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Roles of actin binding proteins in mammalian oocyte maturation and beyond
Suk Namgoong 한국수정란이식학회 2016 한국수정란이식학회 학술대회 Vol.2016 No.10
Actin nucleation factors, which promote the formation of new actin filaments, have emerged in the last decade as key regulatory factors controlling asymmetric division in mammalian oocytes. Actin nucleators such as formin-2, spire, and the ARP2/3 complex have been found to be important regulators of actin remodeling during oocyte maturation. We found that actin nucleation promoting factor called WASP homolog-associated protein with actin, membranes and microtubules (WHAMM) play crucial roles in mouse oocyte maturation by generation of ER-associated actin filaments during meiotic spindle migrations. We also investigate regulatory mechanism of actin nucleator spire and discovered the novel roles of Zinc in regulating spire localization and cytoplasmic actin mesh formation. Another class of actin-binding proteins including cofilin, tropomyosin, capping proteins and tropomodulin, are thought to control actin cytoskeleton dynamics at various steps of oocyte maturation. The heterodimeric actin-capping protein (CP) binds to the fast-growing (barbed) ends of actin filaments and plays essential roles in various actin-mediated cellular processes. When CP is knockdowned or inhibitory component was overexpressed, asymmetric divisions of oocytes have been compromised. It turns out that knockdown or inhibition of CP deplete cytoplasmic actin mesh level, which have been known to be essential for maintain cytoplasmic actin mesh. Another actin binding proteins, tropomodulin 3 (Tmod3), binds to the slow-growing end of actin filaments and knockdown or expression deletion mutant of Tmod3 also decrease actin mesh level in maturing oocyte and it severely ablated asymmetric division of oocyte. Finally, tropomyosin 3, actin filament binding proteins protect actin filament from depolymerization, is also important to maintain cortex integrity in maturing oocyte, therefore showed the importance maintenance of actin filaments during oocyte maturation. Taken together, our study on various actin nucleator and actin binding study showed the importance of actin dynamics in mammalian oocyte maturation and early embryonic developments.
Roles of actin binding proteins in mouse oocyte maturation
Suk Namgoong 한국발생생물학회 2015 한국발생생물학회 학술발표대회 Vol.2015 No.9
Dynamic reorganization of actin filaments is essential for various stages of mammalian oocyte maturation, including spindle migration, actin cap formation, polar body extrusion, and cytokinesis. Various actin binding proteins (ABPs) have been known to be involved in the regulation of actin filament remodeling. We elucidate roles of three different actin binding proteins in mouse oocyte maturation. The heterodimeric actin-capping protein (CP) binds to the fast-growing(barbed) ends of actin filaments and plays essential roles in various actin-mediated cellular processes. When CP is knockdowned or inhibitory component was overexpressed, asymmetric division of oocyte have been compromised. It turns out that knockdown or inhibition of CP deplete cytoplasmic actin mesh level, which have been known to be essential for maintain cytoplasmic actin mesh. Another actin binding proteins, tropomodulin 3 (Tmod3), binds to the slow-growing end of actin filaments and knockdown or expression deletion mutant of Tmod3 also decrease actin mesh level in maturing oocyte and it severely ablated asymmetric division of oocyte. Finally, tropomyosin 3, actin filament binding proteins protect actin filament from depolymerization, is also important to maintain cortex integrity in maturing oocyte. Taken together, these finding showed the essential roles of actin binding proteins in remodeling of actin filaments in mammalian oocyte development.
Roles of actin binding proteins in mammalian oocyte maturation and beyond
Namgoong, Suk,Kim, Nam-Hyung Informa UK (TaylorFrancis) 2016 Cell Cycle Vol.15 No.14
<P>Actin nucleation factors, which promote the formation of new actin filaments, have emerged in the last decade as key regulatory factors controlling asymmetric division in mammalian oocytes. Actin nucleators such as formin-2, spire, and the ARP2/3 complex have been found to be important regulators of actin remodeling during oocyte maturation. Another class of actin-binding proteins including cofilin, tropomyosin, myosin motors, capping proteins, tropomodulin, and Ezrin-Radixin-Moesin proteins are thought to control actin cytoskeleton dynamics at various steps of oocyte maturation. In addition, actin dynamics controlling asymmetric-symmetric transitions after fertilization is a new area of investigation. Taken together, defining the mechanisms by which actin-binding proteins regulate actin cytoskeletons is crucial for understanding the basic biology of mammalian gamete formation and pre-implantation development.</P>
EVS/jORB/Electronic Voting Systems Based on Java and CORBA
Choi, Han Suk,Seo, Jae Hyun,Cho, Sung Eue,Han, Namgoong CHOSUN UNIVERSITY 1997 Basic Science and Engineering Vol.1 No.2
We propose a secure electronic voting protocol, called the Secure Absentee Voting Protocol(SAVT) which guarantees a set of core design goals of electronic voting system such as voter's privacy, democracy, accuracy, and verifiability. Then this paper present the design and implementation of an Electronic Voting Systems based on Java and CORBA(EVS/jORB). This EVS/jORB proposed in this paper consists of four major components; voter's agent, authentication server, validatio server, and tallying server.
Filamin A is required for Spindle Migration and Asymmetric Division in Mouse Oocytes
HaiYang Wang,Suk Namgoong,Jeong Su Oh,Nam-Hyung Kim 한국동물생명공학회(구 한국동물번식학회) 2017 Reproductive & Developmental Biology(Supplement) Vol.41 No.2
Dynamic changes in the actin network are crucial for the cortical migration of spindle and establishment of polarity to ensure asymmetric division during meiotic maturation. Here, we show that Filamin A (FLNA) is an essential actin regulator that controls 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 with a decrease in the amount of cytoplasmic actin mesh and cortical actin levels. Moreover, FLNA knockdown reduced the phosphorylation of Cofilin and Rho kinase (ROCK) near the spindle. Similar phenotypes such as decreased filament actin levels, impaired spindle migration and polar body extrusion were observed when active Cofilin (S3A) was overexpressed or ROCK was inhibited. Notably, we found that FLNA and ROCK interacted directly in mouse oocytes. Taken together, our results show that FLNA plays crucial roles in asymmetric division during meiotic maturation by regulating ROCK-Cofilin-mediated actin reorganization.
Jung-Man Namgoong,Jin-Uk Choi,Shin Hwang,Suk-Hee Oh,Gil-Chun Park 한국간담췌외과학회 2019 Annals of hepato-biliary-pancreatic surgery Vol.23 No.2
Replacement of the retrohepatic inferior vena cava (IVC) after concurrent resection of IVC and hepatocellular carcinoma-containing liver is settled as a feasible living donor liver transplantation (LDLT) technique to cope with tumors around the IVC. This technique makes LDLT comparable to deceased-donor liver transplantation (DDLT). In the current Korean setting, the common substitute for IVC is a Dacron graft for adult recipients. In contrast, such a synthetic graft cannot be used for pediatric patients because of ongoing growth. We present one pediatric LDLT case with IVC homograft replacement for advanced hepatoblastoma. The patient was a 8 year-old boy suffering from large multiple hepatoblastomas. The tumors encroached the retrohepatic IVC. Thus there was high risk of residual tumor cells at the IVC, if it was preserved. Thus, we decided to replace IVC at the time of LDLT. After waiting for >1 month, we finally obtained cold-stored IVC homograft and LDLT was performed with the mother’s left liver. A 4 cm-long IVC allograft was anastomosed at the back table. The left liver graft with IVC interposition was implanted along standard procedure similar to DDLT. The patient recovered uneventfully and is undergoing scheduled adjuvant chemotherapy. We have performed >20 cases of IVC replacement in adult recipients with hepatocellular carcinoma or Budd-Chiari syndrome, but all vessel substitutes were synthetic, because sizable IVC homograft is unavailable. In pediatric recipients, various vein homografts such as iliac vein, IVC and other large-sized veins, can be used depending on body size of recipient and availability of vessel grafts.