Abstract
RING box protein-1 (RBX1) is an essential component of Skp1-cullin-F-box protein (SCF) E3 ubiquitin ligase and participates in diverse cellular processes by targeting various substrates for degradation. However, the physiological function of RBX1 in mouse oocyte maturation remains unknown. Here, we examined the expression, localization and function of RBX1 during mouse oocyte meiotic maturation. Immunofluorescence analysis showed that RBX1 displayed dynamic distribution during the maturation process: it localized around and migrated along with the spindle and condensed chromosomes. Rbx1 knockdown with the appropriate siRNAs led to a decreased rate of first polar body extrusion and most oocytes were arrested at metaphase I. Moreover, downregulation of Rbx1 caused accumulation of Emi1, an inhibitor of the anaphase-promoting complex/cyclosome (APC/C), which is required for mouse meiotic maturation. In addition, we found apparently increased expression of the homologue disjunction-associated protein securin and cyclin B1, which are substrates of APC/C E3 ligase and need to be degraded for meiotic progression. These results indicate the essential role of the SCFβTrCP-EMI1-APC/C axis in mouse oocyte meiotic maturation. In conclusion, we provide evidence for the indispensable role of RBX1 in mouse oocyte meiotic maturation.
Highlights
Immature oocytes become fertilizable eggs through a process called meiotic maturation [1]
When the spindle started to migrate, uniform distribution of RING box protein-1 (RBX1) was still found on the spindle; just before 1st-PBE, stronger accumulation of RBX1 was observed at the pole of the separating chromosomes
The localization of RBX1 in mouse oocytes was analyzed after treatment of the oocytes with a spindle-perturbing agent: metaphase I and metaphase II oocytes were treated with nocodazole, which resulted in disassembly of the microtubules
Summary
Immature oocytes become fertilizable eggs through a process called meiotic maturation [1]. The synthesis of cyclin B1 increases progressively during meiotic maturation, reaching its maximum at the end of the first meiotic M-phase. The Skp1-Cullin-F-box protein (SCF) complex is another very important E3 ubiquitin ligase [12]. RBX1, as one of the core components of the SCF complex, has been shown to play important roles in a range of cellular processes under physiological and pathological conditions, such as embryonic development, cell proliferation and cancer cell survival [19]; its role in the maturation of oocytes has not been confirmed. We found that subcellular localization of RBX1 protein during mouse oocyte maturation changed dynamically and was closely associated with chromosome formation: we found that depletion of RBX1 decreased the rate of first PB extrusion (1st-PBE) and was accompanied by accumulation of Emi
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
