Acetyl-CoA carboxylase obstructs CD8+ T cell lipid utilization in the tumor microenvironment.

The solid tumor microenvironment (TME) imprints a compromised metabolic state in tumor-infiltrating T cells (TILs), hallmarked by the inability to maintain effective energy synthesis for antitumor function and survival. T cells in the TME must catabolize lipids via mitochondrial fatty acid oxidation (FAO) to supply energy in nutrient stress, and it is established that T cells enriched in FAO are adept at cancer control. However, endogenous TILs and unmodified cellular therapy products fail to sustain bioenergetics in tumors. We reveal that the solid TME imposes perpetual acetyl-coenzyme A (CoA) carboxylase (ACC) activity, invoking lipid biogenesis and storage in TILs that opposes FAO. Using metabolic, lipidomic, and confocal imaging strategies, we find that restricting ACC rewires T cell metabolism, enabling energy maintenance in TME stress. Limiting ACC activity potentiates a gene and phenotypic program indicative of T cell longevity, engendering T cells with increased survival and polyfunctionality, which sustains cancer control.

Raising awareness of anti-fat stigma in healthcare through lived experience education: a continuing professional development pilot study.

BACKGROUND: Anti-fat attitudes and weight-based discrimination are prevalent in healthcare settings and among healthcare practitioners and clinical trainees, and can result in immense harm to patients. There is increasing recognition that anti-fat bias in healthcare is a critical issue that must be addressed, but there is a dearth of evidence demonstrating sustained attitude and behavioural change among clinicians, illustrating a need for more innovative educational approaches and rigorous evaluation. We describe the co-design and delivery of a narrative-based continuing professional development curriculum aimed at raising awareness of weight-based bias and stigma. METHODS: Our research team of lived experience educators, clinicians and researchers collaboratively developed a series of seven podcast episodes comprised of narrative descriptions of lived experiences with and impacts of weight bias, stigma and discrimination in healthcare settings, as well as a post-podcast workshop to facilitate reflection and discussion between participants. The curriculum was piloted among 20 clinicians practicing at a large urban hospital in Mississauga, Canada. We explored feasibility, acceptability and learning impact by analyzing responses to questionnaires completed following each podcast episode and responses shared during the workshops and follow-up feedback sessions. RESULTS: We observed high acceptability and feasibility of the curriculum. Participants experienced the podcast as a practical and convenient learning format and the workshop as a valuable opportunity to collectively debrief and reflect. The learning impact of the curriculum was strong; participants described a range of emotions elicited by the podcasts, engaged in self-reflection, and expressed a desire to modify clinical approaches. Barriers to the application of learnings identified by participants include pervasiveness of the use of body mass index (BMI) as an indicator of risk and a criterion for referral; discomfort with difficult conversations; prevalent biomedical understandings about the association between weight and health; and clinicians' defensiveness. CONCLUSION: This pilot study yielded promising findings and demonstrated potential impact on weight bias and stigma among healthcare providers. Necessary next steps include conducting larger scale, rigorous evaluations of the curriculum among broader populations, both health professions trainees and current healthcare providers.

Stable Inner 2H Tautomer of N-Confused-like Porphyrin Embedded with a Carbazole Subunit: Synthesis, Metal Coordination, and Magnetic and Anion Sensing Studies.

A new class of N-confused porphyrin 1 embedded with a carbazole subunit was prepared via [3 + 1] acid-catalyzed condensation of appropriate precursors. 1 underwent smooth metal complexation with Pd(II) and Cu(II) salts to provide the corresponding diamagnetic 1-Pd and paramagnetic 1-Cu, respectively. The single-crystal X-ray structure of 1-Pd is evident with a square-planar Pd-center through C-H activation of inverted pyrrole. Superconducting quantum interference device analysis combined with electron paramagnetic resonance (EPR) results provided insights into the paramagnetic nature of 1-Cu. Further, a ratiometric enhancement of near-IR fluorescence at 746 nm was found to be reversible upon adding CN- and F- ions. The solid-state structure of 1-Pd confirms that the anionic species is due to NH deprotonation.

From Sn(II) to Sn(IV): Enhancing Lewis Acidity Via Oxidation.

We demonstrate the increased Lewis acidity on going from Sn(II) to Sn(IV) by oxidizing TpMe2SnOTf (OTf = SO3CF3) to TpMe2SnF(OTf)2. Replacement of the fluoride ion in TpMe2SnF(OTf)2 by a triflate, resulting in TpMe2Sn(OTf)3 further enhances the Lewis acidity at tin. 119Sn NMR spectroscopy, modified Gutmann-Beckett test, computational analysis, and catalytic phosphine oxide deoxygenation support the claims.

Reactivity of a quasi-four-coordinate butylmagnesium cation.

We present the reactivity of the Mg-C and the ß-CH bonds in the trigonal pyramidal [(pmdta)Mg(nBu)]+ exhibiting a weak Mg⋯F interaction with counter anion, [B(C6F5)4]-. Instantaneous ß-hydride reactivity with benzophenone, reductive alkylation of phenyl benzoate, and straightforward synthesis of [(pmdta)MgH]+via metathesis with pinacolborane/phenylsilane are discussed.

The initial experience with the Embotrap III stent-retriever in a real world setting.

MATERIALS AND METHODS: We performed a retrospective review of our prospectively maintained database to identify all patients treated with the Embotrap 3 stent-retriever between January 2021 and January 2022. We recorded the baseline demographics, NIHSS, ASPECT score and clot characteristics, first pass and final eTICI scores, complications and 90 day mRS. RESULTS: One hundred and ten patients met the inclusion criteria, average age 69 ± 14 years, 50% were male (n = 55). The median NIHSS at presentation was 18 (range 3-30) and 58.2% received IV tPA prior to MT. The median ASPECT score on plain CT was 8 with average clot length 20.2 ± 14.8 mm (n = 93). The first pass effect (FPE) was seen in 41.8% of cases with modified FPE seen in 59.1%. A 24-hour CT scan (n = 97) showed median ASPECTs of 7. 43.8% of patients achieve mRS ≤ 2 at 90-day mRS (n = 64). CONCLUSION: The Embotrap 3 stent-retriever has a high rate of FPE and final recanalization in this real world cohort of patients.

Stress-Mediated Attenuation of Translation Undermines T-cell Activity in Cancer.

Protein synthesis supports robust immune responses. Nutrient competition and global cell stressors in the tumor microenvironment (TME) may impact protein translation in T cells and antitumor immunity. Using human and mouse tumors, we demonstrated here that protein translation in T cells is repressed in solid tumors. Reduced glucose availability to T cells in the TME led to activation of the unfolded protein response (UPR) element eIF2α (eukaryotic translation initiation factor 2 alpha). Genetic mouse models revealed that translation attenuation mediated by activated p-eIF2α undermines the ability of T cells to suppress tumor growth. Reprograming T-cell metabolism was able to alleviate p-eIF2α accumulation and translational attenuation in the TME, allowing for sustained protein translation. Metabolic and pharmacological approaches showed that proteasome activity mitigates induction of p-eIF2α to support optimal antitumor T-cell function, protecting from translation attenuation and enabling prolonged cytokine synthesis in solid tumors. Together, these data identify a new therapeutic avenue to fuel the efficacy of tumor immunotherapy. SIGNIFICANCE: Proteasome function is a necessary cellular component for endowing T cells with tumor killing capacity by mitigating translation attenuation resulting from the unfolded protein response induced by stress in the tumor microenvironment.

The ER-Mitochondria Interface as a Dynamic Hub for T Cell Efficacy in Solid Tumors.

The endoplasmic reticulum (ER) is a large continuous membranous organelle that plays a central role as the hub of protein and lipid synthesis while the mitochondria is the principal location for energy production. T cells are an immune subset exhibiting robust dependence on ER and mitochondrial function based on the need for protein synthesis and secretion and metabolic dexterity associated with foreign antigen recognition and cytotoxic effector response. Intimate connections exist at mitochondrial-ER contact sites (MERCs) that serve as the structural and biochemical platforms for cellular metabolic homeostasis through regulation of fission and fusion as well as glucose, Ca2+, and lipid exchange. Work in the tumor immunotherapy field indicates that the complex interplay of nutrient deprivation and tumor antigen stimulation in the tumor microenvironment places stress on the ER and mitochondria, causing dysfunction in organellar structure and loss of metabolic homeostasis. Here, we assess prior literature that establishes how the structural interface of these two organelles is impacted by the stress of solid tumors along with recent advances in the manipulation of organelle homeostasis at MERCs in T cells. These findings provide strong evidence for increased tumor immunity using unique therapeutic avenues that recharge cellular metabolic homeostasis in T cells.

Cationic Zinc Hydride Catalyzed Carbon Dioxide Reduction to Formate: Deciphering Elementary Reactions, Isolation of Intermediates, and Computational Investigations.

Zinc has been an element of choice for carbon dioxide reduction in recent years. Zinc compounds have been showcased as catalysts for carbon dioxide hydrosilylation and hydroboration. The extent of carbon dioxide reduction can depend on various factors, including electrophilicity at the zinc center and the denticity of the ancillary ligands. In a few cases, the addition of Lewis acids to zinc hydride catalysts markedly influences carbon dioxide reduction. These factors have been investigated by exploring elementary reactions of carbon dioxide hydrosilylation and hydroboration by using cationic zinc hydrides bearing tetradentate tris[2-(dimethylamino)ethyl]amine and tridentate N,N,N',N'',N''-pentamethyldiethylenetriamine in the presence of triphenylborane and tris(pentafluorophenyl)borane.

Stress relief for cancer immunotherapy: implications for the ER stress response in tumor immunity.

The solid tumor microenvironment is replete with factors that present a stress to infiltrating immune cells. Endoplasmic reticulum (ER) stress sensor PKR-like ER kinase (PERK) is primed to sense and respond to the burden of misfolded proteins in the ER lumen induced by cell stressors. PERK has documented roles as a master regulator of acute and chronic responses to cell stress as well as in the regulation of cell metabolism. Here, we provide an overview of the roles of PERK based on what is known and remains to be tested in immune cells in tumors and impacts on tumor control. PERK is one of several ER kinases able to preferentially induce activating transcription factor 4 (ATF4) as a response to cell stress. ATF4 orchestrates the oxidative stress response and governs amino acid metabolism. We discuss the tested role of ATF4 in tumor immunity and provide insight on the dueling protective and deleterious roles that ATF4 may play in the stress of solid tumors.

Organoaluminum cations for carbonyl activation.

In search of stable, yet reactive aluminum Lewis acids, we have isolated an organoaluminum cation, [(Me2NC6H4)2Al(C4H8O)2]+, coordinated with two labile tetrahydrofuran ligands. Its catalytic performance in aldehyde dimerization reveals turn-over frequencies reaching up to 6000 h-1, exceeding that of the reported main group catalysts. The cation is further demonstrated to catalyze hydroelementation of ketones. Mechanistic investigations reveal that aldehyde dimerization and ketone hydrosilylation occur through carbonyl activation.

Amidomagnesium cations.

We report the synthesis, structure and reactivity of molecular amidomagnesium cations bearing tris{2-(dimethylamino)-ethyl}amine (Me6TREN). Me6TREN binds to the cationic magnesium centre exhibiting κ4 and κ3 coordination modes in [Me6TREN-Mg-N(SiHMe2)2]+ and [Me6TREN-Mg-N(SiMe3)2]+ respectively. [Me6TREN-Mg-N(SiHMe2)2]+ reacts with benzophenone resulting in the insertion of the carbonyl group across ß-SiH bond. The reaction between [Me6TREN-Mg-N(SiMe3)2]+ and CO2 leads to [Me6TREN-Mg-OSiMe3]+, while the reaction with H2O results in [Me6TREN-Mg-OH]22+. Attempts to prepare hydridomagnesium cations from [Me6TREN-Mg-N(SiMe3)2]+ using KH resulted in the precipitation of MgH2 and the isolation of [(Me6TREN)K(THF)3]+.

Terminal hydridozinc cation.

A thermally stable terminal hydridozinc cation has been isolated. The nucleophilicity of the hydride ligand is demonstrated by inserting carbon dioxide, carbodiimide and benzophenone across the Zn-H bond in a facile manner. Preliminary studies on catalytic hydrosilylation using PhSiH3 indicate that the hydridozinc cation in the presence of BPh3 can selectively reduce CO2 to PhSi(OCHO)3.

A senataxin-associated exonuclease SAN1 is required for resistance to DNA interstrand cross-links.

Interstrand DNA cross-links (ICLs) block both replication and transcription, and are commonly repaired by the Fanconi anemia (FA) pathway. However, FA-independent repair mechanisms of ICLs remain poorly understood. Here we report a previously uncharacterized protein, SAN1, as a 5' exonuclease that acts independently of the FA pathway in response to ICLs. Deletion of SAN1 in HeLa cells and mouse embryonic fibroblasts causes sensitivity to ICLs, which is prevented by re-expression of wild type but not nuclease-dead SAN1. SAN1 deletion causes DNA damage and radial chromosome formation following treatment with Mitomycin C, phenocopying defects in the FA pathway. However, SAN1 deletion is not epistatic with FANCD2, a core FA pathway component. Unexpectedly, SAN1 binds to Senataxin (SETX), an RNA/DNA helicase that resolves R-loops. SAN1-SETX binding is increased by ICLs, and is required to prevent cross-link sensitivity. We propose that SAN1 functions with SETX in a pathway necessary for resistance to ICLs.

A disguised hydride in a butylmagnesium cation.

The ability of the ß-CH functionality in a butylmagnesium cation [Me6TREN-Mg-n-Bu]+ to quantitatively reduce benzophenone has been demonstrated. The hydridic nature of the ß-CH functionality is highlighted by its abstraction using B(C6F5)3. ß-CH abstraction over alkylation in [Me6TREN-Mg-n-Bu]+ is dependent on the nature of the incoming electrophile and the polarity of the solvent.

Tuning RNA folding and function through rational design of junction topology.

Structured RNAs such as ribozymes must fold into specific 3D structures to carry out their biological functions. While it is well-known that architectural features such as flexible junctions between helices help guide RNA tertiary folding, the mechanisms through which junctions influence folding remain poorly understood. We combine computational modeling with single molecule Förster resonance energy transfer (smFRET) and catalytic activity measurements to investigate the influence of junction design on the folding and function of the hairpin ribozyme. Coarse-grained simulations of a wide range of junction topologies indicate that differences in sterics and connectivity, independent of stacking, significantly affect tertiary folding and appear to largely explain previously observed variations in hairpin ribozyme stability. We further use our simulations to identify stabilizing modifications of non-optimal junction topologies, and experimentally validate that a three-way junction variant of the hairpin ribozyme can be stabilized by specific insertion of a short single-stranded linker. Combined, our multi-disciplinary study further reinforces that junction sterics and connectivity are important determinants of RNA folding, and demonstrates the potential of coarse-grained simulations as a tool for rationally tuning and optimizing RNA folding and function.

Consequence of Ligand Bite Angle on Bismuth Lewis Acidity.

Ligand bite angle, a common parameter to fine-tune reactivity in transition-metal chemistry, is used for the first time in main-group chemistry to control and tune the Lewis acidity in organobismuth cations bearing 2-[(dimethylamino)methyl]phenyl (Me2NCH2C6H4) and 2-(dimethylamino)phenyl (Me2NC6H4) ligands. The latter chelating ligand induces a shorter C-Bi-N bite angle, leading to a weaker Bi-N bond with a corresponding lower Bi-N σ*-acceptor orbital and hence exhibiting remarkably higher Lewis acidity. The Gutmann-Beckett method is successfully employed to quantify the Lewis acidity in organobismuth cations.

Return of warm conditions in the southeastern Bering Sea: Phytoplankton - Fish.

In 2014, the Bering Sea shifted back to warmer ocean temperatures (+2 oC above average), bringing concern for the potential for a new warm stanza and broad biological and ecological cascading effects. In 2015 and 2016 dedicated surveys were executed to study the progression of ocean heating and ecosystem response. We describe ecosystem response to multiple, consecutive years of ocean warming and offer perspective on the broader impacts. Ecosystem changes observed include reduced spring phytoplankton biomass over the southeast Bering Sea shelf relative to the north, lower abundances of large-bodied crustacean zooplankton taxa, and degraded feeding and body condition of age-0 walleye pollock. This suggests poor ecosystem conditions for young pollock production and the risk of significant decline in the number of pollock available to the pollock fishery in 2-3 years. However, we also noted that high quality prey, large copepods and euphausiids, and lower temperatures in the north may have provided a refuge from poor conditions over the southern shelf, potentially buffering the impact of a sequential-year warm stanza on the Bering Sea pollock population. We offer the hypothesis that juvenile (age-0, age-1) pollock may buffer deleterious warm stanza effects by either utilizing high productivity waters associated with the strong, northerly Cold Pool, as a refuge from the warm, low production areas of the southern shelf, or by exploiting alternative prey over the southern shelf. We show that in 2015, the ocean waters influenced by spring sea ice (the Cold Pool) supported robust phytoplankton biomass (spring) comprised of centric diatom chains, a crustacean copepod community comprised of large-bodied taxa (spring, summer), and a large aggregation of midwater fishes, potentially young pollock. In this manner, the Cold Pool may have acted as a trophic refuge in that year. The few age-0 pollock occurring over the southeast shelf consumed high numbers of euphausiids which may have provided a high quality alternate prey. In 2016 a retracted Cold Pool precluded significant refuging in the north, though pollock foraging on available euphausiids over the southern shelf may have mitigated the effect of warm waters and reduced large availability of large copepods. This work presents the hypothesis that, in the short term, juvenile pollock can mitigate the drastic impacts of sustained warming. This short-term buffering, combined with recent observations (2017) of renewed sea ice presence over southeast Bering Sea shelf and a potential return to average or at least cooler ecosystem conditions, suggests that recent warm year stanza (2014-2016) effects to the pollock population and fishery may be mitigated.

A Synthetic Loop Replacement Peptide That Blocks Canonical NF-κB Signaling.

Aberrant canonical NF-κB signaling is implicated in diseases from autoimmune disorders to cancer. A major therapeutic challenge is the need for selective inhibition of the canonical pathway without impacting the many non-canonical NF-κB functions. Here we show that a selective peptide-based inhibitor of canonical NF-κB signaling, in which a hydrogen bond in the NBD peptide is synthetically replaced by a non-labile bond, shows an about 10-fold increased potency relative to the original inhibitor. Not only is this molecule, NBD2, a powerful tool for dissection of canonical NF-κB signaling in disease models and healthy tissues, the success of the synthetic loop replacement suggests that the general strategy could be useful for discovering modulators of the many protein-protein interactions mediated by such structures.