• Molecules and Cells
• /
• 제47권1호
• /
• pp.100004.1-100004.11
• /
• 2024

Insulin is essential for maintaining normoglycemia and is predominantly secreted in response to glucose stimulation by β-cells. Incretin hormones, such as glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide, also stimulate insulin secretion. However, as obesity and type 2 diabetes worsen, glucose-dependent insulinotropic polypeptide loses its insulinotropic efficacy, whereas GLP-1 receptor (GLP-1R) agonists continue to be effective owing to its signaling switch from Gs to Gq. Herein, we demonstrated that endoplasmic reticulum (ER) stress induced a transition from Gs to Gq in GLP-1R signaling in mouse islets. Intriguingly, chemical chaperones known to alleviate ER stress, such as 4-PBA and TUDCA, enforced GLP-1R's Gq utilization rather than reversing GLP-1R's signaling switch induced by ER stress or obese and diabetic conditions. In addition, the activation of X-box binding protein 1 (XBP1) or activating transcription factor 6 (ATF6), 2 key ER stress-associated signaling (unfolded protein response) factors, promoted Gs utilization in GLP-1R signaling, whereas Gq employment by ER stress was unaffected by XBP1 or ATF6 activation. Our study revealed that ER stress and its associated signaling events alter GLP-1R's signaling, which can be used in type 2 diabetes treatment.

• 한국가금학회지
• /
• 제44권1호
• /
• pp.1-9
• /
• 2017

본 연구는 한국재래계(KNC)와 백색레그혼(WLH)에서 lipopolysaccharide(LPS)감염 스트레스가 닭의 품종간 스트레스 연관 유전자들의 발현에 미치는 영향을 비교 분석하고자 실시되었다. 공시계를 대상으로 생리식염수(대조구)와 LPS(처리구)를 복강에 투여한 후, 시간(0, 48 hr) 및 처리별 각 개체로부터 간 조직을 취하고, microarray 및 quantitative RT-PCR(qRT-PCR) 분석을 하였다. 처리에 따른 유전자 발현차이를 보면, KNC(대조구)와 KNC에 LPS를 처리한 경우(KNC-LPS)를 비교한 결과, 대조구 대비 2배 이상 유전자의 발현이 증가한 유전자의 수는 1,044개, 발현이 감소한 유전자의 수는 1,000개였다. WLH(대조구)를 WLH-LPS와 비교한 경우, 유전자의 발현이 증가한 유전자의 수는 1,193개, 발현이 감소한 유전자의 수는 1,072개였다. LPS 처리에 따른 스트레스 연관 유전자들의 microarray 발현에서 스트레스연관 유전자들의 발현은 두 품종 모두에서 감소하였으며, 품종 간 차이는 없는 것으로 나타났다. Microarray의 결과를 바탕으로 HSP90, HMGCR, ATF4, SREBP1, XBP1 등의 유전자 발현을 qRT-PCR을 이용하여 검증한 결과, 대조구와 LPS 감염구 간에 유의적 차이를 나타내었다(P<0.05). 세포 수준의 스트레스(ER 스트레스)에서 ATF4, XBP1, SREBP1은 화이트레그혼에서 microarray와 qRT-PCR에서와 같이 이들 유전자들의 발현이 억제되는 것을 보여주었다. 그러나 한국 재래계에서는 ATF4를 제외한 유전자들은 LPS에 의해 영향을 받지 않거나(XBP1), 오히려 증가(SREBP)하는 양상을 보였다. ER-stress 연관 유전자들의 발현 양상으로 볼 때, KNC이 WLH에 비하여 LPS 감염에 더 민감하게 반응하는 것으로 보인다. HMGCR은 두 품종간에 LPS에 의한 상호작용이 없는 것으로 보아, HMGCR 발현에 의한 감염 차이점을 찾을 수 없었다. 한국재래계에서 HSP70은 LPS 처리 후에 대조구에 비하여 약 2.5배 이상 높은 발현을 보였으나, 백색 레그혼에서는 낮은 발현 양상을 나타내었다. 스트레스 지표 유전자들의 종류뿐만 아니라, 스트레스 종류(예: 환경스트레스, 감염스트레스)에 따라 유전자들의 발현 반응에 차이가 있음을 보여주었다. LPS 감염스트레스에 따른 스트레스연관 유전자 발현연구는 닭의 품종별 질병 저항성 및 동물복지 관련 지표의 탐색에 기여할 것으로 사료된다.

• 한국발생생물학회지:발생과생식
• /
• 제24권1호
• /
• pp.31-41
• /
• 2020

We investigated the effects of endoplasmic reticulum (ER) stress inhibitor and antioxidant treatments during the micromanipulation of somatic cell nuclear transfer (SCNT) on in vitro development of SCNT embryos. Tauroursodeoxycholic acid (TUDCA), an ER stress inhibitor and vitamin C (Vit. C), an antioxidant, were treated by alone or in combination, then, the level of X-box binding protein 1 (Xbp1) splicing and the expressions of ER stress-associated genes, oxidative stress-related genes, and apoptotic genes were confirmed in the 1-cell and blastocyst stages. In the 1-cell stage, the levels of Xbp1 splicing were significantly decreased in TUDCA and Vit. C treatment groups compared to the control (p<0.05). In addition, the expression levels of most ER stress-associated genes and oxidative stress-related genes were significantly lower in all treatment groups than the control (p<0.05), and the transcript levels of apoptotic genes were also significantly lower in all treatment groups than the control (p<0.05). In the blastocyst stage, decreased expression of ER stress-, oxidative stress-, and apoptosis-related genes were observed only in some treatments. However, the blastocyst formation rates in TUDCA and Vit. C treatment groups (24.8% and 22.0%, respectively) and mean blastocyst cell number in all treatment groups (59.7±4.3 to 63.5±3.3) were significantly higher (p<0.05) than those of control. The results showed that the TUDCA or Vit. C treatment during micromanipulation inhibited both ER and oxidative stresses in the early stage of SCNT embryos, thereby reducing cell damage and promoting in vitro development.

• 한방비만학회지
• /
• 제14권1호
• /
• pp.13-23
• /
• 2014

Objectives: This study was performed to evaluate the effects of Metformin and Lonicerae Flos, Agrobacterium Rhizogenes, Coptidis Rhizoma, Atractylodis Rhizoma Alba, Houttuyniae Herba extracs combinations on hypoglycemia in RAW 264.7 cells. Methods: Expressions of Sirt1, p-adenosine monophosphate-activated kinase (p-AMPK), AMPK-alpha, peroxisome proliferator activated receptor (PPAR)-alpha, PPAR-gamma, X-box binding protein 1 (XBP-1), tumor necrosis factor (TNF)-alpha and interleukin (IL)-6 were analyzed by real time polymerase chain reaction and Western blotting analysis. Results: The level of gene expression of Sirt1, p-AMPK, AMPK-alpha, PPAR-alpha and XBP-1 in relation to that of beta-actin were increased or decreased significantly with the Metformin and Lonicerae Flos, Agrobacterium Rhizogenes extracts combination groups. The level of gene expression of TNF-alpha and IL-6 were increased significantly with the Metformin and Houttuyniae Herba, Coptidis Rhizoma extracts combination groups. Conclusions: Metformin and Lonicerae Flos, Agrobacterium Rhizogenes extracts combination groups showed synergistic hypoglycemic effects by increasing AMPK and PPAR gene expression in RAW 264.7 cells.

• Animal Bioscience
• /
• 제35권1호
• /
• pp.22-28
• /
• 2022

Objective: Endoplasmic reticulum (ER) stress engages the unfolded protein response (UPR) that serves as an important mechanism for modulating hepatic fatty acid oxidation and lipogenesis. Chronic fasting in mice induced the UPR activation to regulate lipid metabolism. However, there is no direct evidence of whether negative energy balance (NEB) induces ER stress in the liver of cows. This study aimed to elucidate the relationship between the NEB attributed to feed deprivation and ER stress in bovine hepatocytes. Methods: Blood samples and liver biopsy tissues were collected from 6 non-lactating cows before and after their starvation for 48 h. The blood non-esterified fatty acids (NEFA), β-hydroxybutyric acid (BHBA) and glucose level were analyzed. Real-time quantitative polymerase chain reaction and Western blotting were used to explore the regulation of genes associated with UPR and lipid metabolism. Results: The starvation increased the plasma BHBA and NEFA levels and decreased the glucose level. Additionally, the starvation caused significant increases in the mRNA expression level of spliced X-box binding protein 1 (XBP1s) and the protein level of phosphorylated inositol-requiring kinase 1 alpha (p-IRE1α; an upstream protein of XBP1) in the liver. The mRNA expression levels of peroxisome proliferator-activated receptor alpha and its target fatty acid oxidation- and ketogenesis-related genes were significantly upregulated by the starvation-mediated NEB. Furthermore, we found that the mRNA expression levels of lipogenic genes were not significantly changed after starvation. Conclusion: These findings suggest that in the initial stage of NEB in dairy cows, the liver coordinates an adaptive response by activating the IRE1 arm of the UPR to enhance ketogenesis, thereby avoiding a fatty liver status.

• 한국발생생물학회지:발생과생식
• /
• 제22권3호
• /
• pp.235-244
• /
• 2018

We investigate the effect of endoplasmic reticulum (ER) stress inhibitor treatment during parthenogenetic activation of oocytes on the ER stress generation, apoptosis, and in vitro development of parthenogenetic porcine embryos. Porcine in vitro matured oocytes were activated by 1) electric stimulus (E) or 2) $E+10{\mu}M$ Ca-ionophore (A23187) treatment (EC). Oocytes were then treated by ER stress inhibitors such as salubrinal (200 nM) and tauroursodeoxychloic acid (TUDCA, $100{\mu}M$) for 3 h prior to in vitro culture. Parthenogenetic embryos were sampled to analyze ER stress and apoptosis at the 1-cell and blastocyst stages. The x-box binding protein 1 (Xbp1) mRNA and ER stress-associated genes were analyzed by RT-PCR or RT-qPCR. Apoptotic gene expression was analyzed by RT-PCR. At the 1-cell stage, although no difference was observed in Xbp1 splicing among treatments, BiP transcription level in the E group was significantly reduced by salubrinal treatment, and GRP94 and ATF4 transcription levels in EC group were significantly reduced by all treatments (p<0.05) compared to control. In the EC group, both apoptotic genes were reduced by ER stress inhibitor treatments compared to control (p<0.05) except Caspase-3 gene by TUDCA treatment. These results suggest that the treatment of ER stress inhibitor during parthenogenetic activation can reduce ER stress, and thereby reduce apoptosis and promote in vitro development of porcine parthenogenetic embryos.

• 한국발생생물학회지:발생과생식
• /
• 제25권1호
• /
• pp.43-53
• /
• 2021

We examine the effect of endoplasmic reticulum (ER) stress inhibitor treatment time on the in vitro development of porcine somatic cell nuclear transfer (SCNT) embryos. Porcine SCNT embryos were classified by four groups following treatment time of ER stress inhibitor, tauroursodeoxycholic acid (TUDCA; 100 µM); 1) non-treatment group (control), 2) treatment during micromanipulation process and for 3 h after fusion (NT+3 h group), 3) treatment only during in vitro culture after fusion (IVC group), and 4) treatment during micromanipulation process and in vitro culture (NT+IVC group). SCNT embryos were cultured for six days to examine the X-box binding protein 1 (Xbp1) splicing levels, the expression levels of ER stress-associated genes, oxidative stress-related genes, and apoptosis-related genes in blastocysts, and in vitro development. There was no significant difference in Xbp1 splicing level among all groups. Reduced expression of some ER stress-associated genes was observed in the treatment groups. The oxidative stress and apoptosis-related genes were significantly lower in all treatment groups than control (p<0.05). Although blastocyst development rates were not different among all groups (17.5% to 21.7%), the average cell number in blastocysts increased significantly in NT+3 h (48.5±2.3) and NT+IVC (47.7±2.4) groups compared to those of control and IVC groups (p<0.05). The result of this study suggests that the treatment of ER stress inhibitor on SCNT embryos from the micromanipulation process can improve the reprogramming efficiency of SCNT embryos by inhibiting the ER and oxidative stresses that may occur early in the SCNT process.

• BMB Reports
• /
• 제52권11호
• /
• pp.665-670
• /
• 2019

Nucleotide-binding oligomerization domain protein 2 (NOD2), an intracellular pattern recognition receptor, plays important roles in inflammation and cell death. Previously, we have shown that NOD2 is expressed in vascular smooth muscle cells (VSMCs) and that NOD2 deficiency promotes VSMC proliferation, migration, and neointimal formation after vascular injury. However, its role in endoplasmic reticulum (ER) stress-induced cell death in VSMCs remains unclear. Thus, the objective of this study was to evaluate ER stress-induced viability of mouse primary VSMCs. NOD2 deficiency increased ER stress-induced cell death and expression levels of apoptosis mediators (cleaved caspase-3, Bax, and Bak) in VSMCs in the presence of tunicamycin (TM), an ER stress inducer. In contrast, ER stress-induced cell death and expression levels of apoptosis mediators (cleaved caspase-3, Bax, and Bak) were decreased in NOD2-overexpressed VSMCs. We found that the $IRE-1{\alpha}-XBP1$ pathway, one of unfolded protein response branches, was decreased in NOD2-deficient VSMCs and reversed in NOD2-overexpressed VSMCs in the presence of TM. Furthermore, NOD2 deficiency reduced the expression of XBP1 target genes such as GRP78, PDI-1, and Herpud1, thus improving cell survival. Taken together, these data suggest that the induction of ER stress through NOD2 expression can protect against TM-induced cell death in VSMCs. These results may contribute to a new paradigm in vascular homeostasis.

• Journal of Nutrition and Health
• /
• 제52권2호
• /
• pp.176-184
• /
• 2019

Purpose: Protein overloading in the endoplasmic reticulum (ER) leads to endoplasmic reticulum stress, which exacerbates various disease conditions. Emodin, an anthraquinone compound, is known to have several health benefits. The effect of emodin against palmitic acid (PA) - induced ER stress in HepG2 cells was investigated. Methods: HepG2 cells were treated with varying concentrations of palmitic acid to determine the working concentration that induced ER stress. ER stress associated genes such as ATF4, XBP1s, CHOP and GRP78 were checked using RT- PCR. In addition, the expression levels of unfolded protein response (UPR) associated proteins such as $IRE1{\alpha}$, $eIF2{\alpha}$ and CHOP were checked using immunoblotting to confirm the induction of ER stress. The effect of emodin on ER stress was analyzed by treating HepG2 cells with $750{\mu}M$ palmitic acid and varying concentrations of emodin, then analyzing the expression of UPR associated genes. Results: It was evident from the mRNA and protein expression results that palmitic acid significantly increased the expression of UPR associated genes and thereby induced ER stress. Subsequent treatment with emodin reduced the mRNA expression of ATF4, GRP78, and XBP1s. Furthermore, the protein levels of $p-IRE1{\alpha}$, $p-eIF2{\alpha}$ and CHOP were also reduced by the treatment of emodin. Analysis of sirtuin mRNA expression showed that emodin increased the levels of SIRT4 and SIRT7, indicating a possible role in decreasing the expression of UPR-related genes. Conclusion: Altogether, the results suggest that emodin could exert a protective effect against fatty acid-induced ER stress and could be an agent for the management of various ER stress related diseases.

• 동의생리병리학회지
• /
• 제23권6호
• /
• pp.1368-1378
• /
• 2009

Unfolded protein response (UPR) is an important genomic response to endoplasmic reticulum (ER) stress. The ER response is characterized by changes in specific proteins, induction of ER chaperones and degradation of misfolded proteins. Also, the pathogenesis of several diseases like Alzheimer's disease, neuronal degenerative diseases, and diabetes reveal the role of ER stress as one of the causative mechanisms. Borneolum has been used for neuronal disease in oriental medicine. In the present study, the protective effect of borneolum on thapsigargin-induced apoptosis in rat C6 glial cells. Treatment with C6 glial cells with 5 uM thapsigargin caused the loss of cell viability, and morphological change, which was associated with the elevation of intracellular $Ca^{++}$ level, the increase in Grp78 and CHOP and cleavage of pro-caspase 12 Furthermore, thapsigargin induced Grp98, XBP1, and ATF4 protein expression in C6 glial cells. Borneolum reduced thapsigargin-induced apoptosis through ER pathways. In the ER pathway, borneolum attenuated thapsigargin-induced elevations in Grp78, CHOP, ATF4, and XBP1 as well as reductions in pro-caspase 12 levels. Also, our data showed that borneolum protected thapsigargin-induced cytotoxicity in astrocytes from rat (P3) brain. Taken together, our data suggest that borneolum is neuroprotective against thapsigargin-induced ER stress in C6 glial cells and astrocytes. Accordingly, borneolum may be therapeutically useful for the treatment of thapsigargin-induced apoptosis in central nervous system.