• Nutrition Research and Practice
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• v.18 no.4
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• pp.479-497
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• 2024

BACKGROUND/OBJECTIVES: Activating brown adipose tissue (BAT) and browning of white adipose tissue (WAT) can protect against obesity and obesity-related metabolic conditions. Cryptotanshinone (CT) regulates lipid metabolism and significantly ameliorates insulin resistance. Adenosine-5'-monophosphate (AMP)-activated protein kinase (AMPK), a receptor for cellular energy metabolism, is believed to regulate brown fat activity in humans. MATERIALS/METHODS: The in vivo study included high-fat-fed obese mice administered orally 200/400 mg/kg/d CT. They were evaluated through weight measurement, the intraperitoneal glucose tolerance test (IPGTT), intraperitoneal insulin tolerance test (IPITT), cold stimulation test, serum lipid (total cholesterol, triglycerides, and low-density lipoprotein) measurement, hematoxylin and eosin staining, and immunohistochemistry. Furthermore, the in vitro study investigated primary adipose mesenchymal stem cells (MSCs) with incubation of CT and AMPK agonists (acadesine)/inhibitor (Compound C). Cells were evaluated using Oil Red O staining, Alizarin red staining, flow cytometry, and immunofluorescence staining to identify and observe the osteogenic versus adipogenic differentiation. Quantitative real-time polymerase chain reaction and the Western blot were used to observe related gene expression. RESULTS: In the diet-induced obesity mouse model mice CT suppressed body weight, food intake, glucose levels in the IPGTT and IPTT, serum lipids, the volume of adipose tissue, and increased thermogenesis, uncoupling protein 1, and the AMPK pathway expression. In the in vitro study, CT prevented the formation of lipid droplets from MSCs while activating brown genes and the AMPK pathway. AMPK activator enhanced CT's effects, while the AMPK inhibitor reversed the effects of CT. CONCLUSION: CT promotes adipose tissue browning to increase body thermogenesis and reduce obesity by activating the AMPK pathway. This study provides an experimental foundation for the use of CT in obesity treatment.

• Mycobiology
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• v.39 no.4
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• pp.243-248
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• 2011

The ubiquitin-proteasome system is one of the major protein turnover mechanisms that plays important roles in the regulation of a variety of cellular functions. It is composed of E1 (ubiquitin-activating enzyme), E2 (ubiquitin-conjugating enzyme), and E3 ubiquitin ligases that transfer ubiquitin to the substrates that are subjected to degradation in the 26S proteasome. The Skp1, Cullin, F-box protein (SCF) E3 ligases are the largest E3 gene family, in which the F-box protein is the key component to determine substrate specificity. Although the SCF E3 ligase and its F-box proteins have been extensively studied in the model yeast Saccharomyces cerevisiae, only limited studies have been reported on the role of F-box proteins in other fungi. Recently, a number of studies revealed that F-box proteins are required for fungal pathogenicity. In this communication, we review the current understanding of F-box proteins in pathogenic fungi.

• Molecules and Cells
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• v.21 no.2
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• pp.251-260
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• 2006

During mitosis, genomic integrity is maintained by the proper coordination of anaphase entry and mitotic exit via mitotic checkpoints. In budding yeast, mitotic exit is controlled by a regulatory cascade called the mitotic exit network (MEN). The MEN is regulated by a small GTPase, Tem1p, which in turn is controlled by a two-component GAP, Bfa1p-Bub2p. Recent results suggested that phosphorylation of Bfa1p by the polorelated kinase Cdc5p is also required for triggering mitotic exit, since it decreases the GAP activity of Bfa1p-Bub2p. However, the dispensability of GEF Lte1p for mitotic exit has raised questions about regulation of the MEN by the GTPase activity of Tem1p. We isolated a Bfa1p mutant, $Bfa1p^{E438K}$, whose overexpression only partially induced anaphase arrest. The molecular and biochemical functions of $Bfa1p^{E438K}$ are similar to those of wild type Bfa1p, except for decreased GAP activity. Interestingly, in $BFA1^{E438K}$ cells, the MEN could be regulated with nearly wild type kinetics at physiological temperature, as well as in response to various checkpoint-activating signals, but the cells were more sensitive to spindle damage than wild type. These results suggest that the GAP activity of Bfa1p-Bub2p is responsible for the mitotic arrest caused by spindle damage and Bfa1p overproduction. In addition, the viability of cdc5-2 ${\Delta}bfa1 $ cells was not reduced by $BFA1^{E438K}$, suggesting that Cdc5p also regulates Bfa1p to activate mitotic exit by other mechanism(s), besides phosphorylation.

• Journal of Applied Biological Chemistry
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• v.64 no.4
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• pp.447-451
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• 2021

In this study, we discovered for the first time that linarin, a flavonoid compound, enhances melanin biosynthesis in B16F10 cells, and subsequently elucidated the underlying mechanism of linarin-induced melanogenesis. Linarin showed no cytotoxicity at a concentration of 42 μM and significantly increased intracellular tyrosinase activity and melanin content in B16F10 cells. Mechanistic analysis showed that linarin increased the expression of tyrosinase, tyrosinase-related protein 1 (TRP-1), and microphthalmia-associated transcription factor (MITF) that are related to melanogenesis. Moreover, linarin decreased the phosphorylation of extracellular signal-regulated kinase (ERK) and protein kinase B (AKT). Finally, we evaluated the effect of the structure-activity relationship of linarin and its aglycone on melanogenesis. The results indicated that linarin enhances the expression of melanogenic proteins by activating MITF expression via the modulation of mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K), and protein kinase B signaling pathways in B16F10 cells, thereby enhancing melanogenesis.

• Journal of Microbiology and Biotechnology
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• v.31 no.6
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• pp.794-802
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• 2021

In this study we investigated the role and mechanism of cardamonin on IL-1β induced injury in OA. CHON-001 cells were treated with cardamonin and IL-1β and transfected with silencing nuclear factor erythroid 2-related factor 2 (siNrf2). Cell viability was detected by Cell Counting Kit-8 assay and flow cytometer assay was utilized for cell apoptosis assessment. IL-6, IL-8, TNF-α and Nrf2 mRNA expression was tested by qRT-PCR. Western blot was employed to evaluate MMP-3, MMP-13, Collagen II, Nrf2, NQO-1, NLRP3, Caspase 1 and apoptosis-associated speck-like protein containing a caspase-1 recruitment domain (ASC) protein levels. In CHON-001 cells, IL-1β suppressed cell viability and Collagen II level while promoting cell apoptosis and expression of pro-inflammatory cytokines (IL-6, IL-8, TNF-α), MMPs (MMP-3, MMP-13), NQO-1, and NLRP3 inflammasome (NLRP3, Caspase 1 and ASC), with no significant influence on Nrf2. Cardamonin reversed the effect of IL-1β on cell viability, cell apoptosis, pro-inflammatory cytokines, MMPs, Collagen II, and NLRP3 inflammasome levels. In addition, cardamonin advanced Nrf2 and NQO-1 expression of CHON-001 cells. SiNrf2 reversed the function of cardamonin on IL-1β-induced cell apoptosis and expression of pro-inflammatory cytokines, Nrf2, NQO-1, and NLRP3 inflammasome in chondrocytes. Taken together Cardamonin inhibited IL-1β induced injury by inhibition of NLRP3 inflammasome via activating Nrf2/NQO1 signaling pathway in chondrocyte.

• BMB Reports
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• v.56 no.2
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• pp.65-70
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• 2023

Prominin-1 (PROM1), also called CD133, is a penta-span transmembrane protein that is localized in membrane protrusions, such as microvilli and filopodia. It is known to be expressed in cancer stem cells and various progenitor cells of bone marrow, liver, kidney, and intestine. Accumulating evidence has revealed that PROM1 has multiple functions in various organs, such as eye, tooth, peripheral nerve, and liver, associating with various molecular protein partners. PROM1 regulates PKA-induced gluconeogenesis, TGFβ-induced fibrosis, and IL-6-induced regeneration in the liver, associating with Radixin, SMAD7, and GP130, respectively. In addition, PROM1 is necessary to maintain cancer stem cell properties by activating PI3K and β-Catenin. PROM1-deficienct mice also show distinct phenotypes in eyes, brain, peripheral nerves, and tooth. Here, we discuss recent findings of PROM1-mediated signal transduction.

• Journal of Yeungnam Medical Science
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• v.29 no.2
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• pp.77-82
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• 2012

AMP-activated protein kinase (AMPK) is an important cellular fuel sensor. Its activation requires phosphorylation at Thr-172, which resides in the activation loop of the ${\alpha}1$ and ${\alpha}2$ subunits. Several AMPK upstream kinases are capable of phosphorylating AMPK at Thr-172, including LKB1 and CaMKK${\beta}$ ($Ca^{2+}$/calmodulin-dependent protein kinase kinase${\beta}$). AMPK has been implicated in the regulation of physiological signals, such as in the inhibition of cholesterol fatty acid, and protein synthesis, and enhancement of glucose uptake and blood flow. AMPK activation also exhibits several salutary effects on the vascular function and improves vascular abnormalities. AMPK is modulated by numerous hormones and cytokines that regulate the energy balance in the whole body. These hormone and cytokines include leptin, adiponectin, ghrelin, and even thyroid hormones. Moreover, AMPK is activated by several drugs and xenobiotics. Some of these are in being clinically used to treat type 2 diabetes (e.g., metformin and thiazolidinediones), hypertension (e.g., nifedipine and losartan), and impaired blood flow (e.g., aspirin, statins, and cilostazol). I reviewed the precise mechanisms of the AMPK activation pathway and AMPK-modulating drugs.

• Molecules and Cells
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• v.42 no.11
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• pp.783-793
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• 2019

When endoplasmic reticulum (ER) functions are perturbed, the ER induces several signaling pathways called unfolded protein response to reestablish ER homeostasis through three ER transmembrane proteins: inositol-requiring enzyme 1 (IRE1), PKR-like ER kinase (PERK), and activating transcription factor 6 (ATF6). Although it is important to measure the activity of ATF6 that can indicate the status of the ER, no specific cell-based reporter assay is currently available. Here, we report a new cell-based method for monitoring ER stress based on the cleavage of $ATF6{\alpha}$ by sequential actions of proteases at the Golgi apparatus during ER stress. A new expressing vector was constructed by using fusion gene of GAL4 DNA binding domain (GAL4DBD) and activation domain derived from herpes simplex virus VP16 protein (VP16AD) followed by a human $ATF6{\alpha}$ N-terminal deletion variant. During ER stress, the GAL4DBD-VP16AD(GV)-$hATF6{\alpha}$ deletion variant was cleaved to liberate active transcription activator encompassing GV-$hATF6{\alpha}$ fragment which could translocate into the nucleus. The translocated GV-$hATF6{\alpha}$ fragment strongly induced the expression of firefly luciferase in HeLa Luciferase Reporter cell line containing a stably integrated 5X GAL4 site-luciferase gene. The established double stable reporter cell line HLR-GV-$hATF6{\alpha}$(333) represents an innovative tool to investigate regulated intramembrane proteolysis of $ATF6{\alpha}$. It can substitute active pATF6(N) binding motif-based reporter cell lines.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.3
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• pp.1053-1057
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• 2012

Objective: Identifying cancer-related genes or proteins is critical in preventing and controlling colorectal cancer (CRC). This study was to investigate the clinicopathological and prognostic value of activating transcription factor 1 (ATF1) in CRC. Methods: Protein expression of ATF1 was detected using immunohistochemistry in 66 CRC tissues. Clinicopathological association of ATF1 in CRC was analyzed with chi-square test or Fisher's exact test. The prognostic value of ATF1 in CRC is estimated using the Kaplan-Meier analysis and Cox regression models. Results: The ATF1 protein expression was significantly lower in tumor tissues than corresponding normal tissues (51.5% and 71.1%, respectively, P = 0.038). No correlation was found between ATF1 expression and the investigated clinicopathological parameters, including gender, age, depth of invasion, lymph node status, metastasis, pathological stage, vascular tumoral emboli, peritumoral deposits, chemotherapy and original tumor site (all with P > 0.05). Patients with higher ATF1 expression levels have a significantly higher survival rate than that with lower expression (P = 0.026 for overall survival, P = 0.008 for progress free survival). Multivariate Cox regression model revealed that ATF1 expression and depth of invasion were the predictors of the overall survival (P = 0.008 and P = 0.028) and progress free survival (P = 0.002 and P = 0.005) in CRC. Conclusions: Higher ATF1 expression is a predictor of a favorable outcome for the overall survival and progress free survival in CRC.

• BMB Reports
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• v.42 no.11
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• pp.758-763
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• 2009

Cancer-associated antigen (CAGE) induces the expression of matrix metalloproteinase-2 (MMP-2) by activating Akt, which in turn interacts with inhibitory kappa kinase $\beta$ ($I{\kappa}K{\beta}$) to activate nuclear factor ${\kappa}B$ (NF-${\kappa}B$). Akt and p38 mitogen activated protein kinase (p38 MAPK) are necessary for CAGE-mediated induction of the AP-1 subunit JunB, whereas extracellular regulated kinase (ERK) is necessary for the induction of fos-related antigen-1 (Fra-1). Induction of MMP-2 by CAGE requires activator of protein-1 (AP-1) to be bound. Specific binding of JunB to MMP-2 promoter sequences was shown by chromatin immunoprecipitation (ChIP) analysis.