Biochemical Pharmacology

TRPA1 is a non-selective cation channel that plays a crucial role in several pain and inflammatory conditions. Agents reducing membrane cholesterol decrease TRPA1 activation, but it remains unclear how cholesterol-lowering medications affect TRPA1 function. Given that TRPA1 is activated by a wide variety of chemicals, we explored whether statins have acute effects on this channel. We found that five commonly used statins activate human and mouse TRPA1 in a reversible and concentration-dependent manner. The effective concentrations were above the micromolar range, in the order: simvastatin {approx} lovastatin < fluvastatin < atorvastatin < pravastatin. Statin-induced activation was not correlated to changes in membrane order, nor mediated by N-terminal cysteine residues contributing to electrophilic compound agonism. Molecular docking calculations and the functional characterization of single-point mutants revealed two separate putative binding sites, one situated close to the kink of transmembrane segment 5 (TM5) and the other at the interface between TM4 and TM5. The mTRPA1 inhibitor A-967079 largely abrogated the response to the electrophilic agonist allyl isothiocyanate, but had weaker and varied effects across different statins and menthol. Mutation T877L strongly altered the effect of A-967079, also in an agonist-dependent manner, suggesting competitive binding between this antagonist and the non-electrophilic agonists. The identification of two distinct agonist binding sites may help explaining how TRPA1 is able to respond to a large variety of non-electrophilic compounds, while the finding of competitive interactions at one of these sites may help guide the development of agonist-specific antagonists of therapeutic relevance.

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.

The neurosteroid allopregnanolone is a positive allosteric modulator of GABA(A) receptors, which has proved beneficial in the treatment of major depressive disorder and epilepsies. It also has a role in treating the mood swings that are associated with fluctuations in its level during the menstrual cycle. Nonetheless, a subset of women do not tolerate high levels of allopregnanolone. Iso-allopregnanolone, a negative allosteric modulator, as well as synthetic steroid antagonists are used to treat such conditions. However, steroid-based medications are difficult to deliver and their specificity of action can be unclear. Recently introduced novel nonsteroidal agents that, like iso-allopregnanolone, can reverse the action of positive allosteric modulators without changing the positive action of GABA, might provide an alternative. We surveyed a number of them on human 1{beta}3{delta} GABAARs using a [3H]muscimol binding assay. A 6-membered ring spiro-hydantoin, DKD99, allosterically reversed the positive allosteric action of allopregnanolone over a wide concentration range (6 to 1,000 nM). DKD99 shifted allopregnanolones modulation curve 10-fold to the right. Furthermore, it has a much lower affinity when exerting similar actions on 1{beta}3{gamma}2 receptors. Agents such as this have utility for elucidating underlying mechanisms and may offer an alternative pathway for the development of nonsteroidal therapies against the positive allosteric modulatory actions of neurosteroids.

Temozolomide is the gold standard chemotherapeutic agent used in the treatment of glioblastoma multiforme. Yet its pharmacological use has been linked to the emergence of depressive- and/or anxiety-like behaviors, probably through the inhibition of hippocampal neurogenesis. Since prior studies reporting these negative effects were based on prolonged treatment paradigms (i.e., from 2 weeks to up to 6 months), and given the few reports that have included female rodents in their studies, our approach aimed at further characterizing the behavioral effects induced by temozolomide (25 mg/kg, 1 or 2 cycles, 5 days/cycle) in a mixed-sex cohort of adult rats. To do so, rats were scored across time through specific behavioral tests that capture diverse manifestations of affective-like responses (forced-swim, open field, novelty-suppressed feeding and sucrose preference) or cognitive performance (Barnes maze). At the neurochemical level, we ascertained the effects of 2 cycles of temozolomide on hippocampal neurogenesis (neural progenitors with NeuroD) and other potential neuroplasticity targets (i.e., FADD, BDNF). The main results showed that temozolomide induced unexpected antidepressant-like responses in a treatment-duration manner while decreased hippocampal FADD, a neuroplastic marker previously associated with the acute and repeated actions of most antidepressants. These results break the prior dogma linking increased hippocampal neurogenesis with antidepressant-like efficacy, and suggest that other mechanisms of action, such as the one described through the neuroplastic molecule FADD, might be responsible for the antidepressant-like actions of temozolomide, even in the presence of impaired neurogenesis. Our results, in conjunction with the prior data, suggested cycle- and/or length-dependent treatment effects in terms of temozolomides antidepressant- vs. depressant-like profile, while proposing a novel biomarker of its treatment response.

Background and aimsTherapeutic outcomes for advanced hepatocellular carcinoma remain inadequate, despite recent advances using immunotherapy. Long-term effectiveness of systemic therapies, including second-line multi-tyrosine kinase inhibitor sorafenib, is limited by resistance mechanisms and adverse effects. Upregulated deubiquitinase UCH-L1 is frequently correlated with poor prognosis in cancers. Here, we investigated the therapeutic potential of combining pharmacological UCH-L1-inhibition with sorafenib in HCC. MethodsUCH-L1 expression was analysed in TCGA-LIHC data and patient-derived HCC tissues. Sorafenib and LDN57444 effects were evaluated in vitro in cytotoxicity and invasion assays. Gene and protein expression were examined by RT-qPCR, Western blotting and immunohistochemistry. In vivo efficacy of drug synergy was assessed in an orthotopic xenograft mouse HCC model. ResultsIn silico data-analysis revealed significantly higher UCH-L1 levels in patient HCC tumours versus non-tumour, associated with reduced overall survival. Low-dose sorafenib upregulated UCH-L1 in HCC cell line Hep3B. Paradoxically, this also promoted invasiveness and sustained MEK1/2-ERK1/2-pathway activation. Combining low-dose sorafenib with LDN57444 produced strong synergistic cytotoxicity in vitro, reverted MAPK-activation and suppressed invasion. Consistently, at low sorafenib dose co-treatment with LDN57444 completely inhibited tumour growth of Hep3B xenografts and enhanced sorafenib efficacy. ConclusionLDN57444 sensitises HCC cells to low-dose sorafenib by reverting drug-induced pro-oncogenic signalling and thereby strongly synergises with sorafenib to enhance anti-tumour efficacy in a HCC mouse model. This presents UCH-L1 as a player in treatment-induced adaptive response and supports further exploring UCH-L1-targeting in combination with sorafenib as therapeutic avenue for advanced HCC. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=144 SRC="FIGDIR/small/725527v1_ufig1.gif" ALT="Figure 1"> View larger version (37K): org.highwire.dtl.DTLVardef@176dc91org.highwire.dtl.DTLVardef@8acae8org.highwire.dtl.DTLVardef@f71bborg.highwire.dtl.DTLVardef@1f3c5aa_HPS_FORMAT_FIGEXP M_FIG C_FIG Lay summaryThis study explores a new treatment approach for hepatocellular carcinoma (HCC) by combining two drugs: LDN57444, which blocks the enzyme UCH-L1, and sorafenib, a FDA-approved multi-tyrosine kinase inhibitor. We evaluated the effect of this drug combination in vitro using a HCC cell line and in an mouse HCC-model. The drug combination displayed strong, synergy in lowering HCC cell viability, and greatly reduced invasiveness and in vivo tumour growth. LDN57444 sensitised HCC cells to low doses of sorafenib by preventing UCH-L1-mediated activation of pro-oncogenic signalling. These findings highlight the potential of this new drug combination for treating advanced HCC thereby potentially reducing side-effects and countering drug resistance. Impact and implicationsOur preclinical research introduces a novel combination strategy against advanced HCC that holds potential to improve existing therapies, particularly the second-line multi-tyrosine kinase inhibitor sorafenib. The proposed combination of sorafenib with an inhibitor of the deubiquitinase UCH-L1 not only enhances sorafenib efficacy but present promise to also counter resistance mechanisms. Moreover, because effective responses are achieved at lower drug doses, this may in addition reduce therapy-associated adverse effects further increasing potential impact. While sorafenib is FDA-approved, the UCH-L1 inhibitor LDN57444 needs further (clinical) development to bring our promising findings to full translational potential for HCC patients and physicians.

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.

In some countries, melatonin is sold without a physician prescription and dosage is unregulated. Transdermal products have become popular including those marketed for children. We measured consumer assumptions about these products among adult residents of the United States, analyzed lot-to-lot variability, and compared the pharmacokinetics of melatonin administered in oral, lotion, and bath product forms. Survey respondents (n=199) believed oral melatonin was more effective than transdermal products and that all melatonin products were relatively safe. Melatonin lotion products analyzed by HPLC displayed lot-to-lot variability as well as changes in formulation and product claims. To determine pharmacokinetics, three different treatments (oral tablets, lotion, and bath immersion) were administered to twelve undergraduate participants in a randomized, crossover design. Five additional participants completed bath product treatment only. Participants collected saliva samples up to 48 hours after administration, which were analyzed for melatonin by enzyme-linked immunosorbent assay. Oral (n=11) and lotion formulations (n=12) caused maximum salivary melatonin levels within 30 minutes after administration, but bath immersion did not cause increases in saliva melatonin (n=17). The half-life of oral melatonin was 1.17 [0.69 -- 1.65] hours versus 5.72 [3.75 -- 7.68] hours for lotion treatment (p = 0.011, effect size r = 0.770). Melatonin lotion may pose a risk to consumers who assume it is safe and less effective than oral tablets, when in fact it may be very potent and remain at high physiological levels into the following day. This study is registered on clinicaltrials.gov (NCT06382610) and was funded by the Sleep Research Society.

The ion channel KCa3.1 plays a role in immune regulation, red blood cell function, and is linked to numerous types of cancer. Various animal toxins, such as maurotoxin, bind to the extracellular side of KCa3.1, providing a potential starting point for inhibitor development. We report in this work the discovery of a novel, small-molecule inhibitor, with a micromolar IC50, which was specifically designed to target plasma-membrane KCa3.1 channels from the extracellular side. This compound can serve as a starting point for the development of more selective inhibitors and probes. For the identification of new extracellular inhibitors, molecular dynamics simulations were performed using the experimental structures of KCa3.1 and maurotoxin. The simulations produced a validated binding mode, highlighting key residues involved in the interaction between the toxin and the channel. These findings laid the foundation for the structure-based identification of novel extracellular small-molecule inhibitors of KCa3.1. The Molport database, containing approximately 50 million compounds, was screened using protein-ligand docking, yielding a hit molecule that was experimentally confirmed using patch clamp assays.

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.

BackgroundDichapetalin M (Dic M), an active compound extracted from medicinal plants in the Dichapetalum genus, has been previously shown to possess anti-proliferative activity against cancer cell lines. However, the specific mechanism through which it exerts its anticancer effects remains unknown. PurposeThis study focused on elucidating the mechanism of action of dichapetalin M to further explore its potential as a therapeutic agent for resistant and metastatic breast cancer. MethodWe confirmed the Estrogen Receptor (ER) as a target of Dic M, using an in vitro approach. Furthermore, we examined both the apoptotic and migrastatic effects of dichapetalin M by assessing its impact on the expression of key apoptosis-related and cancer cell migration genes. Finally, we evaluated the compounds effect on Multi-drug Resistance Gene MDR1 expression, a gene linked to cancer drug resistance. ResultsOur target validation experiments demonstrated that Dic M exhibited considerably higher cytotoxicity in ER-positive breast cell lines compared to ER-negative cell lines. Furthermore, treatment of MCF-7 cells (which are ER-positive) with Dic M led to a dose-dependent increase in AREG (amphiregulin), a downstream effector of the Estrogen Receptor. Additionally, Dic M inhibited actin polymerization and significantly downregulated genes involved in the turnover of actin monomers. Scratch-wound assay results further demonstrate that Dic M reduces the rate of cell migration, although its impact on EMT-related gene expression was only observed at high doses. Additionally, Dic M treatment in MCF-7 cells resulted in a significant decrease in the expression of pro-apoptotic genes and MDR1 expression. ConclusionsThese findings indicate that Dic M likely interacts with the Estrogen Receptor and employs the apoptotic pathway to exert its cytotoxic and anti-proliferative effects. Dic M exhibits promising potential, such as anti-migrastatic properties and downregulation of a key breast cancer resistance gene, warranting further investigation.

(1) Aims and hypothesisLoss-of-function mutations in SLC30A8, encoding the zinc ion (Zn2+) transporter ZnT8 in pancreatic beta cells, lower type 2 diabetes risk dose-dependently, but the underlying mechanisms remain unclear. Here, we combine proteomic, transcriptomic and functional approaches in human stem cell-derived islet-like clusters bearing common alleles or the inactivating variant R138X. We hypothesized that this variant protects against the deleterious effect of Zn2+ depletion on cell survival and function. (2) MethodsHuman embryonic stem cells INS(GFP/w) (MEL1), and CRISPR/Cas9-derived heterozygous or homozygous R138X lines were differentiated into stem cell-derived islet-like clusters. Intracellular Zn2+ levels were reduced using the chelator N,N,N',N'-tetrakis(2-pyridylmethyl)-1,2-ethanediamine (TPEN). Apoptosis was assessed by TUNEL staining and protein expression by immunofluorescence. Glucose-stimulated calcium (Ca2+) dynamics were measured using the intracellular probe (Cal590) and insulin secretion by homogenous time-resolved fluorescence. Transcriptomic profiling was performed by bulk mRNA sequencing and proteomics by liquid chromatography-tandem mass spectrometry. (3) ResultsIntracellular Zn2+ depletion increased apoptosis in wild-type islet-like clusters, whereas R138X clusters were protected. R138X heterozygous clusters showed a mild increase in GCG+ cells and R138X homozygous clusters exhibited increased NKX6.1+ cells, without affecting polyhormonal populations. These changes were reversed under Zn2+ depletion. Transcriptomic and proteomic analyses, assessing genotype effects while accounting for Zn2+ depletion, showed that R138X clusters (versus wild-type) exhibited upregulation of genes and proteins involved in vesicle trafficking, secretion, Ca{superscript 2} signaling and mitochondrial metabolism, consistent with enhanced glucose-stimulated insulin secretion in homozygous clusters. Conversely, genes and proteins associated with extracellular matrix remodeling, metal-ion handling, apoptosis and cellular stress were downregulated. R138X clusters displayed altered Ca2+ signaling, with decreased area under the curve and oscillation amplitude, but increased frequency. These differences were reversed by TPEN, while Zn2+ depletion impaired Ca2+ response in wild-type clusters. Despite lowered overall activity, R138X homozygous clusters showed enhanced overall cell-cell connectivity, reversed by TPEN treatment. The opposite effects were observed in R138X heterozygous clusters, showing improved connectivity and activity under Zn2+ depletion. (4) Conclusion and interpretationIntracellular Zn2+ depletion compromises islet-like cluster identity and function, while the R138X variant confers protection against these effects. Under Zn2+-depleted conditions, ZnT8 deficiency promotes a more mature and metabolically active state of the R138X clusters, with enhanced Ca2+ signaling and insulin secretion, supported by a structural remodeling and the downregulation of apoptosis and cellular stress. These findings highlight the therapeutic potential of targeting ZnT8 in type 2 diabetes and support its relevance for further improving cell-based therapies. Research in ContextO_ST_ABSWhat is already know about this subject?C_ST_ABSO_LIRare inactivating mutations in the insulin granule-associated zinc transporter gene, SLC30A8/ZnT8, drive lowered type 2 diabetes risk. C_LIO_LIPrevious studies have indicated that apoptosis is lowered, and glucose-stimulated insulin secretion enhanced, after ZnT8 inactivation. C_LIO_LIThe molecular mechanisms underlying these changes are unclear. C_LI What is the key question?O_LIHow do inactivating mutations in SL30A8/ZnT8 lead to lowered apoptosis and enhanced insulin secretion from stem cell-derived islet-like clusters, and is altered susceptibility to intracellular zinc depletion involved? C_LI What are the new findings?O_LIThe rare inactivating R138X mutation in SLC30A8 leads to gene dose-dependent changes in the transcriptome and proteome of islet-like clusters. C_LIO_LIChanges include upregulation of maturity and downregulation of immaturity genes. C_LIO_LIDepletion of intracellular Zn2+ exaggerates the protective effects of the inactivating mutation on apoptosis and insulin secretion C_LI How might this impact on clinical practice in the foreseeable future?O_LIOur findings suggest that careful monitoring of both dietary zinc intake and of circulating levels of zinc ions, whose effects are mitigated in SLC30A8 mutation carriers, may be helpful in some populations to lower diabetes risk. C_LI

BackgroundInflammation-induced pancreatic islet-cell death and dysfunction are key aspects of both type 1 and type 2 diabetes. Stem cell-derived islets (SC-islets) are an emerging tool in diabetes research, however, our understanding of how inflammation affects SC-islet function is incomplete. We therefore aimed to thoroughly characterize how SC-islets respond to pro-inflammatory cytokines at the functional and transcriptomic levels in comparison with human primary islets and EndoC-{beta}H5 cells. MethodA 7-stage differentiation protocol was used to generate SC-islets with insulin-, glucagon-, and somatostatin-positive cells. SC-islets, primary human islets and EndoC-{beta}H5 cells were exposed to different doses of pro-inflammatory cytokines (IL-1{beta} + IFN{gamma} + TNF) including a high dose for up to 48 h and a low dose up to 144 h to mimic the intense islet inflammation in T1D and chronic low-grade inflammation in T2D, respectively. Differential gene expression (RNA-seq), cell death, activation of key signalling proteins, hormones, and chemokine secretion were determined. ResultsBasal expression of key islet-cell identity genes in SC-islets correlated well with that of primary islets and EndoC-{beta}H5 cells. In SC islets, cytokines dose-dependently induced activation of key proximal signalling pathways (NF{kappa}B, STAT1, and JNK), upregulation of major histocompatibility complex (MHC) class I, and increased cell death (cytotoxicity and caspase 3/7 activity). In head-to-head experiments, SC-islets displayed similar cytokine responses particularly as primary islets regarding induction of cell death, chemokine secretion, differential gene expression, and protein levels of cell death executioners (gasdermin D and caspase-7). Cytokines increased insulin release in SC-islets and primary islets, while diminishing insulin secretion in EndoC-{beta}H5 cells. Cytokines reduced glucagon release in SC-islets, which was partially restored by treatment with the incretin hormone glucose-dependent insulinotropic peptide (GIP) with or without a glucagon-like peptide 1 (GLP-1) receptor agonist (liraglutide). ConclusionSC-islets are highly responsive to inflammation with a high degree of similarity to primary islets. Our results support the use of SC-islets as a valid tool in inflammation and diabetes research.

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.

Ramadan fasting represents a natural model of prolonged daily intermittent fasting associated with metabolic and circadian alterations. This study investigated longitudinal changes in intracortical excitability across pre-, mid-, and post-Ramadan timepoints in healthy adults observing Ramadan fasting. Thirty fasting participants underwent paired-pulse transcranial magnetic stimulation at three timepoints (pre-, mid-, and post-Ramadan). A non-fasting control group (n = 11) was assessed at pre- and mid-Ramadan. Conditioned motor-evoked potentials were recorded at interstimulus intervals of 2-10 ms and normalized to unconditioned responses. A linear mixed-effects model assessed effects of Timepoint and interstimulus interval (ISI). Secondary outcomes included blood glucose, cognitive performance, sleep duration, and reaction time. A significant main effect of Timepoint (p < 0.001) indicated longitudinal modulation of intracortical excitability, with increased MEP ratios at mid-Ramadan and partial persistence post-Ramadan. The ISI effect confirmed the inhibition-facilitation gradient (p < 0.001). The Timepoint x ISI interaction was not significant (p = 0.566), indicating a global shift in excitability without ISI-specific modulation. Blood glucose and sleep duration decreased significantly at mid-Ramadan. Ramadan fasting is associated with a time-dependent increase in intracortical excitability, most appropriately interpreted as a generalized shift rather than selective modulation of inhibitory or facilitatory circuits. These changes occur in the context of concurrent metabolic and sleep alterations and may reflect combined influences of fasting-related metabolic state and reduced sleep duration; however, these factors cannot be disentangled within the present design.

Hypoxemia occurs in intermittent forms, such as obstructive sleep apnea, and in continuous forms, such as at high altitude, and is increasingly recognized as a modulator of cardiometabolic risk. Although hypoxemia alters postprandial glucose and lipid metabolism, its effects on ketone bodies remain unclear. Using a randomized crossover design, we examined whether six hours of normoxemia or intermittent hypoxemia (15 hypoxemic cycles/hour targeting [~]85% peripheral oxyhemoglobin saturation with 100% medical-grade nitrogen) alters plasma {beta}-hydroxybutyrate (BHB) concentrations in 12 young adult females (mean [SD]: 21 [3] years) following a high-fat meal (33% of estimated daily energy requirements; 59% of calories from fat). In a follow-up session, a subset (n = 8) completed six hours of continuous hypoxemia (fraction of inspired oxygen [~]12.0% in a normobaric chamber). Postprandial data were analyzed using baseline-adjusted linear mixed-effects models, with Bonferroni post hoc tests. A time x condition interaction (P = 0.010) indicated that BHB concentrations at 360 minutes were higher during continuous hypoxemia (0.247 mmol/L; 95% CI: 0.218-0.275) than normoxemia (0.176 mmol/L; 95% CI: 0.153-0.200; PBonferroni = 0.029) and intermittent hypoxemia (0.163 mmol/L; 95% CI: 0.139-0.186; PBonferroni = 0.002), representing increases of 13.0% and 14.2% in estimated marginal means, respectively. This response was accompanied by higher postprandial plasma glucose and triglyceride concentrations during continuous hypoxemia than during normoxemia and intermittent hypoxemia (PBonferroni [&le;] 0.002), despite similar plasma insulin and non-esterified fatty acid responses across conditions (P [&ge;] 0.081). These findings indicate that continuous hypoxemia increases late postprandial plasma BHB concentrations in young adult females. New FindingsO_ST_ABSWhat is the central question of this study?C_ST_ABSWhat are the effects of normoxemia, intermittent hypoxemia, and continuous hypoxemia on plasma {beta}-hydroxybutyrate (BHB) concentrations in young adult females after a high-fat meal? What is the main finding and its importance?Compared to normoxemia, young adult females showed higher postprandial plasma BHB concentrations during continuous hypoxemia, but not during intermittent hypoxemia, despite similar changes in plasma concentrations of two main regulators of BHB production (non-esterified fatty acids and insulin) across experimental conditions. These findings suggest that continuous hypoxemia modifies postprandial BHB concentrations through mechanisms not fully explained by circulating non-esterified fatty acids or insulin concentrations alone.

ObjectiveG protein-coupled receptor 180 (GPR180) has been implicated in systemic energy metabolism, primarily in adipose tissue and the liver. Given impaired whole-body glucose tolerance following GPR180 dysfunction, we aimed to determine whether GPR180 regulates pancreatic {beta}-cell function. We investigated whether GPR180 contributes to {beta}-cell insulin secretion by modulating metabolic processes that couple glucose sensing to mitochondrial energy production. MethodsPhenotyping of whole-body (Gpr180 -/-) and {beta} cell-specific Gpr180 (bGpr180-KO) knockout mice was combined with gain- and loss-of-function studies in MIN6 cells. Glucose-stimulated insulin secretion, pancreatic endocrine architecture and identity, transcriptomic and metabolic profiles, as well as mitochondrial function were assessed using in vivo and in vitro approaches, including metabolic challenge tests, histology, RNA sequencing, targeted metabolomics, respirometry, and transmission electron microscopy. ResultsLoss of GPR180 impaired first-phase insulin secretion and glucose tolerance without affecting insulin sensitivity. These defects were {beta}-cell-autonomous, as confirmed in the bGpr180-KO mice and in MIN6 cells. Functional studies revealed that GPR180 regulates mitochondrial substrate utilization, anaplerotic support of the TCA cycle, and ATP generation without affecting glucose uptake or mitochondrial biogenesis. In particular, Gpr180-deficient {beta} cells showed mitochondrial membrane depolarization, reduced oxygen consumption, and endoplasmic reticulum remodeling, altering the local mitochondrial microenvironment. In vivo, Gpr180 deletion in {beta} cells led to downregulation of mitochondrial gene programs in islets, along with altered endocrine cell identity. ConclusionsGPR180 is a previously unrecognized regulator of pancreatic {beta}-cell metabolic competence and identity, linking defects in insulin secretion with alterations in mitochondrial function and endocrine cell identity. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=198 SRC="FIGDIR/small/720098v1_ufig1.gif" ALT="Figure 1"> View larger version (87K): org.highwire.dtl.DTLVardef@1a441ecorg.highwire.dtl.DTLVardef@e41e02org.highwire.dtl.DTLVardef@6e2212org.highwire.dtl.DTLVardef@7ee07a_HPS_FORMAT_FIGEXP M_FIG C_FIG

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.