Sungkyunkwan University · Biochemistry, Genetics and Molecular Biology
Professor Jeong Su Oh's research lab focuses on cell cycle regulation, particularly the molecular mechanisms governing meiotic arrest and resumption in mammalian oocytes. The lab investigates key regulators such as Cdc2-cyclin B (MPF), Wee1/Myt1 kinases, Cdc25 phosphatases, and cyclin degradation pathways that control cell cycle transitions. A central theme is the role of post-translational modifications—especially phosphorylation—by kinases like CaMKII and Cdk1 in coordinating cell cycle progression and DNA damage response. The lab also explores how signaling molecules such as melatonin and proteins like synGAP modulate cellular fate in oocytes and neurons, with implications for fertility and neuroprotection.
Figures are computed from collected data and may differ slightly.
After a long period of quiescence at dictyate prophase I, termed the germinal vesicle (GV) stage, mammalian oocytes reenter meiosis by activating the Cdc2-cyclin B complex (maturation-promoting factor [MPF]). The activity of MPF is regulated by Wee1/Myt1 kinases and Cdc25 phosphatases. In this study, we demonstrate that the sequestration of components that regulate MPF activity in distinct subcellular compartments is essential for their function during meiosis. Down-regulation of either Wee1B or
Waves of cyclin synthesis and degradation regulate the activity of Cdc2 protein kinase during the cell cycle. Cdc2 inactivation by Wee1B-mediated phosphorylation is necessary for arrest of the oocyte at G2-prophase, but it is unclear whether this regulation functions later during the metaphase-to-anaphase transition. We show that reactivation of a Wee1B pathway triggers the decrease in Cdc2 activity during egg activation. When Wee1B is down-regulated, oocytes fail to form a pronucleus in respons
synGAP is a neuron-specific Ras GTPase-activating protein found in high concentration in the postsynaptic density fraction from mammalian forebrain. Proteins in the postsynaptic density, including synGAP, are part of a signaling complex attached to the cytoplasmic tail of the N-methyl-d-aspartate-type glutamate receptor. synGAP can be phosphorylated by a second prominent component of the complex, Ca(2+)/calmodulin-dependent protein kinase II. Here we show that phosphorylation of synGAP by Ca(2+)
Mammalian oocytes are arrested in metaphase of second meiosis (MII) until fertilization. This arrest is enforced by the cytostatic factor (CSF), which maintains the M-phase promoting factor (MPF) in a highly active state. Although the continuous synthesis and degradation of cyclin B to maintain the CSF-mediated MII arrest is well established, it is unknown whether cyclin-dependent kinase 1 (Cdk1) phosphorylations are involved in this arrest in mouse oocytes. Here, we show that a dynamic equilibr
Mammalian oocytes remain arrested at the first prophase of meiosis in ovarian follicles for an extended period. During this protracted arrest, oocytes are remarkably susceptible to the accumulation of DNA damage. Melatonin (N-acetyl-5-methoxytryptamine), a hormone secreted by the pineal gland, has diverse effects on various physiological processes. However, the effect of melatonin on DNA damage response in mammalian oocytes has not been explored. Here, we showed that melatonin protected mouse oo
Our data suggested that MASTL inhibition promoted mitotic catastrophe through PP2A activation, which led to the inhibition of cancer cell growth and a reversal of radioresistance in breast cancer cells.
Although MASTL (microtubule-associated serine/threonine kinase-like) is an attractive target for anticancer treatment, MASTL inhibitors with antitumor activity have not yet been reported. In this study, we have presented a novel MASTL inhibitor, MKI-1, identified through <i>in silico</i> screening and <i>in vitro</i> analysis. Our data revealed that MKI-1 exerted antitumor and radiosensitizer activities in <i>in vitro</i> and <i>in vivo</i> models of breast cancer. The mechanism of action of MKI
Cytokinesis is the final step in cell division that results in the separation of a parent cell into daughter cells. Unlike somatic cells that undergo symmetric division, meiotic division is highly asymmetric, allowing the preservation of maternal resources for embryo development. Beclin-1/BECN1, the mammalian homolog of yeast Atg6, is a key molecule of autophagy. As part of a class III phosphatidylinositol 3-kinase (PI3K-III) complex, BECN1 initiates autophagosome formation by coordinating membr
Because DNA double-strand breaks (DSBs) greatly threaten genomic integrity, effective DNA damage sensing and repair are essential for cellular survival in all organisms. However, DSB repair mainly occurs during interphase and is repressed during mitosis. Here, we show that, unlike mitotic cells, oocytes can repair DSBs during meiosis I through microtubule-dependent chromosomal recruitment of the CIP2A-MDC1-TOPBP1 complex from spindle poles. After DSB induction, we observed spindle shrinkage and
Dynamic changes in the actin network are crucial for the cortical migration of spindles and establishment of polarity, to ensure asymmetric division during meiotic maturation. In this study, filamin A (FLNA) was found to be an essential actin regulator that controlled spindle migration and asymmetric division during oocyte meiosis. FLNA was localized in the cytoplasm and enriched at the cortex and near the chromosomes. Knockdown of FLNA impaired meiotic asymmetric division and spindle migration
Dynamic changes in microtubules during cell cycle progression are essential for spindle organization to ensure proper segregation of chromosomes. There is growing evidence that post translational modifications of tubulins are the key factors that contribute to microtubule dynamics. However, how dynamic properties of microtubules are regulated in mouse oocytes is unclear. Here, we show that tumor suppressor RASSF1A is required for tubulin acetylation by regulating SIRT2 and HDAC6 during meiotic m
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