A Structural Model of the Endogenous Human BAF Complex Informs Disease Mechanisms.

Mammalian SWI/SNF complexes are ATP-dependent chromatin remodeling complexes that regulate genomic architecture. Here, we present a structural model of the endogenously purified human canonical BAF complex bound to the nucleosome, generated using cryoelectron microscopy (cryo-EM), cross-linking mass spectrometry, and homology modeling. BAF complexes bilaterally engage the nucleosome H2A/H2B acidic patch regions through the SMARCB1 C-terminal α-helix and the SMARCA4/2 C-terminal SnAc/post-SnAc regions, with disease-associated mutations in either causing attenuated chromatin remodeling activities. Further, we define changes in BAF complex architecture upon nucleosome engagement and compare the structural model of endogenous BAF to those of related SWI/SNF-family complexes. Finally, we assign and experimentally interrogate cancer-associated hot-spot mutations localizing within the endogenous human BAF complex, identifying those that disrupt BAF subunit-subunit and subunit-nucleosome interfaces in the nucleosome-bound conformation. Taken together, this integrative structural approach provides important biophysical foundations for understanding the mechanisms of BAF complex function in normal and disease states.

ETS1 governs pathological tissue-remodeling programs in disease-associated fibroblasts.

Fibroblasts, the most abundant structural cells, exert homeostatic functions but also drive disease pathogenesis. Single-cell technologies have illuminated the shared characteristics of pathogenic fibroblasts in multiple diseases including autoimmune arthritis, cancer and inflammatory colitis. However, the molecular mechanisms underlying the disease-associated fibroblast phenotypes remain largely unclear. Here, we identify ETS1 as the key transcription factor governing the pathological tissue-remodeling programs in fibroblasts. In arthritis, ETS1 drives polarization toward tissue-destructive fibroblasts by orchestrating hitherto undescribed regulatory elements of the osteoclast differentiation factor receptor activator of nuclear factor-κB ligand (RANKL) as well as matrix metalloproteinases. Fibroblast-specific ETS1 deletion resulted in ameliorated bone and cartilage damage under arthritic conditions without affecting the inflammation level. Cross-tissue fibroblast single-cell data analyses and genetic loss-of-function experiments lent support to the notion that ETS1 defines the perturbation-specific fibroblasts shared among various disease settings. These findings provide a mechanistic basis for pathogenic fibroblast polarization and have important therapeutic implications.

Structural Insights into Mdn1, an Essential AAA Protein Required for Ribosome Biogenesis.

Mdn1 is an essential AAA (ATPase associated with various activities) protein that removes assembly factors from distinct precursors of the ribosomal 60S subunit. However, Mdn1's large size (∼5,000 amino acid [aa]) and its limited homology to other well-studied proteins have restricted our understanding of its remodeling function. Here, we present structures for S. pombe Mdn1 in the presence of AMPPNP at up to ∼4 Å or ATP plus Rbin-1, a chemical inhibitor, at ∼8 Å resolution. These data reveal that Mdn1's MIDAS domain is tethered to its ring-shaped AAA domain through an ∼20 nm long structured linker and a flexible ∼500 aa Asp/Glu-rich motif. We find that the MIDAS domain, which also binds other ribosome-assembly factors, docks onto the AAA ring in a nucleotide state-specific manner. Together, our findings reveal how conformational changes in the AAA ring can be directly transmitted to the MIDAS domain and thereby drive the targeted release of assembly factors from ribosomal 60S-subunit precursors.

Chd4 choreographs self-antigen expression for central immune tolerance.

Autoreactive T cells are eliminated in the thymus to prevent autoimmunity by promiscuous expression of tissue-restricted self-antigens in medullary thymic epithelial cells. This expression is dependent on the transcription factor Fezf2, as well as the transcriptional regulator Aire, but the entire picture of the transcriptional program has been obscure. Here, we found that the chromatin remodeler Chd4, also called Mi-2ß, plays a key role in the self-antigen expression in medullary thymic epithelial cells. To maximize the diversity of self-antigen expression, Fezf2 and Aire utilized completely distinct transcriptional mechanisms, both of which were under the control of Chd4. Chd4 organized the promoter regions of Fezf2-dependent genes, while contributing to the Aire-mediated induction of self-antigens via super-enhancers. Mice deficient in Chd4 specifically in thymic epithelial cells exhibited autoimmune phenotypes, including T cell infiltration. Thus, Chd4 plays a critical role in integrating Fezf2- and Aire-mediated gene induction to establish central immune tolerance.

Super-Enhancer-Mediated RNA Processing Revealed by Integrative MicroRNA Network Analysis.

Super-enhancers are an emerging subclass of regulatory regions controlling cell identity and disease genes. However, their biological function and impact on miRNA networks are unclear. Here, we report that super-enhancers drive the biogenesis of master miRNAs crucial for cell identity by enhancing both transcription and Drosha/DGCR8-mediated primary miRNA (pri-miRNA) processing. Super-enhancers, together with broad H3K4me3 domains, shape a tissue-specific and evolutionarily conserved atlas of miRNA expression and function. CRISPR/Cas9 genomics revealed that super-enhancer constituents act cooperatively and facilitate Drosha/DGCR8 recruitment and pri-miRNA processing to boost cell-specific miRNA production. The BET-bromodomain inhibitor JQ1 preferentially inhibits super-enhancer-directed cotranscriptional pri-miRNA processing. Furthermore, super-enhancers are characterized by pervasive interaction with DGCR8/Drosha and DGCR8/Drosha-regulated mRNA stability control, suggesting unique RNA regulation at super-enhancers. Finally, super-enhancers mark multiple miRNAs associated with cancer hallmarks. This study presents principles underlying miRNA biology in health and disease and an unrecognized higher-order property of super-enhancers in RNA processing beyond transcription.

Synthetic RNA-Based Immunomodulatory Gene Circuits for Cancer Immunotherapy.

Despite its success in several clinical trials, cancer immunotherapy remains limited by the rarity of targetable tumor-specific antigens, tumor-mediated immune suppression, and toxicity triggered by systemic delivery of potent immunomodulators. Here, we present a proof-of-concept immunomodulatory gene circuit platform that enables tumor-specific expression of immunostimulators, which could potentially overcome these limitations. Our design comprised de novo synthetic cancer-specific promoters and, to enhance specificity, an RNA-based AND gate that generates combinatorial immunomodulatory outputs only when both promoters are mutually active. These outputs included an immunogenic cell-surface protein, a cytokine, a chemokine, and a checkpoint inhibitor antibody. The circuits triggered selective T cell-mediated killing of cancer cells, but not of normal cells, in vitro. In in vivo efficacy assays, lentiviral circuit delivery mediated significant tumor reduction and prolonged mouse survival. Our design could be adapted to drive additional immunomodulators, sense other cancers, and potentially treat other diseases that require precise immunological programming.

Transcriptional Pause Sites Delineate Stable Nucleosome-Associated Premature Polyadenylation Suppressed by U1 snRNP.

Regulation of RNA polymerase II (Pol II) elongation is a critical step in gene regulation. Here, we report that U1 snRNP recognition and transcription pausing at stable nucleosomes are linked through premature polyadenylation signal (PAS) termination. By generating RNA exosome conditional deletion mouse embryonic stem cells, we identified a large class of polyadenylated short transcripts in the sense direction destabilized by the RNA exosome. These PAS termination events are enriched at the first few stable nucleosomes flanking CpG islands and suppressed by U1 snRNP. Thus, promoter-proximal Pol II pausing consists of two processes: TSS-proximal and +1 stable nucleosome pausing, with PAS termination coinciding with the latter. While pausing factors NELF/DSIF only function in the former step, flavopiridol-sensitive mechanism(s) and Myc modulate both steps. We propose that premature PAS termination near the nucleosome-associated pause site represents a common transcriptional elongation checkpoint regulated by U1 snRNP recognition, nucleosome stability, and Myc activity.

An Aspirin-Free Versus Dual Antiplatelet Strategy for Coronary Stenting: STOPDAPT-3 Randomized Trial.

BACKGROUND: Bleeding rates on dual antiplatelet therapy (DAPT) within 1 month after percutaneous coronary intervention (PCI) remain high in clinical practice, particularly in patients with acute coronary syndrome or high bleeding risk. Aspirin-free strategy might result in lower bleeding early after PCI without increasing cardiovascular events, but its efficacy and safety have not yet been proven in randomized trials. METHODS: We randomly assigned 6002 patients with acute coronary syndrome or high bleeding risk just before PCI either to prasugrel (3.75 mg/day) monotherapy or to DAPT with aspirin (81-100 mg/day) and prasugrel (3.75 mg/day) after loading of 20 mg of prasugrel in both groups. The coprimary end points were major bleeding (Bleeding Academic Research Consortium 3 or 5) for superiority and cardiovascular events (a composite of cardiovascular death, myocardial infarction, definite stent thrombosis, or ischemic stroke) for noninferiority with a relative 50% margin. RESULTS: The full analysis set population consisted of 5966 patients (no-aspirin group, 2984 patients; DAPT group, 2982 patients; age, 71.6±11.7 years; men, 76.6%; acute coronary syndrome, 75.0%). Within 7 days before randomization, aspirin alone, aspirin with P2Y12 inhibitor, oral anticoagulants, and intravenous heparin infusion were given in 21.3%, 6.4%, 8.9%, and 24.5%, respectively. Adherence to the protocol-specified antiplatelet therapy was 88% in both groups at 1 month. At 1 month, the no-aspirin group was not superior to the DAPT group for the coprimary bleeding end point (4.47% and 4.71%; hazard ratio, 0.95 [95% CI, 0.75-1.20]; Psuperiority=0.66). The no-aspirin group was noninferior to the DAPT group for the coprimary cardiovascular end point (4.12% and 3.69%; hazard ratio, 1.12 [95% CI, 0.87-1.45]; Pnoninferiority=0.01). There was no difference in net adverse clinical outcomes and each component of coprimary cardiovascular end point. There was an excess of any unplanned coronary revascularization (1.05% and 0.57%; hazard ratio, 1.83 [95%CI, 1.01-3.30]) and subacute definite or probable stent thrombosis (0.58% and 0.17%; hazard ratio, 3.40 [95% CI, 1.26-9.23]) in the no-aspirin group compared with the DAPT group. CONCLUSIONS: The aspirin-free strategy using low-dose prasugrel compared with the DAPT strategy failed to attest superiority for major bleeding within 1 month after PCI but was noninferior for cardiovascular events within 1 month after PCI. However, the aspirin-free strategy was associated with a signal suggesting an excess of coronary events. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT04609111.

Aspirin versus Clopidogrel Monotherapy After Percutaneous Coronary Intervention: 1-Year Follow-up of the STOPDAPT-3 Trial.

BACKGROUND AND AIMS: There was no previous trial comparing aspirin monotherapy with a P2Y12 inhibitor monotherapy following short dual antiplatelet therapy (DAPT) after percutaneous coronary intervention (PCI) with drug-eluting stents (DES). METHODS: In the STOPDAPT-3, patients with acute coronary syndrome (ACS) or high bleeding risk (HBR) were randomly assigned to either 1-month DAPT with aspirin and prasugrel followed by aspirin monotherapy (aspirin group) or 1-month prasugrel monotherapy followed by clopidogrel monotherapy (clopidogrel group). This secondary analysis compared aspirin monotherapy with clopidogrel monotherapy by the 30-day landmark analysis. The co-primary endpoints were the cardiovascular endpoint defined as a composite of cardiovascular death, myocardial infarction, definite stent thrombosis, or ischaemic stroke, and the bleeding endpoint defined as Bleeding Academic Research Consortium 3 or 5. RESULTS: Of 6002 assigned patients, 5833 patients (aspirin group: N = 2920 and clopidogrel group: N = 2913) were included in the 30-day landmark analysis. Median age was 73 (interquartile range 64-80) years, women 23.4%, ACS 74.6%, and HBR 54.1%. The assigned monotherapy was continued at 1 year in 87.5% and 87.2% in the aspirin and clopidogrel groups, respectively. The incidence rates beyond 30 days and up to 1 year were similar between the aspirin and clopidogrel groups for both cardiovascular endpoint (4.5 and 4.5 per 100 person-year, hazard ratio [HR] 1.00 [95% confidence interval (CI) 0.77-1.30], P = .97), and bleeding endpoint (2.0 and 1.9, HR 1.02 [95% CI 0.69-1.52], P = .92). CONCLUSIONS: Aspirin monotherapy compared to clopidogrel monotherapy was associated with similar cardiovascular and bleeding outcomes beyond 1 month and up to 1 year after PCI with DES.

In-hospital initiation of angiotensin receptor-neprilysin inhibition in acute heart failure: the PREMIER trial.

BACKGROUND AND AIMS: The efficacy and safety of early sacubitril/valsartan (Sac/Val) initiation after acute heart failure (AHF) has not been demonstrated outside North America. The present study aimed to evaluate the effect of in-hospital Sac/Val therapy initiation after an AHF episode on N-terminal pro-B-type natriuretic peptide (NT-proBNP) level in Japanese patients. METHODS: This was an investigator-initiated, multicentre, prospective, randomized, open-label, blinded-endpoint pragmatic trial. After haemodynamic stabilization within 7 days after hospitalization, eligible inpatients were allocated to switch from angiotensin-converting enzyme inhibitor or angiotensin receptor blocker to Sac/Val (Sac/Val group) or to continue angiotensin-converting enzyme inhibitor or angiotensin receptor blocker (control group). The primary efficacy endpoint was the 8-week proportional change in geometric means of NT-proBNP levels. RESULTS: A total of 400 patients were equally randomized, and 376 (median age 75 years, 31.9% women, de novo heart failure rate 55.6%, and median left ventricular ejection fraction 37%) were analysed. The per cent changes in NT-proBNP level geometric means at Weeks 4/8 were -35%/-45% (Sac/Val group) and -18%/-32% (control group), and their group ratio (Sac/Val vs. control) was 0.80 (95% confidence interval 0.68-0.94; P = .008) at Week 4 and 0.81 (95% confidence interval 0.68-0.95; P = .012) at Week 8, respectively. In the pre-specified subgroup analyses, the effects of Sac/Val were confined to patients with a left ventricular ejection fraction < 40% and were more evident in those in sinus rhythm and taking mineralocorticoid receptor antagonists. No adverse safety signal was evident. CONCLUSIONS: In-hospital Sac/Val therapy initiation in addition to contemporary recommended therapy triggered a greater NT-proBNP level reduction in Japanese patients hospitalized for AHF. These findings may expand the evidence on Sac/Val therapy in this clinical situation outside North America. CLINICAL TRIAL REGISTRATION: ClinicalTrial.gov (NCT05164653) and Japan Registry of Clinical Trials (jRCTs021210046).

SVCT2/SLC23A2 is a sodium-dependent urate transporter: functional properties and practical application.

Urate transporters play a pivotal role in urate handling in the human body, but the urate transporters identified to date do not account for all known molecular processes of urate handling, suggesting the presence of latent machineries. We recently showed that a urate transporter SLC2A12 is also a physiologically important exporter of ascorbate (the main form of vitamin C in the body) that would cooperate with an ascorbate importer, sodium-dependent vitamin C transporter 2 (SVCT2). Based on the dual functions of SLC2A12 and cooperativity between SLC2A12 and SVCT2, we hypothesized that SVCT2 might be able to transport urate. To test this proposal, we conducted cell-based analyses using SVCT2-expressing mammalian cells. The results demonstrated that SVCT2 is a novel urate transporter. Vitamin C inhibited SVCT2-mediated urate transport with a half-maximal inhibitory concentration of 36.59 µM, suggesting that the urate transport activity may be sensitive to physiological ascorbate levels in blood. Similar results were obtained for mouse Svct2. Further, using SVCT2 as a sodium-dependent urate importer, we established a cell-based urate efflux assay that will be useful for identification of other novel urate exporters as well as functional characterization of nonsynonymous variants of already-identified urate exporters including ATP-binding cassette transporter G2. While more studies will be needed to elucidate the physiological impact of SVCT2-mediated urate transport, our findings deepen understanding of urate transport machineries.

Effect of antiemetics on zolbetuximab-induced gastric injury and emesis in ferrets.

Claudin-18 splice variant 2 (CLDN18.2), a tight junction protein, is a highly cell type-specific antigen that is expressed by differentiated gastric mucosa cells. The expression of CLDN18.2 in gastric mucosa cells may be retained upon malignant transformation and is displayed on the surface of several tumors, including gastric/gastroesophageal junction adenocarcinoma. Zolbetuximab is a genetically engineered, highly purified chimeric (mouse/human IgG1) antibody directed against CLDN18.2. Nausea and vomiting were observed as adverse events of zolbetuximab. To investigate the mechanism of nausea and vomiting in humans, we evaluated emesis (retching and vomiting) and conducted histopathologic assessment in ferrets after the administration of zolbetuximab. Emesis was frequently observed in all ferrets treated with zolbetuximab in the first hour after administration. Histopathologic assessment revealed the surface of the gastric mucosa was the primary site of emesis-associated tissue damage. The effect of antiemetics (dexamethasone, ondansetron, fosaprepitant, and olanzapine) on emesis induced by zolbetuximab was investigated. Fosaprepitant showed suppressive effects on emesis, and use of dexamethasone or concomitant use of fosaprepitant with other antiemetics tended to alleviate gastric tissue damage. The onset of emesis in humans receiving zolbetuximab may be associated with damage in the gastric mucosa, and antiemetics may mitigate gastrointestinal adverse events.

Factors Associated With Sacubitril/Valsartan Continuation and the Methods of Combining Heart Failure Medications in Patients With Heart Failure.

BACKGROUND: Sacubitril/valsartan (SV) is recommended for patients with heart failure (HF). In addition, a combination of 4 HF medications, including SV, is recommended in patients with HF with reduced ejection fraction (HFrEF). However, evidence on the characteristics of patients who could continue SV and its initiation methods is limited. OBJECTIVE: To investigate the factors associated with SV continuation and methods of combining HF medications. METHODS: This retrospective cohort study included HF patients who initiated with SV at our institution. The endpoint was SV continuation for 6 months after its initiation. Multivariate analysis was used to extract factors associated with SV continuation. The relationship between the methods of combining HF medications (renin-angiotensin system inhibitors, beta-blockers, mineralocorticoid receptor antagonists, or sodium-glucose cotransporter 2 inhibitors), including the number of HF medications, their combination patterns, and the timing of their initiation, and SV continuation was examined in patients with HFrEF. RESULTS: Of 186 eligible patients, 68.8% had HFrEF, and 79.0% continued SV for 6 months. Significant factors associated with SV continuation were albumin ≥ 3.5 g/dL (odds ratio, 4.81; 95% confidence interval, 2.19-10.59), body mass index (BMI) ≥ 18.5 kg/m2 (4.17; 1.10-15.85), and systolic blood pressure (SBP) ≥ 110 mmHg (2.66; 1.12-6.28). In patients with HFrEF, the proportion of HF medications not initiated simultaneously with SV was significantly higher in the continuation group than in the discontinuation group (67.3% vs 33.3%, P = 0.002). The number of HF medications and their combination patterns were not significantly associated with SV continuation. CONCLUSION AND RELEVANCE: Albumin, BMI, and SBP are useful indicators for selecting patients who are likely to continue SV. In addition, initiating only SV without simultaneously initiating other HF medications in patients with HFrEF may lead to SV continuation.

Crystal structures of the gastric proton pump.

The gastric proton pump-the H+, K+-ATPase-is a P-type ATPase responsible for acidifying the gastric juice down to pH 1. This corresponds to a million-fold proton gradient across the membrane of the parietal cell, the steepest known cation gradient of any mammalian tissue. The H+, K+-ATPase is an important target for drugs that treat gastric acid-related diseases. Here we present crystal structures of the H+, K+-ATPase in complex with two blockers, vonoprazan and SCH28080, in the luminal-open state, at 2.8 Å resolution. The drugs have partially overlapping but clearly distinct binding modes in the middle of a conduit running from the gastric lumen to the cation-binding site. The crystal structures suggest that the tight configuration at the cation-binding site lowers the pK a value of Glu820 sufficiently to enable the release of a proton even into the pH 1 environment of the stomach.

Coupling of bone resorption and formation by RANKL reverse signalling.

Receptor activator of nuclear factor-kappa B (RANK) ligand (RANKL) binds RANK on the surface of osteoclast precursors to trigger osteoclastogenesis. Recent studies have indicated that osteocytic RANKL has an important role in osteoclastogenesis during bone remodelling; however, the role of osteoblastic RANKL remains unclear. Here we show that vesicular RANK, which is secreted from the maturing osteoclasts, binds osteoblastic RANKL and promotes bone formation by triggering RANKL reverse signalling, which activates Runt-related transcription factor 2 (Runx2). The proline-rich motif in the RANKL cytoplasmic tail is required for reverse signalling, and a RANKL(Pro29Ala) point mutation reduces activation of the reverse signalling pathway. The coupling of bone resorption and formation is disrupted in RANKL(Pro29Ala) mutant mice, indicating that osteoblastic RANKL functions as a coupling signal acceptor that recognizes vesicular RANK. RANKL reverse signalling is therefore a potential pharmacological target for avoiding the reduced bone formation associated with inhibition of osteoclastogenesis.

Retrospective evaluation of medical information for predicting tazobactam/piperacillin-induced liver injury.

OBJECTIVE: Tazobactam/piperacillin is a first-line treatment option for hospital-acquired pneumonia; however, drug-induced liver injury (DILI) is relatively frequently observed with tazobactam/piperacillin in clinical practice. This study aimed to verify the usefulness of available patient data for predicting DILI prior to tazobactam/piperacillin administration. MATERIALS AND METHODS: Tazobactam/piperacillin-treated patients were retrospectively selected and divided into patients with and without DILI. Comparative analysis was performed regarding age, gender, dose, duration of treatment, clinical laboratory values prior to treatment initiation, and the types of organ-specific infections in both groups. RESULTS: Multiple logistic regression analyses indicated that elevated C-reactive protein (odds ratio (OR), 1.284; 95% confidence interval (CI), 1.172 - 1.406; p < 0.001) and high hemoglobin (OR, 1.697; 95% CI, 1.259 - 2.286; p < 0.001) levels prior to the administration of tazobactam/piperacillin were risk factors for DILI in males who received a 4.5-g dose. A predictive model for DILI risk was constructed by combining these test values and analyzed using receiver operating characteristic curves, obtaining 0.910 for the model construction set and 0.845 for the validation set. CONCLUSION: The development of DILI was predicted with good accuracy in males who received a 4.5-g dose with elevated C-reactive protein and hemoglobin.

Risk factors for infliximab-induced infusion reactions based on a retrospective study of medical information.

OBJECTIVE: Infliximab is indicated for a wide range of diseases, and infusion reactions (IRs) have been reported after infliximab administration in 17.6% of patients in clinical practice. This study aimed to identify the risk factors for IRs before the administration of infliximab based on available patient information. MATERIALS AND METHODS: We retrospectively analyzed patients treated with infliximab. Data were compared between patients with and without IRs immediately before initiation of infliximab. RESULTS: Elevated C-reactive protein (CRP) (odds ratio (OR), 2.150; 95% confidence interval (CI), 1.329 - 3.477; p = 0.002) before infliximab administration was a significant risk factor for developing an IR. CONCLUSION: Patients with elevated CRP levels before therapy initiation may require more careful monitoring after infliximab administration.

Structural analysis of the water channel AQP2 by single-particle cryo-EM.

Water channels, which are small membrane proteins almost entirely buried in lipid membranes, are challenging research targets for single-particle cryo-electron microscopy (cryo-EM), a powerful technique routinely used to determine the structures of membrane proteins. Because the single-particle method enables structural analysis of a whole protein with flexible parts that interfere with crystallization, we have focused our efforts on analyzing water channel structures. Here, utilizing this system, we analyzed the structure of full-length aquaporin-2 (AQP2), a primary regulator of vasopressin-dependent reabsorption of water at the renal collecting ducts. The 2.9 Å resolution map revealed a cytoplasmic extension of the cryo-EM density that was presumed to be the highly flexible C-terminus at which the localization of AQP2 is regulated in the renal collecting duct cells. We also observed a continuous density along the common water pathway inside the channel pore and lipid-like molecules at the membrane interface. Observations of these constructions in the AQP2 structure analyzed without any fiducial markers (e.g., a rigidly bound antibody) indicate that single-particle cryo-EM will be useful for investigating water channels in native states as well as in complexes with chemical compounds.

Vitamin C transporter SVCT1 serves a physiological role as a urate importer: functional analyses and in vivo investigations.

Uric acid, the end product of purine metabolism in humans, is crucial because of its anti-oxidant activity and a causal relationship with hyperuricemia and gout. Several physiologically important urate transporters regulate this water-soluble metabolite in the human body; however, the existence of latent transporters has been suggested in the literature. We focused on the Escherichia coli urate transporter YgfU, a nucleobase-ascorbate transporter (NAT) family member, to address this issue. Only SLC23A proteins are members of the NAT family in humans. Based on the amino acid sequence similarity to YgfU, we hypothesized that SLC23A1, also known as sodium-dependent vitamin C transporter 1 (SVCT1), might be a urate transporter. First, we identified human SVCT1 and mouse Svct1 as sodium-dependent low-affinity/high-capacity urate transporters using mammalian cell-based transport assays. Next, using the CRISPR-Cas9 system followed by the crossing of mice, we generated Svct1 knockout mice lacking both urate transporter 1 and uricase. In the hyperuricemic mice model, serum urate levels were lower than controls, suggesting that Svct1 disruption could reduce serum urate. Given that Svct1 physiologically functions as a renal vitamin C re-absorber, it could also be involved in urate re-uptake from urine, though additional studies are required to obtain deeper insights into the underlying mechanisms. Our findings regarding the dual-substrate specificity of SVCT1 expand the understanding of urate handling systems and functional evolutionary changes in NAT family proteins.

Prior treatment with oxaliplatin-containing regimens and higher total bilirubin levels are risk factors for neutropenia and febrile neutropenia in patients with gastric or esophagogastric junction cancer receiving weekly paclitaxel and ramucirumab therapy: a single center retrospective study.

BACKGROUND: Weekly paclitaxel + ramucirumab (wPTX + RAM) therapy is recommended as the standard second-line chemotherapy regimen for unresectable advanced/recurrent gastric cancer (GC) or esophagogastric junction cancer. Recent subgroup analysis of the RAINBOW trial revealed a higher frequency of severe neutropenia due to wPTX + RAM in Japanese compared to Western patients. However, no risk factors for severe neutropenia have been identified. METHODS: This retrospective observational study included patients with advanced/unresectable gastric or esophagogastric junction cancer who received wPTX + RAM after failure to respond to platinum and fluoropyrimidine doublet chemotherapy between June 2015 and April 2020. We conducted multivariable logistic regression analyses to identify the risk factors associated with grade 4 neutropenia and febrile neutropenia (FN). In addition, we investigated the relationship between the number of risk factors and overall survival (OS) and progression-free survival (PFS). RESULTS: Among 66 patients who met the inclusion criteria, grade 4 neutropenia and FN occurred in 21 (31.8%) and 12 (18.2%) patients, respectively. Prior treatment with oxaliplatin-containing regimens was identified as an independent risk factor for developing grade 4 neutropenia (odds ratio (OR) 20.034, 95% confidence interval (95% CI) 3.216-124.807, P = 0.001). Total bilirubin of > 1.5 mg/dL (OR 31.316, 95% CI 2.052-477.843, P = 0.013) and prior treatment with oxaliplatin-containing regimen (OR 12.502, 95% CI 1.141-137.022, P = 0.039) were identified as independent risk factors for developing FN. Next, we classified patients with 0, 1, 2 risk factor(s) as RF-0, RF-1, and RF-2 subgroups, respectively, and compared the PFS and OS among the three subgroups. PFS was not significantly different among the three subgroups, whereas OS was significantly shorter in the RF-2 subgroup (median 1.4 month, 95% CI 0.0-5.3 month) than in the RF-0 subgroup (median 10.2 month, 95% CI 6.8-13.5 month, P < 0.01 vs RF-2) and RF-1 subgroup (median 13.3 month, 95% CI 10.9-15.7 month, P < 0.01 vs RF-2). CONCLUSIONS: Careful monitoring for grade 4 neutropenia and FN is needed for patients receiving wPTX + RAM therapy who have a history of treatment with oxaliplatin-containing regimens and higher total bilirubin levels.