pubmed.ncbi.nlm.nih.gov/12525704/

2. Rajkovic, Aleksandar, Lee, Jung Hyun, Yan, Changning, Matzuk, Martin M. . The ret finger protein-like 4 gene, Rfpl4, encodes a putative E3 ubiquitin-protein ligase expressed in adult germ cells. In Mechanisms of development, 112, 173-7. doi:. https://pubmed.ncbi.nlm.nih.gov/11850190/

3. Wakabayashi, Mizuki, Tamura, Shiori, Kanzaki, Satoko, Sekita, Yoichi, Kimura, Tohru. 2020. Five multicopy gene family genes expressed during the maternal-to-zygotic transition are not essential for mouse development. In Biochemical and biophysical research communications, 534, 752-757. doi:10.1016/j.bbrc.2020.11.004. https://pubmed.ncbi.nlm.nih.gov/33162025/