Mechanistic Insights Research Articles

Selective Protein Degradation through Tetrazine Ligation of Genetically Incorporated Unnatural Amino Acids.

Small molecule-responsive tags for targeted protein degradation are valuable tools for fundamental research and drug target validation. Here, we show that genetically incorporated unnatural amino acids bearing a strained alkene or alkyne functionality can act as a minimalist tag for targeted protein degradation. Specifically, we observed the degradation of strained alkene- or alkyne-containing kinases and E2 ubiquitin-conjugating enzymes upon treatment with hydrophobic tetrazine conjugates. The extent of the induced protein degradation depends on the identity of the target protein, unnatural amino acid, and tetrazine conjugate, as well as the site of the unnatural amino acid in the target protein. Mechanistic studies revealed proteins undergo proteasomal degradation after tetrazine tethering, and the identity of tetrazine conjugates influences the dependence of ubiquitination on protein degradation. This work provides an alternative approach for targeted protein degradation and mechanistic insight, facilitating the future development of more effective targeted protein degradation strategies.

Radical-Based Enantioconvergent Reductive Couplings of Racemic Allenes and Aldehydes.

Transition metal-catalyzed radical-based enantioconvergent reactions have become a powerful strategy to synthesize enantiopure compounds from racemic starting materials. However, existing methods primarily address precursors with central chirality, neglecting those with axial chirality. Herein, we describe the enantioconvergent reductive coupling of racemic allenes with aldehydes, facilitated by a photoredox, chromium, and cobalt triple catalysis system. This method selectively affords one product from sixteen possible regio- and stereoisomers. The protocol leverages CoIII-H mediated hydrogen atom transfer (MHAT) and Cr-catalyzed radical-polar crossover for efficient stereoablation of axial chirality and asymmetric addition, respectively. Supported by mechanistic insights from control experiments, deuterium labeling, and DFT calculations, our approach offers synthetic chemists a valuable tool for creating enantioenriched chiral homoallylic alcohols, promising to advance radical-based strategies for synthesizing complex chiral molecules.

Mechanistic insight into the effects of interaction between biochar and soil with different properties on phenanthrene sorption

Soil composition varies considerably in nature, so it is vital to investigate the mechanism of the effect of various soil parameters on biochar sorption capacity. In this study, two biochars (W4 and W7) were derived from wheat straw at temperatures of 400 and 700 oC and were incubated with three different soils. Changes in biochar surface features by aging in the soils and the consequent impact on phenanthrene sorption were examined. The results showed that the effect of adding biochar on phenanthrene sorption capacity (Koc) varied by soil. When biochar was freshly mixed with soil, the Koc value in soil with higher clay content was more dramatically altered by biochar, which is due to clay particles adhering to the biochar surface. Moreover, the Koc value was significantly decreased by the addition of W4 but increased by the addition of W7 in general. After aging, most of the Koc value decreased. The greatest decrease in Koc value was observed in biochar and soil composed with the highest clay content for W4 (24-63%), as well as soil composed with the highest organic matter content for W7 (46-64%). This is because the surface polarity and micropores of biochar dropped the most rapidly in these mixes, resulting in a significant decrease in hydrophobic and pore-filling properties. The results revealed that the impact of biochar-soil interactions on phenanthrene sorption is related to not only biochar properties but also soil clay particles, soil organic matter content and pH. The findings of the study can be utilized to assess the efficacy of biochar application in soil remediation for various features.

Cardiac Arrhythmias in Pulmonary Arterial Hypertension and Chronic Thromboembolic Pulmonary Hypertension: Mechanistic Insights, Pathophysiology, and Outcomes.

Arrhythmias are increasingly recognized as severe complications of precapillary pulmonary hypertension, encompassing pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). Despite their significant contribution to symptoms, morbidity, in-hospital mortality, and potentially sudden death in PAH/CTEPH, there remains a lack of comprehensive data on epidemiology, pathophysiology, and outcomes to inform the management of these patients. This review provides an overview of the latest evidence on this subject, spanning from the molecular mechanisms underlying arrhythmias in the hypertrophied or failing right heart to the clinical aspects of epidemiology, diagnosis, and treatment.

Mechanistic insights and knowledge gaps in the effects of radiation therapy on cardiac arrhythmias

Mechanistic insights and knowledge gaps in the effects of radiation therapy on cardiac arrhythmias

Mechanistic insights into the interaction of Lycium barbarum polysaccharide with whey protein isolate: Functional and structural characterization

Mechanistic insights into the interaction of Lycium barbarum polysaccharide with whey protein isolate: Functional and structural characterization

Controlled Synthesis of Nickel Phosphides: Mechanistic Insights and Catalytic Activity in Hydrogen Peroxide Production

Strategically designing oxygen reduction reaction (ORR) electrocatalysts based on electronic structure is a pivotal method for enhancing the electrocatalytic activity and selectivity of two-electron (2e) reactions. While many transition metal phosphides, including NixPy, have demonstrated activity in electrocatalytic reactions, their effectiveness in 2e ORR electrocatalysis is still uncertain. In this study, guided by the theoretical insights into high electroactivity unveiled by the d-band center (Ed) theory, we engineered and synthesized Ni2P/Ni5P4 nanosheets (NSs). Functioning as 2e ORR electrocatalysts in alkaline environments, the Ni2P/Ni5P4 NSs exhibited outstanding 2e selectivity of up to 95%, with an electron transfer number close to two. Demonstrating a Faradaic efficiency exceeding 95% over a wide potential range (0.2 – 0.5 V), these NSs displayed extended stability for over 48 hours, outperforming most transition metal-based catalysts reported in literature. By employing density functional theory (DFT) calculations, the increased activity is ascribed to the adjustment of the d-band center at the engineered heterostructure interface, effectively regulating the adsorption energy of oxygen-containing intermediates (*OOH). This study offers crucial insights into the methodical design and production of effective transition metal phosphide electrocatalysts guided by the d-band center theory.

Voluntary exercise sensitizes cancer immunotherapy via the collagen inhibition-orchestrated inflammatory tumor immune microenvironment

Physical activity reduces cancer-associated mortality through multiple mechanisms, including tumor immune microenvironment (TIME) reprogramming. However, whether and how physiological interventions promote anti-tumor immunity remain elusive. Here, we report that clinically relevant voluntary exercise promotes muscle-derived extracellular vesicle (EV)-associated miR-29a-3p for tumor extracellular matrix (ECM) inhibition in patients and mouse models, thereby permitting immune cell infiltration and immunotherapy. Mechanistically, an unbiased screening identifies EV-associated miR-29a-3p in response to leisure-time physical activity or voluntary exercise. MiR-29a-3p-containing EVs accumulate in tumors and downregulate collagen composition by targeting COL1A1. Gain- and loss-of-function experiments and cytometry by time of flight (CyTOF) demonstrate that myocyte-secreted miR-29a-3p promotes anti-tumor immunity. Combining immunotherapy with voluntary exercise or miR-29a-3p further enhances anti-tumor efficacy. Clinically, miR-29a-3p correlates with reduced ECM, increased Tcell infiltration, and response to immunotherapy. Our work reveals the predictive value of miR-29a-3p for immunotherapy, provides mechanistic insights into exercise-induced anti-cancer immunity, and highlights the potential of voluntary exercise in sensitizing immunotherapy.

Mechanistic insights into behavioral clusters associated with cancer-related systemic inflammatory response.

This focused, narrative review mostly describes our team's investigations into the potential inflammatory mechanisms that contribute to the development of cancer-related gastrointestinal (GI) mucositis and its associated symptoms. This review summarizes details of our clinical and preclinical findings to test the role of inflammation in the development and occurrence of these cancer-related conditions. GI mucositis (GIM) is a common, distressing condition reported by cancer patients. GIM is often clustered with other behaviors including fatigue, pain, anorexia, depression, and diarrhea. It is hypothesized that there is a common biologic mechanism underpinning this symptom cluster. Our multi-platform investigations revealed that GIM and its associated cluster of behaviors may be triggered by local inflammation spreading systemically causing pro-inflammatory-mediated toxicities, leading to alterations in immune, metabolic, and nervous system functions and activities. For example, behavioral toxicities related to local irradiation for non-metastatic cancer may be triggered by mGluR5 activation influencing prolonged T cell as well as NF-κB transcription factor activities. Thus, interventions targeting inflammation and associated pathways may be a reasonable strategy to alleviate GIM and its symptom cluster. GIM may be a sign of a broader systemic inflammatory response triggered by cancer or its treatment. Addressing GIM and its associated symptoms primarily involves supportive care strategies focused on relieving symptoms, promoting healing, and preventing complications.

Acyl-CoA Synthetase Long-Chain Isoenzymes in Kidney Diseases: Mechanistic Insights and Therapeutic Implications.

Long-chain acyl-CoA synthetases (ACSLs) are pivotal enzymes in fatty acid metabolism, essential for maintaining cellular homeostasis and energy production. Recent research has uncovered their significant involvement in the pathophysiology of various kidney diseases, including acute kidney injury (AKI), chronic kidney disease (CKD), diabetic kidney disease (DKD), and renal cell carcinoma (RCC). While ACSL1, ACSL3, ACSL4, and ACSL5 have been extensively studied for their roles in processes such as ferroptosis, lipid peroxidation, renal fibrosis, epithelial-mesenchymal transition, and tumor progression, the role of ACSL6 in kidney diseases remain largely unexplored. Notably, these isoenzymes exhibit distinct functions in different kidney diseases. Therefore, to provide a comprehensive understanding of their involvement, this review highlights the molecular pathways influenced by ACSLs and their roles in modulating cell death, inflammation, and fibrosis during kidney disease progression. By examining these mechanisms in detail, this review underscores the potential of ACSLs as biomarkers and therapeutic targets, advocating for further research to elucidate the precise roles of individual ACSL isoenzymes in kidney disease progression. Understanding these mechanisms opens new avenues for developing targeted interventions and improving therapeutic outcomes for patients with kidney diseases.

A Systematic Review of Herbal Interventions for the Management of Cardiovascular Diseases.

Cardiovascular diseases represent a significant global health burden, necessitating diverse approaches for effective management. Herbal interventions have gained attention as potential adjuncts or alternatives to conventional therapies due to their perceived safety and therapeutic potential. This structured abstract provides a comprehensive review of herbal interventions for the management of CVDs, summarising key findings, mechanisms of action, and clinical implications. This systematic review aims to evaluate the impact of various herbal interventions employed for managing cardiovascular diseases. We conducted an extensive literature search across electronic databases, including PubMed, Scopus, and Web of Science, from inception to 2022. Studies were included if they investigated the use of herbal remedies for preventing or treating CVDs. Data extraction and synthesis focused on botanical sources, active compounds, mechanisms of action, and clinical outcomes. Numerous herbal interventions have demonstrated promising cardiovascular benefits. A number of medicinal herbs well identified to treat CVD are Moringaoleifera, Ginseng, Ginkgo biloba, Celosia argentea, Gongronematrifolium, Gynostemmapentaphyllum, Bombaxceiba, Gentianalutea, Allium sativum, Crataegusspp, Curcuma longa, Camellia sinensis, and Zingiberofficinale. Mechanistic insights reveal that herbal interventions often target multiple pathways involved in CVD pathogenesis. These mechanisms encompass anti-inflammatory, antioxidant, anti-thrombotic, anti-hypertensive, and lipid-lowering effects. Additionally, some herbs enhance endothelial function, promote nitric oxide production, and exert vasodilatory effects, contributing to improved cardiovascular health. Clinical studies have provided evidence of the efficacy of certain herbal interventions in reducing CVD risk factors and improving patient outcomes. However, more rigorous, large-scale clinical trials are needed to establish their long-term safety and effectiveness. It is crucial to consider potential herb-drug interactions and standardise dosages for reliable therapeutic outcomes. This comprehensive review highlights the potential of herbal interventions as valuable adjuncts or alternatives for managing cardiovascular diseases. Herbal remedies offer diverse mechanisms of action, targeting key CVD risk factors and pathways. While promising, their clinical utility warrants further investigation through well-designed trials to establish their safety and efficacy, paving the way for integrated approaches to cardiovascular disease management. Healthcare providers and patients should engage in informed discussions about the use of herbal interventions alongside conventional therapies in the context of CVD prevention and treatment.

In Vitro Assessment of Inhibitory Effects of Kinase Inhibitors on CYP2C9, 3A and 1A2: Prediction of Drug-Drug Interaction Risk with Warfarin and Direct Oral Anticoagulants.

This study aimed to evaluate the cytochrome P450 (CYP)-mediated drug-drug interaction (DDI) potential of kinase inhibitors with warfarin and direct oral anticoagulants (DOACs). An in vitro CYP probe substrate cocktail assay was used to study the inhibitory effects of fifteen kinase inhibitors on CYP2C9, 3A, and 1A2. Then, DDI predictions were performed using both mechanistic static and physiologically-based pharmacokinetic (PBPK) models. Linsitinib, masitinib, regorafenib, tozasertib, trametinib, and vatalanib were identified as competitive CYP2C9 inhibitors (Ki = 1.4, 1.0, 1.1, 3.8, 0.5, and 0.1 μM, respectively). Masitinib and vatalanib were competitive CYP3A inhibitors (Ki = 1.3 and 0.2 μM), and vatalanib noncompetitively inhibited CYP1A2 (Ki = 2.0 μM). Moreover, linsitinib and tozasertib were CYP3A time-dependent inhibitors (KI = 26.5 and 400.3 μM, kinact = 0.060 and 0.026 min-1, respectively). Only linsitinib showed time-dependent inhibition of CYP1A2 (KI = 13.9 μM, kinact = 0.018 min-1). Mechanistic static models identified possible DDI risks for linsitinib and vatalanib with (S)-/(R)-warfarin, and for masitinib with (S)-warfarin. PBPK simulations further confirmed that vatalanib may increase (S)- and (R)-warfarin exposure by 4.37- and 1.80-fold, respectively, and that linsitinib may increase (R)-warfarin exposure by 3.10-fold. Mechanistic static models predicted a smaller risk of DDIs between kinase inhibitors and apixaban or rivaroxaban. The greatest AUC increases (1.50-1.74) were predicted for erlotinib in combination with apixaban and rivaroxaban. Linsitinib, masitinib, and vatalanib were predicted to have a smaller effect on apixaban and rivaroxaban AUCs (AUCR 1.22-1.53). No kinase inhibitor was predicted to increase edoxaban exposure. Our results suggest that several kinase inhibitors, including vatalanib and linsitinib, can cause CYP-mediated drug-drug interactions with warfarin and, to a lesser extent, with apixaban and rivaroxaban. The work provides mechanistic insights into the risk of DDIs between kinase inhibitors and anticoagulants, which can be used to avoid preventable DDIs in the clinic.

Efficient ofloxacin degradation via peroxymonosulfate activation using an S-scheme MoS2/Co3O4 heterojunction composite under visible light: Performance and mechanistic insights.

Sulfate-radical-mediated photocatalysis technology peroxymonosulfate (PMS) activation via visible light irradiation shows great promise for water treatment applications. However, its effectiveness largely depends on the bifunctional performance of photocatalysis and PMS activation provided by the catalysts. In this study, we successfully synthesized a novel S-scheme MoS2/Co3O4 (MC) heterojunction composite by a hydrothermal method and employed it for the first time to activate PMS for ofloxacin (OFX) degradation under visible light irradiation. The MC-5/PMS/Vis system achieved an impressive 85.11% OFX degradation efficiency within 1 min and complete OFX removal within 15 min under optimal conditions, with an apparent first-order kinetics rate constant of 0.429 min-1. Reactive species trapping experiments and electron spin resonance analysis identified 1O2, h+, and •O2- as the primary active species responsible for OFX degradation. Photoelectrochemical analyses and density functional theory calculations indicated the formation of a built-in electric field between MoS2 and Co3O4, which enhanced the separation and migration of photoinduced carriers. Additionally, the Co-Mo interaction further increased the yield of dominant reactive species, thereby boosting photocatalytic activity. This work underscores the potential of visible-light-assisted PMS-mediated photocatalysis using Co3O4-based catalysts for effective pollutant control.

Mechanistic insights into stepwise activation of malachite for enhancing surface reactivity and flotation performance

Mechanistic insights into stepwise activation of malachite for enhancing surface reactivity and flotation performance

EIF4G2 Promotes Hepatocellular Carcinoma Progression via IRES-dependent PLEKHA1 Translation Regulation.

Hepatocellular carcinoma (HCC) is a highly lethal cancer, and proteomic studies have shown increased protein diversity and abundance in HCC tissues, whereas the role of protein translation has not been extensively explored in HCC. Our research focused on key molecules in the translation process to identify a potential contributor in HCC. We discovered that EIF4G2, a crucial translation initiation factor, is significantly upregulated in HCC tissues and associated with poor prognosis. This study uniquely highlights the impact of EIF4G2 deletion, which suppresses tumor growth and metastasis both in vitro and in vivo. Furthermore, polysome analysis and nascent protein synthesis assays revealed EIF4G2's role in regulating protein translation, specifically identifying PLEKHA1 as a key translational product. This represents a novel mechanistic insight into HCC malignancy. RNA immunoprecipitation (RIP) and Dual-luciferase reporter assays further revealed that EIF4G2 facilitates PLEKHA1 translation via an IRES-dependent manner. Importantly, the synergistic effects of EIF4G2 depletion and PLEKHA1 reduction in inhibiting cell migration and invasion underscore the therapeutic potential of targeting this axis. This study not only advances our understanding of translational regulation in HCC but also identifies the EIF4G2-PLEKHA1 axis as a promising therapeutic target, offering new avenues for intervention in HCC treatment.

Occurrence, Toxicodynamics, and Mechanistic Insights for Atrazine Degradation in the Environment

Occurrence, Toxicodynamics, and Mechanistic Insights for Atrazine Degradation in the Environment

Mechanistic Insight of High-Valent First-Row Transition Metal Complexes for Dehydrogenation of Ammonia Borane.

Designing an efficient and cost-effective catalyst for ammonia borane (AB) dehydrogenation remains a persistent challenge in advancing a hydrogen-based economy. Transition metal complexes, known for their C-H bond activation capabilities, have emerged as promising candidates for AB dehydrogenation. In this study, we investigated two recently synthesized C-H activation catalysts, 1 (CoIV-dinitrate complex) and 2 (NiIV-nitrate complex), and demonstrated their efficacy for AB dehydrogenation. Using density functional theory calculations and a detailed analysis, we elucidated the AB dehydrogenation mechanism of these complexes. Our results revealed that both complexes 1 and 2 can efficiently dehydrogenate AB at room temperature, although the abstraction of molecular H2 from these complexes requires slightly elevated temperatures. We utilized H2 binding free energy calculations to identify potentially active sites and observed that complex 2 can release two equivalents of H2 at a temperature slightly higher than room temperature. Furthermore, we investigated AB dehydrogenation kinetics and thermodynamics in iron (Fe)-substituted systems, complexes 3 and 4. Our results showed that the strategic alteration of the central metal atom, replacing Ni in complex 2 with Fe in complex 4, resulted in enhanced kinetics and thermodynamics for AB dehydrogenation in the initial cycle. These results underscore the potential of high-valent first-row transition metal complexes for facilitating AB dehydrogenation at room temperature. Additionally, our study highlights the beneficial impact of incorporating iron into such mononuclear systems, enhancing their catalytic activity.

Catalytic pyrolysis mechanism of lignin moieties driven by aldehyde, hydroxyl, methoxy, and allyl functionalization: the role of reactive quinone methide and ketene intermediates.

The catalytic pyrolysis of guaiacol-based lignin monomers, vanillin, syringol, and eugenol over commercial HZSM-5 has been investigated using operando Photoelectron Photoion Coincidence (PEPICO) spectroscopy to unveil the reaction mechanism by detecting reactive intermediates, such as quinone methides and ketenes, and products. Vanillin shares the decomposition mechanism with guaiacol due to prompt and efficient decarbonylation, which allows us to control this reaction leading to a phenol selectivity increase by switching to a faujasite catalyst and decreasing the Si/Al ratio. Syringol first demethylates to 3-methoxycatechol, which mainly dehydroxylates to o- and m-guaiacol. Ketene formation channels over HZSM-5 are less important here than for guaiacol or vanillin, but product distributionremains similar. C3 addition to guaiacol yields eugenol, which shows a more complex product distribution upon catalytic pyrolysis. By analogies to monomers with simplified functionalization, namely allylbenzene, 4-allylcatechol, and 4-methylcatechol, the eugenol chemistry could be fully resolved. Previously postulated reactive semi-quinone intermediates are detected spectroscopically, and their involvement opens alternative pathways to condensation and phenol formation. Allyl groups, produced by dehydroxylation of the β-O-4 bond, may not only decompose via C1/C2/C3 loss, but also cyclize to indene and its derivatives over HZSM-5. This comparably high reactivity leads to an unselective branching of the chemistry and to a complex product distribution, which is difficult to control. Indenes and naphthalenes are also prototypical coke precursors efficiently deactivating the catalyst. We rely on these mechanistic insights to discuss strategies to fine-tune process conditions to increase the selectivities of desired products by enhancing either vanillin and guaiacol or supressing eugenol yields from native lignin.

Mechanistic Insights into Cisplatin Response in Breast Tumors: Molecular Determinants and Drug/Nanotechnology-Based Therapeutic Opportunities.

Breast cancer continues to be a major global health challenge, driving the need for effective therapeutic strategies. Cisplatin, a powerful chemotherapeutic agent, is widely used in breast cancer treatment. However, its effectiveness is often limited by systemic toxicity and the development of drug resistance. This review examines the molecular factors that influence cisplatin response and resistance, offering crucial insights for the scientific community. It highlights the significance of understanding cisplatin resistance's genetic and epigenetic contributors, which could lead to more personalized treatment approaches. Additionally, the review explores innovative strategies to counteract cisplatin resistance, including combination therapies, nanoparticle-based drug delivery systems, and targeted therapies. These approaches are under intensive investigation and promise to enhance breast cancer treatment outcomes. This comprehensive discussion is a valuable resource to advance breast cancer therapeutics and address the challenge of cisplatin resistance.

AP-1 contributes to endosomal targeting of ubiquitin ligase RNF13 via a secondary and novel non-canonical binding motif.

Cellular trafficking between organelles is typically assured by short motifs that contact carrier proteins to transport them to their destination. Ubiquitin E3 ligase RING finger protein 13 (RNF13), a regulator of proliferation, apoptosis, and protein trafficking, localizes to endolysosomal compartments through the binding of a dileucine motif to clathrin adaptor protein complex AP-3. Mutations within this motif reduce the ability of RNF13 to interact with AP-3. Here, our study shows the discovery of a glutamine-based motif that resembles a tyrosine-based motif within RNF13's C-terminal region that binds to the clathrin adaptor protein complex AP-1, notably without a functional interaction with AP-3. Using biochemical, molecular, and cellular approaches in HeLa cells, our study demonstrates that a RNF13 dileucine variant uses an AP-1-dependent pathway to be exported from the Golgi towards the endosomal compartment. Overall, this study provides mechanistic insights into the alternate route used by variant of RNF13's dileucine sorting motif.