• Journal of Microbiology and Biotechnology
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• 제25권10호
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• pp.1640-1647
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• 2015

We recently reported that the antimicrobial peptide Lumbricusin (NH₂-RNRRWCIDQQA), isolated from the earthworm, increases cell proliferation in neuroblastoma SH-SY5Y cells. Here, we investigated whether Lumbricusin has neurotropic activity in mouse neural stem cells (MNSCs) and a protective effect in a mouse model of Parkinson's disease (PD). In MNSCs isolated from mouse brains, Lumbricusin treatment significantly increased cell proliferation (up to 12%) and reduced the protein expression of p27^Kip1 through proteasomal protein degradation but not transcriptional regulation. Lumbricusin inhibited the 6-OHDA-induced apoptosis of MNSCs, and also showed neuroprotective effects in a mouse PD model, ameliorating the motor impairments seen in the pole, elevated body swing, and rotation tests. These results suggest that the Lumbricusin-induced promotion of neural cell proliferation via p27^Kip1 degradation has a protective effect in an experimental PD model. Thus, the antimicrobial peptide Lumbricusin could possibly be developed as a potential therapeutic agent for the treatment of PD.

• Journal of Plant Biotechnology
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• 제48권2호
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• pp.106-114
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• 2021

본 연구에서는 갈매나무과에 속하는 Rhamnus yoshinoi (RY, 짝자래나무) 가지 부위의 70% 에탄올 추출물을 이용하여 전립선암세포의 항암 활성을 규명하고자 하였다. 짝자래 나무 가지 추출물을 전립선암 세포 PC-3에 처리하여 β-catenin과 TCF4의 단백질 수준 감소를 확인하였다. 이후, β-catenin과 TCF4의 mRNA 발현을 조사한 결과 β-catenin은 감소하지 않았고, TCF4는 감소하였다. 이를 통해, β-catenin mRNA의 발현에는 영향이 없지만, TCF4 mRNA 발현은 억제하는 것으로 나타났다. 단백질 분해효소억제제인 MG132를 처리한 전립선암 세포 PC-3에서 단백질 수준 확인을 통해 β-catenin의 단백질 분해를 유도할 수 있음을 확인하였다. 또한 전립선암 세포 PC-3에서 짝자래나무 가지 추출물의 GSK-3β 유도 β-catenin 단백질 분해 Kinase 구명과 β-catenin 인산화에 영향을 미치는 것을 확인하였다. 이상의 연구 결과로 짝자래나무 가지 추출물은 GSK-3β 의존성 Wnt/β-catenin 단백질의 분해를 통해 전립선암의 생육 억제와 관련이 있는 것으로 확인된다. 또한 짝자래나무 가지 추출물에서 항암활성과 관련된 활성물질이 있는 것으로 확인되었다. 본 결과는 전립선암의 항암제 개발을 위한 소재로 짝자래나무 가지 추출물의 활용이 가능할 것으로 판단된다.

• BMB Reports
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• 제42권9호
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• pp.552-560
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• 2009

Cyclooxygenases (COX-1 and COX-2) are ER-resident proteins that catalyze the committed step in prostanoid synthesis. COX-1 is constitutively expressed in many mammalian cells, whereas COX-2 is usually expressed inducibly and transiently. Abnormal expression of COX-2 has been implicated in the pathogenesis of chronic inflammation and various cancers; therefore, it is subject to tight and complex regulation. Differences in regulation of the COX enzymes at the posttranscriptional and posttranslational levels also contribute significantly to their distinct patterns of expression. Rapid degradation of COX-2 mRNA has been attributed to AU-rich elements (AREs) at its 3’UTR. Recently, microRNAs that can selectively repress COX-2 protein synthesis have been identified. The mature forms of these COX proteins are very similar in structure except that COX-2 has a unique 19-amino acid (19-aa) segment located near the C-terminus. This C-terminal 19-aa cassette plays an important role in mediation of the entry of COX-2 into the ER-associated degradation (ERAD) system, which transports ER proteins to the cytoplasm for degradation by the 26S proteasome. A second pathway for COX-2 protein degradation is initiated after the enzyme undergoes suicide inactivation following cyclooxygenase catalysis. Here, we discuss these molecular determinants of COX-2 expression in detail.

• Molecules and Cells
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• 제44권7호
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• pp.444-457
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• 2021

Although the mechanism of chronic myeloid leukemia (CML) initiation through BCR/ABL oncogene has been well characterized, CML cell differentiation into erythroid lineage cells remains poorly understood. Using CRISPR-Cas9 screening, we identify Chromobox 8 (CBX8) as a negative regulator of K562 cell differentiation into erythrocytes. CBX8 is degraded via proteasomal pathway during K562 cell differentiation, which activates the expression of erythroid differentiation-related genes that are repressed by CBX8 in the complex of PRC1. During the differentiation process, the serine/threonine-protein kinase PIM1 phosphorylates serine 196 on CBX8, which contributes to CBX8 reduction. When CD235A expression levels are analyzed, the result reveals that the knockdown of PIM1 inhibits K562 cell differentiation. We also identify TRIM28 as another interaction partner of CBX8 by proteomic analysis. Intriguingly, TRIM28 maintains protein stability of CBX8 and TRIM28 loss significantly induces proteasomal degradation of CBX8, resulting in an acceleration of erythroid differentiation. Here, we demonstrate the involvement of the CBX8-TRIM28 axis during CML cell differentiation, suggesting that CBX8 and TRIM28 are promising novel targets for CML research.

• Biomolecules & Therapeutics
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• 제23권4호
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• pp.339-344
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• 2015

Naringenin (NAR) as one of the flavonoids observed in grapefruit has been reported to exhibit an anti-cancer activity. However, more detailed mechanism by which NAR exerts anti-cancer properties still remains unanswered. Thus, in this study, we have shown that NAR down-regulates the level of cyclin D1 in human colorectal cancer cell lines, HCT116 and SW480. NAR inhibited the cell proliferation in HCT116 and SW480 cells and decreased the level of cyclin D1 protein. Inhibition of proteasomal degradation by MG132 blocked NAR-mediated cyclin D1 downregulation and the half-life of cyclin D1 was decreased in the cells treated with NAR. In addition, NAR increased the phosphorylation of cyclin D1 at threonine-286 and a point mutation of threonine-286 to alanine blocked cyclin D1 downregulation by NAR. p38 inactivation attenuated cyclin D1 downregulation by NAR. From these results, we suggest that NAR-mediated cyclin D1 downregulation may result from proteasomal degradation through p38 activation. The current study provides new mechanistic link between NAR, cyclin D1 downregulation and cell growth in human colorectal cancer cells.

• Journal of Ginseng Research
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• 제48권1호
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• pp.40-51
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• 2024

Background: Ginsenoside 20(S)-Rg3 shows promising tumor-suppressive effects in ovarian cancer via inhibiting NF-kB signaling. This study aimed to explore the downstream tumor suppressive mechanisms of ginsenoside Rg3 via this signaling pathway. Materials and methods: A systematical screening was applied to examine the expression profile of 41 kinesin family member genes in ovarian cancer. The regulatory effect of ginsenoside Rg3 on KIF20A expression was studied. In addition, we explored interacting proteins of KIF20A and their molecular regulations in ovarian cancer. RNA-seq data from The Cancer Genome Atlas (TCGA) was used for bioinformatic analysis. Epithelial ovarian cancer cell lines SKOV3 and A2780 were used as in vitro and in vivo cell models. Commercial human ovarian cancer tissue arrays were used for immunohistochemistry staining. Results: KIF20A is a biomarker of poor prognosis among the kinesin genes. It promotes ovarian cancer cell growth in vitro and in vivo. Ginsenoside Rg3 can suppress the transcription of KIF20A. GST pull-down and co-immunoprecipitation (IP) assays confirmed that KIF20A physically interacts with BTRC (β-TrCP1), a substrate recognition subunit for SCF^β-TrCP E3 ubiquitin ligase. In vitro ubiquitination and cycloheximide (CHX) chase assays showed that via interacting with BTRC, KIF20A reduces BTRC-mediated CDC25A poly-ubiquitination and enhances its stability. Ginsenoside Rg3 treatment partly abrogates KIF20A overexpression-induced CDC25A upregulation. Conclusion: This study revealed a novel anti-tumor mechanism of ginsenoside Rg3. It can inhibit KIF20A transcription and promote CDC25A proteasomal degradation in epithelial ovarian cancer.

• Bulletin of the Korean Chemical Society
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• 제34권5호
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• pp.1425-1428
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• 2013

The proteasome, which is highly evolutionarily conserved, is responsible for the degradation of most short-lived proteins in cells. Small-molecule inhibitors targeting the proteasome's degradative activity have been extensively developed as lead compounds for various human diseases. An exemplified molecule is bortezomib, which was approved by FDA in 2003 for the treatment of multiple myeloma. Here, using transiently and stably expressed N-end rule model substrates in mammalian cells, we evaluated and identified that salinosporamide A and salinosporamide B effectively inhibited the proteasomal degradation. Considering that a variety of proteasome substrates are implicated in the pathogenesis of many diseases, they have the potential to be clinically applicable as therapeutic agents.

• BMB Reports
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• 제51권3호
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• pp.143-150
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• 2018

The Hippo signaling pathway plays an essential role in adult tissue homeostasis and organ size control. Abnormal regulation of Hippo signaling can be a cause for multiple types of human cancers. Since the awareness of the importance of the Hippo signaling in a wide range of biological fields has been continually grown, it is also understood that a thorough and well-rounded comprehension of the precise dynamics could provide fundamental insights for therapeutic applications. Several components in the Hippo signaling pathway are known to be targeted for proteasomal degradation via ubiquitination by E3 ligases. ${\beta}-TrCP$ is a well-known E3 ligase of YAP/TAZ, which leads to the reduction of YAP/TAZ levels. The Hippo signaling pathway can also be inhibited by the E3 ligases (such as ITCH) which target LATS1/2 for degradation. Regulation via ubiquitination involves not only complex network of E3 ligases but also deubiquitinating enzymes (DUBs), which remove ubiquitin from its targets. Interestingly, non-degradative ubiquitin modifications are also known to play important roles in the regulation of Hippo signaling. Although there has been much advanced progress in the investigation of ubiquitin modifications acting as regulators of the Hippo signaling pathway, research done to date still remains inadequate due to the sheer complexity and diversity of the subject. Herein, we review and discuss recent developments that implicate ubiquitin-mediated regulatory mechanisms at multiple steps of the Hippo signaling pathway.

• 대한화장품학회지
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• 제46권1호
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• pp.11-22
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• 2020

본 연구에서는 6 개의 아미노산으로 이루어진 헥사펩타이드(hexapeptide)의 미백 효능에 대해 수행하였다. 실험 결과 헥사펩타이드 처리에 의해 유의한 수준의 멜라닌 생성 저해가 관찰 되었고, 멜라닌 생성 과정에 관여하는 주요 효소인 tyrosinase의 활성이 농도 의존적으로 억제됨이 관찰 되었다. 멜라닌 생성 관련 인자들의 발현을 관찰 한 결과 tyrosinase (TYR), tyrosinase-related protein 1 (TYRP1) 및 이들의 상위 전사인자인 microphthalmia-associated transcription factor (MITF)의 발현이 헥사펩타이드 처리에 의해 유의한 수준으로 저해 되었다. 또한 헥사펩타이드 처리에 의해 MITF 발현을 조절하는 상위 전사인자인 cAMP-response element binding protein (CREB)의 인산화가 저해 되었고 MITF 인산화를 통해 프로테아좀 분해(proteasomal degradation)를 유도하는 extracellular signal-regulated kinase (ERK) 인산화가 증가 되었다. 이외에도, 멜라노좀의 세포 내 이동에 관여하는 복합체의 구성 인자들로 알려진 Rab27A, melanophilin, myosinVa의 발현도 헥사펩타이드에 의해 유의한 수준으로 저해 되었다. 이 결과를 통해, 본 연구의 헥사펩타이드는 멜라닌세포의 멜라닌 생성 관련 핵심 전사인자인 MITF의 발현 및 분해 조절을 통해 멜라닌 생성 억제 및 멜라노좀 이동과 같은 전반적인 멜라노좀 성숙 과정에 저해 효과를 나타내는 것으로 보인다. 헥사펩타이드의 이러한 미백 효능은 신규 미백 기능성 화장품 소재로 응용될 수 있을 것으로 기대된다.

• BMB Reports
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• 제50권5호
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• pp.235-236
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• 2017

The circadian clock is an internal system that is synchronized by external stimuli, such as light and temperature, and influences various physiological and developmental processes in living organisms. In the model plant Arabidopsis, transcriptional, translational and post-translational processes are interlocked by feedback loops among morning- and evening-phased genes. In a post-translational loop, plant-specific single-gene encoded GIGANTEA (GI) stabilize the F-box protein ZEITLUPE (ZTL), driving the targeted-proteasomal degradation of TIMING OF CAB EXPRESSION 1 (TOC1) and PSEUDO-RESPONSE REGULATOR 5 (PRR5). Inherent to this, we demonstrate the novel biochemical function of GI as a chaperone and/or co-chaperone of Heat-Shock Protein 90 (HSP90). GI prevents ZTL degradation as a chaperone and facilitates ZTL maturation together with HSP90/HSP70, enhancing ZTL activity in vitro and in planta. GI is known to be involved in a wide range of physiology and development as well as abiotic stress responses in plants, but it could also interact with diverse client proteins to increase protein maturation. Our results provide evidence that GI helps proteostasis of ZTL by acting as a chaperone and a co-chaperone of HSP90 for proper functioning of the Arabidopsis circadian clock.