• BMB Reports
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• 제47권9호
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• pp.518-523
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• 2014

The maternal transcription factor Dorsal (Dl) functions as both an activator and a repressor in a context-dependent manner to control dorsal-ventral patterning in the Drosophila embryo. Previous studies have suggested that Dl is an intrinsic activator and its repressive activity requires additional corepressors that bind corepressor-binding sites near Dl-binding sites. However, the molecular identities of the corepressors have yet to be identified. Here, we present evidence that Capicua (Cic) is involved in Dl-mediated repression in the zerkn$\ddot{u}$llt (zen) ventral repression element (VRE). Computational and genetic analyses indicate that a DNA-binding consensus sequence of Cic is highly analogous with previously identified corepressor-binding sequences and that Dl failed to repress zen expression in lateral regions of cic mutant embryos. Furthermore, electrophoretic mobility shift assay (EMSA) shows that Cic directly interacts with several corepressor-binding sites in the zen VRE. These results suggest that Cic may function as a corepressor by binding the VRE.

• Molecules and Cells
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• 제41권9호
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• pp.842-852
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• 2018

Notch signaling is an evolutionarily conserved pathway and involves in the regulation of various cellular and developmental processes. Ligand binding releases the intracellular domain of Notch receptor (NICD), which interacts with DNA-bound CSL [CBF1/Su(H)/Lag-1] to activate transcription of target genes. In the absence of NICD binding, CSL down-regulates target gene expression through the recruitment of various corepressor proteins including SMRT/NCoR (silencing mediator of retinoid and thyroid receptors/nuclear receptor corepressor), SHARP (SMRT/HDAC1-associated repressor protein), and KyoT2. Structural and functional studies revealed the molecular basis of these interactions, in which NICD coactivator and corepressor proteins competitively bind to ${\beta}-trefoil$ domain (BTD) of CSL using a conserved ${\varphi}W{\varphi}P$ motif (${\varphi}$ denotes any hydrophobic residues). To date, there are conflicting ideas regarding the molecular mechanism of SMRT-mediated repression of CSL as to whether CSL-SMRT interaction is direct or indirect (via the bridge factor SHARP). To solve this issue, we mapped the CSL-binding region of SMRT and employed a 'one- plus two-hybrid system' to obtain CSL interaction-defective mutants for this region. We identified the CSL-interaction module of SMRT (CIMS; amino acid 1816-1846) as the molecular determinant of its direct interaction with CSL. Notably, CIMS contains a canonical ${\varphi}W{\varphi}P$ sequence (APIWRP, amino acids 1832-1837) and directly interacts with CSL-BTD in a mode similar to other BTD-binding corepressors. Finally, we showed that CSL-interaction motif, rather than SHARP-interaction motif, of SMRT is involved in transcriptional repression of NICD in a cell-based assay. These results strongly suggest that SMRT participates in CSL-mediated repression via direct binding to CSL.

• 한국응용곤충학회:학술대회논문집
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• 한국응용곤충학회 2002년도 추계 합동 특강 및 학술발표대회
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• pp.28-28
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• 2002

• 한국자기공명학회논문지
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• 제2권1호
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• pp.33-40
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• 1998

The cross peak intensities versus mixing times of 2D NOESY spectrum for a corepressor L-trp were simulated for the case of a ligand exchanging between free (AX) and bound (A'X') forms in protein/DNA complex. The direct NOE (I(AX)) of the free ligand exhibited a small positive intensity indicative of the strong dominant influence of the bound ligand. The exchange-mediated NOE peak (I(AX')) was very sensitive to corepressor exchange. However, both diagonal (I(A'A')) and direct NOE (I(A'X')) intensities of the bound ligand were not affected much at initial stage. Both peaks were severely influenced by exchange at mixing times of greater than 100 ms. In conclusion, since the NOE intensity is a function of exchange rate, the exchange effect should be considered to properly extract accurate distance information for bound ligand in the presence of conformational exchange.

• Genomics & Informatics
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• 제9권3호
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• pp.93-101
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• 2011

The Hairless (HR ) gene regulates the expression of several target genes as a transcriptional corepressor of nuclear receptors. The hair follicle (HF), a small independent organ of the skin, resides in the epidermis and undergoes regenerative cycling for normal hair formation. HF development requires many genes and signaling pathways to function properly in time and space, one of them being the HR gene. Various mutations of the HR gene have been reported to cause the hair loss pheno-type in rodents and humans. In recent studies, it has been suggested that the HR gene is a critical player in the regulation of the hair cycle and, thus, HF development. Furthermore, the HR gene is associated with the Wnt signaling pathway, which regulates proliferation and differentiation of cells and plays an essential role in hair and skin development. In this review, we summarize the mutations responsible for human hair disorders and discuss the roles of the HR gene in HF development.

• 생명과학회지
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• 제28권7호
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• pp.765-771
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• 2018

$PPAR{\gamma}$는 지방세포의 분화를 조절하는 핵심적인 전사 인자로서 이를 조절하는 후성유전학적 조절 기전이 비만억제 연구에서 중요하게 주목 받고 있다. 선행연구에서 CACUL1이 $PPAR{\gamma}$의 전사 활성 및 지방세포의 분화를 억제하는 corepressor로서 작용함을 밝힌 바 있으며 본 연구에서는 CACUL1의 새로운 결합 단백질로 발굴된 protein arginine methyltransferase 5 (PRMT5)의 $PPAR{\gamma}$ 조절 기능을 분석하였다. PRMT5가 CACUL1과 결합함을 immunoprecipitation assay in vivo와 GST-pull down assay in vitro를 통하여 확인하였다. Luciferase reporter assay 결과로 두 단백질이 상호 협력하여 $PPAR{\gamma}$의 전사 활성을 억제함을 확인하였다. PRMT5가 안정적으로 과발현 또는 knockdown되는 3T3-L1 세포주를 제작하여 지방세포 분화에 미치는 영향을 분석한 결과, PRMT5가 3T3-L1세포의 지방세포 분화를 억제함을 증명하였다. 같은 맥락으로 PRMT5는 $PPAR{\gamma}$의 타겟 유전자인 Lpl과 aP2의 발현을 억제하는 것을 RT-qPCR로 확인하였다. 이상의 연구 결과로 PRMT5이 CACUL1과 결합하여 $PPAR{\gamma}$의 전사 활성을 방해, 나아가 지방세포의 분화를 억제하는 기존에 알려지지 않은 분자적 기전을 처음으로 밝혔다. 따라서, PRMT5 효소 활성의 조절은 비만 억제를 위한 약물 개발에 단서를 제공할 것이다.

• Molecules and Cells
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• 제44권1호
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• pp.1-12
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• 2021

The nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ) is the master transcriptional regulator in adipogenesis. PPARγ forms a heterodimer with another nuclear receptor, retinoid X receptor (RXR), to form an active transcriptional complex, and their transcriptional activity is tightly regulated by the association with either coactivators or corepressors. In this study, we identified T-cell death-associated gene 51 (TDAG51) as a novel corepressor of PPARγ-mediated transcriptional regulation. We showed that TDAG51 expression is abundantly maintained in the early stage of adipogenic differentiation. Forced expression of TDAG51 inhibited adipocyte differentiation in 3T3-L1 cells. We found that TDAG51 physically interacts with PPARγ in a ligand-independent manner. In deletion mutant analyses, large portions of the TDAG51 domains, including the pleckstrin homology-like, glutamine repeat and proline-glutamine repeat domains but not the proline-histidine repeat domain, are involved in the interaction with the region between residues 140 and 506, including the DNA binding domain, hinge, ligand binding domain and activation function-2 domain, in PPARγ. The heterodimer formation of PPARγ-RXRα was competitively inhibited in a ligand-independent manner by TDAG51 binding to PPARγ. Thus, our data suggest that TDAG51, which could determine adipogenic cell fate, acts as a novel negative regulator of PPARγ by blocking RXRα recruitment to the PPARγ-RXRα heterodimer complex in adipogenesis.

• Journal of Ginseng Research
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• 제48권1호
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• pp.89-97
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• 2024

Background: Ginsenoside F2 (GF2), the protopanaxadiol-type constituent in Panax ginseng, has been reported to attenuate metabolic dysfunction-associated steatotic liver disease (MASLD). However, the mechanism of action is not fully understood. Here, this study investigates the molecular mechanism by which GF2 regulates MASLD progression through liver X receptor (LXR). Methods: To demonstrate the effect of GF2 on LXR activity, computational modeling of protein-ligand binding, Time-resolved fluorescence resonance energy transfer (TR-FRET) assay for LXR cofactor recruitment, and luciferase reporter assay were performed. LXR agonist T0901317 was used for LXR activation in hepatocytes and macrophages. MASLD was induced by high-fat diet (HFD) feeding with or without GF2 administration in WT and LXRα^-/- mice. Results: Computational modeling showed that GF2 had a high affinity with LXRα. LXRE-luciferase reporter assay with amino acid substitution at the predicted ligand binding site revealed that the S264 residue of LXRα was the crucial interaction site of GF2. TR-FRET assay demonstrated that GF2 suppressed LXRα activity by favoring the binding of corepressors to LXRα while inhibiting the accessibility of coactivators. In vitro, GF2 treatments reduced T0901317-induced fat accumulation and pro-inflammatory cytokine expression in hepatocytes and macrophages, respectively. Consistently, GF2 administration ameliorated hepatic steatohepatitis and improved glucose or insulin tolerance in WT but not in LXRα^-/- mice. Conclusion: GF2 alters the binding affinities of LXRα coregulators, thereby interrupting hepatic steatosis and inflammation in macrophages. Therefore, we propose that GF2 might be a potential therapeutic agent for the intervention in patients with MASLD.

• 생명과학회지
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• 제30권2호
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• pp.211-220
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• 2020

CAR의 활성은 리간드 결합 뿐만 아니라, 세포외신호전달 경로를 통한 관련 조절인자들의 인산화, 전사 조절인자들과의 상호작용, 그리고 coactivators 및 corepressors의 동원, 분해 및 발현 등에 의해 조절되며, 이러한 CAR의 활성 조절은 또한 외인성 화학물질과 에너지 대사, 세포의 증식 및 사멸을 포함한 다양한 생리적 항상성 조절에 영향을 미친다. CAR는 ERK1/2의 신호전달경로에 의해 인산화되어 Hsp-90/CCRP와 복합체를 형성하여 세포질 내에 잔류하는 반면, PB는 ERK1/2를 억제하여 downstream 신호전달 조절인자들의 탈인산화를 유발하고, 활성화된 RACK-1/PP2A를 동원하여 CAR를 탈인산화 함으로써 핵 이동 및 전사 활성을 유도한다. CAR의 활성은 FoxO1 및 PGC-1α와의 cross-talk을 통하여 각각 전사 활성 억제와 ubiquitination을 통한 단백질 분해를 유도하여 당합성과정에 관여하는 PEPCK 및 G6Pase 유전자의 발현을 억제한다. CAR에 의한 지방의 합성과 산화 조절은 각각 PPARγ 및 PPARα와의 cross-talk에 의한 PGC-1α의 분해와 CPT-1의 발현 억제 또는 PGC-1α와의 결합을 통해 지방 합성 유전자의 발현 억제와 조직 특이적 산화 억제 또는 촉진으로 이루어진다. CAR는 FoxO1의 억제를 통한 p21의 발현 억제와 cyclin D1의 발현을 유도하여 세포 증식을 촉진하는 반면, GADD45B의 발현을 통한 MKK7과 JNK1의 활성을 억제하여 세포 사멸을 억제한다. 결론적으로, CAR는 세포외신호전달 경로와 세포내 조절인자들과의 다양한 상호작용을 통하여 외인성 화학물질의 대사뿐만 아니라 에너지 대사 및 세포의 성장과 사멸의 조절을 통한 항상성 유지에 관여한다.

• 생명과학회지
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• 제21권2호
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• pp.242-250
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• 2011

본 연구에서는 C2C12 근육 세포에서 IGF-I이 리간드 비의존적으로 엔드로젠 수용체 coactivator 유전자 발현에 미치는 영향에 대해 알아보았다. 그 결과 IGF-I 이 리간드 비의존적으로 엔드로젠 수용체의 coactivator인 GRIP-1, SRC-1, ARA70 유전자들의 단백질과 mRNA 발현을 증가시켰으며, p38 MAPK와 ERK1/2 신호전달 경로 억제제인 SB203580과 PD98059를 IGF-I과 함께 처리한 결과 IGF-I에 의한 엔드로젠 수용체 coactivator 유전자 발현의 증가를 감소시켰음을 알 수 있었다. 엔드로젠 수용체 coactivator가 엔드로젠 물질이 없이도 IGF-I에 의해 발현이 증가하였다는 사실은 운동에 의해 근육에서 분비가 증가하는 IGF-I이 리간드 비의존적으로 근육 세포에서 엔드로젠 수용체 활성화 안정에 기여하는 엔드로젠 수용체 coactivator를 활성화 시킬 수 있다는 사실을 증명 하였다는데 의의가 있다고 사료된다. 또한, IGF-I의 하부신호전달 경로로 잘 알려진 p38 MAPK와 ERK1/2 신호전달 경로를 차단하였을 때는 발현이 억제되었는데 이를 통해 IGF-I이 근육세포 내에서 p38 MAPK, ERK1/2 경로를 통해 엔드로젠 수용체 coactivator 발현에 중요한 역할을 한다는 사실을 확인할 수 있었다. 이러한 결과는 근육에서 중요한 기능을 담당하는 IGF-I이 엔드로젠 수용체 coactivator 유전자 발현을 조절하는 기능이 있으며 이러한 IGF-I에 의한 리간드 비의존적인 엔드로젠 수용체 coactivator 유전자 발현 조절에 있어 p38 MAPK와 ERK1/2는 필수적인 신호전달 경로임을 확인하였다는 데서 그 의의가 있다고 할 수 있겠다. 향후 다양한 성장인자들에 의한 coactivator 발현에 관한 연구를 비롯하여, corepressor의 발현 억제 기능 및 신호전달 경로에 관한 연구가 추가적으로 이루어져야 할 것이다.