• Journal of Microbiology and Biotechnology
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• 제20권11호
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• pp.1471-1480
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• 2010

An extremely thermostable xylanase gene, xynB, from the hyperthermophilic bacterium Thermotoga maritima MSB8 was successful expressed in Kluyveromyces lactis. The response surface methodology (RSM) was also applied to optimize the medium components for the production of XynB secreted by the recombinant K. lactis. The secretion level (102 mg/l) and enzyme activity (49 U/ml) of XynB in the optimized medium (yeast extract, lactose, and urea; YLU) were much higher than those (56 mg/l, 16 U/ml) in the original medium (yeast extract, lactose, and peptone; YLP). The secretory efficiency of mature XynB was also improved when using the YLU medium. When the mRNA levels of 13 characterized secretion-related genes in the K. lactis cultured in YLP and YLU were detected using a semiquantitative RT-PCR method, the unfolded protein response (UPR)-related genes, including ero1, hac1, and kar2, were found to be up-regulated in the K. lactis cultured in YLU. Therefore, the nutrient ingredients, especially the nitrogen source, were shown to have a significant influence on the XynB secretory efficiency of the host K. lactis.

• BMB Reports
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• 제51권8호
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• pp.388-393
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• 2018

The activating transcription factor (ATF) 4 belongs to the ATF/CREB (cAMP Response Element Binding bZIP [Basic Leucine Zipper]) transcription factor family, and plays a central role in the UPR (Unfolded Protein Response) process in cells. The induction of ATF4 expression has previously been shown to increase the replication of HIV-1. However, the detailed mechanism underlying this effect and the factors involved in the regulation of ATF4 function are still unknown. Here, we demonstrate first that knocking out ATF4 using siRNA shows a strong negative effect on HIV-1 production, indicating that ATF4 is a functional positive cellular factor in HIV-1 production. To determine the mechanism by which ATF4 regulates the HIV-1 life cycle, we assessed the effect of the overexpression of wild type ATF4 and its various derivatives on HIV-1 LTR-mediated transcriptional activation and the production of HIV-1 particles. This effect was studied through co-transfection experiments with either reporter vectors or proviral DNA. We found that the N-terminal domains of ATF4 are involved in HIV-1 LTR-mediated transcriptional activation, and thus in HIV-1 production.

• 생명과학회지
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• 제34권2호
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• pp.113-121
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• 2024

ER (Endoplasmic reticulume) 스트레스반응은 difenoconazole 등과 같은 다양한 독성물질에 의한 독성반응 동안에 유도되지만, 농업 및 산업에서 전반적으로 사용되는 화학물질로 간독성(Hepatotoxicity)을 유도하는 1,2,3-Trichloropropane (TCP)와의 연관성은 연구된 바 없다. 따라서, 본 연구에서는 TCP처리로 유발된 간독성(Hepatotoxicity) 유발과정 동안에 ER스트레스의 유발기전에 대해 연구하기 위하여, TCP로 처리된 SD(Sprague Dawley)랫드에서 간독성, apoptosis 그리고 ER스트레스에 대한 지표들의 변화를 분석하였다. 그 결과, TCP 처리그룹은 Vehicle 처리그룹에 비하여 체중과 식이 섭취량이 감소하였고, 간 조직에서 괴사(Necrosis)와 공포화(Vaculation) 등이 유의적으로 증가하였다. 또한, apoptosis 관련 인자인 Bax/Bcl-2와 Cleaved Caspase-3(Cas-3)/Cas-3의 발현은 Vehicle 처리그룹보다 TCP 처리그룹에서 유의적으로 증가하였다. ER스트레스 반응지표 분석에서, C/EBP homologous protein (CHOP), p-eukaryotic translation initiation factor 2 alpha subunit (eIF2α), p-iniositor-requiring enzyme 1α (IRE1α)의 발현은 TCP100 처리그룹에서만 증가하였다. 하지만 Growth arrest and DNA damage-34 (GADD34)와 X-box binding protein-1 (XBP1)의 전사는 TCP200 처리그룹에서 유의적으로 변화되었다. 따라서, 이러한 결과는 ER스트레스반응은 TCP 처리에 의해 유도된 간독성과정 동안에 unfolded protein response (UPR) pathway의 조절을 통해 성공적으로 유도됨을 제시하고 있다.

• The Korean Journal of Physiology and Pharmacology
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• 제23권2호
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• pp.95-102
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• 2019

Endoplasmic reticulum (ER) stress is mediated by disturbance of $Ca^{2+}$ homeostasis. The store-operated calcium (SOC) channel is the primary $Ca^{2+}$ channel in non-excitable cells, but its participation in agent-induced ER stress is not clear. In this study, the effects of tunicamycin on $Ca^{2+}$ influx in human umbilical vein endothelial cells (HUVECs) were observed with the fluorescent probe Fluo-4 AM. The effect of tunicamycin on the expression of the unfolded protein response (UPR)-related proteins BiP and CHOP was assayed by western blotting with or without inhibition of Orai1. Tunicamycin induced endothelial dysfunction by activating ER stress. Orai1 expression and the influx of extracellular $Ca^{2+}$ in HUVECs were both upregulated during ER stress. The SOC channel inhibitor SKF96365 reversed tunicamycin-induced endothelial cell dysfunction by inhibiting ER stress. Regulation of tunicamycin-induced ER stress by Orai1 indicates that modification of Orai1 activity may have therapeutic value for conditions with ER stress-induced endothelial dysfunction.