PAF remodels the DREAM complex to bypass cell quiescence and promote lung tumorigenesis.

The DREAM complex orchestrates cell quiescence and the cell cycle. However, how the DREAM complex is deregulated in cancer remains elusive. Here, we report that PAF (PCLAF/KIAA0101) drives cell quiescence exit to promote lung tumorigenesis by remodeling the DREAM complex. PAF is highly expressed in lung adenocarcinoma (LUAD) and is associated with poor prognosis. Importantly, Paf knockout markedly suppressed LUAD development in mouse models. PAF depletion induced LUAD cell quiescence and growth arrest. PAF is required for the global expression of cell-cycle genes controlled by the repressive DREAM complex. Mechanistically, PAF inhibits DREAM complex formation by binding to RBBP4, a core DREAM subunit, leading to transactivation of DREAM target genes. Furthermore, pharmacological mimicking of PAF-depleted transcriptomes inhibited LUAD tumor growth. Our results unveil how the PAF-remodeled DREAM complex bypasses cell quiescence to promote lung tumorigenesis and suggest that the PAF-DREAM axis may be a therapeutic vulnerability in lung cancer.

A Surge of DNA Damage Links Transcriptional Reprogramming and Hematopoietic Deficit in Fanconi Anemia.

Impaired DNA crosslink repair leads to Fanconi anemia (FA), characterized by a unique manifestation of bone marrow failure and pancytopenia among diseases caused by DNA damage response defects. As a germline disorder, why the hematopoietic hierarchy is specifically affected is not fully understood. We find that reprogramming transcription during hematopoietic differentiation results in an overload of genotoxic stress, which causes aborted differentiation and depletion of FA mutant progenitor cells. DNA damage onset most likely arises from formaldehyde, an obligate by-product of oxidative protein demethylation during transcription regulation. Our results demonstrate that rapid and extensive transcription reprogramming associated with hematopoietic differentiation poses a major threat to genome stability and cell viability in the absence of the FA pathway. The connection between differentiation and DNA damage accumulation reveals a novel mechanism of genome scarring and is critical to exploring therapies to counteract the aplastic anemia for the treatment of FA patients.

Surveillance of Complicated Mpox Cases Unresponsive to Oral Tecovirimat in Los Angeles County, 2022.

The Los Angeles County Department of Public Health established a surveillance system to identify complicated (advanced human immunodeficiency virus [HIV] or hospitalized) mpox cases. From 1 August to 30 November 2022, we identified 1581 mpox cases, of which 134 (8.5%) were complicated. A subset of 8 cases did not recover after either initiating or completing a course of oral tecovirimat. All 8 patients were HIV positive and had advanced HIV (CD4 count <200 cells/µL). We identified 8 distinct mutations previously associated with tecovirimat resistance in specimens collected from 6 patients. Ongoing surveillance of viral evolution requires close coordination between health departments and frontline providers.

Unveiling synergistic QTLs associated with slow wilting in soybean (Glycine max [L.] Merr.).

KEY MESSAGE: A stable QTL qSW_Gm10 works with a novel locus, qSW_Gm01, in a synergistic manner for controlling slow-wilting traits at the early vegetative stage under drought stress in soybean. Drought is one of the major environmental factors which limits soybean yield. Slow wilting is a promising trait that can enhance drought resilience in soybean without additional production costs. Recently, a Korean soybean cultivar SS2-2 was reported to exhibit slow wilting at the early vegetative stages. To find genetic loci responsible for slow wilting, in this study, quantitative trait loci (QTL) analysis was conducted using a recombinant inbred line (RIL) population derived from crossing between Taekwangkong (fast-wilting) and SS2-2 (slow-wilting). Wilting score and leaf moisture content were evaluated at the early vegetative stages for three years. Using the ICIM-MET module, a novel QTL on Chr01, qSW_Gm01 was identified, together with a previously known QTL, qSW_Gm10. These two QTLs were found to work synergistically for slow wilting of the RILs under the water-restricted condition. Furthermore, the SNP markers from the SoySNP50K dataset, located within these QTLs, were associated with the wilting phenotype in 30 diverse soybean accessions. Two genes encoding protein kinase 1b and multidrug resistance-associated protein 4 were proposed as candidate genes for qSW_Gm01 and qSW_Gm10, respectively, based on a comprehensive examination of sequence variation and gene expression differences in the parental lines under drought conditions. These genes may play a role in slow wilting by optimally regulating stomatal aperture. Our findings provide promising genetic resources for improving drought resilience in soybean and give valuable insights into the genetic mechanisms governing slow wilting.

Mortality after cardiac arrest in children less than 2 years: relevant factors.

BACKGROUND: There are only scant studies of predicting outcomes of pediatric resuscitation due to lack of population-based data. This study aimed to determine variable factors that may impact the survival of resuscitated children aged under 24 months. METHODS: This is a retrospective study of 66 children under 24 months. Cardiopulmonary resuscitation (CPR) with pediatric advanced life support guideline was performed uniformly for all children. Linear regression analysis with variable factors was conducted to determine impacts on mortality. RESULT: Factors with statistically significant increases in mortality were the number of administered epinephrine (p value < 0.001), total CPR duration (p value < 0.001), in-hospital CPR duration of out-hospital cardiac arrest (p value < 0.001), and changes in cardiac rhythm (p value < 0.040). However, there is no statistically significant association between patient outcomes and remaining factors such as age, sex, underlying disease, etiology, time between last normal to CPR, initial CPR location, initial cardiac rhythm, venous access time, or inotropic usage. CONCLUSION: More than 10 times of epinephrine administration and CPR duration longer than 30 minutes were associated with a higher mortality rate, while each epinephrine administration and prolonged CPR time increased mortality. IMPACT STATEMENT: This study analyzed various factors influencing mortality after cardiac arrest in patients under 24 months. Increased number of administered epinephrine and prolonged cardiopulmonary resuscitation duration do not increase survival rate in patients under 24 months. In patients with electrocardiogram rhythm changes during CPR, mortality increased when the rhythm changed into asystole in comparison to no changes occurring in the rhythm.

Successful Distribution of Tecovirimat During the Peak of the Mpox Outbreak - Los Angeles County, June 2022-January 2023.

Tecovirimat is the first-line antiviral treatment recommended for severe mpox or for persons with mpox who are at risk for severe disease; tecovirimat is available in the United States under an expanded access investigational new drug (IND) protocol. During the 2022-2023 mpox outbreak, local U.S. health jurisdictions facilitated access to tecovirimat. In June 2022, Los Angeles County (LAC) rapidly developed strategies for tecovirimat distribution using existing medical countermeasure distribution networks established by the Public Health Emergency Preparedness Program and the Hospital Preparedness Program, creating a hub and spoke distribution network consisting of 44 hub facilities serving 456 satellite sites across LAC. IND patient intake forms were analyzed to describe mpox patients treated with tecovirimat. Tecovirimat treatment data were matched with case surveillance data to calculate time from specimen collection to patients receiving tecovirimat. Among 2,281 patients with mpox in LAC, 735 (32%) received tecovirimat during June 2022-January 2023. Among treated patients, approximately two thirds (508; 69%) received treatment through community clinics and pharmacies. The median interval from specimen collection to treatment was 2 days (IQR = 0-5 days). Local data collection and analysis helped to minimize gaps in treatment access and facilitated network performance monitoring. During public health emergencies, medical countermeasures can be rapidly deployed across a large jurisdiction using existing distribution networks, including clinics and pharmacies.

Information extraction from weakly structured radiological reports with natural language queries.

OBJECTIVES: Provide physicians and researchers an efficient way to extract information from weakly structured radiology reports with natural language processing (NLP) machine learning models. METHODS: We evaluate seven different German bidirectional encoder representations from transformers (BERT) models on a dataset of 857,783 unlabeled radiology reports and an annotated reading comprehension dataset in the format of SQuAD 2.0 based on 1223 additional reports. RESULTS: Continued pre-training of a BERT model on the radiology dataset and a medical online encyclopedia resulted in the most accurate model with an F1-score of 83.97% and an exact match score of 71.63% for answerable questions and 96.01% accuracy in detecting unanswerable questions. Fine-tuning a non-medical model without further pre-training led to the lowest-performing model. The final model proved stable against variation in the formulations of questions and in dealing with questions on topics excluded from the training set. CONCLUSIONS: General domain BERT models further pre-trained on radiological data achieve high accuracy in answering questions on radiology reports. We propose to integrate our approach into the workflow of medical practitioners and researchers to extract information from radiology reports. CLINICAL RELEVANCE STATEMENT: By reducing the need for manual searches of radiology reports, radiologists' resources are freed up, which indirectly benefits patients. KEY POINTS: • BERT models pre-trained on general domain datasets and radiology reports achieve high accuracy (83.97% F1-score) on question-answering for radiology reports. • The best performing model achieves an F1-score of 83.97% for answerable questions and 96.01% accuracy for questions without an answer. • Additional radiology-specific pretraining of all investigated BERT models improves their performance.

Subclinical diabetes confirmed by 75-g OGTT influence on the prognosis of decompensated cirrhosis.

BACKGROUND AND AIM: Disorders of glucose metabolism, such as impaired glucose tolerance (IGT) and diabetes mellitus (DM), frequently occur in cirrhosis. We aimed to evaluate who needs to be undertaken a 75-g oral glucose tolerance test (OGTT) to find underlying subclinical diabetes. METHODS: This prospective study included 713 patients with either compensated (Child-Turcotte-Pugh [CTP] class A) or decompensated cirrhosis (CTP class B/C) without previous DM history. All patients underwent a 75-g OGTT. The patients were divided into three groups: normal glucose tolerance (NGT), IGT, and newly diagnosed DM (subclinical DM). RESULTS: Among 713 patients, NGT was diagnosed in 139 (19.5%), IGT in 252 (35.3%), and subclinical DM in 322 (45.2%) patients, respectively. During a median follow-up period of 42.0 months, the cumulative survival rates of patients were as follows: NGT, 75.6%; IGT, 57.6%; and subclinical DM, 54.8%. Overall, IGT (adjusted hazard ratio [aHR], 1.605; 95% confidence interval [CI] = 1.009-2.553; P = 0.046) and subclinical DM (aHR, 1.840; 95% CI = 1.183-2.861; P = 0.001) were identified as independent predictors of mortality. In patients with compensated cirrhosis (n = 415), neither IGT nor subclinical DM conferred a higher mortality risk. However, among patients with decompensated cirrhosis (n = 298), those with IGT (aHR, 2.394; P = 0.015) and subclinical DM (aHR, 2.211; P = 0.022) showed a survival rate worse than those with NGT. In addition, subclinical DM was identified as an independent risk factor for infection (aHR, 2.508; P = 0.007). CONCLUSIONS: IGT and subclinical diabetes by OGTT are associated with an unfavorable prognosis in cirrhosis, and the effect is pronounced in the decompensated state. CLINICALTRIALS: gov, Number NCT04828512 (https://clinicaltrials.gov/ct2/show/NCT04828512).

Validation of MELD 3.0 in patients with alcoholic liver cirrhosis using prospective KACLiF cohort.

BACKGROUND AND AIM: The Model for End-Stage Liver Disease (MELD) is a reliable prognostic tool for short-term outcome prediction in patients with end-stage liver disease. MELD 3.0 was introduced to enhance the predictive accuracy. This study assessed the performance of MELD 3.0, in comparison to MELD and MELD-Na, in patients with alcoholic liver cirrhosis. METHODS: This multicenter prospective cohort study comprised patients with alcoholic cirrhosis admitted for acute deterioration of liver function in the Republic of Korea between 2015 and 2019. This study compared the predictive abilities of MELD, MELD-Na, and MELD 3.0, for 30-day and 90-day outcomes, specifically death or liver transplantation, and explored the factors influencing these outcomes. RESULTS: A total of 1096 patients were included in the study, with a mean age of 53.3 ± 10.4 years, and 82.0% were male. The mean scores for MELD, MELD-Na, and MELD 3.0 at the time of admission were 18.7 ± 7.2, 20.6 ± 7.7, and 21.0 ± 7.8, respectively. At 30 and 90 days, 7.2% and 14.1% of patients experienced mortality or liver transplantation. The areas under the receiver operating characteristic curves for MELD, MELD-Na, and MELD 3.0 at 30 days were 0.823, 0.820, and 0.828; and at 90 days were 0.765, 0.772, and 0.776, respectively. Factors associated with the 90-day outcome included concomitant chronic viral hepatitis, prolonged prothrombin time, elevated levels of aspartate transaminase, bilirubin, and creatinine, and low albumin levels. CONCLUSION: MELD 3.0 demonstrated improved performance compared to previous models, although the differences were not statistically significant.

CuO nanostructure-decorated InGaN nanorods for selective H2S gas detection.

Establishing a heterostructure is one of the adequate strategies for enhancing device performance and has been explored in sensing, and energy applications. In this study, we constructed a heterostructure through a two-step process involving hydrothermal synthesis of CuO nanostructures and subsequent spin coating on MBE-grown InGaN NRs. We found that the CuO content on the InGaN NRs has a great impact on carrier injection at the heterojunction and thus the H2S gas sensing performance. Popcorn CuO/InGaN NR shows excellent gas sensing performance towards different concentrations of H2S at room temperature. The highest response is up to 35.54% to a H2S concentration of 100 ppm. Even more significantly, this response is further enhanced significantly (123.70%) under 365 nm UV light. In contrast, this composite structure exhibits negligibly low responses to 100 ppm of NO2, H2, CO, and NH3. The heterostructure band model associated with a surface reaction model is manifested to elucidate the sensing mechanism.

Clinical characteristics and salivary biomarkers of burning mouth syndrome.

OBJECTIVES: To investigate the clinical characteristics and salivary biomarkers in each type of burning mouth syndrome (BMS) patients. MATERIALS AND METHODS: Ninety-eight postmenopausal female patients with BMS were included. Fifty and 21 patients were assigned to the primary and secondary groups, respectively. Twenty-seven patients with both primary and secondary characteristics were assigned to the intermediate group. Comprehensive clinical characteristics and salivary biomarkers were analyzed. RESULTS: Significant differences in age, proportion of hyposalivator patients based on unstimulated whole saliva (UWS), symptom distribution, severties of burning sensation and effect of oral complaints in daily life (Eff-life), and positive symptom distress index (PSDI) were observed among the three groups. The primary group had significant higher UWS flow rate, fewer UWS hyposalivator proportions, and lesser severity of Eff-life than the secondary group. The intermediate group had significantly greater intensities of burning sensation and Eff-life and higher PSDI score than did the primary group. The primary group had significantly higher cortisol and dehydroepiandrosterone (DHEA) levels in stimulated whole saliva than did the secondary group. CONCLUSIONS: This study's findings show that clinical characteristics differentiate each BMS type. Cortisol and DHEA levels are potential salivary biomarkers for discriminating between the primary and secondary types of BMS.

A potential role of protein extractions from Metagonimus yokogawai in amelionating inflammation in patients with ankylosing spondylitis.

Helminth infections and their components has been recognized to have a positive impact on the immune system. This study aimed to investigate the potential of Metagonimus yokogawai-derived proteins (MYp) to provide protection against ankylosing spondylitis (AS) through modulation of immune responses. The cytotoxicity of MYp at various doses was first assessed using MTS and flow cytometry. Peripheral blood mononuclear cells (PBMCs) were collected from AS patients, and the production of inflammatory cytokines was analyzed through flow cytometry. In the experiments with SKG mice, MYp or vehicle was administered and inflammation was evaluated through immunohistochemistry and enzyme-linked immunosorbent assay. The results showed that MYp did not decrease cell viability of PBMCs even after 48 h. Additionally, the frequencies of IFN-γ and IL-17A producing cells were significantly reduced after MYp treatment in the PBMC cultures. Furthermore, MYp treatment significantly suppressed arthritis and enthesitis in the SKG mouse model. The results suggest the first evidence that MYp can effectively alleviate clinical symptoms and restore cytokine balance in patients with AS.

Prior pneumococcal vaccination improves in-hospital mortality among elderly population hospitalized due to community-acquired pneumonia.

BACKGROUND: Pneumococcal vaccination is a preventive method to reduce pneumonia related mortality. However, real-world data on efficacy of the pneumococcal vaccine in reducing mortality is lacking, especially in elderly patients. This study was conducted to assess the effects of prior pneumococcal vaccination in elderly pneumonia patients. METHODS: The data was procured from the Health Insurance Review and Assessment and Quality Assessment database. Hospitalized patients who met the criteria of community-acquired pneumonia (CAP) were included and they were grouped according to vaccination state. Patients were aged ≥ 65 years and treated with beta-lactam, quinolone, or macrolide. Patients were excluded when treatment outcomes were unknown. RESULTS: A total of 4515 patients were evaluated, and 1609 (35.6%) of them were vaccinated prior to hospitalization. Mean age was 77.0 [71.0;82.0], 54.2% of them were male, and mean Charlson comorbidity index (CCI) was 3.0. The patients in the vaccinated group were younger than those in the unvaccinated group (76.0 vs. 78.0 years; P < 0.001), and showed higher in-hospital improvement (97.6 vs. 95.0%; P < 0.001) and lower 30-day mortality (2.6 vs. 5.3%; P < 0.001). After adjusting confounding factors such as age, gender, CURB score and CCI score, the vaccinated group demonstrated a significant reduction in 30-day mortality (hazard ratio [HR] 0.58, 95% confidence interval [CI] 0.41-0.81; P < 0.01) and in-hospital mortality (HR 0.53, 95% CI0.37-0.78; P < 0.001) compared to the unvaccinated group in multivariate analysis. Vaccinated group showed better 30-day survival than those in non-vaccinated group (log-rank test < 0.05). CONCLUSIONS: Among elderly hospitalized CAP patients, prior pneumococcal vaccination was associated with improved in-hospital mortality and 30-day mortality.

The safety of systemic Janus kinase inhibitors in atopic dermatitis: A systematic review and meta-analysis of randomized controlled trials.

Janus kinase (JAK) inhibitors have been recently approved by the FDA and are widely used in the treatment of patients with atopic dermatitis. However, a comprehensive safety profile of JAK inhibitors in patients with atopic dermatitis has not been analysed. This study aimed to establish clinical evidence for the safety of systemic JAK inhibitors in patients with atopic dermatitis. Medline, Embase, Clinicaltrials.gov, Cochrane Central Register of Controlled Trials (CENTRAL) and International Clinical Trials Registry Platform (ICTRP) were considered for search databases. Randomized controlled trials reporting the adverse events of systemic therapy in patients with atopic dermatitis were included. The risk of 11 adverse events was compared between the JAK inhibitors and placebo groups. Fourteen randomized controlled trials were analysed published between 2019 and 2022. The JAK inhibitors included in the analysis were abrocitinib (10, 30, 100 and 200 mg), baricitinib (1, 2 and 4 mg) and upadacitinib (7.5, 15 and 30 mg). The risk of herpes zoster, headache, acne, elevated blood creatinine phosphokinase and nausea was significantly increased, but the risk of serious infection, non-melanoma skin cancer (NMSC), malignancies other than NMSC, major adverse cardiovascular event, venous thromboembolism and nasopharyngitis was not increased. This study provides comprehensive clinical evidence on the risk of various adverse events in patients with atopic dermatitis. However, since the follow-up periods of the studies analysed in this review were mostly limited to 16 weeks or less, it is recommended that comprehensive long-term observational studies be conducted to determine any potential adverse events associated with major cardiovascular events or malignancies, which typically have prolonged courses.

Association between the skin microbiome and lichen striatus hypopigmentation: Cutibacterium acnes as a potential cause.

BACKGROUND: Lichen striatus (LS) is an acquired skin disorder with a linear pattern along Blaschko's lines. It commonly occurs in childhood, and the lesions spontaneously regress within several months. OBJECTIVES: Although up to 50% of LS cases exhibit hypopigmentation that can persist for several months to years, it is unknown why LS is associated with such a high incidence of hypopigmentation compared to other inflammatory skin diseases. Therefore, this study aimed to analyse the differences in the skin microbiome between LS patients with and without hypopigmentation. METHODS: Differences in skin microbiome were analysed using whole genome sequencing of skin biopsies and subsequent bioinformatics analyses. RESULTS: Some microbes commonly found in hypopigmented skin disorders, including Cutibacterium acnes, were more abundant in patients with LS showing hypopigmentation than in those not showing hypopigmentation. CONCLUSIONS: The skin microbiota may be involved in the development of hypopigmentation in LS and may be considered a treatment target to reduce LS duration and hypopigmentation.

Risk Factors of Postpartum Depression Among Korean Women: An Analysis Based on the Korean Pregnancy Outcome Study (KPOS).

BACKGROUND: Postpartum depression (PPD) can negatively affect infant well-being and child development. Although the frequency and risk factors of PPD symptoms might vary depending on the country and culture, there is limited research on these risk factors among Korean women. This study aimed to elucidate the potential risk factors of PPD throughout pregnancy to help improve PPD screening and prevention in Korean women. METHODS: The pregnant women at 12 gestational weeks (GW) were enrolled from two obstetric specialized hospitals from March 2013 to November 2017. A questionnaire survey was administered at 12 GW, 24 GW, 36 GW, and 4 weeks postpartum. Depressive symptoms were assessed using the Edinburgh Postnatal Depression Scale, and PPD was defined as a score of ≥ 10. RESULTS: PPD was prevalent in 16.3% (410/2,512) of the participants. Depressive feeling at 12 GW and postpartum factors of stress, relationship with children, depressive feeling, fear, sadness, and neonatal intensive care unit admission of baby were significantly associated with a higher risk of PPD. Meanwhile, high postpartum quality of life and marital satisfaction at postpartum period were significantly associated with a lower risk of PPD. We developed a model for predicting PPD using factors as mentioned above and it had an area under the curve of 0.871. CONCLUSION: Depressive feeling at 12 GW and postpartum stress, fear, sadness, relationship with children, low quality of life, and low marital satisfaction increased the risk of PPD. A risk model that comprises significant factors can effectively predict PPD and can be helpful for its prevention and appropriate treatment.

Prediction of Soluble-Solid Content in Citrus Fruit Using Visible-Near-Infrared Hyperspectral Imaging Based on Effective-Wavelength Selection Algorithm.

Citrus fruits were sorted based on external qualities, such as size, weight, and color, and internal qualities, such as soluble solid content (SSC), acidity, and firmness. Visible and near-infrared (VNIR) hyperspectral imaging techniques were used as rapid and nondestructive techniques for determining the internal quality of fruits. The applicability of the VNIR hyperspectral imaging technique for predicting the SSC in citrus fruits was evaluated in this study. A VNIR hyperspectral imaging system with a wavelength range of 400-1000 nm and 100 W light source was used to acquire hyperspectral images from citrus fruits in two orientations (i.e., stem and calyx ends). The SSC prediction model was developed using partial least-squares regression (PLSR). Spectrum preprocessing, effective wavelength selection through competitive adaptive reweighted sampling (CARS), and outlier detection were used to improve the model performance. The performance of each model was evaluated using the coefficient of determination (R2) and root mean square error (RMSE). In the present study, the PLSR model was developed using only a citrus cultivar. The SSC prediction CARS-PLSR model with outliers removed exhibited R2 and RMSE values of approximatively 0.75 and 0.56 °Brix, respectively. The results of this study are expected to be useful in similar fields such as agricultural and food post-harvest management, as well as in the development of an online system for determining the SSC of citrus fruits.

Interferon-ß Overexpression in Adipose Tissue-Derived Stem Cells Induces HepG2 and Macrophage Cell Death in Liver Tumor Organoids via Induction of TNF-Related Apoptosis-Inducing Ligand Expression.

Liver tumor organoids derived from liver tumor tissues and pluripotent stem cells are used for liver tumor research but have several challenges in primary cell isolation and stem cell differentiation. Here, we investigated the potential of HepG2-based liver tumor organoids for screening anticancer drugs by evaluating their responsiveness to IFN-ß produced by mesenchymal stem cells (MSCs). Liver tumor organoids were prepared in three days on Matrigel using HepG2, primary liver sinusoidal epithelial cells (LSECs), LX-2 human hepatic stellate cells, and THP-1-derived macrophages at a ratio of 4:4:1:1, with 105 total cells. Hepatocyte-related and M2 macrophage-associated genes increased in liver tumor organoids. IFN-ß treatment decreased the viability of liver tumor organoids and increased M1 macrophage marker expression (i.e., TNF-α and iNOS) and TRAIL. TRAIL expression was increased in all four cell types exposed to IFN-ß, but cell death was only observed in HepG2 cells and macrophages. Further, MSCs overexpressing IFN-ß (ASC-IFN-ß) also expressed TRAIL, contributing to the reduced viability of liver tumor organoids. In summary, IFN-ß or ASC-IFN-ß can induce TRAIL-dependent HepG2 and macrophage cell death in HepG2-based liver tumor organoids, highlighting these liver tumor organoids as suitable for anticancer drug screening and mechanistic studies.

Putrescine Upregulates Melanogenesis Through Modulation of MITF Transcription Factor in B16F1 Mouse Melanoma Cells.

Research background: Ageing is a biochemical, metabolic and genetic physiological phenomenon. The suppression of melanin biosynthesis, evident in the greying of the hair, is a hallmark of ageing resulting from translation failure, reduced enzyme activity and cellular senescence. Putrescine, the smallest member of the polyamine family and an organic chemical, is present in living mammalian cells and plays a crucial role in regulating skin melanogenesis. Therefore, the purpose of this study is to explore the effect of putrescine on the signalling pathways of melanogenesis in melanoma cells. Experimental approach: Melanin production capacity of putrescine was analysed using a tyrosinase activity assay. To assess the cell viability of B16F1 cells exposed to putrescine, a tetrazolium dye MTT assay was performed. The effect of putrescine on melanin synthesis in the presence of H2O2 was evaluated using various in vitro assays in B16F1 cells. The effect of putrescine on melanin production in B16F1 cells was determined using a specific melanin production assay. Gene expression was analysed using real-time polymerase chain reaction (RT-PCR). Furthermore, the effect of putrescine on the expression of proteins related to melanin production in the cells treated with H2O2 was analysed by immunofluorescence and Western blot analysis. Results and conclusions: Putrescine increased tyrosinase activity and showed no cytotoxicity in B16F1 cells. In addition, putrescine effectively scavenged H2O2, as shown by the reduction of intracellular H2O2 amounts in 2',7'-dichlorofluorescin diacetate analysis, and promoted melanin production in living cells. The stimulation of melanogenesis by putrescine was attributed to the increased expression of Mitf, Tyr, Trp-1 and Trp-2 genes. Immunofluorescence assays revealed that putrescine enhanced the expression of proteins associated with melanogenesis and upregulated TYR, TRP-1 and TRP-2 via the microphthalmia-associated transcription factor (MITF) and increased the expression of methionine sulfoxide reductases A (MSRA) and B (MSRB) in the cells treated with H2O2, effectively promoting melanogenesis. These results suggest that putrescine can be used to stimulate melanin synthesis. Novelty and scientific contribution: This is the first study to investigate the effect of putrescine on the signalling pathways of melanogenesis in B16F1 melanoma cells. The results confirm that putrescine can promote melanogenesis through the expression of TYR, TRP-1 and TRP-2 via the MITF in cells treated with H2O2. Putrescine can be used exclusively as a cosmetic product to prevent premature greying of hair.

Revisiting the Ramachandran plot based on statistical analysis of static and dynamic characteristics of protein structures.

Ramachandran plots, which describe protein structures by plotting the dihedral angle pairs of the backbone on a two-dimensional plane, have played an important role in structural biology over the past few decades. However, despite continued discovery of new protein structures to date, the Ramachandran plot is still constructed by only a small number of data points, and further it cannot reflect the steric information of proteins. Here, we investigated the secondary structure of proteins in terms of static and dynamic characteristics. As for static feature, the Ramachandran plot was revisited for the dataset consisting of 9,148 non-redundant high-resolution protein structures released in the protein data bank until April 1, 2022. By calculating amino acid propensities, it was found that the proportion of secondary structures with respect to residue depth is directly related to their hydrophobicity. As for dynamic feature, normal mode analysis (NMA) based on an elastic network model (ENM) was carried out for the dataset using our KOSMOS web server (http://bioengineering.skku.ac.kr/kosmos/). All ENM-based NMA results were stored in the KOSMOS database, allowing researchers to use them in various ways. In this process, it was commonly found that high B-factors appeared at the edge of the alpha helix region, which was elucidated by introducing residue depth. In addition, by investigating the change in dihedral angle, it was possible to quantitatively survey the contribution of structural change of protein on the Ramachandran plot. In conclusion, our statistical analysis of protein characteristics will provide insight into a range of protein structural studies.