Molecular Mechanisms Research Articles

RNA Binding Proteins as Potential Therapeutic Targets in Colorectal Cancer

RNA-binding proteins (RBPs) play critical roles in regulating post-transcriptional gene expression, managing processes such as mRNA splicing, stability, and translation. In normal intestine, RBPs maintain the tissue homeostasis, but when dysregulated, they can drive colorectal cancer (CRC) development and progression. Understanding the molecular mechanisms behind CRC is vital for developing novel therapeutic strategies, and RBPs are emerging as key players in this area. This review highlights the roles of several RBPs, including LIN28, IGF2BP1–3, Musashi, HuR, and CELF1, in CRC. These RBPs regulate key oncogenes and tumor suppressor genes by influencing mRNA stability and translation. While targeting RBPs poses challenges due to their complex interactions with mRNAs, recent advances in drug discovery have identified small molecule inhibitors that disrupt these interactions. These inhibitors, which target LIN28, IGF2BPs, Musashi, CELF1, and HuR, have shown promising results in preclinical studies. Their ability to modulate RBP activity presents a new therapeutic avenue for treating CRC. In conclusion, RBPs offer significant potential as therapeutic targets in CRC. Although technical challenges remain, ongoing research into the molecular mechanisms of RBPs and the development of selective, potent, and bioavailable inhibitors should lead to more effective treatments and improved outcomes in CRC.

Molecular mechanism of proteolytic cleavage-dependent activation of CadC-mediated response to acid in E. coli

Colonizing in the gastrointestinal tract, Escherichia coli confronts diverse acidic challenges and evolves intricate acid resistance strategies for its survival. The lysine-mediated decarboxylation (Cad) system, featuring lysine decarboxylase CadA, lysine/cadaverine antiporter CadB, and transcriptional activator CadC, plays a crucial role in E. coli’s adaptation to moderate acidic stress. While the activation of the one-component system CadC and subsequent upregulation of cadBA operon in response to acid and lysine presence have been proposed, the molecular mechanisms governing the transition of CadC from an inactive to an active state remain elusive. Under neutral conditions, CadC is inhibited by forming a complex with lysine-specific permease LysP, stabilized in this inactive state by a disulfide bond. Our study unveils that, in an acidic environment, the disulfide bond in CadC is reduced by the disulfide bond isomerase DsbC, exposing R184 to periplasmic proteases, namely DegQ and DegP. Cleavage at R184 by DegQ and DegP generates an active N-terminal DNA-binding domain of CadC, which binds to the cadBA promoter, resulting in the upregulated transcription of the cadA and cadB genes. Upon activation, CadA decarboxylates lysine, producing cadaverine, subsequently transported extracellularly by CadB. We propose that accumulating cadaverine gradually binds to the CadC pH-sensing domain, preventing cleavage and activation of CadC as a feedback mechanism. The identification of DegP, DegQ, and DsbC completes a comprehensive roadmap for the activation and regulation of the Cad system in response to moderate acidic stress in E. coli.

Cardiac Amyloidosis: State-of-the-Art Review in Molecular Pathology

Amyloidosis refers to a group of diseases caused by extracellular deposits of misfolded proteins, which alter tissue function and structure, potentially affecting any organ. The term “amyloid” was introduced in the 19th century and later associated with pathological protein deposits. Amyloid fibrils, which are insoluble and resistant to degradation, originate from soluble proteins that undergo misfolding. This process can be triggered by several factors, such as aging, elevated protein concentrations, or pathogenic variants. Amyloid deposits damage organs both by disrupting tissue architecture and through direct cytotoxic effects, leading to conditions such as heart failure. Amyloidosis can be classified into acquired or inherited forms and can be systemic or localized. Diagnosing cardiac amyloidosis is complex and often requires tissue biopsies, which are supported by Congo Red dye staining. In some cases, bisphosphonate bone scans may provide a less invasive diagnostic option. In this state-of-the-art review, we focus on the most common forms of cardiac amyloidosis, from epidemiology to therapy, emphasizing the differences in molecular mechanisms and the importance of pathological diagnosis for appropriate treatment using a multidisciplinary approach.

Resistance gene Ty-1 restricts TYLCV infection in tomato by increasing RNA silencing

A major antiviral mechanism in plants is mediated by RNA silencing through the action of DICER-like (DCL) proteins, which cleave dsRNA into discrete small RNA fragments, and ARGONAUTE (AGO) proteins, which use the small RNAs to target single-stranded RNA. RNA silencing can also be amplified through the action of RNA-dependent RNA polymerases (RDRs), which use single stranded RNA to generate dsRNA that in turn is targeted by DCL proteins. As a counter-defense, plant viruses encode viral suppressors of RNA silencing (VSRs) that target different components in the RNA silencing pathway. The tomato Ty-1 gene confers resistance to the DNA virus tomato yellow leaf curl virus (TYLCV) and has been reported to encode an RDRγ protein. However, the molecular mechanisms by which Ty-1 controls TYLCV infection, including whether Ty-1 is involved in RNA silencing, are unknown. Here, by using a transient expression assay, we have confirmed that Ty-1 shows antiviral activity against TYLCV in Nicotiana benthamiana. Also, in transient expression-based silencing assays, Ty-1 augmented systemic transgene silencing in GFP transgenic N. benthamiana plants. Furthermore, co-expression of Ty-1 or other RDRγ proteins from N. benthamiana or Arabidopsis with various proteins resulted in lower protein expression. These results are consistent with a model wherein Ty-1-mediated resistance to TYLCV is due, at least in part, to an increase in RNA silencing activity.

AR expression-independent XRCC3 mediates DNA damage-induced p53/Bax signaling pathway activation against prostate cancer

BackgroundAndrogen deprivation therapy (ADT) resistance is closely associated with altered AR status. Aberrant AR expression is critical for the induction of ADT resistance, necessitating the identification of an anti-PCa target independent of AR expression.MethodsTranscriptomic data and clinical information of PRAD were obtained from TCGA database. Genes with PCa-related and AR expression-independent were screened by bioinformatics, and characterized by PPI and GO functional enrichment analyses. Candidate genes were locked by co-expression correlation and disease-free survival (DFS) analyses. A prognostic gene set was established using LASSO Cox regression algorithm. Cox proportional risk regression was performed to identify a key prognostic gene. Expression of the target protein in PCa tissues was verified by The Human Protein Atlas database. In vitro validation of cellular function and molecular mechanism by knockdown and overexpression of the target gene.ResultsTwo AR expression-independent genes (SLC43A1 and XRCC3) were available for the optimal prognostic model. This gene set effectively predicted PRAD patients’ DFS at 1-, 3- and 5-year, where XRCC3 and tumor (T) stage were independent risk factors. XRCC3 was higher expressed in PRAD patients with T3-T4 stages and accompanied by poorer DFS. IHC staining also validated its higher expression in high-risk PCa tissues. In vitro experiments demonstrated that silencing XRCC3 significantly inhibited 22Rv1 and DU145 cell proliferation, migration and invasion, while promoted apoptosis. Further, silencing XRCC3 promoted DNA damage-induced p53/Bax signaling pathway activation, which was absent with overexpression.ConclusionSilencing XRCC3 exerts anti-PCa effects by promoting DNA damage-induced p53/Bax signaling pathway activation in an AR expression-independent manner.

RettDb: the Rett syndrome omics database to navigate the Rett syndrome genomic landscape.

Rett syndrome (RTT) is a neurodevelopmental disorder occurring almost exclusively in females and leading to a variety of impairments and disabilities from mild to severe. In >95% cases, RTT is due to mutations in the X-linked gene MECP2, but the molecular mechanisms determining RTT are unknown at present, and the complexity of the system is challenging. To facilitate and provide guidance to the unraveling of those mechanisms, we developed a database resource for the visualization and analysis of the genomic landscape in the context of wild-type or mutated Mecp2 gene in the mouse model. Our resource allows for the exploration of differential dynamics of gene expression and the prediction of new potential MECP2 target genes to decipher the RTT disorder molecular mechanisms. Database URL: https://biomedinfo.di.unipi.it/rett-database/.

Physiological and Transcriptomic Analyses Reveal the Role of the Antioxidant System and Jasmonic Acid (JA) Signal Transduction in Mulberry (Morus alba L.) Response to Flooding Stress

In recent decades, the frequency of flooding has increased as a result of global climate change. Flooding has become one of the major abiotic stresses that seriously affect the growth and development of plants. Mulberry (Morus alba L.) is an important economic tree in China. Flooding stress is among the most severe abiotic stresses that affect the production of mulberry. However, the physiological and molecular biological mechanisms of mulberry responses to flooding stress are still unclear. In the present study, reactive oxygen species (ROS) metabolism, antioxidant mechanism, and plant hormones in mulberry associated with the response to flooding stress were investigated using physiological and transcriptomic analysis methods. The results showed significant increases in the production rate of superoxide anion (O2•−) and the content of hydrogen peroxide (H2O2) in leaves on the 5th day of flooding stress. This led to membrane lipid peroxidation and elevated malondialdehyde (MDA) levels. Antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) exhibited enhanced activities initially, followed by fluctuations. The ascorbic acid–glutathione (AsA-GSH) cycle played a crucial role in scavenging ROS, promoting the reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH). Transcriptomic analysis revealed the up-regulation of the gene-encoding antioxidant enzymes (APX, MDHAR, GPX, GR, GST) involved in ROS scavenging and stress tolerance mechanisms. Jasmonic acid (JA) levels and the expression of JA synthesis-related genes increased significantly in mulberry leaves under flooding stress. This activation of the JA signaling pathway contributed to the plant’s adaptability to flooding conditions. Proline (Pro) and soluble sugar (SS) contents increased notably in response to flooding stress. Proline helped maintain cell turgor and protected enzymes and membranes from damage, while soluble sugars supported anaerobic respiration and energy supply. However, soluble protein (SP) content decreased, suggesting inhibition of protein synthesis. The study provides insights into mulberry’s flooding tolerance mechanisms, guiding future molecular breeding efforts. This summary captures the key findings and implications of the study on mulberry’s response to flooding stress, focusing on physiological and molecular mechanisms identified in the research.

Spatial proteomics identifies JAKi as treatment for a lethal skin disease.

Toxic epidermal necrolysis (TEN) is a fatal drug-induced skin reaction triggered by common medications and is an emerging public health issue1-3. Patients with TEN undergo severe and sudden epidermal detachment caused by keratinocyte cell death. Although molecular mechanisms that drive keratinocyte cell death have been proposed, the main drivers remain unknown, and there is no effective therapy for TEN4-6. Here, to systematically map molecular changes that are associated with TEN and identify potential druggable targets, we utilized deep visual proteomics, which provides single-cell-based, cell-type-resolution proteomics7,8. We analysed formalin-fixed, paraffin-embedded archived skin tissue biopsies of three types of cutaneous drug reactions with varying severity and quantified more than 5,000 proteins in keratinocytes and skin-infiltrating immune cells. This revealed a marked enrichment of type I and type II interferon signatures in the immune cell and keratinocyte compartment of patients with TEN, as well as phosphorylated STAT1 activation. Targeted inhibition with the pan-JAK inhibitor tofacitinib in vitro reduced keratinocyte-directed cytotoxicity. In vivo oral administration of tofacitinib, baricitinib or the JAK1-specific inhibitors abrocitinib or upadacitinib ameliorated clinical and histological disease severity in two distinct mouse models of TEN. Crucially, treatment with JAK inhibitors (JAKi) was safe and associated with rapid cutaneous re-epithelialization and recovery in seven patients with TEN. This study uncovers the JAK/STAT and interferon signalling pathways as key pathogenic drivers of TEN and demonstrates the potential of targeted JAKi as a curative therapy.

Transcriptomic and Proteomic Integration Reveals Key Tapping-Responsive Factors for Natural Rubber Biosynthesis in the Rubber Tree Hevea brasiliensis

Natural rubber is a crucial industrial material, and it is primarily harvested from the latex of the rubber tree Hevea brasiliensis by tapping the tree trunk. During the regular tapping process, mechanical damage seriously affects latex reproduction and rubber yield, but the molecular mechanisms on tapping stimulation remain unclear. In this study, we firstly determined the changed physiological markers on latex regeneration, overall latex yield, and latex flow time during the tapping process. Then, we combined proteomics and transcriptomics analyses of latex during tapping and identified 3940 differentially expressed genes (DEGs) and 193 differentially expressed proteins (DEPs). Among them, 773 DEGs and 120 DEPs displayed a persistent upregulation trend upon tapping. It is interesting that, in the detected transcription factors, basic helix-loop-helix (bHLH) family members occupied the highest proportion among all DEGs, and this trend was similarly observed in DEPs. Notably, 48 genes and 34 proteins related to natural rubber biosynthesis were identified, and most members of small rubber particle protein (SRPP) and rubber elongation factor (REF) showed a positive response to tapping stimulation. Among them, SRPP6 and REF5 showed significant and sustained upregulation at the gene and protein levels following tapping, indicating their pivotal roles for post-tapping rubber biosynthesis. Our results deepen the comprehension of the regulation mechanism underlying tapping and provide candidate genes and proteins for improving latex production in the Hevea rubber tree in future.

Molecular Mechanism of Mok I Gene Overexpression in Enhancing Monacolin K Production in Monascus pilosus

Monascus species are capable of producing various active metabolites, including monacolin K (MK) and pigments. Studies have shown that the overexpression of the mok I gene from the MK synthesis gene cluster in Monascus species can significantly increase MK production; however, the molecular mechanism has not yet been fully elucidated. Therefore, this study focused on the mok I gene of Monascus pilosus to construct overexpression strains of the mok I gene, resulting in high-yield MK production. Sixteen positive transformants were obtained, seven of which produced 9.63% to 41.39% more MK than the original strain, with no citrinin detected in any of the transformants. The qRT-PCR results revealed that the expression levels of mok I in the transformed strains TI-13, TI-24, and TI-25 increased by more than 50% compared to the original strain at various fermentation times, with the highest increase being 10.9-fold. Furthermore, multi-omics techniques were used to analyze the molecular mechanisms underlying enhanced MK production in transformed strains. The results indicated that mok I overexpression may enhance MK synthesis in M. pilosus by regulating the expression of key genes (such as MAO, HPD, ACX, and PLC) and the synthesis levels of key metabolites (such as delta-tocopherol and alpha-linolenic acid) in pathways linked to the biosynthesis of cofactors, the biosynthesis of unsaturated fatty acids, tyrosine metabolism, ubiquinone and other terpenoid-quinone biosynthesis, alpha-linolenic acid metabolism, and glycerophospholipid metabolism. These findings provide a theoretical basis for further study of the metabolic regulation of MK in Monascus species and for effectively enhancing their MK production.

The Genetics of Chiari 1 Malformation

Chiari malformation type 1 (CM1) is a structural defect that involves the herniation of the cerebellar tonsils through the foramen magnum, causing mild to severe neurological symptoms. Little is known about the molecular and developmental mechanisms leading to its pathogenesis, prompting current efforts to elucidate genetic drivers. Inherited genetic disorders are reported in 2–3% of CM1 patients; however, CM1, including familial forms, is predominantly non-syndromic. Recent work has focused on identifying CM1-asscoiated variants through the study of both familial cases and de novo mutations using exome sequencing. This article aims to review the current understanding of the genetics of CM1. We discuss three broad classes of CM1 based on anatomy and link them with genetic lesions, including posterior fossa-linked, macrocephaly-linked, and connective tissue disorder-linked CM1. Although the genetics of CM1 are only beginning to be understood, we anticipate that additional studies with diverse patient populations, tissue types, and profiling technologies will reveal new insights in the coming years.

ADAM8 promotes alcoholic liver fibrosis through the MAPK signaling pathway

The effect and molecular regulatory mechanism of A Disintegrin and Metalloproteinase 8 (ADAM8) were explored in alcoholic liver fibrosis (ALF). C57BL/6N male mice were randomly divided into control, alcohol, and ADAM8-sgRNA3 plasmid groups. The control group received control liquid diet, while the alcohol and ADAM8-sgRNA3 plasmid groups were given alcohol liquid feed diet combined with ethanol gavage treatment for 8 weeks to induce ALF modeling. In addition, the ADAM8-sgRNA3 plasmid group was injected with the effective ADAM8-sgRNA3 plasmid, while the alcohol and control group mice were injected with an equivalent amount of physiological saline. LX-2 human hepatic stellate cells were divided into control, alcohol, si-ADAM8-2, and si-ADAM8-NC groups and induced for 48 h for model establishment in vitro. Serological detection, pathological staining, Western blotting, qRT-PCR and CCK8 assay were performed for experiments. Compared with the alcohol group, ADAM8 mRNA, protein and, positive area rate, serological indicators, pathological changes, and the expression of liver fibrosis marker and MAPK signaling pathway-related factors in the ADAM8-sgRNA3 plasmid group significantly decreased in vivo. Compared with the alcohol group, ADAM8 mRNA and protein expression, cell viability, and the expression of liver fibrosis markers and MAPK signaling pathway-related factors (p-ERK1/2, PCNA, Bcl-2, p-c-Jun, TGFβ1, p–p38 MAPK and HSP27) reduced significantly in the si-ADAM8-2 group. Therefore, ADAM8 promotes ALF through the MAPK signaling pathway, a promising target for treating ALF.

Network dynamics-based subtyping of Alzheimer’s disease with microglial genetic risk factors

BackgroundThe potential of microglia as a target for Alzheimer’s disease (AD) treatment is promising, yet the clinical and pathological diversity within microglia, driven by genetic factors, poses a significant challenge. Subtyping AD is imperative to enable precise and effective treatment strategies. However, existing subtyping methods fail to comprehensively address the intricate complexities of AD pathogenesis, particularly concerning genetic risk factors. To address this gap, we have employed systems biology approaches for AD subtyping and identified potential therapeutic targets.MethodsWe constructed patient-specific microglial molecular regulatory network models by utilizing existing literature and single-cell RNA sequencing data. The combination of large-scale computer simulations and dynamic network analysis enabled us to subtype AD patients according to their distinct molecular regulatory mechanisms. For each identified subtype, we suggested optimal targets for effective AD treatment.ResultsTo investigate heterogeneity in AD and identify potential therapeutic targets, we constructed a microglia molecular regulatory network model. The network model incorporated 20 known risk factors and crucial signaling pathways associated with microglial functionality, such as inflammation, anti-inflammation, phagocytosis, and autophagy. Probabilistic simulations with patient-specific genomic data and subsequent dynamics analysis revealed nine distinct AD subtypes characterized by core feedback mechanisms involving SPI1, CASS4, and MEF2C. Moreover, we identified PICALM, MEF2C, and LAT2 as common therapeutic targets among several subtypes. Furthermore, we clarified the reasons for the previous contradictory experimental results that suggested both the activation and inhibition of AKT or INPP5D could activate AD through dynamic analysis. This highlights the multifaceted nature of microglial network regulation.ConclusionsThese results offer a means to classify AD patients by their genetic risk factors, clarify inconsistent experimental findings, and advance the development of treatments tailored to individual genotypes for AD.

Elucidating the Supramolecular Interaction of Positively Supercharged Fluorescent Protein with Anionic Phthalocyanines.

Developing bioinspired materials to convert sunlight into electricity efficiently is paramount for sustainable energy production. Fluorescent proteins are promising candidates as photoactive materials due to their high fluorescence quantum yield and absorption extinction coefficients in aqueous media. However, developing artificial bioinspired photosynthetic systems requires a detailed understanding of molecular interactions and energy transfer mechanisms in the required operating conditions. Here, the supramolecular self-assembly and photophysical properties of fluorescent proteins complexed with organic dyes are investigated in aqueous media. Supercharged mGreenLantern protein, mutated to have a charge of +22, is complexed together with anionic zinc phthalocyanines having 4 or 16 carboxylate groups. The structural characterization reveals a strong electrostatic interaction between the moieties, accompanied by partial conformational distortion of the protein structure, yet without compromising the mGreenLantern chromophore integrity as suggested by the lack of emission features related to the neutral form of the chromophore. The self-assembled biohybrid shows a total quenching of protein fluorescence, in favor of an energy transfer process from the protein to the phthalocyanine, as demonstrated by fluorescence lifetime and ultrafast transient absorption measurements. These results provide insight into the rich photophysics of fluorescent protein-dye complexes, anticipating their applicability as water-based photoactive materials.

Machine learning-derived peripheral blood transcriptomic biomarkers for early lung cancer diagnosis: Unveiling tumor-immune interaction mechanisms.

Lung cancer continues to be the leading cause of cancer-related mortality worldwide. Early detection and a comprehensive understanding of tumor-immune interactions are crucial for improving patient outcomes. This study aimed to develop a novel biomarker panel utilizing peripheral blood transcriptomics and machine learning algorithms for early lung cancer diagnosis, while simultaneously providing insights into tumor-immune crosstalk mechanisms. Leveraging a training cohort (GSE135304), we employed multiple machine learning algorithms to formulate a Lung Cancer Diagnostic Score (LCDS) based on peripheral blood transcriptomic features. The LCDS model's performance was evaluated using the area under the receiver operating characteristic (ROC) curve (AUC) in multiple validation cohorts (GSE42834, GSE157086, and an in-house dataset). Peripheral blood samples were obtained from 20 lung cancer patients and 10 healthy control subjects, representing an in-house cohort recruited at the Sixth People's Hospital of Chengdu. We employed advanced bioinformatics techniques to explore tumor-immune interactions through comprehensive immune infiltration and pathway enrichment analyses. Initial screening identified 844 differentially expressed genes, which were subsequently refined to 87 genes using the Boruta feature selection algorithm. The random forest (RF) algorithm demonstrated the highest accuracy in constructing the LCDS model, yielding a mean AUC of 0.938. Lower LCDS values were significantly associated with elevated immune scores and increased CD4+ and CD8+ T-cell infiltration, indicative of enhanced antitumor-immune responses. Higher LCDS scores correlated with activation of hypoxia, peroxisome proliferator-activated receptor (PPAR), and Toll-like receptor (TLR) signaling pathways, as well as reduced DNA damage repair pathway scores. Our study presents a novel, machine learning-derived peripheral blood transcriptomic biomarker panel with potential applications in early lung cancer diagnosis. The LCDS model not only demonstrates high accuracy in distinguishing lung cancer patients from healthy individuals but also offers valuable insights into tumor-immune interactions and underlying cancer biology. This approach may facilitate early lung cancer detection and contribute to a deeper understanding of the molecular and cellular mechanisms underlying tumor-immune crosstalk. Furthermore, our findings on the relationship between LCDS and immune infiltration patterns may have implications for future research on therapeutic strategies targeting the immune system in lung cancer.

Distinct methylome profile of cfDNA in AMI patients reveals significant alteration in cAMP signaling pathway genes regulating cardiac muscle contraction

BackgroundThe role of epigenetics in cardiovascular diseases has paved the way for innovative therapeutic approaches. Investigating epigenetic changes using cell-free DNA (cfDNA) holds substantial promise beyond mere diagnostics, especially for heart-related conditions like acute myocardial infarction (AMI), where obtaining tissue samples is a challenge. This study explores the methylation patterns of cfDNA in AMI patients and compares them with genomic DNA (gDNA) from the same individuals, aiming to evaluate the effectiveness of cfDNA as a valuable resource for studying heart-related diseases.MethodologyWe generated global methylome profiles of cfDNA and gDNA from 25 AMI patients using EM-Seq. Tissue deconvolution analysis was performed to estimate tissue specificity based on the methylation patterns. Differentially methylated loci were identified and explored to understand AMI pathophysiology.ResultsComparative analysis of cfDNA and gDNA methylation patterns in AMI patients reveals cfDNA holds more significance than gDNA. Principal component analysis revealed distinct clusters for cfDNA and gDNA, indicating distinct methylome profiles. cfDNA originated from multiple sources, predominantly from neutrophils (~ 75%) and about 10% from the left atrium, highlighting cardiac-specific changes. In contrast, immune cells are the major source of gDNA, indicative of inflammatory responses. Gene set enrichment analysis (GSEA) associates cfDNA methylation patterns with pathways related to cardiac muscle contraction, inflammation, hypoxia, and lipid metabolism. The affected genes include G protein-coupled receptors (GHSR, FFAR2, HTR1A, and VIPR2) that are part of the cAMP signaling pathway.ConclusionEpigenetic changes in cfDNA are more specific to cardiac tissue compared to those in gDNA, providing better insights into the molecular mechanisms involved in AMI. Genes that are differentially methylated in cfDNA and regulate core pathways, such as cAMP signaling, could be targeted for clinical applications, including the development of effective biomarkers and therapeutic targets.

Hippocampal Nogo66-NgR1 signaling activation restricts postsynaptic assembly in aged mice with postoperative neurocognitive disorders.

Postoperative neurocognitive disorders (pNCD) are a common neurological complication, especially in elderly following anesthesia and surgery. Yet, the underlying mechanisms of pNCD remain elusive. This study aimed to investigate the molecular mechanisms that compromise synaptic metaplasticity in pNCD development with a focus on the involvement of Nogo-66 receptor 1 (NgR1) in the pathogenesis of pNCD in aged mice. Aged mice subjected to anesthesia and laparotomy surgery exhibited anxiety-like behavior and contextual fear memory impairment. Moreover, the procedure significantly increased NogoA and NgR1 expressions, particularly in the hippocampal CA1 and CA3 regions. This increase led to the depolymerization of F-actin, attributed to the activation of the RhoA-GTPase, resulting in a reduction of dendritic spines and changes in their morphology. Additionally, these changes hindered the efficient postsynaptic delivery of the subunit GluA1 and GluA2 of AMPA receptors (AMPARs), consequently diminishing excitatory neurotransmission in the hippocampus. Importantly, administering the competitive NgR1 antagonist peptide NEP1-40 (Nogo-A extracellular peptide residues 1-40 amino acids of Nogo-66) and Fasudil (a Rho-kinase inhibitor) effectively mitigated synaptic impairments and reversed neurocognitive deficits in aged mice following anesthesia and surgery. Our work indicates that high hippocampal Nogo66-NgR1 signaling disrupts postsynaptic AMPA receptor surface delivery due to F-actin depolymerization in the pathophysiology of pNCD.

Molecular Mechanisms for the Selective Transport of Dichlorofluorescein by Human Organic Anion Transporting Polypeptide 1B1.

Human organic anion transporting polypeptide (OATP) 1B1 and 1B3 are two highly homologous liver-specific uptake transporters. However, 2',7'-dichlorofluorescein (DCF) is preferably transported by OATP1B1. In the present study, the molecular mechanisms for the selective transport of DCF by OATP1B1 were investigated by constructing and characterizing an array of OATP1B1/1B3 chimeras and site-directed mutagenesis. Our results show that transmembrane domain (TM) 10 is crucial for the surface expression and function of OATP1B1, in which Q541 and L545 play the most important roles in DCF transport. Replacement of TM10 in OATP1B1 with its OATP1B3 counterpart led to OATP1B1's complete intracellular retention. Q541 and L545 may interact with DCF directly via hydrogen bonding and hydrophobic interactions. The decrease of DCF uptake by Q541A and L545S was due to their reduced binding affinity for DCF as compared with OATP1B1. In addition, Q541 and L545 are also crucial for the transport of estradiol-17β-glucuronide (E17βG) but not for the transport of estrone-3-sulfate (E3S), indicating different interaction modes between DCF/E17βG and E3S in OATP1B1. Taken together, Q541 and L545 in TM10 are critical for OATP1B1-mediated DCF uptake, but their effect is substrate-dependent. SIGNIFICANCE STATEMENT: The key TMs and amino acid residues for the selective transport of DCF by OATP1B1 were identified. TM10 is crucial for the surface expression and function of OATP1B1. Within TM10, Q541 and L545 played the most significant roles and affected the function of OATP1B1 in a substrate-dependent manner. This information is crucial for a better understanding of the mechanism of the multispecificity of OATP1B1 and as a consequence the mechanism of OATP1B1-mediated drug-drug interactions.

Terazosin, a repurposed GPR119 agonist, ameliorates mitophagy and β-cell function in NAFPD by inhibiting MST1-Foxo3a signalling pathway.

GPR119 agonists are being developed to safeguard the function of pancreatic β-cells, especially in the context of non-alcoholic fatty pancreas disease (NAFPD) that is closely associated with β-cell dysfunction. This study aims to employ a drug repurposing strategy to screen GPR119 agonists and explore their potential molecular mechanisms for enhancing β-cell function in the context of NAFPD. MIN6 cells were stimulated with palmitic acid (PA), and a NAFPD model was established in GPR119-/- mice fed with a high-fat diet (HFD). Terazosin, identified through screening, was utilized to assess its impact on enhancing β-cell function via the MST1-Foxo3a pathway and mitophagy. Terazosin selectively activated GPR119, leading to increased cAMP and ATP synthesis, consequently enhancing insulin secretion. Terazosin administration improved high blood glucose, obesity, and impaired pancreatic β-cell function in NAFPD mice. It inhibited the upregulation of MST1-Foxo3a expression in pancreatic tissue and enhanced damaged mitophagy clearance, restoring autophagic flux, and improving mitochondrial quantity and structure in β-cells. Nevertheless, GPR119 deficiency negated the positive impact of terazosin on pancreatic β-cell function in NAFPD mice and abolished its inhibitory effect on the MST1-Foxo3a pathway. Terazosin activates GPR119 on the surface of pancreatic β-cells, enhancing mitophagy and alleviating β-cell dysfunction in the context of NAFPD by suppressing the MST1-Foxo3a signalling pathway. Terazosin could be considered a priority treatment for patients with concomitant NAFPD and hypertension.

BCAT1 contributes to the development of TKI-resistant CML.

Although most of chronic myeloid leukemia (CML) patients can be effectively treated by the tyrosine kinase inhibitors (TKIs), such as Imatinib, TKI-resistance still occurs in approximately 15-17% of cases. Although many studies indicate that branched chain amino acid (BCAA) metabolism may contribute to the TKI resistance in CML, the detailed mechanisms remains largely unknown. The cell proliferation, colony formation and in vivo transplantation were used to determined the functions of BCAT1 in leukemogenesis. Quantitative real-time PCR (RT-PCR), western blotting, RNA sequencing, BCAA stimulation in vitro were applied to characterize the underlying molecular mechanism that control the leukemogenic activity of BCAT1-knockdown cells. In this report, we revealed that branched chain amino acid transaminase 1 (BCAT1) is highly enriched in both mouse and human TKI-resistant CML cells. Leukemia was almost completely abrogated upon BCAT1 knockdown during transplantation in a BCR-ABLT315I-induced murine TKI-resistant CML model. Moreover, knockdown of BCAT1 led to a dramatic decrease in the proliferation of TKI-resistant human leukemia cell lines. BCAA/BCAT1 signaling enhanced the phosphorylation of CREB, which is required for maintenance of TKI-resistant CML cells. Importantly, blockade of BCAA/BCAT1 signaling efficiently inhibited leukemogenesis both in vivo and in vitro. These findings demonstrate the role of BCAA/BCAT1 signaling in cancer development and suggest that targeting BCAA/BCAT1 signaling is a potential strategy for interfering with TKI-resistant CML.