Search

HEPN–MNT, a type VII TA module, comprises the HEPN toxin and the MNT antitoxin, which acts as a nucleotidyltransferase that transfers the NMP moiety to the corresponding HEPN toxin, thereby interfering with its toxicity. Here, we report crystal structures of the Legionella pneumophila HEPN–MNT module, including HEPN, AMPylated HEPN, MNT, and the HEPN–MNT complex. Our structural analysis and biochemical assays, suggest that HEPN is a metal-dependent RNase and identify its active site residues. We also elucidate the oligomeric state of HEPN in solution. Interestingly, L. pneumophila MNT, which lacks a long C-terminal α4 helix, controls the toxicity of HEPN toxin via a distinct binding mode with HEPN. Finally, we propose a comprehensive regulatory mechanism of the L. pneumophila HEPN–MNT module based on structural and functional studies. These results provide insight into the type VII HEPN–MNT TA system. HEPN–MNT is a bacterial type VII toxin-antitoxin (TA) system, comprising the HEPN toxin and the MNT antitoxin. Crystal structures and functional assays of the HEPN–MNT module suggest that HEPN is a metal-dependent RNase and identify its active site residues and regulatory mechanism. [ABSTRACT FROM AUTHOR]

Prostaglandin E2 (PGE2) interacts with four specific G protein-coupled receptors, namely EP1, EP2, EP3, and EP4, playing a pivotal role in determining the fate of cells. Our previous findings highlighted that stimulating the EP4 receptor with its agonist, CAY10598, triggers apoptosis in colon cancer HCT116 cells via the production of reactive oxygen species (ROS). This process also reduces the phosphorylation of the oncogenic protein JAK2 and leads to its degradation in these cells. In this study, our goal was to explore the pathways through which CAY10598 leads to JAK2 degradation. We focused on Hsp90, a heat shock protein family member known for its role as a molecular chaperone maintaining the stability of several key proteins including EGFR, MET, Akt, and JAK2. Our results show that CAY10598 decreases the levels of client proteins of Hsp90 in HCT116 cells, an effect reversible by pretreatment with the ROS scavenger N-acetyl cysteine (NAC) or the proteasome inhibitor MG132, indicating that the degradation is likely driven by ROS. Furthermore, we observed that CAY10598 cleaves both α and β isoforms of Hsp90, the process inhibited by NAC. Inhibition of EP4 with the antagonist GW627368x not only prevented the degradation of Hsp90 client proteins but also the cleavage of Hsp90 itself in CAY10598-treated HCT116 cells. Additionally, CAY10598 suppressed the growth of HCT116 cells implanted in mice. Our findings reveal that CAY10598 induces apoptosis in cancer cells by a novel mechanism involving the ROS-dependent cleavage of Hsp90, thereby inhibiting the function of crucial Hsp90 client proteins. [ABSTRACT FROM AUTHOR]

Peptide-based therapeutics have traditionally faced challenges, including instability in the bloodstream and limited cell membrane permeability. However, recent advancements in α-helix stapled peptide modification techniques have rekindled interest in their efficacy. Notably, these developments ensure a highly effective method for improving peptide stability and enhancing cell membrane penetration. Particularly in the realm of antimicrobial peptides (AMPs), the application of stapled peptide techniques has significantly increased peptide stability and has been successfully applied to many peptides. Furthermore, constraining the secondary structure of peptides has also been proven to enhance their biological activity. In this review, the entire process through which hydrocarbon-stapled antimicrobial peptides attain improved drug-like properties is examined. First, the essential secondary structural elements required for their activity as drugs are validated, specific residues are identified using alanine scanning, and stapling techniques are strategically incorporated at precise locations. Additionally, the mechanisms by which these structure-based stapled peptides function as AMPs are explored, providing a comprehensive and engaging discussion. [ABSTRACT FROM AUTHOR]

Iron is crucial for the metabolism and growth of most prokaryotic cells. The ferric uptake regulator (Fur) protein plays a central role in regulating iron homeostasis and metabolic processes in bacteria. It ensures the proper utilization of iron and the maintenance of cellular functions in response to environmental cues. Fur proteins are composed of an N-terminal DNA-binding domain (DBD) and a C-terminal dimerization domain (DD), typically existing as dimers in solution. Fur proteins have conserved metal-binding sites named S1, S2, and S3. Among them, site S2 serves as a regulatory site, and metal binding at S2 results in conformational changes. Additionally, as a transcriptional regulator, Fur specifically binds to a consensus DNA sequence called the Fur box. To elucidate the structural and functional properties of Fur proteins, various structures of metal- or DNA-bound Fur proteins or apo-Fur proteins have been determined. In this review, we focus on the structural properties of Fur proteins according to their ligand-bound state and the drug development strategies targeting Fur proteins. This information provides valuable insights for drug discovery. [ABSTRACT FROM AUTHOR]

Lipids, as multifunctional molecules, play a crucial role in a variety of cellular processes. These include regulating membrane glycoprotein functions, controlling membrane trafficking, influencing apoptotic pathways, and affecting drug transport. In addition, lipid metabolites can alter the surrounding microenvironment in ways that might encourage tumor progression. The reprogramming of lipid metabolism is pivotal in promoting tumorigenesis and cancer progression, with tumors often displaying significant changes in lipid profiles. This review concentrates on the essential factors that drive lipid metabolic reprogramming, which contributes to the advancement and drug resistance in melanoma. Moreover, we discuss recent advances and current therapeutic strategies that employ small-molecule inhibitors to target lipid metabolism in skin cancers, particularly those associated with inflammation and melanoma. [ABSTRACT FROM AUTHOR]

Klebsiella pneumoniae causes severe human diseases, but its resistance to current antibiotics is increasing. Therefore, new antibiotics to eradicate K. pneumoniae are urgently needed. Bacterial toxin–antitoxin (TA) systems are strongly correlated with physiological processes in pathogenic bacteria, such as growth arrest, survival, and apoptosis. By using structural information, we could design the peptides and small-molecule compounds that can disrupt the binding between K. pneumoniae MazE and MazF, which release free MazF toxin. Because the MazEF system is closely implicated in programmed cell death, artificial activation of MazF can promote cell death of K. pneumoniae. The effectiveness of a discovered small-molecule compound in bacterial cell killing was confirmed through flow cytometry analysis. Our findings can contribute to understanding the bacterial MazEF TA system and developing antimicrobial agents for treating drug-resistant K. pneumoniae. [ABSTRACT FROM AUTHOR]

Epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) such as gefitinib and osimertinib have primarily been used as first-line treatments for patients with EGFR-activating mutations in non-small cell lung cancer (NSCLC). Novel biomarkers are required to distinguish patients with lung cancer who are resistant to EGFR-TKIs. The aim of the study is to investigate the expression and functional role of YES1, one of the Src-family kinases, in EGFR-TKI-resistant NSCLC. YES1 expression was elevated in gefitinib-resistant HCC827 (HCC827/GR) cells, harboring EGFR mutations. Moreover, HCC827/GR cells exhibited increased reactive oxygen species (ROS) levels compared to those of the parent cells, resulting in the phosphorylation/activation of YES1 due to oxidation of the cysteine residue. HCC827/GR cells showed elevated expression levels of YES1-associated protein 1 (YAP1), NF-E2-related factor 2 (Nrf2), cancer stemness-related markers, and antioxidant proteins compared to those of the parent cells. Knockdown of YES1 in HCC827/GR cells suppressed YAP1 phosphorylation, leading to the inhibition of Bcl-2, Bcl-xL, and Cyclin D1 expression. Silencing YES1 markedly attenuated the proliferation, migration, and tumorigenicity of HCC827/GR cells. Dasatinib inhibited the proliferation of HCC827/GR cells by targeting YES1-mediated signaling pathways. Furthermore, the combination of gefitinib and dasatinib demonstrated a synergistic effect in suppressing the proliferation of HCC827/GR cells. Notably, YES1- and Nrf2-regulated genes showed a positive regulatory relationship in patients with lung cancer and in TKI-resistant NSCLC cell lines. Taken together, these findings suggest that modulation of YES1 expression and activity may be an attractive therapeutic strategy for the treatment of drug-resistant NSCLC. [ABSTRACT FROM AUTHOR]

Src family kinases (SFKs) are non-receptor tyrosine kinases that are recognized as proto-oncogenic products. Among SFKs, YES1 is frequently amplified and overexpressed in a variety of human tumors, including lung, breast, ovarian, and skin cancers. YES1 plays a pivotal role in promoting cell proliferation, survival, and invasiveness during tumor development. Recent findings indicate that YES1 expression and activation are associated with resistance to chemotherapeutic drugs and tyrosine kinase inhibitors in human malignancies. YES1 undergoes post-translational modifications, such as lipidation and nitrosylation, which can modulate its catalytic activity, subcellular localization, and binding affinity for substrate proteins. Therefore, we investigated the diverse mechanisms governing YES1 activation and its impact on critical intracellular signal transduction pathways. We emphasized the function of YES1 as a potential mechanism contributing to the anticancer drug resistance emergence. [ABSTRACT FROM AUTHOR]

Mycobacterium tuberculosis, a major cause of mortality from a single infectious agent, possesses a remarkable mycobacterial cell envelope. Penicillin-Binding Proteins (PBPs) are a family of bacterial enzymes involved in the biosynthesis of peptidoglycan. PBP4 (DacB) from M. tuberculosis (MtbPBP4) has been known to function as a carboxypeptidase, and the role and significance of carboxypeptidases as targets for anti-tuberculosis drugs or antibiotics have been extensively investigated over the past decade. However, their precise involvement remains incompletely understood. In this study, we employed predictive modeling and analyzed the three-dimensional structure of MtbPBP4. Interestingly, MtbPBP4 displayed a distinct domain structure compared to its homologs. Docking studies with meropenem verified the presence of active site residues conserved in PBPs. These findings establish a structural foundation for comprehending the molecular function of MtbPBP4 and offer a platform for the exploration of novel antibiotics. [ABSTRACT FROM AUTHOR]

The reprogramming of lipid metabolism and its association with oncogenic signaling pathways within the tumor microenvironment (TME) have emerged as significant hallmarks of cancer. Lipid metabolism is defined as a complex set of molecular processes including lipid uptake, synthesis, transport, and degradation. The dysregulation of lipid metabolism is affected by enzymes and signaling molecules directly or indirectly involved in the lipid metabolic process. Regulation of lipid metabolizing enzymes has been shown to modulate cancer development and to avoid resistance to anticancer drugs in tumors and the TME. Because of this, understanding the metabolic reprogramming associated with oncogenic progression is important to develop strategies for cancer treatment. Recent advances provide insight into fundamental mechanisms and the connections between altered lipid metabolism and tumorigenesis. In this review, we explore alterations to lipid metabolism and the pivotal factors driving lipid metabolic reprogramming, which exacerbate cancer progression. We also shed light on the latest insights and current therapeutic approaches based on small molecular inhibitors and phytochemicals targeting lipid metabolism for cancer treatment. Further investigations are worthwhile to fully understand the underlying mechanisms and the correlation between altered lipid metabolism and carcinogenesis. [ABSTRACT FROM AUTHOR]

Objective: A growing number of Korean adolescents consume energy drinks, which may increase the risk of obesity, anxiety and insomnia. We examined whether poor sleep was associated with energy drink consumption among study participants. Design: We used a cross-sectional design. Setting: The Korea Youth Risk Behavior Web-Based Survey data from 2019. Participants: To determine the association between sleep and energy drink consumption, we compared the independent variables for 50,455 adolescents in Korea (aged 14–19 years) using multivariate logistic regression and sensitivity analyses. Results: In Korea, 69·5 % adolescents consumed energy drinks, 17·1 % slept for less than 5 h, 22·4 % slept for 5–6 h, 23·8 % slept for 6–7 h, 19·9 % slept for 7–8 h and 16·7 % slept for 8 h or more. Regarding sleep satisfaction, 21·0 % reported sufficient, 32·6 % reported just enough and 46·5 % reported insufficient. Regarding sleep duration, it was found that less than 5 h (OR, 2·36; 95 % CI (2·14, 2·60)) and lower sleep satisfaction (OR, 1·12; 95 % CI (1·03, 1·21)) were highly associated with energy drink consumption, with statistical significance at P < 0·05. Adolescents with lower sleep duration (adjusted OR (aOR), 6·37; 95 % CI (4·72, 8·61)) and a lack of sleep satisfaction (aOR, 1·44; 95 % CI (1·16, 1·78)) reported drinking a high amount of energy drinks, that is, at least once a day. Conclusion: In addition to efforts to decrease the amount of energy drinks consumed, sleep hygiene education needs to be strengthened. [ABSTRACT FROM AUTHOR]

Health providers are striving to create a more positive, patient-centred experience. However, existing scholarly research about the association between determinants of patient choice of provider and patient-reported experience remains insufficient to effectively promote patient-centredness in healthcare systems. This study used a sample from the nationally representative 2020 Healthcare Experience Survey. Among the respondents (n  = 12 133), 6809 who used outpatient services were selected for analysis. The variable of interest was the determinant of the patient choice of provider, and the dependent variables were patient-reported experiences (e.g. general satisfaction, experience with doctors, and experience with health providers and nurses). Data were analyzed using a multivariable logistic regression model by correcting for covariates. General satisfaction was positively associated with providers' expertise factors and public image factors [providers' expertise factors: odds ratio (OR), 2.96; 95% confidence interval (CI), 2.44–3.59; public image factors: OR, 1.26; 95% CI, 1.02–1.55] satisfied more general satisfaction. Similar results were found for experience with doctors (providers' expertise factors: OR, 4.50; 95% CI, 2.77–7.32; other factors: OR, 0.37; 95% CI, 0.16–0.81) and experience with health providers and nurses (providers' expertise factors: OR, 2.66; 95% CI, 1.99–3.57; image factors: OR, 1.53; 95% CI, 1.09–2.14). Our study's findings suggest that to improve patient-reported experience, health providers must better manage providers' expertise factors and public image factors. Health providers can improve patient-reported experience by increasing communication skills and proper information about the nature is important. Moreover, health providers must manage public image factors comprehensively and continuously by maintaining good quality of care and to brand patients. [ABSTRACT FROM AUTHOR]

Background: Frequent Emergency Department (ED) visitors are identified by the policymakers to reduce avoidable ED visits and lessen the financial and operational burden. This study aimed to identify the factors related to the frequent use of ED services. Methods: This nationwide, cross-sectional observational study was conducted using information obtained from the 2019 National Emergency Department Information System (NEDIS) database. Frequent ED users were defined as patients with four or more ED visits a year. We performed multiple logistic regression analyses to verify the relationship among sociodemographic characteristics, residential characteristics, clinical characteristics, and frequency of ED visits. Results: Among 4,063,640 selected patients, 137,608 patients visited the ED four or more times a year (total number of visits = 735,502 times), which accounted for 3.4% and 12.8% of the total number of ED users and ED visits, respectively. A high ED visit frequency was associated with male sex, age < 9 or ≥ 70 years, Medical Aid (based on the insurance type), lower number of medical institutions and beds compared with that of the national average, and conditions, such as cancer, diabetes, renal failure, and mental illness. A low ED-visit frequency was associated with residence in regions vulnerable to emergency medical care and regions with high income. The possibility of frequent ED visits was high for patients with level 5 severity (non-emergent) and those with an increased need for medical treatment, including older patients and patients with cancer or mental illness. The possibility of frequent ED visits was low for patients aged > 19 years with level 1 severity (resuscitation). Conclusions: Health service accessibility factors, including low income and medical resource imbalance, were associated with frequent ED visits. Future large-scale prospective cohort studies are warranted to establish an efficient emergency medical system. [ABSTRACT FROM AUTHOR]

Polyketide metabolism‐associated proteins in Mycobacterium tuberculosis play an essential role in the survival of the bacterium, which makes them potential drug targets for the treatment of tuberculosis (TB). The novel ribonuclease protein Rv1546 is predicted to be a member of the steroidogenic acute regulatory protein‐related lipid‐transfer (START) domain superfamily, which comprises bacterial polyketide aromatase/cyclases (ARO/CYCs). Here, we determined the crystal structure of Rv1546 in a V‐shaped dimer. The Rv1546 monomer consists of four α‐helices and seven antiparallel β‐strands. Interestingly, in the dimeric state, Rv1546 forms a helix‐grip fold, which is present in START domain proteins, via three‐dimensional domain swapping. Structural analysis revealed that the conformational change of the C‐terminal α‐helix of Rv1546 might contribute to the unique dimer structure. Site‐directed mutagenesis followed by in vitro ribonuclease activity assays was performed to identify catalytic sites of the protein. This experiment suggested that surface residues R63, K84, K88, and R113 are important in the ribonuclease function of Rv1546. In summary, this study presents the structural and functional characterization of Rv1546 and supplies new perspectives for exploiting Rv1546 as a novel drug target for TB treatment. PDB Code(s): 8H0H and 8H2D; [ABSTRACT FROM AUTHOR]

The dysregulation of lipid metabolism and alterations in the ratio of monounsaturated fatty acids (MUFAs) to saturated fatty acids (SFAs) have been implicated in cancer progression and stemness. Stearoyl-CoA desaturase 1 (SCD1), an enzyme involved in lipid desaturation, is crucial in regulating this ratio and has been identified as an important regulator of cancer cell survival and progression. SCD1 converts SFAs into MUFAs and is important for maintaining membrane fluidity, cellular signaling, and gene expression. Many malignancies, including cancer stem cells, have been reported to exhibit high expression of SCD1. Therefore, targeting SCD1 may provide a novel therapeutic strategy for cancer treatment. In addition, the involvement of SCD1 in cancer stem cells has been observed in various types of cancer. Some natural products have the potential to inhibit SCD1 expression/activity, thereby suppressing cancer cell survival and self-renewal activity. [ABSTRACT FROM AUTHOR]

It remains uncertain whether albuminuria can identify elderly patients with diabetes at a high risk of incident end-stage kidney disease (ESKD) or mortality. 3065 patients (aged ≥ 65 years) with type 2 diabetes were included. We examined the association between albuminuria stages (normoalbuminuria, A1; microalbuminuria, A2; and macroalbuminuria, A3) and the risk of incident ESKD and all-cause mortality for each age group (65–69, 70–74, and ≥ 75 years). A2 and A3 were observed in 25.5% and 9.4% of the subjects, respectively. For A1, A2, and A3, the probabilities of ESKD at 8 years were 1.0%, 6.3%, and 29.7% (P < 0.001 for all), and the all-cause mortality was 13.1%, 27.4%, and 31.7% (P < 0.001 for A1 vs A2, P < 0.001 for A1 vs A3), respectively. Albuminuria stages were independently associated with an increased risk of ESKD [fully adjusted hazard ratios (HR): 3.650 (1.987–6.702) for A2, 10.404 (5.706–18.972) for A3 vs. A1]. The HRs of all-cause mortality were 1.742 (1.411–2.153) for A2 and 1.810 (1.344–2.441) for A3. The associations between albuminuria stages and the risk of ESKD and all-cause mortality were consistent across all age groups. Even microalbuminuria is also a risk factor for incident ESKD and mortality in elderly patients with diabetes. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the association between socioeconomic status (SES) and healthcare utilization by children with allergic diseases. We determined SES based on parental occupation and household income. A cross-sectional study was conducted using the Korean National Health and Nutritional Examination Survey (KNHANES) between 2015 and 2019 with participants who were under 18 years of age. The presence of allergic conditions was determined by a self-reported survey of parental response and healthcare utilization data (such as inpatient and outpatient visits). Moreover, we categorized SES into four quantiles (Q1–Q4) based on household income per annum. Then, the data were analyzed using chi-square tests and multivariate logistic regression analysis with confidence intervals (CIs) of 95%, and p < 0.05 was considered significant. A total of 3250 participants were involved in this study. The percentage of allergic diseases was 67.9% for allergic asthma and 32.1% for atopic dermatitis. It was found that the participants who were over 13 years old had atopic dermatitis and were more likely to visit the hospital than younger children. Additionally, the highest SES group in Q4 demonstrated higher healthcare utilization (OR = 1.58; 95% CI, 1.14–1.76) than other SES groups. Our study reveals that parental socioeconomic characteristics are related to the use of healthcare services for children with allergic disorders in Korea. These results highlight the need for public health actions and research to overcome the SES gap among children with allergic diseases. [ABSTRACT FROM AUTHOR]

Rationale: The production of bottled water requires a forensic discriminant technique that enables the identification of the brands or accidents caused by intended contaminants. The bottled water poisoning crimes have drawn much attention, and such crimes may recur in the future. The water is colorless and odorless, and thus it is difficult to detect contaminated water through visual observation. Thus, bottled water can be easily exploited for poisoning, and a method for tracing their origin is currently required. Methods: In this study, a total of 27 brands of bottled water samples were analyzed to determine stable oxygen isotopes, strontium isotopes, major and trace elements. The geographical origin of the water was traced based on the climatic and geographical characteristics of the location from where water was sourced, which was assumed to be reflected in the bottled water. Furthermore, we investigated whether this method can be applied to identify bottled water products. Results: The results demonstrated that the characteristics of the bottled water, including the oxygen stable isotope ratios, reflect the latitude and altitude of bottled water source in South Korea, from the high‐latitude region to the coastal regions. In addition, the results indicated that excellent discrimination was achieved using strontium isotopes to identify source areas with different types of bedrock, complex underlying lithologies, and ocean areas in South Korea. A statistical method based on discriminant analysis was applied to measure trace elements, and the results effectively reflected the characteristics of water–rock interactions (cross‐validated classification probability: ≥92%). Conclusions: These data suggest that the geographical characteristics of the source area are well reflected in commercial bottled water in South Korea. The proposed analytical methods can be utilized to trace the geographical origin of different bottled water samples and identify bottled water products used in poisoning crimes. [ABSTRACT FROM AUTHOR]

This study aimed to identify the characteristics of walk-in patients who visited a dental university hospital more than once (returning patient). The factors affecting walk-in visits were analyzed in relation to demographic, appointment, and treatment characteristics among 146,567 cases treated between 1 March 2019 and 29 February 2020. Multiple logistic regression was used to assess factors influencing walk-in visits. The walk-in rate was 14.1%. The likelihood of walk-in visits was higher in men, patients aged 20–39 years, patients residing in Seoul, and hospital employees or their family members. Walk-in visits were more likely to take place from 8:00 to 9:59 and on Saturdays and Mondays. The walk-in odds ratios differed depending on the treatment department and diagnosis. Return patients had higher odds of walk-in visits for treatments not covered by insurance. The probability of being a walk-in patient was lower among patients who also received treatment in other departments on the same day than among those who did not. These results indicate that each examined factor has a predictable pattern. The findings also suggest a relatively high percentage of walk-in cases in dental university hospitals and that walk-in patients differ in their characteristics from patients with appointments. [ABSTRACT FROM AUTHOR]

Nuclear factor erythroid 2-related factor 2 (NRF2) is a key transcription factor involved in protection against initiation of carcinogenesis in normal cells. Notably, recent studies have demonstrated that aberrant activation of NRF2 accelerates the proliferation and progression of cancer cells. The differential effects of NRF2 on multi-stage carcinogenesis have raised a concern about the validity of NRF2 activators for chemoprevention. This prompted us to assess the effects of sulforaphane (SFN), a prototypic NRF2 activating chemopreventive phytochemical, on experimentally induced carcinogenesis. In the present study, SFN was daily injected intraperitoneally (25 mg/kg) for 3 months to male C57BL/6 mice at 6 months after single intraperitoneal administration of a hepatocarcinogen, diethylnitrosamine (DEN). The liver to body weight ratio, tumor growth, and the number and the size of hepatomas measured at 9 months after DEN administration were significantly higher in SFN-treated mice than those in vehicle-treated mice. Moreover, the expression of NRF2, its target protein NAD(P)H:quinone oxidoreductase 1, and the cell proliferation marker, proliferating cell nuclear antigen was further elevated in DEN plus SFN-treated mice. These results suggest that once hepatocarcinogenesis is initiated, SFN may stimulate tumor progression. [ABSTRACT FROM AUTHOR]

The inflammatory tumor microenvironment has been known to be closely connected to all stages of cancer development, including initiation, promotion, and progression. Systemic inflammation in the tumor microenvironment is increasingly being recognized as an important prognostic marker in cancer patients. Inflammasomes are master regulators in the first line of host defense for the initiation of innate immune responses. Inflammasomes sense pathogen-associated molecular patterns and damage-associated molecular patterns, following recruitment of immune cells into infection sites. Therefore, dysregulated expression/activation of inflammasomes is implicated in pathogenesis of diverse inflammatory disorders. Recent studies have demonstrated that inflammasomes play a vital role in regulating the development and progression of cancer. This review focuses on fate-determining roles of the inflammasomes and the principal downstream effector cytokine, IL-1β, in the tumor microenvironment. [ABSTRACT FROM AUTHOR]

Toxin–antitoxin (TA) systems regulate key cellular functions in bacteria. Here, we report a unique structure of the Streptococcus pneumoniae HigBA system and a novel antimicrobial agent that activates HigB toxin, which results in mRNA degradation as an antibacterial strategy. In this study, protein structure‐based peptides were designed and successfully penetrated the S. pneumoniae cell membrane and exerted bactericidal activity. This result represents the time during which inhibitors triggered S. pneumoniae cell death via the TA system. This discovery is a remarkable milestone in the treatment of antibiotic‐resistant S. pneumoniae, and the mechanism of bactericidal activity is completely different from those of current antibiotics. Furthermore, we found that the HigBA complex shows a crossed‐scissor interface with two intermolecular β‐sheets at both the N and C termini of the HigA antitoxin. Our biochemical and structural studies provided valuable information regarding the transcriptional regulation mechanisms associated with the structural variability of HigAs. Our in vivo study also revealed the potential catalytic residues of HigB and their functional relationships. An inhibition study with peptides additionally proved that peptide binding may allosterically inhibit HigB activity. Overall, our results provide insights into the molecular basis of HigBA TA systems in S. pneumoniae, which can be applied for the development of new antibacterial strategies. Databases: Structural data are available in the PDB database under the accession number 6AF4. [ABSTRACT FROM AUTHOR]

Recent studies report that nuclear factor-erythroid-2-related factor 2 (Nrf2) facilitates tumor progression through metabolic reprogramming in cancer cells. However, the molecular mechanism underlying the oncogenic functions of Nrf2 is not yet well understood. Some of the pentose phosphate pathway (PPP) enzymes are considered to play a role in the cancer progression. The present study was intended to explore the potential role of phosphogluconate dehydrogenase (PGD), one of the PPP enzymes, in the proliferation and migration of human hepatoma HepG2 cells. Genetic ablation of Nrf2 attenuated the expression of PGD at both transcriptional and translational levels. Notably, Nrf2 regulates the transcription of PGD through direct binding to the antioxidant response element in its promoter region. Nrf2 overexpression in HepG2 cells led to increased proliferation, survival, and migration, and these events were suppressed by silencing PGD. Interestingly, knockdown of the gene encoding this enzyme not only attenuated the proliferation and clonogenicity of HepG2 cells but also downregulated the expression of Nrf2. Thus, there seems to exist a positive feedback loop between Nrf2 and PGD which is exploited by hepatoma cells for their proliferation and survival. Treatment of HepG2 cells with ribulose-5-phosphate, a catalytic product of PGD, gave rise to a concentration-dependent upregulation of Nrf2. Collectively, the current study shows that Nrf2 promotes hepatoma cell growth and progression, partly through induction of PGD transcription. [ABSTRACT FROM AUTHOR]

While our recent studies have suggested that effective acupoints display neurogenic inflammation and can be identified as neurogenic spots (Neuro-Sps), the optimal stimulation conditions and the underlying mechanisms remain uncharacterized. We developed a combined mechano-electrical acupuncture device (MEA) and examined the effects of acupuncture at Neuro-Sps on systolic blood pressure (BP) in a rat model of immobilization-induced hypertension (IMH) and the mediation of endogenous opioid systems in its effect. Cutaneous neurogenic spots were found mostly in the forelimb. Electrical and mechanical acupuncture of Neuro-Sps increased 22-kHz ultrasonic vocalizations (USVs), c-Fos expression and cell excitability in the midbrain and synergistically alleviated the development of hypertension following immobilization stress, which was prevented by administration of the opioid antagonist naloxone into the rostral ventrolateral medulla (rVLM). These findings suggest that mechanical and electrical stimulation at Neuro-Sps suppresses the development of hypertension via mediation of the endogenous opioid system. [ABSTRACT FROM AUTHOR]

Transcriptional regulator proteins are closely involved in essential survival strategies in bacteria. AcrR is a one‐component allosteric repressor of the genes associated with lipid transport and antibiotic resistance. When fatty acid ligands bind to the C‐terminal ligand‐binding cavity of AcrR, a conformational change in the N‐terminal operator‐binding region of AcrR is triggered, which releases the repressed DNA and initiates transcription. This paper focuses on the structural transition mechanism of AcrR of Mycobacterium tuberculosis upon DNA and ligand binding. AcrR loses its structural integrity upon ligand‐mediated structural alteration and bends toward the promoter DNA in a more compact form, initiating a rotational motion. Our functional characterization of AcrR and description of the ligand‐ and DNA‐recognition mechanism may facilitate the discovery of new therapies for tuberculosis. [ABSTRACT FROM AUTHOR]

Several reports indicate crosstalk between the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) and estrogen, which has a protective effect in colorectal cancer (CRC). The aim of this study was to investigate the role of Nrf2 signaling in the anti-inflammatory effect of estrogen using Nrf2 knockout (Nrf2 KO) mouse embryonic fibroblasts (MEFs), a powerful system to test the function of target genes due to their easy accessibility, and rapid growth rates. After inducing inflammation by tumor necrosis factor alpha (TNF-α), the effects of 17β-estradiol (E2) on the expression of proinflammatory mediators [i.e., NF-κB and inducible nitric oxide synthase (iNOS)] and estrogen receptors were evaluated by Western blot. In wild type (WT) MEFs, E2 treatment ameliorated TNF-α-induced nuclear translocation of NF-κB and expression of its target protein iNOS. Estrogen receptor beta (ERβ) expression was decreased by TNF-α-induced inflammation and restored by E2 treatment. When treated to WT MEFs, E2 induced nuclear translocation of Nrf2. The inhibitory effect of E2 on TNF-α-induced enhancement of iNOS was markedly dampened in Nrf2 KO MEFs. Notably, ERβ expression was significantly diminished in Nrf2 KO MEFs compared to that in WT cells. Promoter Database (EPD) revealed two putative anti-oxidant response elements (AREs) within the mouse ERβ promoter. Furthermore, in WT MEFs, E2 treatment repressed TNF-α-induced expression of iNOS protein and recovered by 4-(2-phenyl-5,7-bis(trifluoromethyl)pyrazolo(1,5-a)pyrimidin-3-yl)phenol (PHTPP), a selective ERβ antagonist, treatment, but not in Nrf2 KO MEFs. In conclusion, Nrf2 plays a pivotal role in the anti-inflammatory of estrogen by direct regulating the expression of ERβ. [ABSTRACT FROM AUTHOR]

Sirt1, a member of the sirtuin gene family, encodes the most conserved mammalian NAD+-dependent deacetylase enzyme responsible for removing acetyl groups from many proteins. The Sirt1 gene is known as a longevity gene whose knockout in mice leads to decreased lifespan relative to the wild type. This study aimed to explore phenotypic changes in zebrafish Sirt1-knockouts and to investigate the function of the Sirt1 gene. Targeted knockout of Sirt1 in zebrafish (Danio rerio) was achieved using the CRISPR-Cas9 genome editing system. We created a 4-bp insertion-homozygote Sirt1-knockout zebrafish. Although there was no evident difference in appearance in the early stages of development, a significant increase in reactive oxygen species and in the extent of apoptosis in Sirt1-knockout zebrafish was observed. Sirt1 knockout caused inflammatory genes, including IL-1b, IL-6 and TNF-α to be highly expressed. Additionally, the lack of Sirt1 caused chronic inflammation and intestinal atrophy, thereby increasing pro-apoptotic events, which ultimately reduced the lifespan of transgenic zebrafish. Overall, our data demonstrate that lack of Sirt1 caused a significantly increased generation of reactive oxygen species that resulted in chronic inflammation and regeneration. Continuous repetition of these events played an important role in accelerating aging, thereby decreasing lifespan. Our findings using the knockout zebrafish model confirmed the association of the Sirt1 gene to aging processes and lifespan. Furthermore, the Sirt1-knockout mutant zebrafish developed in our study will surely be a valuable model to explore the mechanism of chronic inflammation. [ABSTRACT FROM AUTHOR]

Oxidative stress caused as a result of iron overload is implicated in clinical manifestation of beta-thalassemia/haemoglobin E (β-Thal/HbE). In this study, we investigated the cellular adaptation against oxidative stress in β-Thal/HbE patients. Twenty-four paediatric β-Thal/HbE patients and 22 healthy controls were recruited in the study. Blood samples from patients exhibited iron overload, elevation of lipid peroxidation, and marked diminution in the reduced glutathione (GSH) level. However, expression of glutamate-cysteine ligase catalytic (GCLC) subunit, a key enzyme in GSH biosynthesis, was up-regulated when compared with that in controls. GCLC protein levels were correlated with serum iron. There was an enhanced binding activity of the oligonucleotide probe for Nrf2-driven antioxidant response element (ARE) to nuclear protein from blood mononuclear cells of thalassemia subjects. In conclusion, β-Thal/HbE patients exhibit elevated plasma levels of GCLC expression and Nrf2-ARE binding activity, which may account for their adaptive survival response to oxidative stress. [ABSTRACT FROM AUTHOR]

15-Hydroxyprostaglandin dehydrogenase (15-PGDH) is the key enzyme that catalyses the conversion of prostaglandin E2 to a keto metabolite. The expression of 15-PGDH is ubiquitously repressed in various human malignancies. However, the molecular mechanisms underlying down-regulation of 15-PGDH expression remain largely unknown. 15-Deoxy-△12,14-prostaglandin J2 (15d-PGJ2), an endogenous ligand of peroxisome proliferator-activated receptor γ, has been reported to have anti-inflammatory and anticarcinogenic activities. In the present study, we have found that 15d-PGJ2 induces expression and catalytic activity of 15-PGDH in human breast cancer (MDA-MB-231) cells. 15d-PGJ2 decreased the level of CpG methylation in the 15-PGDH promoter in MDA-MB-231 cells as determined by the bisulphite genome sequencing and methyl-specific PCR. 15d-PGJ2 inhibited the catalytic activity of methyltransferase 1 (DNMT1) but did not influence its expression. Biotinylated 15d-PGJ2 directly interacted with DNMT1 and reduced its catalytic activity. Chromatin-immunoprecipitation analysis revealed that 15d-PGJ2 significantly attenuated DNMT1 binding to the activator protein-1 transcription factor present in the 15-PGDH promoter region. A nonelectrophilic analogue 9,10-dihydro-15d-PGJ2 failed to suppress the methylation of CpG islands present in 15-PGDH promoter and did not affect both DNMT1 activity and 15-PGDH expression. These findings suggest that the α,β-unsaturated carbonyl group present in 15d-PGJ2 is essential for its inactivation on DNMT1 and expression of 15-PGDH. In conclusion, 15d-PGJ2 plays as a hypomethylating agent through direct interaction with DNMT1 and consequently suppresses DNMT1-mediated hypermethylation of 15-PGDH promoter, leading to up-regulation of 15-PGDH expression. [ABSTRACT FROM AUTHOR]

Acupuncture has been used to treat a variety of diseases and symptoms for more than 2,500 years. While a number of studies have shown that nerves are responsible for initiating the effects of acupuncture, several lines of study have emphasized the role of connective tissue in the initiation of acupuncture signals. To determine whether nerves or connective tissue mediate the action of acupuncture, we constructed a robotic acupuncture needle twister that mimicked the twisting of the needle by an acupuncturist, and we examined the role of nerves and connective tissues in the generation of acupuncture effects in rat cocaine-induced locomotion, stress-induced hypertension, and mustard oil-induced visceral pain models. Robotic or manual twisting of acupuncture needles effectively suppressed cocaine-induced hyperactivity, elevated systemic blood pressure or mustard oil-induced visceral pain in rats. These acupuncture effects were completely abolished by injecting bupivacaine, a local anesthetic, into acupoints. However, disruption of connective tissue by injecting type I collagenase into acupoints did not affect these acupuncture effects. Our findings suggest that nerve tissue, but not connective tissue, is responsible for generating the effects of acupuncture. [ABSTRACT FROM AUTHOR]

Focuses on a study which analyzed the structural and electrical characteristics of ion implanted epitaxial ReSi[sub2] films grown on a silicon substrate. Background on epitaxial semiconducting silicides; Experimental details; Results and discussion.

Cancer stem cells (CSCs) constitute a subpopulation of transformed cells that possess intrinsic ability to undergo selfrenewal and differentiation, which drive tumour resistance and cancer recurrence. It has been reported that CSCs possess enhanced protection against oxidative stress induced by reactive oxygen species compared with nonstem-like cancer cells. In the present work, we investigated the role of heme oxygenase-1 (HO-1), a representative antioxidant enzyme, on the stemness and selfrenewal of human breast CSCs. We found that pharmacologic or genetic inhibition of HO-1 attenuated the sphere formation, whereas HO-1 inducers enhanced the number and the size of tumourspheres in breast CSCs. Carbon monoxide (CO) is endogenously generated as a consequence of degradation of heme by HO-1. The proportion of populations of CD44+/CD24− cells retaining CSC properties was increased in MDA-MB-231 cells treated with a CO-releasing molecule (CORM-2). Following CORM-2 treatment, the expression of Notch-1 and related genes Jagged-1 and Hes1 was increased, which was accompanied by the mammosphere formation. Taken together, these findings suggest that HO-1-derived CO production stimulates the formation of mammospheres in breast cancer cells through activation of Notch-1 signalling. [ABSTRACT FROM AUTHOR]

We previously reported a series of amphipathic helices of stapled heptapeptides as membrane-lytic antimicrobial peptides. These peptides possess three lysine residues as the sole cationic amino acid residues in their hydrophilic face of the helix. Lysine-to-arginine substitution is often shown to increase antimicrobial activity of many natural AMPs due to the more favorable interactions of guanidinium moiety of arginine with membranes. In an effort to further improve the pharmacological properties of our novel AMP series, we here examined the impact of lysine-to-arginine substitution on their structures and antimicrobial and hemolytic activities. Our results indicate that the lysine-to-arginine substitution does not always guarantee enhancement in the antimicrobial potency of AMPs. Instead, we observed varied potency and selectivity depending on the number of substitutions and the positions substituted. Our results imply that, in the given helical scaffold stabilized by a hydrocarbon staple, antimicrobial potency and selectivity are influenced by a complex effect of various structural and chemical changes accompanied by lysine-to-arginine substitution rather than solely by the type of cationic residue. These data show potential for use in our scaffold-assisted development of short, selective, and metabolically stable AMPs. [ABSTRACT FROM AUTHOR]

Background: The orientation of the pelvis is of particular importance to the sagittal curve of the spine and has geometric relationships with the top of the spine and lumbar lordosis. Changes in spinal shape or disruptions of sagittal balance in the spine, such as a flattened lumbar spine, have significant negative effects.Objective: The aim of this study was to investigate the effects of the posterior superior iliac spine support device (PSD) on upper trunk acceleration during gait in individuals with flat lumbar back posture.Methods: In total, 10 young male subjects with reduced lumbar lordosis (global lumbar lordosis angle (T10-S2): <-20∘) were recruited for this study. Participants walked 7 m with and without wearing a PSD at a self-selected speed while fitted with an accelerometer attached over the T7 spinous process.Results: The normalized AP acceleration of T7 with PSD (40.57 ± 11.22%) was significantly higher than those without PSD (37.10 ± 10.46%, p= 0.035).Conclusions: We found that wearing the PSD immediately improved pelvic physiological movement during walking in individuals with lumbar flat back posture. Our findings may help healthcare professionals manage flat back posture in asymptomatic younger individuals. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the effects of chronic and repetitive diving in cold sea water on physiological responses to cold in older Korean female divers, Haenyeo, who have been exposed to cold water through breath-hold diving since their teens. Young and older females, who have no experience of swimming in cold sea water, were recruited as control groups: older haenyeos (N = 10, 70 ± 3 years of age), young non-diving females (N = 10, 23 ± 2 years), and older non-diving females (N = 6, 73 ± 4 years). For the test of cold exposure, all subjects were exposed to cold in an air temperature of 12 °C with 45% RH in a sitting position for 60 min. The changes in core temperature showed no significant differences between older haenyeos and the other two groups. The decreases in mean skin temperature were greater for older haenyeos than the other two groups (P < 0.01). Older haenyeos had significantly lower energy expenditure during cold exposure when compared to older non-diving females (P < 0.05). Heart rate was significantly lower in older haenyeos than that of young non-diving females (P < 0.05). Older haenyeos felt cooler at the face with lower face temperature when compared with older non-diving females. The results indicate that older haenyeos respond to cold through reducing heat loss from the skin rather than increasing metabolic rate. These responses are distinctive features from the cold defensive system of young or older non-diving females. [ABSTRACT FROM AUTHOR]

The overproduction of nitric oxide (NO) and prostaglandin E2 (PGE2) by microglia may cause neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease. From the activity-guided purification of Cullen corylifolium (L.) Medik. (syn. Psoralea corylifolia L.), three prenylated chalcones were identified: isobavachalcone (1), bavachromene (2), and kanzonol B (3). These prenylated chalcones showed concentration-dependent inhibitory effects on NO and PGE2 production in lipopolysaccharide (LPS)-activated microglia. Western blotting and RT-PCR analysis demonstrated that these prenylchalcones reduced the expression of protein and mRNA of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in LPS-activated microglia. Furthermore, three prenylated chalcones blocked the inhibitory-κBα (I-κBα) degradation and down-regulated nuclear factor κB (NF-κB) level of nucleus in LPS-stimulated BV-2 microglia. Therefore, these prenylated chalcones from Psoralea corylifolia may be beneficial for the treatment of neuro-inflammatory diseases by modulating iNOS and COX-2 expressions in activated microglial cells. [ABSTRACT FROM AUTHOR]

Polybia-MP1 is a well-known natural antimicrobial peptide isolated from the venom of the social wasp Polybia paulista. A recent study showed that this peptide displays a broad antibacterial spectrum as well as low toxicity to human red blood cells and normal fibroblasts. However, its moderate antimicrobial activity and high susceptibility to protease have been a major hurdle for clinical use. This study examined the possibility of developing biologically more potent, yet metabolically more stable, analogues of MP1 using an emerging technology termed 'all-hydrocarbon stapling.' The stapled analogues of MP1 showed more than a threefold increase in helicity as well as an approximately 70-fold enhancement in proteolytic stability. These stapled analogues also exhibited a significant increase in inhibition against some Gram-positive bacteria while displaying a modest enhancement in hemolytic activity. Overall, the current study demonstrated that the all-hydrocarbon stapling system is a highly useful tool for the development of biologically more potent and metabolically more stable analogues of natural antimicrobial peptides. [ABSTRACT FROM AUTHOR]

The tumor suppressor phosphatase and tensin homologue (PTEN) has phosphatase activity, with phosphatidylinositol (3,4,5)-trisphosphate (PIP3), a product of phosphatidylinositol 3-kinase (PI3K), as one of the principal substrates. PTEN is a negative regulator of the Akt pathway, which plays a fundamental role in controlling cell growth, survival, and proliferation. Loss of PTEN function has been observed in many different types of cancer. Functional inactivation of PTEN as a consequence of germ-line mutations or promoter hypermethylation predisposes individuals to malignancies. PTEN undergoes posttranslational modifications, such as oxidation, acetylation, phosphorylation, SUMOylation, and ubiquitination, which influence its catalytic activity, interactions with other proteins, and subcellular localization. Cellular redox status is crucial for posttranslational modification of PTEN and its functional consequences. Oxidative stress and inflammation are major causes of loss of PTEN function. Pharmacologic or nutritional restoration of PTEN function is considered a reliable strategy in the management of PTEN-defective cancer. In this review, we highlight natural compounds, such as curcumin, indol-3 carbinol, and omega-3 fatty acids, that have the potential to restore or potentiate PTEN expression/activity, thereby suppressing cancer cell proliferation, survival, and resistance to chemotherapeutic agents. [ABSTRACT FROM AUTHOR]

KLOTHOwas originally identified as an aging-suppressor gene that causes a human aging-like phenotype when tested inKLOTHO-deficient-mice. Recent evidence suggests thatKLOTHOfunctions as a tumor suppressor by inhibitingWntsignaling.KLOTHOgene silencing, including DNA methylation, has been observed in some human cancers. Aberrant activation ofWntsignaling plays a significant role in aging, and its silencing may be related to prostate cancer and other types of cancers. Thus, we investigated whether the expression of the anti-aging geneKLOTHOwas associated with epigenetic changes in prostate cancer cell lines.KLOTHOmRNA was detected in the 22Rv1 cell line while it was not detected in DU145 and PC-3 cell lines. The restoration ofKLOTHOmRNA in the DU145 and PC-3 cell lines was induced with a DNA methyltransferase inhibitor. Methylation-specific PCR was performed to determine the specific CpG sites in theKLOTHOpromoter responsible for expression. In addition, the level of methylation was assessed in each CpG by performing bisulfite sequencing and quantitative pyrosequencing analysis. The results suggested a remarkable inverse relationship betweenKLOTHOexpression and promoter methylation in prostate cancer cell lines. [ABSTRACT FROM AUTHOR]

We previously reported a de novo design of antimicrobial heptapeptide helices using Verdine's all-hydrocarbon peptide stapling system. One of the important structure-activity relationships we found from these previous studies was that extending of the hydrophobic face by replacing of alanine with leucine in positon 5 increases antimicrobial activity. In this study, to further improve the activity profile of this peptide series, we investigated the substitution effects of position 5 on conformational and proteolytic stability as well as antimicrobial and hemolytic activity. We found that antimicrobial activity and cell selectivity can differ depending on the physicochemical properties of the residue in that specific position. The results shown in this work suggest that the stapled amphipathic heptapeptide helix can serve as a promising platform for developing new antibiotics that can cope with antibiotic resistance problem. Graphical Abstract: [ABSTRACT FROM AUTHOR]

The effects of different deastringency treatments (untreated, carbon dioxide, warm water, or ethanol), before drying on the quality characteristics of dried fruit slices prepared from whole 'Cheongdobansi' persimmons were evaluated. L* (lightness) and a* (redness) values of dried slices from warm water- and ethanol-treated groups were higher, respectively, compared to that of dried slices from other groups. Hardness was lower in dried slices from ethanol-treated fruits. Moisture, water activity, soluble solids, titratable acidity, and sensory properties (color, aroma, texture, sweetness, and overall acceptability) of the dried slices from astringency-removed fruits were higher when compared to those of the dried slices from non-treated persimmons. In particular, the dried slices from ethanol-treated fruits showed the highest values for these parameters. Moreover, soluble tannin and DPPH radical scavenging activity decreased by deastringency treatment. Results suggest that ethanol deastringency treatment before drying could be a useful method to improve most quality characteristics, except antioxidative activity, of dried persimmon slices. [ABSTRACT FROM AUTHOR]

15-Deoxy-Δ12,14-prostaglandin J2(15d-PGJ2), a representative J-series cyclopentenone prostaglandin, has biphasic roles in cell proliferation and apoptosis. Hypoxia inducible factor-1 (HIF-1) regulates expression of various genes involved in tumor growth and angiogenesis. In the present study, treatment of human breast cancer (MCF-7) cells with 15d-PGJ2resulted in the accumulation of the α-subunit of HIF-1. Pretreatment with zinc protoporphyrin IX, a pharmacological inhibitor of heme oxygenase-1 (HO-1), as well as siRNA knockdown ofHO-1gene in MCF-7 cells attenuated 15d-PGJ2-mediated HIF-1α accumulation. 15d-PGJ2treatment increased intracellular production of reactive oxygen species (ROS), which was mediated by HO-1 induction. Preincubation of MCF-7 cells with trolox, a water-soluble form of vitamin E, attenuated 15d-PGJ2-induced HIF-1α expression although HO-1 expression was unchanged. This finding suggests that ROS accumulated as a consequence of HO-1 up-regulation can enhance HIF-1α expression in MCF-7 cells treated with 15d-PGJ2. Alternatively, 15d-PGJ2was found to covalently bind to HIF-1α prolyl-4-hydroxylase 2 (PHD2) in MCF-7 cells, which hampers the proline hydroxylation of HIF-1α, thereby disrupting ubiquitin-dependent proteasomal degradation of this transcription factor. Pretreatment with thiol reducing agents blunted 15d-PGJ2-induced HIF-1α stabilization, indicative of a cysteine residue as a direct target of 15d-PGJ2. Molecular docking analysis suggests that 15d-PGJ2preferentially binds to PHD2 in the vicinity of the Cys201residue based on binding energies and carbon–sulfur distances. In summary, 15d-PGJ2stabilizes HIF-1α in MCF-7 cells through HO-1 induction with subsequent ROS generation and also through direct modification of PHD2. [ABSTRACT FROM AUTHOR]

Background Recent studies have shown that Helicobacter pylori ( H. pylori) activates signal transducer and activator of transcription 3 (STAT3) that plays an important role in gastric carcinogenesis. However, the molecular mechanism underlying H. pylori-mediated STAT3 activation is still not fully understood. In this study, we investigated H. pylori-induced activation of STAT3 signaling in AGS human gastric cancer cells and the underlying mechanism. Materials and Methods AGS cells were cocultured with H. pylori, and STAT3 activation was assessed by Western blot analysis, electrophoretic mobility shift assay and immunocytochemistry. To demonstrate the involvement of reactive oxygen species (ROS) in H. pylori-activated STAT3 signaling, the antioxidant N-acetylcysteine was utilized. The expression and production of interleukin-6 (IL-6) were measured by reverse-transcription polymerase chain reaction and enzyme-linked immunosorbent assay (ELISA), respectively. The interaction between IL-6 and IL-6 receptor (IL-6R) was determined by the immunoprecipitation assay. Results H. pylori activates STAT3 as evidenced by increases in phosphorylation on Tyr705, nuclear localization, DNA binding and transcriptional activity of this transcription factor. The nuclear translocation of STAT3 was also observed in H. pylori-inoculated mouse stomach. In the subsequent study, we found that H. pylori-induced STAT3 phosphorylation was dependent on IL-6. Notably, the increased IL-6 expression and the IL-6 and IL-6R binding were mediated by ROS produced as a consequence of H. pylori infection. Conclusions H. pylori-induced STAT3 activation is mediated, at least in part, through ROS-induced upregulation of IL-6 expression. These findings provide a novel molecular mechanism responsible for H. pylori-induced gastritis and gastric carcinogenesis. [ABSTRACT FROM AUTHOR]

To improve the antimicrobial activity of the hydrocarbon-stapled amphipathic heptapeptide helix identified from our previous study, we prepared a series of its dimeric analogs using several different linkers. All of these dimers showed a significant increase in antimicrobial activity although their hemolytic activity was also largely increased. One particular analog bearing a proline linker displayed notably low hemolytic activity compared to others, indicating that the conformational characteristics of the linker play a key role in disassociating undesirable hemolytic activity from antimicrobial activity in this series of antimicrobial peptides. We believe that this analog can serve as a stepping stone for further development of novel antimicrobial agents to combat antibiotic-resistance. [ABSTRACT FROM AUTHOR]