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The transcriptome serves as a bridge that links genomic variation and phenotype diversity. A vast number of studies using next-generation RNA sequencing (RNA-seq) in the last two decades emphasize the essential roles of plant transcriptome in response to developmental and environmental conditions, leading to numerous insights into the dynamic change, evolutionary trace and elaborate regulation of plant transcriptome. With substantial improvement in accuracy and throughput, direct RNA sequencing (DRS) has emerged as a new and powerful sequencing platform for the precise detection of native and full-length transcripts, which overcomes many limitations such as read length and PCR bias that are inherent to short-read RNA-seq. Here, we reviewed recent advances in dissecting the complexity and diversity of plant transcriptome utilizing DRS as a main technological mean from many aspects of RNA metabolism, including novel isoforms, poly(A) tail and RNA modification, and proposed a comprehensive workflow for the data process of plants DRS. Many challenges concerning the application of DRS in plants, such as machine learning tools tailored to plant transcriptome, remain to be solved, and together we prospect the future biological questions that can be potentially answered by DRS such as allele-specific RNA modification. This technology provides convenient support on which the connection of distinct RNA features is tightly built, sustainably refining our understanding of the biological functions of plant transcriptome.
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Long-read sequencing technologies can capture entire RNA transcripts in a single sequencing read, reducing the ambiguity in constructing and quantifying transcript models in comparison to more common and earlier methods, such as short-read sequencing. Recent improvements in the accuracy of long-read sequencing technologies have expanded the scope for novel splice isoform detection and have also enabled a far more accurate reconstruction of complex splicing patterns and transcriptomes. Additionally, the incorporation and advancements of machine learning and deep learning algorithms in bioinformatic software have significantly improved the reliability of long-read sequencing transcriptomic studies. However, there is a lack of consensus on what bioinformatic tools and pipelines produce the most precise and consistent results. Thus, this review aims to discuss and compare the performance of available methods for novel isoform discovery with long-read sequencing technologies, with 25 tools being presented. Furthermore, this review intends to demonstrate the need for developing standard analytical pipelines, tools, and transcript model conventions for novel isoform discovery and transcriptomic studies.
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Accurate quantification of gene and transcript-specific expression, with the underlying knowledge of precise transcript isoforms, is crucial to understanding many biological processes. Analysis of RNA sequencing data has benefited from the development of alignment-free algorithms which enhance the precision and speed of expression analysis. However, such algorithms require a reference transcriptome. Here we generate a reference transcript dataset (LsRTDv1) for lettuce (cv. Saladin), combining long- and short-read sequencing with publicly available transcriptome annotations, and filtering to keep only transcripts with high-confidence splice junctions and transcriptional start and end sites. LsRTDv1 identifies novel genes (mostly long non-coding RNAs) and increases the number of transcript isoforms per gene in the lettuce genome from 1.4 to 2.7. We show that LsRTDv1 significantly increases the mapping rate of RNA-seq data from a lettuce time-series experiment (mock- and Botrytis cinerea-inoculated) and enables detection of genes that are differentially alternatively spliced in response to infection as well as transcript-specific expression changes. LsRTDv1 is a valuable resource for investigation of transcriptional and alternative splicing regulation in lettuce.
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Background: High lipoprotein (a) [Lp(a)] is associated with adverse limb events in patients undergoing lower extremity revascularization. Lp(a) levels are genetically pre-determined, with LPA gene encoding for two apolipoprotein (a) [apo(a)] isoforms. Isoform size variations are driven by the number of kringle IV type 2 (KIV-2) repeats. Lp(a) levels are inversely correlated with isoform size. In this study, we examined the role of Lp(a) levels, apo(a) size, and inflammatory markers with lower extremity revascularization outcomes. Methods: Twenty-five subjects with chronic peripheral arterial disease (PAD) underwent open or endovascular lower extremity revascularization (mean age, 66.7 ± 9.7 years; Female = 12; Male = 13; Black = 8; Hispanic = 5; and White = 12). Pre- and postoperative medical history, self-reported symptoms, ankle-brachial indices (ABIs), and lower extremity duplex ultrasounds were obtained. Plasma Lp(a), apoB100, lipid panel, and pro-inflammatory markers (IL-6, IL-18, hs-CRP, TNFα) were assayed preoperatively. Isoform size was estimated using gel electrophoresis and weighted isoform size (wIS) calculated based on % isoform expression. Firth logistic regression was used to examine the relationship between Lp(a) levels and wIS with procedural outcomes: symptoms (better/worse), early primary patency at 2 to 4 weeks, ABIs, and reintervention within 3 to 6 months. We controlled for age, sex, history of diabetes, smoking, statin, antiplatelet, and anticoagulation use. Results: Median plasma Lp(a) level was 108 (interrquartile range, 44-301) nmol/L. The mean apoB100 level was 168.0 ± 65.8 mg/dL. These values were not statistically different among races. We found no association between Lp(a) levels and wIS with measured plasma pro-inflammatory markers. However, smaller apo(a) wIS was associated with occlusion of the treated lesion(s) in the postoperative period (odds ratio, 1.97; 95% confidence interval, 1.01-3.86; P < .05). The relationship of smaller apo(a) wIS with reintervention was not as strong (odds ratio, 1.57; 95% confidence interval, 0.96-2.56; P = .07). We observed no association between wIS with patient reported symptoms or change in ABIs. Conclusions: In this small study, subjects with smaller apo(a) isoform size undergoing peripheral arterial revascularization were more likely to experience occlusion in the postoperative period and/or require reintervention. Larger cohort studies identifying the mechanism and validating these preliminary data are needed to improve understanding of long-term peripheral vascular outcomes.
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A Disintegrin and Metalloproteinase 10 (ADAM10) is a crucial transmembrane protein involved in diverse cellular processes, including cell adhesion, migration, and proteolysis. ADAM10's ability to cleave over 100 substrates underscores its significance in physiological and pathological contexts, particularly in Alzheimer's disease (AD). This review comprehensively examines ADAM10's multifaceted roles, highlighting its critical function in the non-amyloidogenic processing of the amyloid precursor protein (APP), which mitigates amyloid beta (Aß) production, a critical factor in AD development. We summarize the regulation of ADAM10 at multiple levels: transcriptional, translational, and post-translational, revealing the complexity and responsiveness of its expression to various cellular signals. A standardized nomenclature for ADAM10 isoforms is proposed to improve clarity and consistency in research, facilitating better comparison and replication of findings across studies. We address the challenges in detecting ADAM10 isoforms using antibodies, advocating for standardized detection protocols to resolve discrepancies in results from different biological matrices. This review underscores the potential of ADAM10 as a biomarker for early diagnosis and a therapeutic target in AD. By consolidating current knowledge on ADAM10's regulation and function, we aim to provide insights that will guide future research and therapeutic strategies in the AD context.
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Calcium (Ca2+)/calmodulin-dependent protein kinase II (CaMKII) is activated during exercise by reactive oxygen species (ROS) and Ca2+ transients initiating muscle contraction. CaMKII modulates the antioxidant, inflammatory, metabolic and autophagy signalling pathways. CaMKII is coded by four homologous genes (α, ß, γ, and δ). In rat skeletal muscle δD, δA, γD, γB and ßM have been described while different characterisations of human skeletal muscle CaMKII isoforms have been documented. Precisely discerning between the various isoforms is pivotal for understanding their distinctive functions and regulatory mechanisms in response to exercise and other stimuli. This study aimed to optimise the detection of the different CaMKII isoforms by western blotting using eight different CaMKII commercial antibodies in human skeletal muscle. This research describes a systematic and cost-effective approach to discern between CaMKII isoforms in human skeletal muscle. Exercise-induced posttranslational modifications, i.e. phosphorylation and oxidations, allowed the identification of specific bands by multitargeting them with different antibodies after stripping and reprobing. The methodology proposed has confirmed the molecular weight of ßM CaMKII and allows distinguishing between γ/δ and δD CaMKII. The corresponding molecular weight for the CaMKII isoforms resolved were: δD, at 54.2±2.1kDa; γ/δ, at 59±1.2kDa and 61.6±1.3kDa; and ßM isoform, at 76±1.8kDa. Some tested antibodies showed high specificity for the δD isoform, the most responsive to ROS and intracellular Ca2+ transients isoform in human skeletal muscle, while others, despite the commercial claims, failed to show such specificity.
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Adenosine to inosine (A-to-I) RNA editing plays essential roles in modulating normal development and homeostasis. This process is catalyzed by Adenosine Deaminase Acting on RNA (ADAR) family proteins. The most well-understood biological processes modulated by A-to-I editing are innate immunity and neurological development, attributed to ADAR1 and ADAR2 respectively. A-to-I editing by ADAR1 is also critical in regulating hematopoiesis. This review will focus on the role of A-to-I RNA editing and ADAR enzymes, particularly ADAR1, during normal hematopoiesis in humans and mice. Furthermore, we will discuss Adar1 mouse models that have been developed to understand the contribution of ADAR1 to hematopoiesis and its role in innate immune pathways.
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Proteomics, the study of proteins within biological systems, has seen remarkable advancements in recent years, with protein isoform detection emerging as one of the next major frontiers. One of the primary challenges is achieving the necessary peptide and protein coverage to confidently differentiate isoforms as a result of the protein inference problem and protein false discovery rate estimation challenge in large data. In this chapter, we describe the application of artificial intelligence-assisted peptide property prediction for database search engine rescoring by Oktoberfest, an approach that has proven effective, particularly for complex samples and extensive search spaces, which can greatly increase peptide coverage. Further, it illustrates a method for increasing isoform coverage by the PickedGroupFDR approach that is designed to excel when applied on large data. Real-world examples are provided to illustrate the utility of the tools in the context of rescoring, protein grouping, and false discovery rate estimation. By implementing these cutting-edge techniques, researchers can achieve a substantial increase in both peptide and isoform coverage, thus unlocking the potential of protein isoform detection in their studies and shedding light on their roles and functions in biological processes.
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Inteligência Artificial , Bases de Dados de Proteínas , Isoformas de Proteínas , Proteômica , Software , Isoformas de Proteínas/análise , Proteômica/métodos , Humanos , Biologia Computacional/métodos , Ferramenta de Busca , Peptídeos/química , Peptídeos/análise , Algoritmos , Proteínas/química , Proteínas/análiseRESUMO
BACKGROUND AND AIM: Inflammatory bowel disease is challenging to diagnose. Fecal biomarkers offer noninvasive solutions. The renin-angiotensin-aldosterone system is implicated in intestinal inflammation. Angiotensin-converting enzyme (ACE) and angiotensin-converting enzyme 2 (ACE2) regulate its activity, but conflicting findings on these enzymes in colitis require further investigation. We aimed to assess ACE and ACE2 presence and activities in the feces, serum, and colon of 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced rats. METHODS: Colitis was induced in male rats by rectal instillation of a 21% ethanolic TNBS solution. After rats' sacrifice, colonic portions, serum, and feces were collected. ACE and ACE2 presence in the feces was analyzed by western Blot, and colonic and serum enzymes' concentrations were quantified using ELISA kits. ACE activity was assessed using Hippuryl-His-Leu and Z-Phe-His-Leu as substrates. ACE2 activity was assessed using Mca-APK (Dnp) as a substrate in the presence and absence of DX600 (ACE2 inhibitor). RESULTS: An ACE isoform of ~70 kDa was found only in the feces of TNBS-induced rats. ACE concentration was higher than that of ACE2 in the serum and the inflamed colon. ACE N-domain activity was higher than that of the C-domain in all matrices. ACE2 activity was higher in the feces of TNBS-induced animals compared to controls. CONCLUSION: A 70 kDa ACE isoform only detected in the feces of TNBS-induced rats may have translational relevance. ACE N-domain seems to play a significant role in regulating colonic lesions. Further research using human samples is necessary to validate these findings.
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BRCA1, a crucial tumor suppressor gene, has several splicing isoforms, including Δ9-11, Δ11, and Δ11q, which lack exon 11, coding for significant portions of the protein. These isoforms are naturally present in both normal and cancerous cells, exhibiting altered activity compared to the full-length BRCA1. Despite this, the impact on cancer risk of the germline intronic variants promoting the exclusive expression of these Δ11 isoforms remains uncertain. Consequently, they are classified as variants of uncertain significance (VUS), posing challenges for traditional genetic classification methods due to their rarity and complexity. Our research utilizes a yeast-based functional assay, previously validated for assessing missense BRCA1 variants, to compare the activity of the Δ11 splicing isoforms with known pathogenic missense variants. This approach allows us to elucidate the functional implications of these isoforms and determine whether their exclusive expression could contribute to increased cancer risk. By doing so, we aim to provide insights into the pathogenic potential of intronic VUS-generating BRCA1 splicing isoforms and improve the classification of BRCA1 variants.
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Proteína BRCA1 , Isoformas de Proteínas , Saccharomyces cerevisiae , Humanos , Proteína BRCA1/genética , Proteína BRCA1/metabolismo , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Processamento Alternativo , Splicing de RNA , Íntrons/genética , Éxons/genética , Mutação de Sentido IncorretoRESUMO
Histone lysine demethylases (KDMs) play an essential role in biological processes such as transcription regulation, RNA maturation, transposable element control, and genome damage sensing and repair. In most cases, their action requires catalytic activities, but non-catalytic functions have also been shown in some KDMs. Indeed, some strictly KDM-related proteins and some KDM isoforms do not act as histone demethylase but show other enzymatic activities or relevant non-enzymatic functions in different cell types. Moreover, many studies have reported on functions potentially supported by catalytically dead mutant KDMs. This is probably due to the versatility of the catalytical core, which can adapt to assume different molecular functions, and to the complex multi-domain structure of these proteins which encompasses functional modules for targeting histone modifications, promoting protein-protein interactions, or recognizing nucleic acid structural motifs. This rich modularity and the availability of multiple isoforms in the various classes produced variants with enzymatic functions aside from histone demethylation or variants with non-catalytical functions during the evolution. In this review we will catalog the proteins with null or questionable demethylase activity and predicted or validated inactive isoforms, summarizing what is known about their alternative functions. We will then go through some experimental evidence for the non-catalytical functions of active KDMs.
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Histona Desmetilases , Histona Desmetilases/metabolismo , Histona Desmetilases/genética , Histona Desmetilases/química , Humanos , Animais , Histonas/metabolismoRESUMO
Vascular endothelial growth factor (VEGF) is a pleiotropic growth factor that binds a broad spectrum of cell types and regulates diverse cellular processes, including angiogenesis, growth and survival. However, it is technically difficult to quantify VEGF-cell binding activity because of reversible nature of ligand-receptor interactions. Here we used T7 bacteriophage display to quantify and compare binding activity of three human VEGF-A (hVEGF) isoforms, including hVEGF111, 165 and 206. All three isoforms bound equally well to immobilized aflibercept, a decoy VEGF receptor. hVEGF111-Phage exhibited minimal binding to immobilized heparan sulfate, whereas hVEGF206-Phage and hVEGF165-Phage had the highest and intermediate binding to heparan, respectively. In vitro studies revealed that all three isoforms bound to human umbilical vein endothelial cells (HUVECs), HEK293 epithelial and SK-N-AS neuronal cells. hVEGF111-Phage has the lowest binding activity, while hVEGF206-Phage has the highest binding. hVEGF206-Phage was the most sensitive to detect VEGF-cell binding, albeit with the highest background binding to SK-N-AS cells. These results suggest that hVEGF206-Phage is the best-suited isoform to quantify VEGF-cell binding even though VEGF165 is the most biologically active. Furthermore, this study demonstrates the utility of T7 phage display as a platform for rapid and convenient ligand-cell binding quantification with pros and cons discussed.
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Células Endoteliais da Veia Umbilical Humana , Ligação Proteica , Fator A de Crescimento do Endotélio Vascular , Humanos , Fator A de Crescimento do Endotélio Vascular/metabolismo , Células Endoteliais da Veia Umbilical Humana/metabolismo , Células HEK293 , Isoformas de Proteínas/metabolismo , Receptores de Fatores de Crescimento do Endotélio Vascular/metabolismo , Bacteriófago T7/metabolismo , Bacteriófago T7/genética , Técnicas de Visualização da Superfície Celular/métodos , Heparitina Sulfato/metabolismo , Proteínas Recombinantes de FusãoRESUMO
HSPB8 is a heat shock protein belonging to a family of ATP-independent stress proteins called HSPB which are present far and wide in the cells of various organisms. They are committed to protein quality control (PQC) and strive to avert protein aggregation and to procreate a pool of non-native proteins that can be swiftly folded. Their fundamental expression or stress inducibility is regulated by various cis-elements localized in the HSPB regulatory regions. In the current study we have predicted and confirmed two alternatively spliced novel transcripts of HSPB8 gene in liver, brain, and heart. These spliced variants have smaller sizes owing to smaller N terminal regions and showed remarkable changes in their cellular localization. Novel isoform (HSPB8-N1) was predicted to be majorly localized to nuclear region while the reported isoform (HSPB8) and one of the novel isoforms (HSPB8-N2) were predicted to be cytoplasmic in nature. There were many changes observed in the phosphorylation sites of the novel isoforms as well. The newly reported isoforms lack several structural motifs that are essential for various functional endeavors of the HSPB8 protein. In silico analysis of the conceptually translated protein was carried out using various bioinformatics tools to gain an understanding of their properties in order to explore their possible potential in therapeutics.
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Processamento Alternativo , Proteínas de Choque Térmico , Chaperonas Moleculares , Isoformas de Proteínas , Humanos , Isoformas de Proteínas/genética , Isoformas de Proteínas/química , Proteínas de Choque Térmico/genética , Proteínas de Choque Térmico/química , Proteínas de Choque Térmico/metabolismo , Chaperonas Moleculares/genética , Chaperonas Moleculares/metabolismo , Chaperonas Moleculares/química , Sequência de AminoácidosRESUMO
The AMP-activated protein kinase α (AMPKα) subunit is the catalytic subunit in the AMPK complex, playing a crucial role in AMPK activation. It has two isoforms: AMPKα1 and AMPKα2. Emerging evidence suggests that the AMPKα subunit exhibits subtype-specific effects in Alzheimer's disease (AD). This review discusses the role of the AMPKα subunit in the pathogenesis of AD, including its impact on ß-amyloid (Aß) pathology, Tau pathology, metabolic disorders, inflammation, mitochondrial dysfunction, inflammasome and pyroptosis. Additionally, it reviews the distinct roles of its isoforms, AMPKα1 and AMPKα2, in AD, which may provide more precise targets for future drug development in AD.
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Alternative splicing (AS) of pre-mRNA occurs widely in human genes to produce multiple isoforms with different or even opposite functions. Aberrant AS is often associated with gene mutations and can be corrected by gene therapy. Oral diseases are important public health problems worldwide. Accumulated pieces of evidence demonstrate that AS of pathogenic genes plays key roles in some oral diseases. However, considering the extensiveness and complexity of AS, it may affect the initiation and development of oral diseases deeply and widely. This review describes the diversity of AS and resulting isoforms in genetic, infectious, and malignant oral diseases and highlights the key roles of AS in determining the function of isoforms and the occurrence and progression of these diseases. The studies of alternative splicing may provide great opportunities for the understanding and treatment of oral diseases.
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BACKGROUND: Nitric oxide synthase (NOS) is an enzyme that catalyzes the formation of nitric oxide (NO), the altered production of which is characteristic of diabetic nephropathy. NOS exists in three isoforms: NOS1, NOS2, and NOS3. Moreover, there are reports about the potential role of NOS3 polymorphisms in the development of diabetes complications. The aim of this study was to assess the role of selected NOS polymorphisms-rs3782218 (NOS1), rs1137933 (NOS2), rs1799983, rs2070744, and rs61722009 (NOS3)-in the risk of developing diabetic nephropathy and in the likelihood of renal replacement therapy. METHODS: The studied polymorphisms were analyzed in a group of 232 patients divided into three groups. Four polymorphisms (rs3782218, rs1137933, rs1799983, rs2070744) were genotyped using the PCR-RFLP, while the rs61722009 polymorphism was genotyped using the PCR. RESULTS: The C/C genotype and the C allele of the rs3782218 polymorphism (NOS1) were associated with an increased risk of developing diabetic nephropathy and an increased likelihood of renal replacement therapy. In turn, the G allele of the rs1137933 polymorphism (NOS2) reduces the likelihood of renal replacement therapy. CONCLUSIONS: The specific genotypes or alleles of the rs3782218 (NOS1) and rs1137933 (NOS2) polymorphisms seem to be potential risk factors for diabetic nephropathy and renal replacement therapy.
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Actin, which plays a crucial role in cellular structure and function, interacts with various binding proteins, notably myosin. In mammals, actin is composed of six isoforms that exhibit high levels of sequence conservation and structural similarity overall. As a result, the selection of actin isoforms was considered unimportant in structural studies of their binding with myosin. However, recent high-resolution structural research discovered subtle structural differences in the N-terminus of actin isoforms, suggesting the possibility that each actin isoform may engage in specific interactions with myosin isoforms. In this study, we aimed to explore this possibility, particularly by understanding the influence of different actin isoforms on the interaction with myosin 7A. First, we compared the reported actomyosin structures utilizing the same type of actin isoforms as the high-resolution filamentous skeletal α-actin (3.5 Å) structure elucidated using cryo-EM. Through this comparison, we confirmed that the diversity of myosin isoforms leads to differences in interaction with the actin N-terminus, and that loop 2 of the myosin actin-binding sites directly interacts with the actin N-terminus. Subsequently, with the aid of multiple sequence alignment, we observed significant variations in the length of loop 2 across different myosin isoforms. We predicted that these length differences in loop 2 would likely result in structural variations that would affect the interaction with the actin N-terminus. For myosin 7A, loop 2 was found to be very short, and protein complex predictions using skeletal α-actin confirmed an interaction between loop 2 and the actin N-terminus. The prediction indicated that the positively charged residues present in loop 2 electrostatically interact with the acidic patch residues D24 and D25 of actin subdomain 1, whereas interaction with the actin N-terminus beyond this was not observed. Additionally, analyses of the actomyosin-7A prediction models generated using various actin isoforms consistently yielded the same results regardless of the type of actin isoform employed. The results of this study suggest that the subtle structural differences in the N-terminus of actin isoforms are unlikely to influence the binding structure with short loop 2 myosin 7A. Our findings are expected to provide a deeper understanding for future high-resolution structural binding studies of actin and myosin.
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Actinas , Miosinas , Ligação Proteica , Isoformas de Proteínas , Actinas/química , Actinas/metabolismo , Isoformas de Proteínas/química , Isoformas de Proteínas/metabolismo , Miosinas/química , Miosinas/metabolismo , Sítios de Ligação , Animais , Modelos Moleculares , Sequência de Aminoácidos , Microscopia Crioeletrônica , HumanosRESUMO
Protein kinases (PKs) including RAF, perform a principal role in regulating countless cellular events such as cell growth, differentiation, and angiogenesis. Overexpression and mutation of RAF kinases are significant contributors to the development and spread of cancer. Therefore, RAF kinase inhibitors show promising outcomes as anti-cancer small molecules by suppressing the expression of RAF protein, blocking RAS/RAF interaction, or inhibiting RAF enzymes. Currently, there are insufficient reports about approving drugs with minimal degree of toxicity. Therefore, it is an urgent need to develop new RAF kinase inhibitors correlated with increased anticancer activity and lower cytotoxicity. This review outlines reported RAF kinase inhibitors for cancer treatment in patents and literature from 2019 to 2023. It highlights the available inhibitors by shedding light on their chemical structures, biochemical profiles, and current status. Additionally, we highlighted the hinge region-binding moiety of the reported compounds by showing the hydrogen bond patterns of representative inhibitors with the hinge region for each class. In recent years, RAF kinase inhibitors have gained considerable attention in cancer research and drug development due to their potential to be studied under clinical trials and their demonstration of various degrees of efficacy and safety profiles across different cancer types. However, addressing challenges related to drug resistance and safety represents a major avenue for the optimization and enhancement of RAF kinase inhibitors. Strategies to overcome such obstacles were discussed such as developing novel pan-RAF inhibitors, RAF dimer inhibitors, and combination treatments.
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Antineoplásicos , Neoplasias , Inibidores de Proteínas Quinases , Quinases raf , Humanos , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/química , Quinases raf/antagonistas & inibidores , Quinases raf/metabolismo , Antineoplásicos/farmacologia , Antineoplásicos/química , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Estrutura Molecular , Animais , Relação Estrutura-AtividadeRESUMO
The actin cytoskeleton is one of the most important players in cell motility, adhesion, division, and functioning. The regulation of specific microfilament formation largely determines cellular functions. The main actin-binding protein in animal cells is tropomyosin (Tpm). The unique structural and functional diversity of microfilaments is achieved through the diversity of Tpm isoforms. In our work, we studied the properties of the cytoplasmic isoforms Tpm1.8 and Tpm1.9. The results showed that these isoforms are highly thermostable and differ in the stability of their central and C-terminal fragments. The properties of these isoforms were largely determined by the 6th exons. Thus, the strength of the end-to-end interactions, as well as the affinity of the Tpm molecule for F-actin, differed between the Tpm1.8 and Tpm1.9 isoforms. They were determined by whether an alternative internal exon, 6a or 6b, was included in the Tpm isoform structure. The strong interactions of the Tpm1.8 and Tpm1.9 isoforms with F-actin led to the formation of rigid actin filaments, the stiffness of which was measured using an optical trap. It is quite possible that the structural and functional features of the Tpm isoforms largely determine the appearance of these isoforms in the rigid actin structures of the cell cortex.
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Citoesqueleto de Actina , Actinas , Isoformas de Proteínas , Tropomiosina , Tropomiosina/metabolismo , Tropomiosina/química , Tropomiosina/genética , Isoformas de Proteínas/metabolismo , Isoformas de Proteínas/química , Isoformas de Proteínas/genética , Citoesqueleto de Actina/metabolismo , Animais , Actinas/metabolismo , Actinas/química , Citoplasma/metabolismo , Humanos , Éxons , Ligação Proteica , Estabilidade ProteicaRESUMO
Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS) gene variations are linked to the development of numerous cancers, including non-small cell lung cancer (NSCLC), colorectal cancer (CRC), and pancreatic ductal adenocarcinoma (PDAC). The lack of typical drug-binding sites has long hampered the discovery of therapeutic drugs targeting KRAS. Since "CodeBreaK 100" demonstrated Sotorasib's early safety and efficacy and led to its approval, especially in the treatment of non-small cell lung cancer (NSCLC), the subsequent identification of specific inhibitors for the p.G12C mutation has offered hope. However, the CodeBreaK 200 study found no significant difference in overall survival (OS) between patients treated with Docetaxel and Sotorasib (AMG 510), adding another degree of complexity to this ongoing challenge. The current study compares the three-dimensional structures of the two major KRAS isoforms, KRAS4A and KRAS4B. It also investigates the probable structural changes caused by the three major mutations (p.G12C, p.G12D, and p.G12V) within Sotorasib's pocket domain. The computational analysis demonstrates that the wild-type and mutant isoforms have distinct aggregation propensities, resulting in the creation of alternate oligomeric configurations. This study highlights the increased complexity of the biological issue of using KRAS as a therapeutic target. The present study stresses the need for a better understanding of the structural dynamics of KRAS and its mutations to design more effective therapeutic approaches. It also emphasizes the potential of computational approaches to shed light on the complicated molecular pathways that drive KRAS-mediated oncogenesis. This study adds to the ongoing efforts to address the therapeutic hurdles presented by KRAS in cancer treatment.