Biology subjects

Jung, G. I.

Publications and source records attributed to Jung, G. I..

3 recordsLinked to original sources

bioRxiv2023

Distinct Aurora B pools at the inner centromere and kinetochore have different contributions to meiotic and mitotic chromosome segregation

Proper chromosome segregation depends on establishment of bioriented kinetochore-microtubule attachments, which often requires multiple rounds of release and reattachment. Aurora B and C kinases phosphorylate kinetochore proteins to release tensionless attachments. Multiple pathways recruit Aurora B/C to the centromere and kinetochore. We studied how these pathways contribute to anaphase onset timing and correction of kinetochore-microtubule attachments in budding yeast meiosis and mitosis. We find that the pool localized by the Bub1/Bub3 pathway sets the normal duration of meiosis and mitosis, in differing ways. Our meiosis data suggests that disruption of this pathway leads to PP1 kinetochore localization, which dephosphorylates Cdc20 for premature anaphase onset. For error correction, the Bub1/Bub3 and COMA pathways are individually important in meiosis but compensatory in mitosis. Finally, we find that the haspin and Bub1/3 pathways function together to ensure error correction in mouse oogenesis. Our results suggest that each recruitment pathway localizes spatially distinct kinetochore-localized Aurora B/C pools that function differently between meiosis and mitosis.

cell biology↗

bioRxiv2022

A meiotic midbody structure in mouse oocytes acts as a barrier for nascent translation to ensure developmental competence

Successful embryo development is dependent upon maternally deposited components. During egg formation, developmental competence is acquired through regulated translation of maternal mRNA stores. In addition, egg precursors undergo two rounds of chromosome segregation, each coupled to an asymmetric cytokinesis that produces two non-functional polar bodies. In somatic cells, cytokinesis produces two daughter cells and one midbody remnant (MBR), a signaling organelle assembled from the midbody (MB), which first appears in Telophase. MBs contain transcription and translation factors, and epigenetic modifiers. Once MBs mature to MBRs by abscission, they can be subsequently phagocytosed by another cell and influence cellular function or fate. Although the significance of MBs is elucidated in several cell types like neurons, cancer cells and stem cells, the presence and function of MBs in gametes and their roles in reproductive fitness are unknown. Here, we examined the formation and regulation of meiotic midbodies (mMB) in mouse oocytes. We find that although mouse oocyte mMBs contain analogous structures to somatic MBs, they also have a unique cap-like structure composed of the centralspindlin complex, and that cap formation depends upon an asymmetric microtubule abundance in the egg compared to the polar body. Furthermore, our results show that mMBs are translationally active ribonucleoprotein granules, supported by detection of ribosomes, polyadenylated mRNAs and nascent translation. Finally, by pharmacological and laser ablation-based approaches, we demonstrate that the mMB cap is a barrier to prevent translated products from leaving the egg and escaping into the polar body. Crucially, this barrier is critical for successful early embryonic development. Here, we document an evolutionary adaptation to the highly conserved process of cytokinesis in mouse oocytes and describe a new structure and new mechanism by which egg quality and embryonic developmental competence are regulated.

cell biology↗

bioRxiv2020

Fate of the M-phase-assembled centrioles during the cell cycle in the TP53;PCNT;CEP215-deleted cells

Cancer cells frequently include supernumerary centrioles. Here, we generated TP53;PCNT;CEP215 triple knockout cell lines and observed precocious separation and amplification of the centrioles at M phase. Many of the triple KO cells maintained supernumerary centrioles throughout the cell cycle. The M-phase-assembled centrioles lack an ability to function as templates for centriole assembly during S phase. They also lack an ability to organize microtubules in interphase. However, we found that a fraction of them acquired an ability to organize microtubules during M phase. Our works provide an example how supernumerary centrioles behave in dividing cells.

cell biology↗