Biochemical Pharmacology

The MYC associated factor X (MAX) is the heterodimeric partner of the MYC paralogs (MYC, MYCN and MYCL). When deregulated, high level of the MYC paralogs contribute to all aspects of tumorigenesis and tumor growth. MAX can also heterodimerize with the MXD proteins, MNT and MGA. Heterodimerization and sequence specific DNA binding to the E-Box sequences at gene promoters is controlled by their heterodimerization with the MAX b-HLH-LZ. As a heterodimer with MAX, MYC proteins activate genes involved in cell metabolism, growth and proliferation whereas MXD proteins, MNT and MGA repress them. MAX can also bind to the E-Bos sequence as a homodimer. Being devoid of a transactivation domain it can act as an antagonist of the MYC/MAX heterodimers. Variants of MAX have been reported to be linked to cancer. These variants are either not expressed, inactivated or lead to missense mutations. This has led to the notion that MAX may have a tumor suppressor role. Here, we characterize three of those variants with missense mutations in the basic region, i.e. E32K, R35P and R35C. We analyzed their heterodimerization with the b-HLH-LZ of MYC and their DNA binding properties as homo-and heterodimers. The R35C variant b-HLH-LZ was found to have a markedly increased affinity for the b-HLH-LZ of MYC. We also observed that all three b-HLH-LZ variants have a lower affinity as homodimers for the E-Box than the WT. This was shown to lead to a preferential binding of all the heterodimeric b-LHLH-LZ to the E-Box. This effect is exacerbated in the case of the R35C variant. We argue that this preferential binding of MYC as heterodimers with these variants to E-Box sequences could contribute to tumorigenesis. Hence, our results suggest that, mechanistically, the MAX homodimer bound to the E-Box could act as a tumor suppressor. MATERIALS AND METHODSO_ST_ABSMolecular modelingC_ST_ABSThe open source version 1.7.6.0 of Pymol was used for modeling and molecular rendering [1]. The crystal structure of the MAX homodimer bound to the E-Box (1HLO [2]) was used as a template for the generation of the models. The variants were generated using the mutagenesis function in the wizard. The conformation of the K32 side chain was manually set in order to avoid introducing steric clashes with DNA. Protein expression and purificationThe cDNA, coding for the MAX b-HLH-LZ (Max* hereafter, residues 22-103, UniProt entry P61244-1) to which are added the GSGC residues in c-terminal, inserted in the pET3a vector was already available in the laboratory [3] and was used as a template to generate the plasmids with inserts coding for each of the mutants (E32K, R35C and R35P) through quick-change PCR with Q5 DNA polymerase and DpnI from New England Biolabs. The primers used were purchased from IDT DNA, their sequences are listed in Table S1. Sequence for each construct was confirmed by Sanger sequencing at the Plateforme de sequencage SANGER - Centre de recherche du CHU de Quebec - Universite Laval. The primary structure for the basic region of each construct is given in Fig. 2A. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=137 SRC="FIGDIR/small/715400v1_fig2.gif" ALT="Figure 2"> View larger version (41K): org.highwire.dtl.DTLVardef@1b05d5eorg.highwire.dtl.DTLVardef@1c1d692org.highwire.dtl.DTLVardef@ee469dorg.highwire.dtl.DTLVardef@15e0ba4_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 2.C_FLOATNO Structure schematics, specific and non-specific interactions dictating specificity and stability of binding of the basic region of MAX to the canonical (CACGTG) E-Box. A. Primary structure for the basic region of MAX and each of the variants. Positions making the most important contacts with the E-box are indicated by black arrows. Positions for the variants studied here are colored according to the Zappo colour scheme, following their physico-chemical properties: red for negative, blue for positive, magenta for proline and yellow for cysteine. B. The side chain (carboxylate) of E32 receives H-Bonds from the CA nucleobases in the leading strand (white carbon atoms). R35 and R36 make a salt bridges with phosphate groups while and the guanidino moiety of R36 makes a specific H-Bond with the nucleobase of the G in the strand of the reverse complement (cyan carbon atoms). C. The R35C mutation removes one non-specific salt-bridge at the interface of the complex. D. The aliphatic portion of the K side chain in the E32K variant is unable to accept the H-Bonds from the CA nucleobases and leads to the stabilisation of the complex and the helical structure of the basic region. E. In addition to removing a salt-bride, the Pro residue in the R35P kinks the path of the basic region, prevents the establishment of the specific H-Bonds mandatory for recognition of the E-Box and leads to unfolding of the helical state. C_FIG The MYC b-HLH-LZ (Myc*), the Max*WT b-HLH-LZ and its variants were expressed and purified as previously described [3,4] After lyophilisation, the b-HLH-LZs were kept at -20{degrees}C and solubilised in Myc buffer (50 mM NaCl, 50 mM NaH2PO4 pH 5.5) for Myc* or PBS for Max* at a final concentration of 1 mM before use. Circular dichroismAll circular dichroism (CD) measurements were performed on a Jasco J-810 spectropolarimeter equipped with a Peltier-type thermostat. The instrument was routinely calibrated using an aqueous solution of d-10-(+)-camphorsulfonic acid at 290.5 nm. Samples were prepared as follows: Max* (either WT or a variant) was diluted in 100 {micro}l 2X CD buffer (40 mM KCl, 11.4 mM K2HPO4, 28.6 mM KH2PO4, pH 6.8) and the volume adjusted to 106 {micro}l with PBS. 10 {micro}l TCEP 16 mM were added, and the volume further adjusted to 192 {micro}l with ddH2O before samples were incubated overnight at room temperature. After reduction, Myc* was added and the volume adjusted to 198 {micro}l with Myc buffer (Na2HPO4 0.95 mM, NaH2PO4 49.05 mM, 50 mM NaCl, pH 5.5). The DNA complexes were prepared as follows. After a 10 minutes incubation of the protein samples at room temperature, 0, 1 or 2 {micro}l of 2 mM of specific or non-specific DNA duplexes in 10 mM Tris pH 8.0 were added and the volume adjusted to 200 {micro}l with 10 mM Tris pH 8.0. The strands of the specific probe were: 5-ATT ACC CAC GTG TCC T*AC-3 and 5-GTA GGA CAC GTG GGT* AAT-3 (with the E-box sequence underlined) and the non-specific probe: 5-ATT ACC TCC GGA TCC T*AC-3 and 5-GTA GGA TCC GGA GGT* AAT-3 (Integrated DNA Technologies). Samples were further incubated for 10 minutes at room temperature and transferred to a 1 mm path length quartz cuvette. All spectra were recorded from 250 to 195 nm at 0.1 nm intervals by accumulating 10 spectra at 25 {degrees}C. Thermal denaturations were recorded at 222 nm from 5 to 95 {degrees}C at a heating rate of 1 {degrees}C/min. CD signal for spectra and thermal denaturations was corrected by substracting the signal from corresponding spectra or thermal denaturation either for buffer alone or the appropriate DNA duplex. CD signal was then converted to mean residue ellipticity using the following formula [5]: [{theta}] = {delta} {middle dot} MRW/(10{middle dot}c l) where [{theta}] is the mean residue ellipticity in deg {middle dot} cm2 dmol-1, {delta} is the CD signal in millidegrees, MRW is the mean residue weight, c is the concentration in mg/ml and l is the pathlength in mm. For the heterodimers, the concentration used was the sum of Max* and Myc* and the MRW was determined using a weighted average.

NLRP3 inflammasome is a cytosolic multi-protein complex that plays a crucial role in the immune system, responding to various exogenous and endogenous stimuli by triggering protective inflammatory responses. However, aberrant NLRP3 inflammasome activation is implicated in numerous inflammatory diseases. Therefore, the NLRP3 inflammasome is an important pharmacological target for the treatment of multiple diseases. In this context, we screened various US-FDA-approved drugs for NLRP3 inflammasome inhibition. We found that among various drugs, minoxidil hydrochloride (MXL) effectively inhibits NLRP3 inflammasome, evidenced by reduced secretion of IL-1{beta} and IL-18 in J774A.1 cells treated with MXL. The IC50 values of MXL for inhibition of IL-1{beta} and IL-18 were calculated to be 1.2 and 1.06 {micro}M, respectively. MXL was found to prevent ASC oligomerization, thereby inhibiting the NLRP3 inflammasome and leading to CASP1 cleavage. Further investigation revealed that MXL also utilizes AMPK-mediated autophagy to modulate NLRP3 inflammasome activity. Using siAMPK and bafilomycin A1, an end-stage autophagy inhibitor, we elucidated crosstalk between the NLRP3 inflammasome and autophagic pathways, which was modulated by MXL. Furthermore, we demonstrated the efficacy of MXL in two different mouse models of inflammation, involving the NLRP3 inflammasome. MXL at doses of 10 and 20 mg/kg effectively inhibited the activation of NLRP3 inflammasome by monosodium urate in the air pouch model and by ATP in the peritoneal inflammation model, as evidenced by reduced secretion of 1{beta} and IL-18 in the lavage. Our study identifies MXL as a potent NLRP3 inflammasome inhibitor, warranting further investigation as a potential therapeutic agent for inflammatory diseases.

Obesity affects millions of people worldwide and has serious complications such as cardiovascular disease and diabetes. Current treatments for obesity target proteins such as the receptors for glucagon-like peptide-1 (GLP-1), gastric inhibitory polypeptide (GIP) and/or glucagon (GCG). These interventions have revolutionized the treatment of obesity and represent first-line pharmacotherapeutic strategies. One major weakness to these strategies is that once drug treatment stops, most patients are unable to maintain the new body weight setpoint, often gaining weight back rapidly. Thus, the identification of new therapies that focus on the ability to maintain homeostatic setpoint are necessary. The glucocorticoid receptor (GR) has been implicated in several pathways including reward-seeking, inflammation, stress and energy balance. Here, we investigated the effects of 30 days treatment with PT150 (40 mg/kg), a novel GR antagonist, alone and in combination with semaglutide (30 nmol/kg) on food intake, glucose homeostasis, body weight and setpoint maintenance using a C57Bl/6 diet-induced obesity (DIO) mouse model. We monitored food intake and body weight throughout treatment and after drug washout for 20 days to evaluate defended body weight maintenance (body weight setpoint). Our results indicate that treatment with PT150 alone does not significantly alter body weight but in combination with semaglutide it shows the most promising effects in body weight reduction and homeostatic setpoint maintenance. Together, these data suggest that PT150, a GR modulator, may be effective as a homeostatic setpoint modulator when combined with semaglutide.

Nicotinic acetylcholine receptors (nAChRs) belong to the pentameric ligand-gated ion channel superfamily (pLGICs). Among them, the neuronal homomeric 7 nAChR is highly permeable to calcium and plays critical roles in synaptic transmission, cell signaling, and inflammation modulation. The biogenesis of 7 nAChRs is enhanced by the chaperone proteins RIC-3 and NACHO. Previously, we reported a motif in the 5-HT3A receptor, another pLGIC, involved in RIC-3 modulation. Residues in this motif are conserved and also found within the L1-MX segment of the 7 nACh subunit. We therefore explored the regulatory roles of these conserved residues in the biogenesis of 7 nAChRs using multiple approaches, including heterologous expression in Xenopus laevis oocytes, mutagenesis, pull-down assays, cell-surface labeling, and two-electrode voltage-clamp (TEVC) recordings. We find that synthetic 7 L1-MX peptide interacts with both RIC-3 and NACHO. In particular, conserved residues W330, R332, and L336 in the L1-MX positively regulates the assembly of 7 oligomers and the biogenesis of 7nAChR. In presence of residues W330, R332, and L336, NACHO promotes an assembly of an 7 pentamer which is resistant to strong denaturing conditions. NACHO-promoted 7 pentamer is also resistant to Endo H enzyme. Sensitivity of the pentamer to moderate temperatures (37 {degrees}C, 45 {degrees}C, and 50 {degrees}C) suggests that NACHO stabilizes the pentamer via non-covalent interactions. In contrast, Ala replacements at these residues disrupt the biogenesis and abolish 7 current. NACHO and RIC-3 co-expression yields partial rescue of functional expression for some Ala replacement constructs. SUMMARYThis work identifies regulatory roles of conserved residues W330, R332, and L336 in the biogenesis of 7 nAChR. This discovery positions MX subdomain as a promising target for future drug development that can minimize adverse effects.

BackgroundIn the course of testing mAb-based therapies to eradicate the persistent reservoir of HIV infection, we investigated the efficacy and mode of killing of HIV-infected cells by two categories of cytotoxic immunoconjugates (CICs) targeted by the same mAb, an immunotoxin (IT) and antibody-drug conjugate (ADC). MethodsWe performed metabolic and transcriptional analyses of treatment effects on the persistently-infected cell line H9/NL4-3. Cells were treated with CICs consisting of the anti-gp41 mAb 7B2 conjugated to either deglycosylated ricin A chain (dgA) or to the highly cytotoxic anthracycline derivative PNU-159682. At intervals up to 24 hr, intracellular metabolites were quantified by 1H nuclear magnetic resonance spectroscopy, and the transcriptome analyzed by RNA-Seq. ResultsSix hr post treatment, 7B2-dgA elicited both metabolic and transcriptional alterations, whereas 7B2-PNU treated cells did not differ from untreated cells. 7B2-dgA treated cells exhibited elevated intracellular levels of many amino acids, and activation of gene pathways for apoptosis, intracellular signaling, and immune activation. By 24 hr, both 7B2-dgA and 7B2-PNU treated cells differed markedly from untreated. Many of the changes observed following 7B2-PNU treatment at 24 hr were similar to those observed at 6hr following 7B2-dgA, likely indicating processes involved in cell death, but a number of alterations were unique to either IT or ADC treated cells. ConclusionsAn IT and ADC showed both similarities and differences in their cytotoxic effects. These results raise the question of whether the mode of cell killing could be a determinant of clinical efficacy. Although these studies were aimed at targeting the persistent reservoir of HIV infection, they have relevance for the design of CICs to treat cancer and other conditions. SUMMARYThe use of cytotoxic immunoconjugates, wherein an antibody is attached to a cellular poison, is effective in the treatment of cancer and other conditions. We seek to extend these results to treating HIV and other chronic viral infections. We analyzed the molecular mechanisms of cell killing when the same antibody was attached to different toxic structures. We report that each immunoconjugate induced both common and distinct patterns of killing. Such differences may have clinical relevance.

The association between higher levels of physical activity and lower cancer risk and mortality is well established. However, a causal link is yet to be proven. Recent studies showed a decrease in the proliferation rates of cultured human cancer cells when the human serum employed to stimulate them was conditioned by acute exercise. Here, we tested the hypothesis that serum mediates some of the putative benefits of exercise on cancer through alterations to the growth pattern and susceptibility to chemotherapy agents of cancer cells. To this end, human non-small cell lung cancer (NSCLC) cells were exposed to serum from two cohorts that differed significantly on their levels of physical activity and, accordingly, cardiorespiratory fitness, but were otherwise identical (master athletes and non-exercisers), collected before and after an acute exercise intervention. Serum levels of glucose, lipids, albumin, C-reactive protein and cytokines were determined and the impact of the serum responses to acute and lifelong exercise on the above-mentioned parameters were analyzed. We found that acute exercise decreased the cells proliferation rate, yet shortened the cells lag phase after detachment, whereas lifelong exercise had the opposite effects. Significantly, we showed, for the first time, that lifelong exercise increased susceptibility to a chemotherapy agent (cisplatin), which may contribute to the decreased cancer mortality rates found among those who exercise regularly. Similar to the cellular effects, changes to serum cytokine levels - several of them linked to the senescence-associated secretory phenotype - depended on whether serum was conditioned by acute or by chronic exercise. Key pointsChronic exercise increased the in vitro susceptibility of lung cancer cells to cisplatin. Acute and chronic exercise modulated the in vitro tumorigenic potential of lung cancer cells. Effects were mediated by serological changes produced by exercise. Acute and chronic exercise had distinct impacts on serological cytokine levels.

BackgroundThis study investigates the role of the pioneer transcription factor FOXA1 as a master gene in sustaining epithelial cell polarization in early-stage lung adenocarcinoma. The partial loss of FOXA1 is explored to determine if it will affect plasticity and progression of lung adenocarcinoma. The study also addresses the transcriptional circuitry that links polarity defects to lysosome homeostasis. MethodsA multiomics approach was used to define the status of the chromatin in epithelial and mesenchymal states of A549 adenocarcinoma cells obtained with a newly synthetized TGF-{beta} receptor inhibitor or TGF-{beta} respectively. The study leveraged ATAC-seq, RNA sequencing, Cut&Tag sequencing of FOXA1 and histone marks profiling. The functional impact of FOXA1 was examined by partial silencing in vitro and by heterozygous FOXA1 deletion in a KrasG12D mouse model. Three-dimensional organoid culture, high-resolution electron microscopy, spatial transcriptomics and multiplex immunohistochemistry assessed carcinoma cell polarity, proliferation, the tumor microenvironment and organelle content. Group differences were evaluated with two-tailed t tests or one-way analysis of variance. ResultsFOXA1 binding and expression were highest in cells harboring an epithelial phenotype. In mouse KrasG12D LUAD tumors FOXA1 marked polarized, CDH1-positive cells; heterozygous loss diminished CDH1, disrupted apical-basal architecture, lowered organoid-forming efficiency and remodeled the immune microenvironment. Spatial transcriptomics and ultrastructural analyses showed that FOXA1-deficient carcinoma cells accumulated lysosomes, down-regulated vesicle fusion genes of the SNARE family and activated the lysosomal CLEAR gene network. FOXA1 occupied enhancers of lysosome-associated genes and competed with the transcription factor TFE3, thereby suppressing transcription of cathepsin B and cathepsin C and restricting lysosome biogenesis. ConclusionsFOXA1 is a central regulator that preserves epithelial cell polarity and limits lysosome formation in lung adenocarcinoma. Targeting the FOXA1-TFE3-lysosome axis may affect tumor plasticity and provide new therapeutic opportunities.

Metabolic dysfunction-associated steatohepatitis (MASH) is associated with increased expression of peroxisome proliferator-activated receptor gamma (PPAR{gamma}, Pparg) and reduced expression of genes involved in methionine metabolism in the liver. The nuclear receptor PPAR{gamma} is activated by fatty acids, and the knockout of Pparg in hepatocytes (Pparg{Delta}Hep) reduced the negative effects of MASH on methionine metabolism. Here, we sought to determine whether hepatocyte Pparg is required for the transcriptional regulation of genes involved in hepatic methionine metabolism in conditions with altered fatty acid flux to the liver: fasting, refeeding, and high-fat diet (HFD)-induced obesity/steatosis. Fasting induced liver steatosis and increased the expression of key genes involved in the methionine metabolism in the liver, while 6h-refeeding reversed these effects and reduced the expression of phosphatidylethanolamine N-methyltransferase (Pemt) and cystathionine beta synthase (Cbs). Overall, fasting and refeeding did not alter hepatocyte Pparg expression nor Pparg{Delta}Hep affected fasting and refeeding-mediated regulation of methionine metabolism gene expression. Diet-induced steatosis reduced hepatic Pemt expression in control (Pparg-intact) mice, and the thiazolidinedione (TZD)-mediated activation of PPAR{gamma} in diet-induced obese control (Pparg-intact) mice reduced the expression of betaine homocysteine S-methyltransferase (Bhmt) and Cbs. However, diet-induced steatosis increased hepatocyte Pparg expression, and Pparg{Delta}Hep blocked the negative effects of HFD and TZD on hepatic methionine metabolism. The PPAR{gamma}-dependent reduction of hepatic Bhmt and Cbs expression was confirmed in mouse primary hepatocytes. Taken together, hepatocyte Pparg may serve as a negative regulator of hepatic methionine metabolism in diet-induced obese mice and these actions could contribute to promoting the onset of MASH.

Tyrosine Kinase inhibitors (TKIs) are widely used as effective chemotherapeutic agents for treating patients with EGFR-mutated NSCLC. Unfortunately, after treatment, patients eventually develop resistance to TKI therapy. The most common resistance mechanism for the TKI Osimertinib is the overexpression of the MET Proto-Oncogene, Receptor Tyrosine Kinase (MET). We previously demonstrated that miR-411-5p A-to-I edited at position 5 (miR-411ed) can directly target MET in A549 and H1299 cells. MiR-411ed in combination with Osimertinib reduced cell proliferation in two TKI resistant EGFR-mutated cell lines: HCC827R and PC9R. MiR-411ed did not downregulate MET expression in HCC827R, suggesting an alternative mechanism for TKI response. In this study, we aim to identify the mechanism of miR-411ed TKI response using a multi-omics approach of RNAseq and protein mass spectrometry. In our cellular model, we identified miR-411ed affected genes independent of MET activity, resulting in 211 genes (RNAseq) and 36 proteins (proteomics). Pathway analysis identified an increase in interferon signaling for RNAseq and combined omics, and a decrease in ERK/MAPK signaling in proteomics. Using the IsoTar target prediction tool, we identified STAT3 as a key regulator and confirmed STAT3 protein downregulation upon transfection with miR-411ed. We further investigated the effect of miR-411ed in vivo, observing a reduction in tumor size with miR-411ed in combination with Osimertinib but not with miR-411ed or Osimertinib treatment alone, confirming the effectiveness of miR-411ed in TKI response.

BackgroundElevated postprandial hypertriglyceridemia (PP-HTG) is a significant risk factor for development of cardiovascular diseases, however, the mechanisms underlying its exaggerated rise remains poorly understood. MicroRNAs (miRs) are known to be implicated in the regulation of lipid metabolism, thus identifying them as potential key players. We presently investigated whether miRs may control postprandial triglyceride (PP-TG) response. MethodsPostprandial changes in circulating miR expression as a function of the degree of postprandial TG response were evaluated in non-dyslipidemic healthy subjects (n=32). The impact of miR-100-5p on hepatic gene expression was evaluated in differentiated Caco2 and HepG2 cells by analysis of hepatic transcriptome (RNAseq), western blot and ELISA. In vivo studies were conducted in C57BL/6J mice overexpressing mimic miR-100-5p. ResultsPostprandial variation in circ-miR-100-5p levels inversely correlate with PP-TG response. Cir-miR-100-5p was preferentially associated with TGRL particles of intestinal origin in subjects exhibited a low PP TG response. Differential analysis of transcriptome from HepG2 cells transfected by either mimic miR-100-5p or scrambled mimic miR as control allowed us to identify PCSK9 as a down-regulated gene. Overexpression of miR-100-5p in HepG2 cells significantly decreased PCSK9 mRNA levels by 52% (p<0.0001), cellular protein content by 28 % (p<0.0001) as well as PCSK9 secretion by 39% (p<0.0001). In vivo systemic delivery of mimic miR-100-5p induced a two-fold reduction (p<0.0001) on PP-TG in mice, such effect being abolished by blocking the circulating form of PCSK9 with alirocumab. Finally, we revealed a significant inverse relationship between circulating miR-100-5p expression levels and both PCSK9 levels and the magnitude of postprandial hypertriglyceridemia. ConclusionTaken together, our observations reveal that miR-100-5p regulates postprandial hypertriglyceridemia by targeting PCSK9, thus enhancing hepatic triglyceride-rich lipoproteins (TGRL) uptake. Our findings allow us to propose circ-miR-100-5p as a potential biomarker for early identification of subjects at high cardiovascular risk, prior to appearance of classical clinical features of metabolic disorders. Postprandial clinical study, HDL-PP (NCT03109067) Lay summaryThis study examined whether miRs may control postprandial triglyceride response Key findingsOur data reveal that miR-100-5p regulates postprandial hypertriglyceridemia by targeting PCSK9 Our observations allow us to propose miR-100-5p as a potential biomarker for early identification of subjects at high cardiovascular risk

BackgroundThe ability of TRAIL to specifically induce apoptosis in cancer cells makes it a promising candidate to be an effective chemotherapeutic drug. But resistance to TRAIL treatment is a major obstacle. Finding combinatorial therapies that make resistant tumors more susceptible to TRAIL is an effective preclinical approach. In this work, we investigated the possibility that pre-treatment of paclitaxel may promote apoptosis in TRAIL-resistant breast cancer cells. MethodsIn silico analysis was done to investigate the binding affinity between TRAIL receptors (DR5 and DCR2) and paclitaxel via docking and MD simulation. To check whether any non-lethal dose of paclitaxel can modulate the expression of TRAIL receptors, qPCR was done in paclitaxel treated breast cancer cells. Next, paclitaxel was pre-administered to TRAIL-resistant MCF7 and MDA-MB-453 human breast cancer cells followed by rhTRAIL treatment. Cell viability and survival was evaluated using the MTT assay and colony formation assay, respectively. Immunoblot for caspase-3 was performed to study apoptosis. The expression level changes of DR5 and DCR2 were analyzed post-treatment using qPCR and immunoblot assay. ResultsIn silico analysis showed that paclitaxel can bind with higher stability to DCR2 in comparison to DR5 thereby changing the preference of TRAIL molecules towards DR5. Next, in cell line experiments we observed that administering a non-lethal dose of paclitaxel to MDA-MB-231 and MCF7 breast cancer cells resulted in no significant cell death but led to an increase in DR5 and a decrease in DCR2 expression at both the transcript and protein levels. Furthermore, in TRAIL-resistant MCF7 and MDA-MB-453 cells, pre-treatment with paclitaxel followed by rhTRAIL administration induced significant cell death due to paclitaxel induced increase in DR5 as well as decrease in DCR2 expression at both the transcript and protein levels. Moreover, long term survival of MDA-MB-453 cells was significantly lower when pretreated with paclitaxel and exposed to rhTRAIL compared to control, paclitaxel alone or rhTRAIL alone group. ConclusionThus, our study uncovers a novel therapeutic strategy to overcome TRAIL resistance underscoring the clinical potential of using a non-lethal dose of paclitaxel to modulate TRAIL receptor dynamics. Future research should be aimed at exploring the potentiality of using paclitaxel-based combinatorial approaches in crafting effective TRAIL therapies.

Neuroactive steroids modulate GABAA and NMDA receptors allosterically, typically requiring specific structural features for their activity. In this study, we characterize YX84, a novel neuroactive steroid bearing a 3{beta} sulfate and p-trifluoroacetylbenzyl alcohol attached in an ether linkage to a hydroxyl group at steroid carbon 17. This compound and similar analogues exhibit an atypical pharmacological profile, with three distinct actions at GABAA receptors. First, YX84 is a full agonist, with EC50 near 1 {micro}M and comparable efficacy to GABA at GABAA receptors in native hippocampal neurons. It presents as a full agonist relative to GABA at 4/{delta} subunit-containing receptors. Second, YX84 acts as a slow-onset, potent positive allosteric modulator (PAM) of GABAA receptors at concentrations below those that gate a response. Finally, YX84 exhibits rapid desensitizing and/or blocking kinetics; voltage dependence is consistent with a contribution of channel block. Structure- activity relationship analyses reveal that both functional groups are essential for gating activity, while classical requirements such as carbon 3 hydroxyl stereoselectivity and carbon 5 reduction are dispensable. YX84 also modestly inhibits NMDA receptor currents, suggesting weak negative allosteric modulation. Behavioral assays show that intraperitoneal administration of YX84 (30 mg/kg) does not impair sensorimotor function, unlike allopregnanolone. These findings identify YX84 as a structurally distinct neuroactive steroid with dual receptor activity and favorable behavioral tolerability, offering a promising scaffold for therapeutic development targeting excitatory/inhibitory imbalance in neuropsychiatric disorders if pharmacokinetic considerations can be overcome.

Asparagus racemosus commonly known as Shatamull, is a medicinal plant with pharmacological applications documented in both Indian and British Pharmacopoeias and various traditional medicinal practices. Previous studies have reported that A. racemosus reduces hyperglycemia by enhancing insulin secretion. The aim of the current study was to assess the antihyperglycemic actions and explore the underlying mechanisms of action of A. racemosus utilizing in vitro carbohydrate digestion, glucose diffusion, glucose uptake, 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and preliminary phytochemical screening. The inhibition of carbohydrate digestion was assessed using -amylase and -glucosidase enzyme assays. The effect on glucose diffusion was evaluated using cellulose ester dialysis tube. Subsequently, glucose uptake was measured in a yeast cell model at different glucose concentrations, and the antioxidant potential was evaluated by measuring DPPH radical scavenging activity. A. racemosus notably reduced (p<0.05, 0.001) glucose release during in vitro starch digestion by 37.69%, whereas glucose absorption decreased significantly by 33.60% (p<0.01-0.001). Additionally, the most significant enhancement (p<0.05, 0.001) in glucose uptake by 67.53%, was observed at 5 mM glucose concentration. Furthermore, it showed significant antioxidant activity by scavenging DPPH (p<0.01-0.001) radicals by 55.06%. Preliminary phytoconstituent screening indicated the existence of flavonoids, tannins, steroids, glycosides and saponins. In conclusion, A. racemosus shows an inhibitory effect on carbohydrate digestion and absorption, enhances glucose uptake and demonstrates significant DPPH radical scavenging activity, potentially due to the presence of naturally occurring phytochemicals. Thus, A. racemosus may contribute as a promising antidiabetic drug for the treatment of diabetes mellitus. More investigations are needed to determine the active compounds in A. racemosus that contribute to its antidiabetic effects.

The emergence of antimicrobial resistance (AMR) has driven the search for alternative therapeutic strategies, including antivirulence approaches targeting bacterial quorum sensing (QS). Azelaic acid (AzA), a naturally occurring dicarboxylic acid with known antimicrobial properties, has not previously been characterized as a QS inhibitor in Gram-negative pathogens. This study evaluated the dual antimicrobial and antivirulence activity of AzA against reference strains and clinical isolates of Pseudomonas aeruginosa, Enterobacteriaceae, and Staphylococcus aureus through in vitro assays and molecular docking analyses. Minimum inhibitory concentration (MIC) values ranged from 250 to 1000 {micro}g/mL, with lower MICs observed in clinical isolates of E. coli and S. aureus. Subinhibitory concentrations (250, 500 and 750 {micro}g/mL) were used to assess QS-regulated virulence factors in P. aeruginosa, including pyocyanin, elastase, alginate, and protease production. AzA exhibited a significant, dose-dependent inhibition of all evaluated virulence factors across both reference and multidrug-resistant (MDR) and pan-drug-resistant (PDR) clinical strains (p < 0.001), achieving inhibition levels exceeding 90% in several cases, particularly for protease activity. Molecular docking analyses revealed that AzA interacts with key QS-related proteins (LasI, LasR, PqsD, and PqsR), showing moderate binding affinities (-5.3 to -6.5 kcal/mol) and stable interactions within conserved ligand-binding domains. These findings suggest a multitarget modulatory mechanism affecting interconnected QS pathways. Overall, this study demonstrates, for the first time, that AzA acts as a quorum sensing inhibitor in P. aeruginosa, attenuating virulence without directly affecting bacterial growth, highlighting its potential as a promising antivirulence therapeutic strategy.

BackgroundThere is currently no approved antiviral therapy against measles virus (MeV). Repurposing available compounds with broad antiviral activity may rapidly identify candidate drugs for clinical evaluation. Here we evaluated the antiviral activity of the clinically approved drugs azelastine hydrochloride and zafirlukast as well as the flavonoids quercetin and isoquercetin against MeV in preventative and therapeutic in vitro studies. MethodsCompounds were tested for antiviral activity against MeV in preventative (prophylactic and virucidal) and therapeutic (steady-state and persistent) assays in Vero/hSLAM cells. Viral loads and cell viability were measured 48h post-infection, and dose-response curves were used to calculate EC50 values. Flavonoids were also tested in the presence of 1 mM ascorbic acid. ResultsAzelastine hydrochloride did not show evidence of antiviral activity against MeV under these conditions, whereas zafirlukast, quercetin, and isoquercetin showed therapeutic activity against MeV. The addition of ascorbic acid enhanced the therapeutic potency of quercetin to 4.2-4.8 {micro}M and of isoquercetin to 10.7-10.9 {micro}M. Antiviral activity was dose-dependent when administered post-infection. ConclusionAmong the four compounds tested, quercetin showed the most potent therapeutic antiviral activity against MeV in vitro. Isoquercetin and zafirkulast also showed therapeutic activity. These findings support further evaluation of quercetin, isoquercetin, and zafirlukast as candidate antiviral drugs for MeV and highlight the utility of in vitro platforms for rapid antiviral drug screening.

G protein-coupled receptors rely on dynamic conformational changes to coordinate G protein activation and recruitment of regulatory transducers such as G protein-coupled receptor kinases and {beta}-arrestins. The chemotactic receptor GPR183 has been implicated in a context-dependent role in hematological malignancies. Here, we investigated the impact of A338V mutation located within the C-terminal tail of GPR183. This mutation is associated with acute myeloid leukaemia. Using bioluminescence resonance energy transfer-based assays in HEK293A cells, we assessed receptor-proximal signaling events. The A338V variant displayed preserved agonist potency and comparable agonist-induced Gi activation relative to wild type, although constitutive activity towards Gi was modestly reduced. In contrast, recruitment of GRK2 and {beta}-arrestin2 was consistently impaired across multiple assay configurations. These differences were not attributable to altered receptor abundance, as the C-tail untagged mutant exhibited increased plasma membrane expression despite reduced regulatory transducer engagement. While intramolecular conformational biosensor measurements revealed subtle differences in global receptor conformation between WT and A338V, extensive molecular dynamics simulations supported the altered conformational sampling of the C-terminal tail in the A338V variant. Together, these data support a model in which the A338V substitution selectively alters C-terminal structural dynamics, impairing GRK2 and {beta}-arrestin2 recruitment while preserving G protein activation.

Background/ObjectivesThe quality and characteristics of approved medicines can vary substantially depending on manufacturing processes and standards within a given country. The aim of the study was to compare the available marketed brands of ademetionine tablets derived from various countries in order to identify potential differences between the different formulations. MethodsWe performed comprehensive analyses of the physical, chemical, and dissolution characteristics of different formulations of ademetionine tablets marketed in China, India, Russia, Ukraine, and Uzbekistan, using the originator formulation of Heptral(R) as the reference standard. The formulations were evaluated at initial analysis and after 3 months at 40{degrees}C/75% relative humidity. Clinical parameters such as ademetionine content, degradation products, S,S-isomer, and water content were assessed using HPLC, and a dissolution profile analysis performed in 2 hours of acid solution followed by 90 minutes in a buffer solution. ResultsThe Nusam (India) and Ximeixin (China) products were the two products most comparable to the Heptral products. Adenomak (Ukraine), the only food-grade product and only one with the tosylate salt showed the most significant quality variations compared to Heptral including dissolution failure as well as considerable variability between batches. ConclusionsThe study highlights the importance of using pharmaceutical-grade ademetionine products to maintain clinical efficacy and ensuring standards are maintained across global markets.

BackgroundCarnitine plays an obligatory role in energetics owing to its role in the translocation of long-chain fatty acids into the mitochondrion for oxidation. Here, we determined the metabolic and behavioral consequences of systemic carnitine deficiency (SCD) in mice. MethodsFemale C57BL/6J mice were randomized to receive normal drinking water (control, n = 8) or drinking water supplemented with mildronate 4g.L-1 (mildronate, n = 8) for 21 days. Body composition was assessed at baseline and post treatment. Metabolic and behavioral phenotyping was performed continuously over 72 hours following 14 days of control or mildronate treatment. Stable isotope were used to assess whole-body substrate oxidation. Carnitine subfractions were quantified in skeletal muscle and liver, as was mitochondrial respiratory function. Liver and muscle samples also underwent proteomic analysis. ResultsMildronate treatment depleted total carnitine in muscle and liver by [~]97% (P < 0.001) and [~]90% (P < 0.001), respectively. Carnitine depletion was accompanied by lower total energy expenditure (P = 0.01), attributable to lower voluntary wheel running (P = 0.01). Oxidation rates of palmitate (P < 0.01) but not octanoate were lower whereas rates of glucose oxidation were greater in carnitine depleted mice (P < 0.01). Mitochondrial respiratory capacity was unaltered by carnitine deficiency. Carnitine deficiency remodeled muscle and liver proteomes to support lipid oxidation and energy production. SummaryIn mice, carnitine deficiency is characterized by decreased long-chain fatty acid oxidation despite preserved mitochondrial respiratory capacity. Carnitine deficiency resulted in lower voluntary exercise and a concomitant reduction in energy expenditure.

The RUNX1 transcription factor is a critical regulator of hematopoiesis and frequently mutated in myeloid malignancies. In the myeloproliferative neoplasm, chronic myeloid leukemia (CML), secondary somatic RUNX1 mutations and RUNX1::MECOM/EVI1, are associated with tyrosine kinase inhibitor (TKI) resistance and progression to the blast-phase (BP-CML). Research has predominantly focussed on transcriptional dysregulation mediated by RUNX1 mutations in myeloid malignancies, whilst post-transcriptional dysregulation remains comparatively unexplored. To address this, we used orthogonal organic phase separation (OOPS), to characterise the RNA-binding proteome of RUNX1 deficient BP-CML cells. RUNX1 depleted BP-CML cells exhibited significant alterations to RBP abundance involved in stress response pathways and translation/ribosome-biogenesis (RiBi). Furthermore, RUNX1 depletion or expression of RUNX1::EVI1 in BP-CML cells induced expression and RNA binding activity of SPATS2L, a component of stress granules (SG); membraneless cytoplasmic condensates protecting mRNAs from degradation, promoting survival under stress. Whilst RUNX1 depletion increased SG-assembly, SPATS2L depletion reduced SG-assembly in BP-CML cells and inhibited the growth and survival of multiple BP-CML cell lines. The translation inhibitor homoharringtonine (HHT), used historically in TKI-resistant CML, ablated SG-assembly in BP-CML cells with RUNX1 depletion, and, primary BP-CML cells with LOF/hypomorphic RUNX1 mutations (characterised by defective DNA-binding/CBF{beta}-interaction) were preferentially sensitised to HHT. Finally, suppressing SPATS2L expression induced by RUNX1 depletion, increased the HHT-sensitivity of RUNX1 depleted BP-CML cells, suggesting SPATS2L contributes to therapeutic resistance in CML with RUNX1 mutations. This study suggests that SPATS2L and SG induction could be critical to RUNX1-mutant leukemias, and, provides preliminary evidence for a mutationally-targeted approach in CML with RUNX1 aberrations.

The muscarinic acetylcholine receptor 1 (mAChR1, M1) has been identified as a primary target for Alzheimers disease (AD) and better understanding of the receptor biology, especially in regard to biased signalling of the receptor, will allow for the development of improved drugs targeting cholinergic dysfunction in AD. The aim of this study was to determine the contribution of phosphorylation of M1 to the learning and memory (LM) effects of M1 agonism. The contribution of M1 phosphorylation dependent signalling in LM was assessed using the mAChR1 positive allosteric modulator, VU0486846, in a scopolamine (1.5 mg/kg) induced LM deficit model in mice expressing HA-tagged M1 (M1-WT), phosphorylation deficient HA-tagged M1 (M1-PD), or mice deficient in M1 (M1-KO). LM was assessed using a fear conditioning (FC) testing paradigm where context and cued memory retrieval was measured 24 hrs after training and a higher level of freezing indicated intact memory. Results demonstrated that scopolamine induced a significant LM deficit in both context and cued retrieval in M1-WT mice which was partially rescued by VU0486846 confirming a contribution of M1 signalling in LM. The scopolamine induced deficit in contextual retrieval in M1-KO mice was not rescued by VU0486846, which is an M1 selective ligand, while scopolamine did not induce a deficit in cued retrieval in M1-KO mice. In M1-PD mice, scopolamine induced a LM deficit in contextual retrieval, however this was also not rescued by VU0486846 treatment. Similarly to M1-KO animals, M1-PD mice did not display a scopolamine induced deficit in cued retrieval. When freezing responses were compared across strains, M1-PD mice displayed a deficit compared to M1-WT and M1-KO mice in contextual retrieval, while both M1-PD and M1-KO mice displayed a deficit compared to M1-WT mice in cued retrieval. These results demonstrate that although M1 agonism can restore a LM deficit in both contextual and cued testing paradigms, only the cued retrieval response is dependent on the M1. Additionally, biased Gq M1 signalling is not sufficient to restore contextual memory and requires phosphorylation of the receptor. Furthermore, biased M1 signalling results in LM deficits not seen with KO of the receptor. Overall, these results reiterate the importance of considering the bias of ligands when developing M1 agonists for dementia in the future.