• Journal of Microbiology and Biotechnology
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• 제16권9호
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• pp.1453-1458
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• 2006

PKR-like endoplasmic reticulum (ER) kinase (PERK) is a type I transmembrane ER-resident protein containing a cytoplasmic catalytic domain with a Ser/Thr kinase activity, which is most closely related to the eukaryotic translation initiation factor-$2{\alpha}$ ($eIF2{\alpha}$) kinase PKR involved in the antiviral defense pathway by interferon. We cloned and expressed the PERK C-terminal kinase domain (cPERK) in Escherichia coli. Like PERK activation in cells under ER stress, wild-type cPERK underwent autophosphorylation when overexpressed in E. coli, whereas the cPERK(K621M) with a methionine substitution for the lysine at amino acid 621 lost the autophosphorylation activity. The activated form cPERK which was purified to near homogeneity, formed an oligomer and was able to trans-phosphorylate specifically its cellular substrate $eIF2{\alpha}$. Two-dimensional phosphoamino acids analysis revealed that phosphorylation of cPERK occurs at the Ser and Thr residues. The functionally active recombinant cPERK, and its inactive mutant should be useful for the analysis of biochemical functions of PERK and for the determination of their three-dimensional structures.

• 한국동물생명공학회지
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• 제34권3호
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• pp.212-221
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• 2019

Sestrin-2 (SESN2) as a stress-metabolic protein is known for its anti-oxidative effects as a downstream factor of PERK pathways in mammalian cells. However, the expression patterns of SESN2 in conjunction with the UPR signaling against to ER stress on porcine oocyte maturation in vitro, have not been reported. Therefore, we confirmed the expression pattern of SESN2 protein, for which to examine the relationship between PERK signaling and SESN2 in porcine oocyte during IVM. We investigated the SESN2 expression patterns using Western blot analysis in denuded oocytes (DOs), cumulus cells (CCs), and cumulus-oocyte complexes (COCs) at 22 and 44 h of IVM. As expected, the SESN2 protein level significantly increased (p < 0.01) in porcine COCs during 44 h of IVM. We investigated the meiotic maturation after applying ER stress inhibitor in various concentration (50, 100 and 200 μM) of tauroursodeoxycholic acid (TUDCA). We confirmed significant increase (p < 0.05) of meiotic maturation rate in TUDCA 200 μM treated COCs for 44 h of IVM. Finally, we confirmed the protein level of SESN2 and meiotic maturation via regulating ER-stress by only tunicamycin (Tm), only TUDCA, and Tm + TUDCA treatment in porcine COCs. As a result, treatment of the TUDCA following Tm pre-treatment reduced SESN2 protein level in porcine COCs. In addition, SESN2 protein level significantly reduced in only TUDCA treated porcine COCs. Our results suggest that the SESN2 expression is related to the stress mediator response to ER stress through the PERK signaling pathways in porcine oocyte maturation.

• Biomolecules & Therapeutics
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• 제32권3호
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• pp.341-348
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• 2024

Endoplasmic reticulum (ER) stress plays a crucial role in liver diseases, affecting various types of hepatic cells. While studies have focused on the link between ER stress and hepatocytes as well as hepatic stellate cells (HSCs), the precise involvement of hepatic macrophages in ER stress-induced liver injury remains poorly understood. Here, we examined the effects of ER stress on hepatic macrophages and their role in liver injury. Acute ER stress led to the accumulation and activation of hepatic macrophages, which preceded hepatocyte apoptosis. Notably, macrophage depletion mitigated liver injury induced by ER stress, underscoring their detrimental role. Mechanistic studies revealed that ER stress stimulates macrophages predominantly via the PERK signaling pathway, regardless of its canonical substrate ATF4. hnRNPA1 has been identified as a crucial mediator of PERK-driven macrophage activation, as the overexpression of hnRNPA1 effectively reduced ER stress and suppressed pro-inflammatory activation. We observed that hnRNPA1 interacts with mRNAs that encode UPR-related proteins, indicating its role in the regulation of ER stress response in macrophages. These findings illuminate the cell type-specific responses to ER stress and the significance of hepatic macrophages in ER stress-induced liver injury. Collectively, the PERK-hnRNPA1 axis has been discovered as a molecular mechanism for macrophage activation, presenting prospective therapeutic targets for inflammatory hepatic diseases such as acute liver injury.

• Clinical and Experimental Pediatrics
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• 제62권3호
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• pp.95-101
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• 2019

Purpose: Increased apoptosis was recently found in the hypertrophied left ventricle of spontaneously hypertensive rats (SHRs). Although the available evidence suggests that apoptosis can be induced in cardiac cells by various insults including pressure overload, cardiac apoptosis appears to result from an exaggerated local production of angiotensin in adult SHRs. Altered expressions of Bcl associated X (Bax), Bcl-2, chemokine receptor (CCR)-2, monocyte chemoattractant protein (MCP)-1, transforming growth factor $(TGF)-{\beta}1$, phosphorylated extracellular signal-regulated kinases (PERK), and connexin 43 proteins, and kallikrein mRNA were investigated to explore the effects of losartan on the SHR model. Methods: Twelve-week-old male rats were grouped as follows: control (C), SHR (hypertension: H), and losartan (L; SHRs were treated with losartan [10 mg/kg/day] for 5 weeks). Western blot and reverse transcription polymerase chain reaction assays were performed. Results: Expression of Bax, CCR-2, MCP-1, $TGF-{\beta}1$, PERK, and connexin 43 proteins, and kallikrein mRNA was significantly increased in the H group compared to that in the C group at weeks 3 and 5. Expression of Bax, CCR-2, MCP-1, $TGF-{\beta}1$, and connexin 43 proteins and kallikrein mRNA was significantly decreased after losartan treatment at week 5. PERK protein expression was significantly decreased after losartan treatment at weeks 3 and 5. Bcl-2 protein expression was significantly decreased in the H group compared to that in the C group at weeks 3 and 5. Conclusion: Losartan treatment reduced expression of Bax, CCR-2, MCP-1, $TGF-{\beta}1$, PERK, and connexin 43 proteins, and kallikrein mRNA in SHRs, along with decreased inflammation and apoptosis.

• BMB Reports
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• 제52권11호
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• pp.647-652
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• 2019

G protein-coupled estrogen receptor (GPER) is known to play an important role in hormone-associated cancers. G-1, a novel synthetic GPER agonist, has been reported to exhibit anti-carcinogenic properties. However, the chemotherapeutic mechanism of GPER is yet unclear. Here, we evaluated GPER expression in human gastric cancer tissues and cells. We found that G-1 treatment attenuates GPER expression in gastric cancer. GPER expression increased G-1-induced antitumor effects in mouse xenograft model. We analyzed the effects of knockdown/overexpression of GPER on G-1-induced cell death in cancer cells. Increased GPER expression in human gastric cancer cells increased G-1-induced cell death via increased levels of cleaved caspase-3, -9, and cleaved poly ADP-ribose polymerase. Interestingly, during G-1-induced cell death, GPER mRNA and protein expression was attenuated and associated with ER stress-induced expression of PERK, ATF-4, GRP-78, and CHOP. Furthermore, PERK-dependent induction of ER stress activation increased G-1-induced cell death, whereas PERK silencing decreased cell death and increased drug sensitivity. Taken together, the data suggest that the induction of ER stress via GPER expression may increase G-1-induced cell death in gastric cancer cells. These results may contribute to a new paradigm shift in gastric cancer therapy.

• Molecules and Cells
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• 제42권4호
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• pp.292-300
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• 2019

Immunometabolism, defined as the interaction of metabolic pathways with the immune system, influences the pathogenesis of metabolic diseases. Metformin and carbon monoxide (CO) are two pharmacological agents known to ameliorate metabolic disorders. There are notable similarities and differences in the reported effects of metformin and CO on immunometabolism. Metformin, an anti-diabetes drug, has positive effects on metabolism and can exert anti-inflammatory and anti-cancer effects via adenosine monophosphate-activated protein kinase (AMPK)-dependent and AMPK-independent mechanisms. CO, an endogenous product of heme oxygenase-1 (HO-1), can exert anti-inflammatory and antioxidant effects at low concentration. CO can confer cytoprotection in metabolic disorders and cancer via selective activation of the protein kinase R-like endoplasmic reticulum (ER) kinase (PERK) pathway. Both metformin and CO can induce mitochondrial stress to produce a mild elevation of mitochondrial ROS (mtROS) by distinct mechanisms. Metformin inhibits complex I of the mitochondrial electron transport chain (ETC), while CO inhibits ETC complex IV. Both metformin and CO can differentially induce several protein factors, including fibroblast growth factor 21 (FGF21) and sestrin2 (SESN2), which maintain metabolic homeostasis; nuclear factor erythroid 2-related factor 2 (Nrf2), a master regulator of the antioxidant response; and REDD1, which exhibits an anticancer effect. However, metformin and CO regulate these effects via different pathways. Metformin stimulates p53- and AMPK-dependent pathways whereas CO can selectively trigger the PERK-dependent signaling pathway. Although further studies are needed to identify the mechanistic differences between metformin and CO, pharmacological application of these agents may represent useful strategies to ameliorate metabolic diseases associated with altered immunometabolism.

• 생명과학회지
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• 제20권8호
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• pp.1249-1253
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• 2010

Sericin은 실크를 싸고 있는 고분자 수용성 당단백질로서 세포배양에 사용되며 세포분화를 촉진한다. 본 연구의 목적은 갑상선세포(FRTL-5)에서 thyroglobulin (Tg)의 분비에 sericin이 영향을 주는지를 알려고 한다. Sericin에 의해서 Tg의 분비가 촉진되었지만 Tg-mRNA의 발현은 촉진되지 않았다. 이런 상태에서 소포체 샤페론(Bip & calreticulin)과 소포체 막 단백질(IRE1, PERK & ATF6)의 발현이 증가한 것이 확인되었다. 한편 IRE1의 하부 신호전달자인 XBP1의 mRNA splicing 이 약하게 확인되었지만 PERK의 하부 신호전달자인 $eIF2{\alpha}$의 인산화는 일어나지 않았다. 그리고 sericin은 MTT assay 결과 cell viability을 촉진시키는 것도 확인되었다. 위의 결과는 sericin은 재조합 단백질생산에 유용하게 이용될 수 있는 새로운 생체물질로 증명되었다.

• 생명과학회지
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• 제20권12호
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• pp.1820-1828
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• 2010

PC12 세포에서 $CoCl_2$에 의한 hypoxia 유도는 HIF1 alpha의 상승 발현으로 확인하였다. 이때 apoptosis의 유도는 genomic DNA의 fragmentation과 apoptotic body는 Hoechst 염색으로 확인되었고, ER luminal chaperone의 발현 및 ER stress signal에 관여하는 ER membrane kinase인 IRE1, PERK, ATF6의 발현도 확인되었다. 이들이 apoptosis로 연결되는 고리 역할을 하는 IRE1-XBP1 mRNA splicing, PERK-eIF2 alpha, ATF6 protein cleavage도 반응하는 것으로 확인되었다. 위의 결과는 신경세포의 hypoxia상태는 ER stress signal pathway를 거쳐서 apoptosis가 된다는 것을 증명한 것으로 신경세포의 hypoxia치료를 위한 기초 자료가 될 것으로 생각한다.

• 생명과학회지
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• 제22권2호
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• pp.281-284
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• 2012

갑상선 배양세포(FRTL5)에서 ER stress에 의해서 ER chaperone (Bip, ERp29, Calnexin and PDI), ER stress sensor (PERK, ATF6 and Ire1)와 cAMP phosphodiesterase 7A1 (cAMP PDE7A1) 유전자발현이 증가하는 것을 알았다. 세포배양배지에서 A23187을 제거하면 cAMP PDE7A1 유전자발현이 회복되지만, thapsigagin의 경우는 회복되지 않았다. 그리고 A23187과 TSH를 함께 처리한 경우는 아주 강하게 cAMP PDE7A1 유전자의 발현이 억제되었다. 이 같은 결과는 ER stress에 의해서 cAMP PDE7A1 유전자발현이 상승 발현된다는 첫 보고이다.

• 한국기록관리학회지
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• 제20권1호
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• pp.159-175
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• 2020

본 연구는 기록전문직 교육의 개선을 위한 정책 대안을 논하는 데 목적이 있다. 이론 연구로서, Greenwood, Goode 등의 고전적 전문직 이론을 정리하고, 우리나라의 기록전문직이 Perk가 주장한 전문직의 6가지 기준을 형식적으로 충족하고 있음을 확인하였다. 하지만 전문성이란 어느 시점에 완성되는 것이 아니라, 지속적으로 추구해야 할 지향이라는 관점에서, 기록전문직의 전문성 획득의 출발점이라 할 수 있는 기록전문가 교육 및 양성제도와 이를 뒷받침하는 법제도를 분석하였다. 이에 더해, 전문직은 스스로 권위를 지키기 위해 교육과 훈련에 대한 자신의 기준을 정하고, 전문직 공동체의 규범을 가져야 한다는 맥락에서 기록전문직 주도의 인증제도를 실시하고 있는 영국 ARA와 미국 ACA의 사례를 분석하였다. 결론에 갈음하여, 인증제도를 중심으로 하는 기록전문직 교육제도 개선 방안을 제시하였다.