Malic enzyme 2 maintains metabolic state and anti-tumor immunity of CD8+ T cells.

The functional integrity of CD8+ T cells is closely linked to metabolic reprogramming; therefore, understanding the metabolic basis of CD8+ T cell activation and antitumor immunity could provide insights into tumor immunotherapy. Here, we report that ME2 is critical for mouse CD8+ T cell activation and immune response against malignancy. ME2 deficiency suppresses CD8+ T cell activation and anti-tumor immune response in vitro and in vivo. Mechanistically, ME2 depletion blocks the TCA cycle flux, leading to the accumulation of fumarate. Fumarate directly binds to DAPK1 and inhibits its activity by competing with ATP for binding. Notably, pharmacological inhibition of DAPK1 abolishes the anti-tumor function conferred by ME2 to CD8+ T cells. Collectively, these findings demonstrate a role for ME2 in the regulation of CD8+ T cell metabolism and effector functions as well as an unexpected function for fumarate as a metabolic signal in the inhibition of DAPK1.

p53 protects against alcoholic fatty liver disease via ALDH2 inhibition.

The tumor suppressor p53 is critical for tumor suppression, but the regulatory role of p53 in alcohol-induced fatty liver remains unclear. Here, we show a role for p53 in regulating ethanol metabolism via acetaldehyde dehydrogenase 2 (ALDH2), a key enzyme responsible for the oxidization of alcohol. By repressing ethanol oxidization, p53 suppresses intracellular levels of acetyl-CoA and histone acetylation, leading to the inhibition of the stearoyl-CoA desaturase-1 (SCD1) gene expression. Mechanistically, p53 directly binds to ALDH2 and prevents the formation of its active tetramer and indirectly limits the production of pyruvate that promotes the activity of ALDH2. Notably, p53-deficient mice exhibit increased lipid accumulation, which can be reversed by ALDH2 depletion. Moreover, liver-specific knockdown of SCD1 alleviates ethanol-induced hepatic steatosis caused by p53 loss. By contrast, overexpression of SCD1 in liver promotes ethanol-induced fatty liver development in wild-type mice, while it has a mild effect on p53-/- or ALDH2-/- mice. Overall, our findings reveal a previously unrecognized function of p53 in alcohol-induced fatty liver and uncover pyruvate as a natural regulator of ALDH2.

Cellular redox homeostasis maintained by malic enzyme 2 is essential for MYC-driven T cell lymphomagenesis.

T cell lymphomas (TCLs) are a group of rare and heterogeneous tumors. Although proto-oncogene MYC has an important role in driving T cell lymphomagenesis, whether MYC carries out this function remains poorly understood. Here, we show that malic enzyme 2 (ME2), one of the NADPH-producing enzymes associated with glutamine metabolism, is essential for MYC-driven T cell lymphomagenesis. We establish a CD4-Cre; Myc flox/+transgenic mouse mode, and approximately 90% of these mice develop TCL. Interestingly, knockout of Me2 in Myc transgenic mice almost completely suppresses T cell lymphomagenesis. Mechanistically, by transcriptionally up-regulating ME2, MYC maintains redox homeostasis, thereby increasing its tumorigenicity. Reciprocally, ME2 promotes MYC translation by stimulating mTORC1 activity through adjusting glutamine metabolism. Treatment with rapamycin, an inhibitor of mTORC1, blocks the development of TCL both in vitro and in vivo. Therefore, our findings identify an important role for ME2 in MYC-driven T cell lymphomagenesis and reveal that MYC-ME2 circuit may be an effective target for TCL therapy.

Vimentin regulates nuclear segmentation in neutrophils.

Granulocytes are indispensable for various immune responses. Unlike other cell types in the body, the nuclei of granulocytes, particularly neutrophils, are heavily segmented into multiple lobes. Although this distinct morphological feature has long been observed, the underlying mechanism remains incompletely characterized. In this study, we utilize cryo-electron tomography to examine the nuclei of mouse neutrophils, revealing the cytoplasmic enrichment of intermediate filaments on the concave regions of the nuclear envelope. Aided by expression profiling and immuno-electron microscopy, we then elucidate that the intermediate-filament protein vimentin is responsible for such perinuclear structures. Of importance, exogenously expressed vimentin in nonimmune cells is sufficient to form cytoplasmic filaments wrapping on the concave nuclear surface. Moreover, genetic deletion of the protein causes a significant reduction of the number of nuclear lobes in neutrophils and eosinophils, mimicking the hematological condition of the Pelger-Huët anomaly. These results have uncovered a new component establishing the nuclear segmentation of granulocytes.

Inactivation of Malic Enzyme 1 in Endothelial Cells Alleviates Pulmonary Hypertension.

BACKGROUND: Pulmonary hypertension (PH) is a progressive cardiopulmonary disease with a high mortality rate. Although growing evidence has revealed the importance of dysregulated energetic metabolism in the pathogenesis of PH, the underlying cellular and molecular mechanisms are not fully understood. In this study, we focused on ME1 (malic enzyme 1), a key enzyme linking glycolysis to the tricarboxylic acid cycle. We aimed to determine the role and mechanistic action of ME1 in PH. METHODS: Global and endothelial-specific ME1 knockout mice were used to investigate the role of ME1 in hypoxia- and SU5416/hypoxia (SuHx)-induced PH. Small hairpin RNA and ME1 enzymatic inhibitor (ME1*) were used to study the mechanism of ME1 in pulmonary artery endothelial cells. Downstream key metabolic pathways and mediators of ME1 were identified by metabolomics analysis in vivo and ME1-mediated energetic alterations were examined by Seahorse metabolic analysis in vitro. The pharmacological effect of ME1* on PH treatment was evaluated in PH animal models induced by SuHx. RESULTS: We found that ME1 protein level and enzymatic activity were highly elevated in lung tissues of patients and mice with PH, primarily in vascular endothelial cells. Global knockout of ME1 protected mice from developing hypoxia- or SuHx-induced PH. Endothelial-specific ME1 deletion similarly attenuated pulmonary vascular remodeling and PH development in mice, suggesting a critical role of endothelial ME1 in PH. Mechanistic studies revealed that ME1 inhibition promoted downstream adenosine production and activated A2AR-mediated adenosine signaling, which leads to an increase in nitric oxide generation and a decrease in proinflammatory molecule expression in endothelial cells. ME1 inhibition activated adenosine production in an ATP-dependent manner through regulating malate-aspartate NADH (nicotinamide adenine dinucleotide plus hydrogen) shuttle and thereby balancing oxidative phosphorylation and glycolysis. Pharmacological inactivation of ME1 attenuated the progression of PH in both preventive and therapeutic settings by promoting adenosine production in vivo. CONCLUSIONS: Our findings indicate that ME1 upregulation in endothelial cells plays a causative role in PH development by negatively regulating adenosine production and subsequently dysregulating endothelial functions. Our findings also suggest that ME1 may represent as a novel pharmacological target for upregulating protective adenosine signaling in PH therapy.

p53 regulation of ammonia metabolism through urea cycle controls polyamine biosynthesis.

Cancer cells exhibit altered and usually increased metabolic processes to meet their high biogenetic demands1,2. Under these conditions, ammonia is concomitantly produced by the increased metabolic processing. However, it is unclear how tumour cells dispose of excess ammonia and what outcomes might be caused by the accumulation of ammonia. Here we report that the tumour suppressor p53, the most frequently mutated gene in human tumours, regulates ammonia metabolism by repressing the urea cycle. Through transcriptional downregulation of CPS1, OTC and ARG1, p53 suppresses ureagenesis and elimination of ammonia in vitro and in vivo, leading to the inhibition of tumour growth. Conversely, downregulation of these genes reciprocally activates p53 by MDM2-mediated mechanism(s). Furthermore, the accumulation of ammonia causes a significant decline in mRNA translation of the polyamine biosynthetic rate-limiting enzyme ODC, thereby inhibiting the biosynthesis of polyamine and cell proliferation. Together, these findings link p53 to ureagenesis and ammonia metabolism, and further reveal a role for ammonia in controlling polyamine biosynthesis and cell proliferation.

Publisher Correction: p53 regulation of ammonia metabolism through urea cycle controls polyamine biosynthesis.

In Fig. 1c of this Letter, the labels p53+/+ and p53-/- were inadvertently swapped. The original figure has been corrected online.

A benchmarking framework for the accurate and cost-effective detection of clinically-relevant structural variants for cancer target identification and diagnosis.

BACKGROUND: Accurate clinical structural variant (SV) calling is essential for cancer target identification and diagnosis but has been historically challenging due to the lack of ground truth for clinical specimens. Meanwhile, reduced clinical-testing cost is the key to the widespread clinical utility. METHODS: We analyzed massive data from tumor samples of 476 patients and developed a computational framework for accurate and cost-effective detection of clinically-relevant SVs. In addition, standard materials and classical experiments including immunohistochemistry and/or fluorescence in situ hybridization were used to validate the developed computational framework. RESULTS: We systematically evaluated the common algorithms for SV detection and established an expert-reviewed SV call set of 1,303 tumor-specific SVs with high-evidence levels. Moreover, we developed a random-forest-based decision model to improve the true positive of SVs. To independently validate the tailored 'two-step' strategy, we utilized standard materials and classical experiments. The accuracy of the model was over 90% (92-99.78%) for all types of data. CONCLUSION: Our study provides a valuable resource and an actionable guide to improve cancer-specific SV detection accuracy and clinical applicability.

PDGFRA exhibits potential as an indicator of angiogenesis within the tumor microenvironment and is up-regulated in BLCA.

Bladder cancer (BLCA) is a common type of urogenital malignancy worldwide. The recurrence and metastasis of bladder cancer are closely related to angiogenesis, but the underlying mechanisms are unclear. In this study, we developed a method to predict survival outcomes among BLCA patients, which could be used to guide immunotherapy and chemotherapy. We obtained patient data from The Cancer Genome Atlas (TCGA) and identified angiogenesis-related genes from the GeneCards database. First, we used differential expression analysis and univariate Cox analysis to identify angiogenesis-related genes and used correlation analysis to generate molecular subtypes based on M2 macrophages. Next, we constructed a prognostic signature consisting of four genes (ECM1, EFEMP1, SLIT2, and PDGFRΑ), which was found to be an independent prognostic factor. Higher risk scores were associated with worse overall survival and higher expression of immune checkpoints. We also evaluated immune cell infiltration using the CIBERSORT and ssGSEA algorithms. Additionally, we performed stratification analyses, constructed a nomogram, and predicted chemotherapeutic responses based on the risk signature. Finally, we validated our findings by using qRT-PCR as well as IHC data to detect the expression levels of the four genes at mRNA and protein levels in BLCA patients and obtained results that were consistent with our predictions. Our study demonstrates the utility of a four-gene prognostic signature for prognostication in bladder cancer patients and designing personalized treatments, which could provide new avenues for personalized management of these patients.

Negative corona discharge strategy for efficient quantum dot light-emitting diodes.

In colloid quantum dot light-emitting diodes (QLEDs), the control of interface states between ZnO and quantum dots (QDs) plays a vital role. We present a straightforward and efficient method using a negative corona discharge to modify the QD film, creating a dipole moment at the interface of QDs and magnesium-doped ZnO (ZnMgO) for balanced charge carrier distribution within the QDs. This process boosts external quantum efficiencies in red, green, and blue QLEDs to 17.71%, 14.53%, and 9.04% respectively. Notably, optimized devices exhibit significant enhancements, especially at lower brightness levels (1000 to 10,000 cd·m-2), vital for applications in mobile displays, TV screens, and indoor lighting.