Potential Microemboli Formation Risk and its Management during the Heated Saline Enhanced Radiofrequency (SERF) Needle-tip Catheter Ablation.

BACKGROUND: The potential risk of embolic events during ablation in the left ventricle (LV) with a heated saline-enhanced radiofrequency needle-tip ablation catheter (SERF) has not been characterized. OBJECTIVE: This study aims to investigate formation of microemboli or other untoward events during SERF ablation. METHODS: Ninety-three radiofrequency (RF) ablations were performed in the LV of 14 pigs using a SERF (35W, 70 sec and 60°C normal or degassed saline [NS or DS] irrigation with a flow rate of 10mL/min) versus a standard irrigated-tip RF catheter (S-RF) (30 or 50W, 30sec, and 17ml/min). Microbubble formation was graded based on intracardiac echography (ICE). Microbubbles, microembolic signals and microparticles were monitored using our established model. RESULTS: There was no significant difference in microbubble volume among SERF-NS, SERF-DS and S-RF 30W with "Grade 1" ICE microbubble grade (0.201µL [0.011-3.13], 0.455µL [0.06-2.66] and 0.004µL [0.00-0.16], median [quartiles], respectively). There was no significant difference in microembolic signals among SERF-NS, SERF-DS, and S-RF 30W with "Grade 1" bubbles (n=8.0±5.8, 7.6±4.2 and 6.1±6.1, respectively). Both SERF-NS and SERF-DS created larger lesions than both S-RF 30 and 50W deliveries (1241.5±658.6mm3, 1497.7±893.4mm3, 75.0±24.8mm3 and 184.0±93.8mm3, mean±standard deviation, p<0.001). There was no significant difference in the microparticle incidence among groups (p=0.675). No evidence of embolic events was found in the brain and other organs at the histology assessment. CONCLUSIONS: In the setting of SERF ablation, significantly large LV lesion can be created without any increment in embolic microbubble or particle events. Grade 1 microbubble is related to the efficacy and safety.

Sildenafil amplifies calcium influx and insulin secretion in pancreatic ß cells.

Sildenafil, a phosphodiesterase-5 (PDE5) inhibitor, has been shown to improve insulin sensitivity in animal models and prediabetic patients. However, its other metabolic effects remain poorly investigated. This study examines the impact of sildenafil on insulin secretion in MIN6-K8 mouse clonal ß cells. Sildenafil amplified insulin secretion by enhancing Ca2+ influx. These effects required other depolarizing stimuli in MIN6-K8 cells but not in KATP channel-deficient ß cells, which were already depolarized, indicating that sildenafil-amplified insulin secretion is depolarization-dependent and KATP channel-independent. Interestingly, sildenafil-amplified insulin secretion was inhibited by pharmacological inhibition of R-type channels, but not of other types of voltage-dependent Ca2+ channels (VDCCs). Furthermore, sildenafil-amplified insulin secretion was barely affected when its effect on cyclic GMP was inhibited by PDE5 knockdown. Thus, sildenafil stimulates insulin secretion and Ca2+ influx through R-type VDCCs independently of the PDE5/cGMP pathway, a mechanism that differs from the known pharmacology of sildenafil and conventional insulin secretory pathways. Our results reposition sildenafil as an insulinotropic agent that can be used as a potential antidiabetic medicine and a tool to elucidate the novel mechanism of insulin secretion.

Effects of hypernatremia on the microglia.

Signs and symptoms of hypernatremia largely indicate central nervous system dysfunction. Acute hypernatremia can cause demyelinating lesions similar to that observed in osmotic demyelination syndrome (ODS). We have previously demonstrated that microglia accumulate in ODS lesions and minocycline protects against ODS by inhibiting microglial activation. However, the direct effect of rapid rise in the sodium concentrations on microglia is largely unknown. In addition, the effect of chronic hypernatremia on microglia also remains elusive. Here, we investigated the effects of acute (6 or 24 h) and chronic (the extracellular sodium concentration was increased gradually for at least 7 days) high sodium concentrations on microglia using the microglial cell line, BV-2. We found that both acute and chronic high sodium concentrations increase NOS2 expression and nitric oxide (NO) production. We also demonstrated that the expression of nuclear factor of activated T-cells-5 (NFAT5) is increased by high sodium concentrations. Furthermore, NFAT5 knockdown suppressed NOS2 expression and NO production. We also demonstrated that high sodium concentrations decreased intracellular Ca2+ concentration and an inhibitor of Na+/Ca2+ exchanger, NCX, suppressed a decrease in intracellular Ca2+ concentrations and NOS2 expression and NO production induced by high sodium concentrations. Furthermore, minocycline inhibited NOS2 expression and NO production induced by high sodium concentrations. These in vitro data suggest that microglial activity in response to high sodium concentrations is regulated by NFAT5 and Ca2+ efflux through NCX and is suppressed by minocycline.

Soluble SLAMF7 is generated by alternative splicing in multiple myeloma cells.

Not available.

A Study on the Compatibility of a Food-Recording Application with Questionnaire-Based Methods in Healthy Japanese Individuals.

In Japan, nutritional guidance based on food-recording apps and food frequency questionnaires (FFQs) is becoming popular. However, it is not always recognized that different dietary assessment methods have different nutritional values. Here, we compared the compatibility of dietary intake data obtained from an app with those obtained from FFQs in 59 healthy individuals who recorded information regarding their diet for at least 7 days per month using an app developed by Asken (Tokyo, Japan). The diurnal coefficient of variation in total energy and protein intake was 20%, but those for vitamins B12 and D were >80%, reflecting the importance of 7 days of recording rather than a single day of recording for dietary intake analyses. Then, we compared the results of two FFQs-one based on food groups and one based on a brief self-administered diet history questionnaire-for 7 days, as recorded by the app. There was a correlation coefficient of >0.4 for all the items except salt. Regarding the compatibility between the app and FFQs, the percentage errors for total energy and nutrients were >40-50%, suggesting no agreement between the app and the two FFQs. In conclusion, careful attention should be paid to the impact of different dietary assessment methods on nutrient assessment.

Hepatocytes differentiate into intestinal epithelial cells through a hybrid epithelial/mesenchymal cell state in culture.

Hepatocytes play important roles in the liver, but in culture, they immediately lose function and dedifferentiate into progenitor-like cells. Although this unique feature is well-known, the dynamics and mechanisms of hepatocyte dedifferentiation and the differentiation potential of dedifferentiated hepatocytes (dediHeps) require further investigation. Here, we employ a culture system specifically established for hepatic progenitor cells to study hepatocyte dedifferentiation. We found that hepatocytes dedifferentiate with a hybrid epithelial/mesenchymal phenotype, which is required for the induction and maintenance of dediHeps, and exhibit Vimentin-dependent propagation, upon inhibition of the Hippo signaling pathway. The dediHeps re-differentiate into mature hepatocytes by forming aggregates, enabling reconstitution of hepatic tissues in vivo. Moreover, dediHeps have an unexpected differentiation potential into intestinal epithelial cells that can form organoids in three-dimensional culture and reconstitute colonic epithelia after transplantation. This remarkable plasticity will be useful in the study and treatment of intestinal metaplasia and related diseases in the liver.

Prognostic factors in patients with heart failure and sarcopenia: an observational retrospective study.

BACKGROUND: Heart failure (HF) prevalence increases with age, and sarcopenia is a poor prognostic factor in patients with HF. We aimed to evaluate the characteristics and prognostic factors in patients with HF and sarcopenia. RESULTS: We retrospectively reviewed 256 consecutive patients admitted to our hospital for HF between May 2018 and May 2021, underwent dual-energy X-ray absorptiometry, and were diagnosed with sarcopenia. The primary endpoint was all-cause mortality. The prognoses and characteristics were evaluated and compared between patients with left ventricular ejection fraction (LVEF) < 50% (reduced LVEF, HF with reduced ejection fraction [HFrEF]) and those with LVEF ≥ 50% (preserved LVEF, HF with preserved ejection fraction [HFpEF]). 83 (32%) and 173 (68%) patients had HFrEF and HFpEF, respectively. The HFrEF group had fewer women, lower hypertension rates, higher ischemic heart disease rates, and brain natriuretic peptide (BNP) levels than did the HFpEF group. Kaplan-Meier analysis for all-cause death showed that the HFrEF group had a significantly worse prognosis than the HFpEF group [log-rank p = 0.002]. CONCLUSIONS: In patients with HF and sarcopenia, older age, higher New York Heart Association (NYHA) class, BNP levels, and reduced LVEF were independent predictors of death after evaluation. During the treatment of patients with HF and sarcopenia, it is necessary to manage treatment with close attention to BNP and LVEF.

Changes in repair pathways of radiation-induced DNA double-strand breaks at the midblastula transition in Xenopus embryo.

Ionizing radiation (IR) causes DNA damage, particularly DNA double-strand breaks (DSBs), which have significant implications for genome stability. The major pathways of repairing DSBs are homologous recombination (HR) and nonhomologous end joining (NHEJ). However, the repair mechanism of IR-induced DSBs in embryos is not well understood, despite extensive research in somatic cells. The externally developing aquatic organism, Xenopus tropicalis, serves as a valuable model for studying embryo development. A significant increase in zygotic transcription occurs at the midblastula transition (MBT), resulting in a longer cell cycle and asynchronous cell divisions. This study examines the impact of X-ray irradiation on Xenopus embryos before and after the MBT. The findings reveal a heightened X-ray sensitivity in embryos prior to the MBT, indicating a distinct shift in the DNA repair pathway during embryo development. Importantly, we show a transition in the dominant DSB repair pathway from NHEJ to HR before and after the MBT. These results suggest that the MBT plays a crucial role in altering DSB repair mechanisms, thereby influencing the IR sensitivity of developing embryos.

Incidence of phrenic nerve injury during pulmonary vein isolation using different cryoballoons: data from a large prospective ablation registry.

AIMS: Phrenic nerve injury (PNI) is the most common complication during cryoballoon ablation. Currently, two cryoballoon systems are available, yet the difference is unclear. We sought to compare the acute procedural efficacy and safety of the two cryoballoons. METHODS: This prospective observational study consisted of 2,555 consecutive atrial fibrillation (AF) patients undergoing pulmonary vein isolation (PVI) using either conventional (Arctic Front Advance) (AFA-CB) or novel cryoballoons (POLARx) (POLARx-CB) at 19 centers between January 2022 and October 2023. RESULTS: Among 2,555 patients (68.8 ± 10.9 years, 1,740 men, paroxysmal AF[PAF] 1,670 patients), PVIs were performed by the AFA-CB and POLARx-CB in 1,358 and 1,197 patients, respectively. Touch-up ablation was required in 299(11.7%) patients. The touch-up rate was significantly lower for POLARx-CB than AFA-CB (9.5% vs. 13.6%, p = 0.002), especially for right inferior PVs (RIPVs). The touch-up rate was significantly lower for PAF than non-PAF (8.8% vs. 17.2%, P < 0.001) and was similar between the two cryoballoons in non-PAF patients. Right PNI occurred in 64(2.5%) patients and 22(0.9%) were symptomatic. It occurred during the right superior PV (RSPV) ablation in 39(1.5%) patients. The incidence was significantly higher for POLARx-CB than AFA-CB (3.8% vs. 1.3%, P < 0.001) as was the incidence of symptomatic PNI (1.7% vs. 0.1%, P < 0.001). The difference was significant during RSPV (2.5% vs. 0.7%, P < 0.001) but not RIPV ablation. The PNI recovered more quickly for the AFA-CB than POLARx-CB. CONCLUSIONS: Our study demonstrated a significantly higher incidence of right PNI and lower touch-up rate for the POLARx-CB than AFA-CB in the real-world clinical practice.

Supplementation with cassis polyphenol has no effect on menopausal symptoms in healthy middle-aged women: A randomized, double-blind, parallel-group, placebo-controlled trial.

Hormonal changes during the menopause transition may lead to vasomotor symptoms, including hot flashes (HFs) and neuropsychiatric symptoms such as anxiety and irritability. We hypothesized that the effects of cassis polyphenol (CaP) to improve microcirculation and vasorelaxation may alleviate menopausal symptoms. We performed a randomized, double-blind, parallel-group, placebo-controlled trial involving 59 healthy women (mean [standard deviation] age, 51.3 [4.3] years; body mass index, 20.8 [2.6] kg/m2). Participants experiencing subjective menopausal symptoms consumed CaP tablets (400 mg/d, CaP group) or placebo tablets (placebo group) for 4 weeks. Participants were evaluated using questionnaires at baseline, during the 4-week intervention period, and during a 2-week postinterventional observation period. The primary objective was to evaluate the effects of supplementation with CaP on HFs in healthy Japanese women with menopausal symptoms. Additional assessments included the modified Kupperman menopausal index, World Health Organization-5 Well-Being Index, World Health Organization quality-of-life 26-item index, State-Trait Anxiety Inventory (anxiety and trait components), and Oguri-Shirakawa-Azumi sleep inventory (middle-aged and elderly versions). During the 4-week intervention period, no significant between-group differences were detected in the HF frequency, HF score, sweating frequency, menopausal symptoms, quality of life, anxiety, or sleep. During the 2-week postintervention observational period, the HF score and sweating frequency were significantly decreased in the CaP group compared with the placebo group. These findings suggest that twice daily intake of CaP for 4 weeks does not alleviate menopause symptoms, but the improvement observed in the CaP intake group during the postintervention period warrants confirmation through further large-scale studies.

Raise-up technique for the creation of left atrial roof lesion: A useful technique with cryoballoon for persistent atrial fibrillation.

INTRODUCTION: Recent studies have reported the efficacy of the cryoballoon (CB)-guided left atrial roof block line (LARB) creation in patients with persistent atrial fibrillation (AF). However, it can be technically challenging to attach the balloon to the left atrial (LA) roof due to its anatomical variations. We designed a new procedure called the "Raise-up Technique," which may facilitate the firm adhesion of the CB to the LA roof during freezing. This study aimed to evaluate the efficacy of the Raise-up technique in LARB creation. METHODS AND RESULTS: In total, 100 consecutive patients with persistent AF who underwent CB-LARB creation were enrolled. Fifty-seven patients underwent LARB creation using the Raise-up technique (Raise-up group), and the remaining 43 did not use it (control group). The Raise-up technique was performed as follows: An Achieve catheter was inserted as deeply as possible into the upper branch of the right superior pulmonary vein to anchor the CB. The balloon was placed below the targeted site on the LA roof and frozen. When the temperature of the CB reached approximately -10°C and the CB was easier to attach to the LA tissue, the CB was raised and pressed against the LA roof immediately by sheath advancement. Then the balloon could be in firm contact with the target site on the roof. If necessary, additional sheath advancement after sufficient freezing (-20°C to -30°C) was allowed the CB to have more firm and broad contact with the target site. LARB creation without touch-up ablation was achieved in 54 of 57 patients (94.7%) in the Raise-up group and 33 of 43 patients (76.7%) in the control group (p < .05). The lesion size of the LARB in the Raise-up group was significantly larger than that in the control group (15.2 cm2 vs. 12.8 cm2, p < .05). Moreover, the width of the LARB lesion in the Raise-up group was wider than that in the control group (32.0 mm vs. 26.6 mm, p < .05). CONCLUSION: The Raise-up technique enabled the creation of seamless and thick LARB lesions with a single stroke. In addition, the CB-LARB lesions created using the Raise-up technique tended to be large, resulting in extensive debulking of the LA posterior wall arrhythmia substrates. In CB ablation for persistent AF, the Raise-up technique can be considered one of the key strategies for LARB creation.

A Pregnant Woman with Excess Vasopressinase-Induced Diabetes Insipidus Complicated by Central Diabetes Insipidus like Lymphocytic Infundibulo-Neurohypophysitis.

Background: Gestational diabetes insipidus (DI) is a very rare complication of pregnancy. We present a case of gestational DI combining two different types of DI. Case Presentation. A 39-year-old pregnant woman suddenly presented with thirst, polydipsia, and polyuria after 31 gestation weeks (GWs). Based on laboratory findings of hypotonic urine (78 mOsm/kgH2O) with higher plasma osmolality (298 mOsm/kgH2O) and higher serum sodium levels (149 mEq/L), gestational DI was suspected, and the clinical course was monitored without therapy until the results of a measurement of plasma arginine vasopressin (AVP) levels were available. However, she subsequently developed acute prerenal failure and underwent an emergency cesarean section at 34 GWs. Her resected placenta weighed 920 g, nearly twice the normal weight. Immediately following delivery, intranasal 1-desamino-8-D-arginine vasopressin was administered, and her symptoms promptly disappeared. Afterward, her predelivery plasma AVP level was found to have been inappropriately low (0.7 pg/mL) given her serum sodium level. The patient's serum vasopressinase level just before delivery was 2,855 ng/mL, more than 1,000 times the upper limit of the normal range, suggesting excess vasopressinase-induced DI. The presence of anti-rabphilin-3A antibodies in the patient's blood, a hypertonic saline infusion test result, and loss of the high-intensity signal of the posterior pituitary on fat-suppressed T1-weighted magnetic resonance images without thickening of the stalk and enlargement of the neurohypophysis suggested concurrent central DI-like lymphocytic infundibulo-neurohypophysitis (LINH). Conclusion: In addition to the degradation of AVP by excess placental vasopressinase due to the enlarged placenta, an insufficient compensatory increase in AVP secretion from the posterior pituitary gland due to LINH-like pathogenesis might have led to DI symptoms.

Transgenerational acclimation to acidified seawater and gene expression patterns in a sea urchin.

Transgenerational responses of susceptible calcifying organisms to progressive ocean acidification are an important issue in reducing uncertainty of future predictions. In this study, a two-generation rearing experiment was conducted using mature Mesocentrotus nudus, a major edible sea urchin that occurs along the coasts of northern Japan. Morphological observations and comprehensive gene expression analysis (RNA-seq) of resulting larvae were performed to examine transgenerational acclimation to acidified seawater. Two generations of rearing experiments showed that larvae derived from parents acclimated to acidified seawater tended to have higher survival and show less reduction in body size when exposed to acidified seawater of the same pH, suggesting that a positive carry-over effect occurred. RNA-seq analysis showed that gene expression patterns of larvae originated from both acclimated and non-acclimated parents to acidified seawater tended to be different than control condition, and the gene expression pattern of larvae originated from acclimated parents was substantially different than that of larvae of non-acclimated and control parents.

IgG4-Related Membranous Nephropathy After COVID-19 Vaccination: A Case Report.

Although immunoglobulin G4 (IgG4)-related kidney diseases are typically characterized by tubulointerstitial nephritis with abundant infiltration of IgG4-positive plasma cells and fibrosis, there have been relatively rare cases of IgG4-related glomerulonephritis. Several cases of IgG4-related disease (IgG4-RD) following coronavirus disease 2019 (COVID-19) mRNA vaccination have been reported. However, there are no reports of IgG4-related glomerulonephritis following COVID-19 vaccination. Herein, we present a case of IgG4-related membranous nephropathy (MN) occurring after COVID-19 vaccination. A 69-year-old Japanese male presented to our hospital with edema that started the day after his second COVID-19 vaccination. The patient exhibited nephrotic syndrome and was diagnosed with MN based on the results of a kidney biopsy. Although serum IgG4 levels were elevated to 946 mg/dL, no evidence of organ involvement suggestive of IgG4-RD was observed. Treatment with prednisolone and cyclosporine resulted in complete remission, and immunosuppressive agents were tapered. However, one month after discontinuing the immunosuppressive agents, the patient was readmitted with swelling around the submandibular glands and exertional dyspnea. Serum IgG4 level was markedly elevated at 2,320 mg/dL, and computed tomography revealed submandibular gland swelling and thickening of the interlobular septum and bronchovascular bundles in both lungs. The patient was diagnosed with IgG4-RD based on elevated serum IgG4 levels and infiltration of IgG4-positive plasma cells in the submandibular gland biopsy. Upon resuming treatment with prednisolone, the symptoms attributed to IgG4-RD improved within a few days. In cases of nephrotic syndrome following COVID-19 vaccination, it may be advisable to conduct detailed examinations to assess the possibility of the development of IgG4-RDs.

Single-polyp metabolomics for coral health assessment.

Coral reef ecosystems supported by environmentally sensitive reef-building corals face serious threats from human activities. Our understanding of these reef threats is hampered by the lack of sufficiently sensitive coral environmental impact assessment systems. In this study, we established a platform for metabolomic analysis at the single-coral-polyp level using state-of-the-art mass spectrometry (probe electrospray ionization/tandem mass spectrometry; PESI/MS/MS) capable of fine-scale analysis. We analyzed the impact of the organic UV filter, benzophenone (BP), which has a negative impact on corals. We also analyzed ammonium and nitrate samples, which affect the environmental sensitivity of coral-zooxanthella (Symbiodiniaceae) holobionts, to provide new insights into coral biology with a focus on metabolites. The method established in this study breaks new ground by combining PESI/MS/MS with a technique for coral polyps that can control the presence or absence of zooxanthellae in corals, enabling functions of zooxanthellae to be assessed on a polyp-by-polyp basis for the first time. This system will clarify biological mechanisms of corals and will become an important model system for environmental impact assessment using marine organisms.

Impact of coronavirus disease 2019 on medical practice in endocrine and metabolic diseases in Japan: a nationwide surveillance study conducted by the Japan Endocrine Society.

We investigated the impact of the Coronavirus disease 2019 (COVID-19) pandemic on the management of endocrine and metabolic disorders in Japan. We conducted a cross-sectional nationwide questionnaire survey targeting board-certified endocrinologists under the auspices of the Japan Endocrine Society. The questionnaire consisted of multiple-choice questions and open-ended responses. Out of approximately 2,700 specialists, 528 (19.5%) opted to participate, suggesting a high level of interest in COVID-19 management among endocrinologists. The study found that almost half of participants had encountered cases of endocrine and metabolic disorders following COVID-19 infection or vaccination. Conditions related to thyroid diseases, glucose metabolism disorders/diabetes, and hypothalamic-pituitary disorders were particularly prevalent. Diabetes and obesity were identified as having high rates of severe cases or fatalities due to COVID-19. The study also highlighted challenges in routine diagnosis and treatment, emphasizing the potential benefits of combining remote consultations with in-person visits to optimize the frequency of examinations and check-ups during infectious disease outbreak which disrupts access to healthcare providers. The insights obtained from this survey are expected to contribute to ensuring appropriate healthcare provision for patients with endocrine and metabolic disorders by using flexible consultation formats, particularly even in the conditions where medical access may be limited due to future outbreaks of emerging or re-emerging infectious diseases.

Prospective Multicenter Registry-Based Study on Thyroid Storm: The Guidelines for the Management from Japan are Useful.

CONTEXT: The mortality rate in thyroid storm (TS) has been reported to be higher than 10%. OBJECTIVE: We aimed to evaluate the effectiveness of the 2016 guidelines for the management of TS proposed by the Japan Thyroid Association and Japan Endocrine Society. DESIGN: Prospective registry-based study through a secure web platform. SETTING: Prospective multicenter registry. PATIENTS AND MEASUREMENTS: Patients with new-onset TS were registered in the Research Electronic Data Capture (REDCap). On day 30 after admission, clinical information and prognosis of each patient were added to the platform. On day 180, the prognosis was described. RESULTS: This study included 110 patients with TS. The median of Acute Physiology and Chronic Health Evaluation (APACHE) II score was 13, higher than the score in the previous nationwide epidemiological study, 10 (p = 0.001). Nonetheless, the mortality rate at day 30 was 5.5%, approximately half compared with 10.7% in the previous nationwide survey. Lower body mass index, shock and lower left ventricular ejection fraction were positively associated with poor prognosis at day 30, while the lack of fever ≥ 38℃ was related to the outcome. The mortality rate in patients with an APACHE II score ≥12 for whom the guidelines were not followed was significantly higher than the rate in patients for whom the guidelines were followed (50% vs. 4.7%) (p = 0.01). CONCLUSIONS: Prognosis seemed better than in the previous nationwide survey, even though disease severity was higher. The mortality rate was lower when the guidelines were followed. Thus, the guidelines are useful for managing TS.

An extensive ion-pair/hydrogen-bond network contributes to the thermostability of the MutL ATPase domain from Aquifex aeolicus.

Proteins from hyperthermophiles often contain a large number of ionic interactions. Close examination of the previously determined crystal structure of the ATPase domain of MutL from a hyperthermophile, Aquifex aeolicus, revealed that the domain contains a continuous ion-pair/hydrogen-bond network consisting of 11 charged amino acid residues on a ß-sheet. Mutations were introduced to disrupt the network, showing that the more extensively the network was disrupted, the greater the thermostability of the protein was decreased. Based on urea denaturation analysis, a thermodynamic parameter, energy for the conformational stability, was evaluated, which indicated that amino acid residues in the network contributed additively to the protein stability. A continuous network rather than a cluster of isolated interactions would pay less entropic penalty upon fixing the side chains to make the same number of ion pairs/hydrogen bonds, which might contribute more favorably to the structural formation of thermostable proteins.

PRMT1 Sustains De Novo Fatty Acid Synthesis by Methylating PHGDH to Drive Chemoresistance in Triple-Negative Breast Cancer.

Triple-negative breast cancer (TNBC) chemoresistance hampers the ability to effectively treat patients. Identification of mechanisms driving chemoresistance can lead to strategies to improve treatment. Here, we revealed that protein arginine methyltransferase-1 (PRMT1) simultaneously methylates D-3-phosphoglycerate dehydrogenase (PHGDH), a critical enzyme in serine synthesis, and the glycolytic enzymes PFKFB3 and PKM2 in TNBC cells. 13C metabolic flux analyses showed that PRMT1-dependent methylation of these three enzymes diverts glucose toward intermediates in the serine-synthesizing and serine/glycine cleavage pathways, thereby accelerating the production of methyl donors in TNBC cells. Mechanistically, PRMT1-dependent methylation of PHGDH at R54 or R20 activated its enzymatic activity by stabilizing 3-phosphoglycerate binding and suppressing polyubiquitination. PRMT1-mediated PHGDH methylation drove chemoresistance independently of glutathione synthesis. Rather, activation of the serine synthesis pathway supplied α-ketoglutarate and citrate to increase palmitate levels through activation of fatty acid synthase (FASN). Increased palmitate induced protein S-palmitoylation of PHGDH and FASN to further enhance fatty acid synthesis in a PRMT1-dependent manner. Loss of PRMT1 or pharmacologic inhibition of FASN or protein S-palmitoyltransferase reversed chemoresistance in TNBC. Furthermore, IHC coupled with imaging MS in clinical TNBC specimens substantiated that PRMT1-mediated methylation of PHGDH, PFKFB3, and PKM2 correlates with chemoresistance and that metabolites required for methylation and fatty acid synthesis are enriched in TNBC. Together, these results suggest that enhanced de novo fatty acid synthesis mediated by coordinated protein arginine methylation and protein S-palmitoylation is a therapeutic target for overcoming chemoresistance in TNBC. SIGNIFICANCE: PRMT1 promotes chemoresistance in TNBC by methylating metabolic enzymes PFKFB3, PKM2, and PHGDH to augment de novo fatty acid synthesis, indicating that targeting this axis is a potential treatment strategy.

Injury-induced cooperation of InhibinßA and JunB is essential for cell proliferation in Xenopus tadpole tail regeneration.

In animal species that have the capability of regenerating tissues and limbs, cell proliferation is enhanced after wound healing and is essential for the reconstruction of injured tissue. Although the ability to induce cell proliferation is a common feature of such species, the molecular mechanisms that regulate the transition from wound healing to regenerative cell proliferation remain unclear. Here, we show that upon injury, InhibinßA and JunB cooperatively function for this transition during Xenopus tadpole tail regeneration. We found that the expression of inhibin subunit beta A (inhba) and junB proto-oncogene (junb) is induced by injury-activated TGF-ß/Smad and MEK/ERK signaling in regenerating tails. Similarly to junb knockout (KO) tadpoles, inhba KO tadpoles show a delay in tail regeneration, and inhba/junb double KO (DKO) tadpoles exhibit severe impairment of tail regeneration compared with either inhba KO or junb KO tadpoles. Importantly, this impairment is associated with a significant reduction of cell proliferation in regenerating tissue. Moreover, JunB regulates tail regeneration via FGF signaling, while InhibinßA likely acts through different mechanisms. These results demonstrate that the cooperation of injury-induced InhibinßA and JunB is critical for regenerative cell proliferation, which is necessary for re-outgrowth of regenerating Xenopus tadpole tails.