새 정부에 바란다 - 국가 경쟁력은 기초연구 육성에서

서판길,Seo, Pan-Gil 한국과학기술단체총연합회 2013 과학과 기술 Vol.526 No.-

지방세포의 Lipid Raft/Caveolae에서 인슐린의 분자적 작용기전

서판길,배순식,윤성지,김은경,김치대,최장현 한국생명과학회 2007 생명과학회지 Vol.17 No.2

Insulin stimulates the fusion of intracellular vesicles containing glucose transporter 4 (GLUT4) with plasma membrane in adipocytes and muscle cells. Here we show that adipocyte differentiation results in enhanced insulin sensitivity of glucose uptake. On the other hand, glucose uptake in response to platelet-derived growth factor (PDGF) stimulation was markedly reduced by adipocyte differentiation. Expression level of insulin receptor and caveolin-1 was dramatically increased during adipocyte differentiation. Adipocyte differentiation caused slightly enhanced activation of acutely transforming retrovirus AKT8 in rodent T cell lymphoma (Akt) by insulin stimulation. However, activation of Akt by PDGF stimulation was largely reduced. Activation of ERK was not detected in both fibroblasts and adipocytes after stimulation with insulin. PDGF-dependent activation of ERK was reduced by adipocyte differentiation. Insulin-dependent glucose uptake was abrogated by LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor, in both fibroblasts and adipocytes. Also disassembly of caveolae structure by methyl-β-cyclodextrin caused impairment of Akt activation and glucose uptake. Finally, insulin receptor, Akt, SH2-domain-containing inositol 5-phosphatase 2 (SHIP2), and regulatory subunit of PI3K are localized at lipid raft domain and the translocation was facilitated upon insulin stimulation. Given these results, we suggest that lipid raft provide proper site for insulin action for glucose uptake. 인슐린은 지방세포 또는 근육세포에서 포도당 흡수 조절 통로단백질이 함유되어 있는 소포제를 세포막으로의 이동을 촉진시킨다. 우리는 여기서 지방세포로의 분화는 인슐린에 의한 포도당 흡수에 대한 반응이 증가됨을 보였다. 반면에 지방세포로의 분화는 PDGF에 의한 포도당 흡수 반응이 감소됨을 보였다. 인슐린 수용체나 caveolae는 지방세포로의 분화과정 동안 발현이 증가된다. 또한 지방세포로의 분화는 인슐린에 의한 Akt의 활성을 증가시켰다. 하지만 PDGF에 의한 Akt의 활성은 크게 감소하였다. 하지만 인슐린은 지방세포 또는 섬유아 전구세포에서 ERK의 활성을 유도하지 않았다. PDGF에 의한 ERK 활성 또한 지방세포로의 분화과정에 따라 감소하였다. P13K의 저해제인 LY294002는 지방세포 뿐만 아니라 섬유아 전구세포에서 인슐린에 의한 포도당 흡수를 저해하였다. 마지막으로 인슐린 수용체, Akt, SHIP2, p85등이 lipid raft/caveolae에 존재함을 확인하였고 인슐린에 의해 이런 단백질 들이 lipid raft/caveolae로 이동함을 관찰하였다. 이런 결과를 토대로 lipid raft는 포도당 흡수를 위한 인슐린의 기능적 작용을 하는데 매우 중요한 환경을 제공함을 주장한다.

NHERF2 functions as linker between LPA receptor(EDG-4) and phospholipase C-β3

서판길,류성호,오용석,서상원 이화여자대학교 세포신호전달연구센터 2003 고사리 세포신호전달 심포지움 Vol. No.5

The lysophospholipid(LPL) such as lysophosphatidic acid(LPA), sphingosine-1-phosphate(SIP), and sphingosyl phosphoryl choline(SPC) are generated enzymatically from membrane lipid precursors in many different types of normal and malignant cells. Among them, LPA has been known to contribute to the regulation of physiological and pathophysiological processes including cell proliferation, angiogenesis, tumor initiation, and cancer development. LPA binds to and activates G-protein coupled receptors, encoded by endothelial differentiation genes 2, 4, 7(edg-2, -4, -7). Three isoforms of LPA receptors are differentially coupled to a variety of intracellular signals, which is responsible for distinct physiological roles. However, little is known about the molecular mechanism underlying the differential coupling to downstream signaling and the regulation of respective receptors. In this study, we show that EDG-4 interacts with Na^(+)/H^(+) exchanger regulatory factor 2(NHERF2) in a PDZ(PSD-95/D1g/Z0-1 homology) domain-dependent manner. Biochemical studies demonstrates that NHERF2 binds specifically with EDG-4, but not with the other LPA receptor isoforms such as EDG-2 and -7. In addition, EDG4 prefers NHERF2 over NHERF1. This interaction depends on both carboxy-terminal DSTL motif of EDG-4 and the second PDZ domain of NHERF2. In HeLa, endogenously expressing NHERF2, LPA-induced PLC-β activation was significantly attenuated by not only the mutation in the PDZ binding motif of EDG-4 but also the knock-down of NHERF2 using small interference RNA(siRNA) technology. Conversely, over-expression of NHERF2 potentiates LPA-induced phospholipase Cβ-mediated signaling events such as IP3-dependent Ca^(2+) mobilization and DAG-dependent PKC activation in Rat-1 cells, which leads to downstream mitogenic signaling such as ERK activation and COX-2 induction. Furthermore, overexpression of wild-type NHERF2 markedly facilitates LPA-induced cell proliferation, but not its second PDZ domain deletion mutant. PLC-β3 was previously shown to be another binding partner of NHERF2(Hwang, J.I. et al, J. Biol. Chem. 275, pp16632-16637). Here we present evidence that NHERF2 functions as molecular scaffold for efficient coupling between EDG4 and PLC-β3. Our results suggest that complex of EDG4, NHERF2, and PLC-β3 playa pivotal role in the organization and modulation of LPA-induced mitogenic signaling.

유용 리간드의 발굴 및 응용

서판길 한국생물공학회 2009 한국생물공학회 학술대회 Vol.2009 No.10

Off-regulation of phospholipase C-γ1-mediated signal transduction

서판길 이화여자대학교 세포신호전달연구센터 2007 고사리 세포신호전달 심포지움 Vol. No.9

Phospholipase C-γ1(PLC-γ1) plays pivotal roles in cellular growth and proliferation through its two Src homology (SH)2 and single SH3 domains, which interact with signaling molecules stimulated by various growth factors and hormones. Upon the stimulation of growth factors, PLC-γ1 is rapidly phosphorylated at three known sites; Tyr^(771), Tyr^(783) and Tyr^(1254) and its enzymatic activity is up-regulated. After activation signaling, the target cells undergo a process of inactivation or off-regulation, which a cell reversibly adjusts its sensitivity to the stimuli. Although it has been well known how PLC-γ1 is activated by growth factors treatment, it has been still unclear how PLC-γ1 might be negatively regulated. We have studied the off-regulation mechanism of PLC-γ1-mediated signal transduction through protein-protein interaction. We demonstrate that PLC-γ1 modulate the action of growth hormone (GH)-mediated signaling through the direct interaction with the tyrosine kinase JAK2. While the activation of GH-mediated signaling is well understood, the precise mechanism responsible for its regulation has not been well assessed. In this study, we demonstrate that GH-induced JAK2 and STAT5 phosphorylations significantly increased in PLC-γ1^(-/-) MEFs and the re-expression of PLC-γ1 reduced GH-induced Jak2 activation. Furthermore, GH-induced JAK2 phosphorylation was enhanced by the specific knockdown of PLC-γ1 using siRNA. Interestingly, PLC-γ1 physically linked Jak2 with protein tyrosine phosphatase-1B(PTP-1B), which was implicated in the modulation of cytokine signaling via Jak2. In PLC-γ1^(-/-) MEFs, GH-dependent activation of both STAT-5 and c-Fos were up-regulated, and GH-induced proliferation was potentiated. These results suggest that PLC-γ1 plays a key role in regulation of GH-mediated signaling by attenuating the activation of JAK2. To further characterize physiological roles of PLC-γ1 on GH-mediated signaling, we generate conditional knock-out and knock-in mice for PLC-γ1. From mutational studies, we observed that the SH2 and SH3 domains of PLC-γ1 is essential for the interaction with Jak2 and PTP-1B, reciprocally. So, using knock-in mice introducing mutants of SH2 or SH3 domains, we will get the physiological insights for novel functions of PLC-γ1 on GH-mediated signaling.

생화학 논단 : Phospholipase D 의 최근 연구 동향

서판길,류성호,이영한 한국생화학분자생물학회 (구 한국생화학회) 1994 생화학분자생물학회 소식 Vol.14 No.5

Phospholipase C-γ1 유전자의 발현

서판길 암연구센터 1993 암연구의최신지견 Vol.1993 No.-

BMB Reports Review : Differential roles of Phosphoinositides-Phospholipase C(PI-PLC) Isozymes

서판길 한국생화학분자생물학회 (구 한국생화학회) 2008 생화학분자생물학회 소식 Vol.28 No.2

산학협력단의 성공적 운영 사례

서판길,Seo, Pan-Gil 한국대학교육협의회 2005 大學敎育 Vol.137 No.-

Phospholipase C mediated signal transduction

서판길 忠北大學校 遺傳工學硏究所 1995 遺傳工學硏究 Vol.9 No.1