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1.
Anal Biochem ; 684: 115360, 2024 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-37865269

RESUMO

CONTEXT: Echinacoside (ECH) is a natural anti-cancer compound and is of great value in cancer treatment. However, the mechanism underlying this effect on breast cancer (BC) was unclear. OBJECTIVE: To explore the mechanism of ECH treating BC by network pharmacology and experimental validation. MATERIALS & METHODS: Several databases were searched to screen potential targets of ECH and obtain information on targets related to BC. STRING was applied to construct a Protein-protein interaction (PPI) network. DAVID was applied for Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Gene Expression Profiling Interactive Analysis (GEPIA) was searched for the relationship between the expression profile and overall survival of major targets in normal breast and BC tissues. Finally, the results of network pharmacology analysis were validated by experiments. RESULTS: Seventeen targets of ECH overlapped with targets in BC. Ten hub targets were determined through PPI. By GO and KEGG analysis 15 entries and 25 pathways were obtained, in which phosphatidylinositol 3-kinase (PI3K), protein kinase B (AKT), hypoxia inducible factor-1 (HIF-1) and vascular endothelial growth factor (VEGF) played greater roles. Validation of key targets in the GEPIA database showed that PIK3R1 and PIK3CD remained consistent with the results of the study. Experiments in vitro showed ECH inhibited proliferation, induced apoptosis and reduced mRNA levels and protein expression of PI3K, AKT, hypoxia inducible factor-1α (HIF-1α) and vascular endothelial growth factor A (VEGFA) in MCF-7 cells. Furthermore, experiments in vivo revealed that ECH significantly reduced tumor growth, promoted apoptosis and decreased the related mRNA levels and protein expression, suggesting ECH works on BC by regulating PI3K/AKT/HIF-1α/VEGF signaling pathway. DISCUSSION & CONCLUSION: In summary, ECH played an important role in anti-BC by regulating PI3K/AKT/HIF-1α/VEGF signaling pathway. Furthermore, ECH had multi-target and multi-pathway effects, which may be a promising natural compound for treating BC.


Assuntos
Neoplasias da Mama , Proteínas Proto-Oncogênicas c-akt , Feminino , Humanos , Neoplasias da Mama/metabolismo , Proliferação de Células , Hipóxia , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Mensageiro/metabolismo , Transdução de Sinais , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/metabolismo , Fatores de Crescimento do Endotélio Vascular
2.
Phytother Res ; 38(7): 3801-3824, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38886838

RESUMO

Due to a scarcity of appropriate therapeutic approaches capable of ameliorating or eliminating non-alcoholic fatty liver disease (NAFLD), many researchers have come to focus on natural products based on traditional medicine that can be utilized to successfully treat NAFLD. In this study, we aimed to evaluate the effects exerted by seven natural products (curcumin, silymarin, resveratrol, artichoke leaf extract, berberine, catechins, and naringenin) on patients with NAFLD. For this purpose, PubMed, Embase, Cochrane Library, and Web of Science, were searched for randomized controlled trials (RCTs) exclusively. The selected studies were evaluated for methodological quality via the Cochrane bias risk assessment tool, and data analysis software was used to analyze the data accordingly. The RCTs from the earliest available date until September 2022 were collected. This process resulted in 37 RCTs with a total sample size of 2509 patients being included. The results of the network meta-analysis showed that artichoke leaf extract confers a relative advantage in reducing the aspartate aminotransferase (AST) levels (SUCRA: 99.1%), alanine aminotransferase (ALT) levels (SUCRA: 88.2%) and low-density lipoprotein cholesterol (LDL-C) levels (SUCRA: 88.9%). Naringenin conferred an advantage in reducing triglyceride (TG) levels (SUCRA: 97.3%), total cholesterol (TC) levels (SUCRA: 73.9%), and improving high-density lipoprotein cholesterol (HDL-C) levels (SUCRA: 74.9%). High-density catechins significantly reduced body mass index (BMI) levels (SUCRA: 98.5%) compared with the placebo. The Ranking Plot of the Network indicated that artichoke leaf extract and naringenin performed better than the other natural products in facilitating patient recovery. Therefore, we propose that artichoke leaf extract and naringenin may exert a better therapeutic effect on NAFLD. This study may help guide clinicians and lead to further detailed studies.


Assuntos
Metanálise em Rede , Hepatopatia Gordurosa não Alcoólica , Extratos Vegetais , Ensaios Clínicos Controlados Aleatórios como Assunto , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Humanos , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , Produtos Biológicos/uso terapêutico , Produtos Biológicos/farmacologia , Aspartato Aminotransferases/sangue , Alanina Transaminase/sangue , Cynara scolymus/química , LDL-Colesterol/sangue , Folhas de Planta/química
3.
Zhongguo Zhong Yao Za Zhi ; 48(19): 5304-5314, 2023 Oct.
Artigo em Zh | MEDLINE | ID: mdl-38114120

RESUMO

This study aims to observe the effects of diosgenin on the expression of mammalian target of rapamycin(mTOR), sterol regulatory element-binding protein-1c(SREBP-1c), heat shock protein 60(HSP60), medium-chain acyl-CoA dehydrogenase(MCAD), and short-chain acyl-CoA dehydrogenase(SCAD) in the liver tissue of the rat model of non-alcoholic fatty liver disease(NAFLD) and explore the mechanism of diosgenin in alleviating NAFLD. Forty male SD rats were randomized into five groups: a control group, a model group, low-(150 mg·kg~(-1)·d~(-1)) and high-dose(300 mg·kg~(-1)·d~(-1)) diosgenin groups, and a simvastatin(4 mg·kg~(-1)·d~(-1)) group. The rats in the control group were fed with a normal diet, while those in the other four groups were fed with a high-fat diet. After feeding for 8 weeks, the body weight of rats in the high-fat diet groups increased significantly. After that, the rats were administrated with the corresponding dose of diosgenin or simvastatin by gavage every day for 8 weeks. The levels of triglyceride(TG), total cholesterol(TC), alanine transaminase(ALT), and aspartate transaminase(AST) in the serum were determined by the biochemical method. The levels of TG and TC in the liver were measured by the enzyme method. Oil-red O staining was employed to detect the lipid accumulation, and hematoxylin-eosin(HE) staining to detect the pathological changes in the liver tissue. The mRNA and protein levels of mTOR, SREBP-1c, HSP60, MCAD, and SCAD in the liver tissue of rats were determined by real-time fluorescence quantitative polymerase chain reaction(RT-qPCR) and Western blot, respectively. Compared with the control group, the model group showed increased body weight, food uptake, liver index, TG, TC, ALT, and AST levels in the serum, TG and TC levels in the liver, lipid deposition in the liver, obvious hepatic steatosis, up-regulated mRNA and protein expression levels of mTOR and SREBP-1c, and down-regulated mRNA and protein expression levels of HSP60, MCAD, and SCAD. Compared with the model group, the rats in each treatment group showed obviously decreased body weight, food uptake, liver index, TG, TC, ALT, and AST levels in the serum, TG and TC levels in the liver, lessened lipid deposition in the liver, ameliorated hepatic steatosis, down-regulated mRNA and protein le-vels of mTOR and SREBP-1c, and up-regulated mRNA and protein levels of HSP60, MCAD, and SCAD. The high-dose diosgenin outperformed the low-dose diosgenin and simvastatin. Diosgenin may prevent and treat NAFLD by inhibiting the expression of mTOR and SREBP-1c and promoting the expression of HSP60, MCAD, and SCAD to reduce lipid synthesis, improving mitochondrial function, and promoting fatty acid ß oxidation in the liver.


Assuntos
Diosgenina , Hepatopatia Gordurosa não Alcoólica , Ratos , Masculino , Animais , Hepatopatia Gordurosa não Alcoólica/etiologia , Hepatopatia Gordurosa não Alcoólica/genética , Proteína de Ligação a Elemento Regulador de Esterol 1/metabolismo , Dieta Hiperlipídica/efeitos adversos , Diosgenina/metabolismo , Chaperonina 60/metabolismo , Chaperonina 60/farmacologia , Chaperonina 60/uso terapêutico , Ratos Sprague-Dawley , Fígado , Transdução de Sinais , Serina-Treonina Quinases TOR/genética , Serina-Treonina Quinases TOR/metabolismo , Triglicerídeos , RNA Mensageiro/metabolismo , Sinvastatina/metabolismo , Sinvastatina/farmacologia , Sinvastatina/uso terapêutico , Peso Corporal , Metabolismo dos Lipídeos , Mamíferos/genética , Mamíferos/metabolismo
4.
Brain Res ; 1827: 148743, 2024 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-38159592

RESUMO

By safeguarding the neurological system, insulin-like growth factor 1 (IGF-1) may have a role in the etiology of Alzheimer's disease (AD). The mechanism and signaling route, however, remain unclear. This research aimed to investigate the impact of IGF-1 on AD as well as its possible mechanism and signaling route. In this work, intracerebroventricular AAV9-IGF-1 was delivered to APP/PS1 transgenic mice. Following therapy, the Morris water maze and passive avoidance tests were administered to evaluate spatial learning and memory. The elevated plus maze, the open field test, and the sucrose preference test were used to evaluate anxious-depressive-like behavior. Thioflavin S staining was employed to visualize Aß deposition, and ELISA was used to determine the quantities of soluble Aß1-40 and Aß1-42. Transmission electron microscopy was used to view the mitochondrial structure and mitophagy vesicles. The protein expression levels of PINK1, Parkin, and LC3-II/LC3-I were finally determined by Western blotting. AAV9-IGF-1 therapy enhanced spatial learning and memory, relieved anxious-depressive-like behavior impairments, lowered amyloid-ß deposition, and decreased levels of soluble Aß1-40 and Aß1-42. In addition, AAV9-IGF-1 therapy restored mitochondrial integrity and increased the number of mitophagy in transgenic mice expressing APP/PS1. These results indicate that IGF-1 is protective for APP/PS1 mice. The mechanism of the favorable benefits mediated by IGF-1 was connected to an increase in mitophagy, which might give a novel therapy target in the future.


Assuntos
Doença de Alzheimer , Mitofagia , Animais , Camundongos , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Camundongos Transgênicos , Regulação para Cima , Modelos Animais de Doenças
5.
Int J Biol Macromol ; 261(Pt 1): 129670, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38280697

RESUMO

The oxidative microenvironment in fibrotic livers often diminishes the effectiveness of mesenchymal stem cells (MSCs)-based therapy. Recent research suggests that pharmacological pre-treatment could enhance the therapeutic performance of MSCs. In this study, we assessed the impact of Arctium lappa L. polysaccharides (ALP) on the biological properties of nasal ectomesenchymal stem cells (EMSCs) and investigated the augmenting effect of ALP pretreatment on EMSCs (ALP-EMSCs) for the treatment of liver fibrosis. ALP treatment demonstrated multiple biological impacts on EMSC functions regarding liver fibrosis: firstly, it maintained the stemness of the cells while boosting the EMSCs' paracrine effects; secondly, it increased the expression of anti-inflammatory and antioxidant factors; thirdly, it inhibited the activation of hepatic stellate cells (HSCs) and liver collagen build-up by modulating the Wnt/ß-catenin signaling pathways. Collectively, these effects helped to halt the progression of liver fibrosis. Therefore, the use of ALP-EMSCs presents an innovative and promising approach for treating hepatic fibrosis in clinical scenarios.


Assuntos
Arctium , Células-Tronco Mesenquimais , Humanos , beta Catenina/metabolismo , Via de Sinalização Wnt , Cirrose Hepática/tratamento farmacológico , Cirrose Hepática/metabolismo
6.
J Cardiovasc Pharmacol Ther ; 29: 10742484241248046, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38656132

RESUMO

Atherosclerosis is now widely considered to be a chronic inflammatory disease, with increasing evidence suggesting that lipid alone is not the main factor contributing to its development. Rather, atherosclerotic plaques contain a significant amount of inflammatory cells, characterized by the accumulation of monocytes and lymphocytes on the vessel wall. This suggests that inflammation may play a crucial role in the occurrence and progression of atherosclerosis. As research deepens, other pathological factors have also been found to influence the development of the disease. The Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway is a recently discovered target of inflammation that has gained attention in recent years. Numerous studies have provided evidence for the causal role of this pathway in atherosclerosis, and its downstream signaling factors play a significant role in this process. This brief review aims to explore the crucial role of the JAK/STAT pathway and its representative downstream signaling factors in the development of atherosclerosis. It provides a new theoretical basis for clinically affecting the development of atherosclerosis by interfering with the JAK/STAT signaling pathway.


Assuntos
Aterosclerose , Janus Quinases , Fatores de Transcrição STAT , Transdução de Sinais , Humanos , Aterosclerose/metabolismo , Aterosclerose/tratamento farmacológico , Fatores de Transcrição STAT/metabolismo , Janus Quinases/metabolismo , Animais , Inibidores de Janus Quinases/uso terapêutico , Inibidores de Janus Quinases/farmacologia , Anti-Inflamatórios/uso terapêutico , Anti-Inflamatórios/farmacologia , Mediadores da Inflamação/metabolismo
7.
Curr Drug Deliv ; 21(10): 1300-1319, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39034715

RESUMO

With the acceleration of people's pace of life, non-alcoholic fatty liver disease (NAFLD) has become the most common chronic liver disease in the world, which greatly threatens people's health and safety. Therefore, there is still an urgent need for higher-quality research and treatment in this area. Nuclear factor Red-2-related factor 2 (Nrf2), as a key transcription factor in the regulation of oxidative stress, plays an important role in inducing the body's antioxidant response. Although there are no approved drugs targeting Nrf2 to treat NAFLD so far, it is still of great significance to target Nrf2 to alleviate NAFLD. In recent years, studies have reported that many natural products treat NAFLD by acting on Nrf2 or Nrf2 pathways. This article reviews the role of Nrf2 in the pathogenesis of NAFLD and summarizes the currently reported natural products targeting Nrf2 or Nrf2 pathway for the treatment of NAFLD, which provides new ideas for the development of new NAFLD-related drugs.


Assuntos
Produtos Biológicos , Fator 2 Relacionado a NF-E2 , Hepatopatia Gordurosa não Alcoólica , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Hepatopatia Gordurosa não Alcoólica/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Humanos , Produtos Biológicos/farmacologia , Produtos Biológicos/uso terapêutico , Animais , Estresse Oxidativo/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Antioxidantes/farmacologia , Antioxidantes/uso terapêutico
8.
Heliyon ; 10(3): e25171, 2024 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-38352746

RESUMO

Depression is considered to be an "emotional disease" in ancient books of traditional Chinese medicine. Its clinical features are similar to those of "Lily disease" in the ancient Chinese medicine book Synopsis of the Golden Chamber written by Zhang Zhongjing in the Han Dynasty. Baihe Zhimu (Lilium lancifolium bulb and Anemarrhena asphodeloides rhizome) decoction (LBRAD) is the first prescription of "Lily Disease" in this book. It is also a special remedy for "Lily disease" after sweating. The classic recipe LBRAD consists of two herbs, fresh lily bulbs and dried Rhizoma Anemarrhena slice. It has the effect of supplementing nutrition and clearing heat, nourishing Yin and moistening. After more than two thousand years of clinical practice, it has been currently widely used in clinical treatment of depression. In this paper, the relationship between LBRAD and depression was systematically reviewed from both clinical and experimental studies, as well as the preparation, the clinical application, the pharmacological mechanism and the effective material basis for the treating depression of LBRAD. The core targets and biological processes of the depression treatment were explored through network pharmacological analysis, so as to speculate its potential mechanism. Finally, the association between LBRAD and post-COVID-19 depression was discussed. We concluded with a summary and future prospects. This review may provide a theoretical basis for the expansion of the clinical application of LBRAD and the development of new drugs for the treatment of depression, as well as new ideas for the secondary development of classical prescriptions.

9.
Int Immunopharmacol ; 138: 112581, 2024 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-38944952

RESUMO

Metabolic-associated fatty liver disease (MAFLD) is one of the most common liver diseases worldwide; however, its pathogenesis and treatment methods have not been perfected. NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) is a promising therapeutic target for MAFLD. Diosgenin (DG) is a natural compound that was identified in a traditional Chinese herbal medicine, which has pharmacological effects, such as anti-inflammatory, antioxidant, hepatoprotective, and hypolipidemic activities. In this study, we examined the effects and molecular mechanisms of DG on MAFLD in vitro and in vivo. We established a rat model by administering a high-fat diet (HFD). We also generated an in vitro MAFLD model by treating HepG2 cells with free fatty acids (FFAs). The results indicated that DG attenuated lipid accumulation and liver injury in both in vitro and in vivo models. DG downregulated the expression of NLRP3, apoptosis-associated speckle-like protein (ASC), cysteinyl aspartate specific proteinase-1 (caspase-1), gasdermin D (GSDMD), GSDMD-n, and interleukin-1ß (IL-1ß). In addition, we silenced and overexpressed NLRP3 in vitro to determine the effects of DG on antiMAFLD. Silencing NLRP3 enhanced the effect of DG on the treatment of MAFLD, whereas NLRP3 overexpression reversed its beneficial effects. Taken together, the results show that DG has a favorable effect on attenuating MAFLD through the hepatic NLRP3 inflammasome-dependent signaling pathway. DG represents a natural NLRP3 inhibitor for the MAFLD treatment.


Assuntos
Diosgenina , Inflamassomos , Fígado , Proteína 3 que Contém Domínio de Pirina da Família NLR , Hepatopatia Gordurosa não Alcoólica , Ratos Sprague-Dawley , Transdução de Sinais , Animais , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Inflamassomos/metabolismo , Humanos , Transdução de Sinais/efeitos dos fármacos , Masculino , Células Hep G2 , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Ratos , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Hepatopatia Gordurosa não Alcoólica/metabolismo , Hepatopatia Gordurosa não Alcoólica/imunologia , Diosgenina/farmacologia , Diosgenina/uso terapêutico , Dieta Hiperlipídica/efeitos adversos , Modelos Animais de Doenças , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/uso terapêutico
10.
Eur J Pharmacol ; 977: 176737, 2024 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-38866362

RESUMO

The prevalence of nonalcoholic fatty liver disease (NAFLD) has been increasing worldwide in recent years, causing severe economic and social burdens. Therefore, the lack of currently approved drugs for anti-NAFLD has gradually gained attention. SIRT1, as a member of the sirtuins family, is now the most widely studied in the pathophysiology of many metabolic diseases, and has great potential for preventing and treating NAFLD. Natural products such as Diosgenin (DG) have the potential to be developed as clinical drugs for the treatment of NAFLD due to their excellent multi-target therapeutic effects. In this study, we found that DG can activate the SIRT1/PGC-1α pathway and upregulate the expression of its downstream targets nuclear respiratory factor 1 (NRF1), complex IV (COX IV), mitofusin-2 (MFN2), and PPARα (perox-isome proliferator-activated receptor α) in SD rats induced by high-fat diet (HFD) and HepG2 cells caused by free fatty acids (FFAs, sodium oleate: sodium palmitate = 2:1). Conversely, the levels of dynamin-related protein 1 (DRP1) and inflammatory factors, including NF-κB p65, IL6, and TNFα, were downregulated both in vitro and in vivo. This improved mitochondrial dysfunction, fatty acid oxidation (FAO), lipid accumulation, steatosis, oxidative stress, and hepatocyte inflammation. Subsequently, we applied SIRT1 inhibitor EX527 and SIRT1 agonist SRT1720 to confirm further the necessity of activating SIRT1 for DG to exert therapeutic effects on NAFLD. In summary, these results further demonstrate the potential therapeutic role of DG as a SIRT1 natural agonist for NAFLD. (Graphical Abstracts).


Assuntos
Diosgenina , Fígado , Hepatopatia Gordurosa não Alcoólica , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Transdução de Sinais , Sirtuína 1 , Animais , Humanos , Masculino , Ratos , Dieta Hiperlipídica/efeitos adversos , Diosgenina/farmacologia , Diosgenina/uso terapêutico , Diosgenina/análogos & derivados , Células Hep G2 , Metabolismo dos Lipídeos/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Fígado/patologia , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Hepatopatia Gordurosa não Alcoólica/metabolismo , Hepatopatia Gordurosa não Alcoólica/patologia , Estresse Oxidativo/efeitos dos fármacos , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Ratos Sprague-Dawley , Transdução de Sinais/efeitos dos fármacos , Sirtuína 1/metabolismo
11.
Front Neurol ; 14: 1295051, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38322794

RESUMO

Objective: Some previous studies have suggested a potential link between stroke and gastroesophageal reflux disease (GERD). We used a two-sample bidirectional Mendelian randomization (MR) method to explore the causal relationship between stroke and GERD. Design: Summary-level data derived from the published genome-wide association studies (GWAS) were employed for analyses. Single-nucleotide polymorphisms (SNPs) as instrumental variables (IVs) for stroke (n = 446,696) and its common subtypes ischemic stroke (IS) (n = 440,328), large vessel stroke (LVS) (n = 410,484), small vessel stroke (SVS) (n = 198,048), and cardioembolic stroke (CES) (n = 413,304) were obtained from the MEGASTROKE consortium. The data on intracerebral hemorrhage (ICH) (n = 721,135) come from the UK Biobank. Instrumental variables (IVs) for lacunar stroke (LS) (n = 474,348) and GERD (n = 602,604) were screened from publicly available genetic summary data. The inverse variance weighted (IVW) method was used as the main MR method. Pleiotropy was detected by the MR-Egger intercept test, MR pleiotropy residual sum and outlier, and leave-one-out analysis. Cochran Q statistics were used as supplements to detect pleiotropy. Results: We found that GERD can causally increase the risk of stroke [IVW odds ratio (OR): 1.22, 95% confidence interval (CI): 1.13-1.32, p = 1.16 × 10-6] and its common subtypes IS (OR: 1.19, 95% CI: 1.10-1.30, p = 3.22 × 10-5), LVS (OR: 1.49, 95% CI: 1.21-1.84, p = 1.47 × 10-4), and LS (OR: 1.20, 95% CI: 1.001-1.44, p = 0.048). Several important risk factors for stroke have also been implicated in the above causal relationship, including type 2 diabetes, sleep apnea syndrome, high body mass index, high waist-to-hip ratio, and elevated serum triglyceride levels. In reverse MR analysis, we found that overall stroke (OR: 1.09, 95% CI: 1.004-1.19, p = 0.039) and IS (OR: 1.10, 95% CI: 1.03-1.17, p = 0.007) have the causal potential to enhance GERD risk. Conclusion: This MR study provides evidence supporting a causal relationship between GERD and stroke and some of its common subtypes. We need to further explore the interconnected mechanisms between these two common diseases to better prevent and treat them.

12.
bioRxiv ; 2023 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-38187566

RESUMO

The ADP-Ribosylation Factor (ARF) small GTPases have been found to act in vesicle fission through a direct ability to tubulate membrane. Here, we have used cryo-electron microscopy (EM) to solve the structure of an ARF6 protein lattice assembled on tubulated membrane to 3.9 Å resolution. ARF6 forms tetramers that polymerize into helical arrays to form this lattice. We identify, and confirm functionally, protein contacts critical for this lattice formation. The solved structure also suggests how the ARF amphipathic helix is positioned in the lattice for membrane insertion, and how a GTPase-activating protein (GAP) docks onto the lattice to catalyze ARF-GTP hydrolysis in completing membrane fission. As ARF1 and ARF6 are structurally conserved, we have also modeled ARF1 onto the ARF6 lattice, which has allowed us to pursue the reconstitution of Coat Protein I (COPI) vesicles to confirm more definitively that the ARF lattice acts in vesicle fission. Our findings are notable for having achieved the first detailed glimpse of how a small GTPase bends membrane and having provided a molecular understanding of how an ARF protein acts in vesicle fission.

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