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Double-stranded DNA (dsDNA) is recognized as a danger signal by cyclic GMP-AMP synthase (cGAS), which triggers innate immune responses. cGAS activity must be properly regulated to maintain immune homeostasis. However, the mechanism by which cGAS activation is controlled remains to be better understood. In this study, we identified USP15 as a cGAS-interacting partner. USP15 promoted DNA-induced cGAS activation and downstream innate immune responses through a positive feedback mechanism. Specifically, USP15 deubiquitylated cGAS and promoted its activation. In the absence of DNA, USP15 drove cGAS dimerization and liquid condensation through the USP15 intrinsic disordered region (IDR), which prepared cGAS for a rapid response to DNA. Upon DNA stimulation, USP15 was induced to express and boost cGAS activation, functioning as an efficient amplifier in innate immune signal transduction. In summary, the positive role played by USP15-mediated cGAS activation may be a novel regulatory mechanism in the fine-tuning of innate immunity.

Cyclic GMP-AMP synthase (cGAS) binds to microbial and self-DNA in the cytosol and synthesizes cyclic GMP-AMP (cGAMP), which activates stimulator of interferon genes (STING) and downstream mediators to elicit an innate immune response. Regulation of cGAS activity is essential for immune homeostasis. Here, we identified the E3 ubiquitin ligase MARCH8 (also known as MARCHF8, c-MIR, and RNF178) as a negative regulator of cGAS-mediated signaling. The immune response to double-stranded DNA was attenuated by overexpression of MARCH8 and enhanced by knockdown or knockout of MARCH8. MARCH8 interacted with the enzymatically active core of cGAS through its conserved RING-CH domain and catalyzed the lysine-63 (K63)–linked polyubiquitylation of cGAS at Lys 411 . This polyubiquitylation event inhibited the DNA binding ability of cGAS, impaired cGAMP production, and attenuated the downstream innate immune response. Furthermore, March8 -deficient mice were less susceptible than their wild-type counterparts to herpes simplex virus 1 (HSV-1) infection. Together, our findings reveal a mechanism underlying the functional regulation of cGAS and the fine-tuning of the innate immune response.

All-inorganic perovskite quantum dot (PeQD) light-emitting diodes (QLEDs) are promising candidates for the next-generation flat-panel displays and semiconductor lighting technology. However, the st...

Double‐stranded DNA is recognized as a danger signal by cyclic guanosine monophosphate‐adenosine monophosphate synthase (cGAS), triggering innate immune responses. Palmitoylation is an important post‐translational modification (PTM) catalyzed by DHHC‐palmitoyl transferases, which participate in the regulation of diverse biological processes. However, whether palmitoylation regulates cGAS function has not yet been explored. Here, we found that palmitoylation of cGAS at C474 restricted its enzymatic activity in the presence of double‐stranded DNA. cGAS palmitoylation was catalyzed mainly by the palmitoyltransferase ZDHHC18 and double‐stranded DNA promoted this modification. Mechanistically, palmitoylation of cGAS reduced the interaction between cGAS and double‐stranded DNA, further inhibiting cGAS dimerization. Consistently, ZDHHC18 negatively regulated cGAS activation in human and mouse cell lines. In a more biologically relevant model system, Zdhhc18‐deficient mice were found to be resistant to infection by DNA viruses, in agreement with the observation that ZDHHC18 negatively regulated cGAS mediated innate immune responses in human and mouse primary cells. In summary, the negative role of ZDHHC18‐mediated cGAS palmitoylation may be a novel regulatory mechanism in the fine‐tuning of innate immunity.

Significance There is an urgent need for alternative antimalarials with the emergence of artemisinin-resistant malaria parasites. Blocking sugar uptake in Plasmodium falciparum by selectively inhibiting the hexose transporter P. falciparum hexose transporter 1 (PfHT1) kills the blood-stage parasites without affecting the host cells, making PfHT1 a promising therapeutic target. Here, we report the development of a series of small-molecule inhibitors that simultaneously target the orthosteric and the allosteric binding sites of PfHT1. These inhibitors all exhibit selective potency on the P. falciparum strains over human cell lines. Our findings establish the basis for the rational design of next-generation antimalarial drugs., Artemisinin-resistant malaria parasites have emerged and have been spreading, posing a significant public health challenge. Antimalarial drugs with novel mechanisms of action are therefore urgently needed. In this report, we exploit a “selective starvation” strategy by inhibiting Plasmodium falciparum hexose transporter 1 (PfHT1), the sole hexose transporter in P. falciparum, over human glucose transporter 1 (hGLUT1), providing an alternative approach to fight against multidrug-resistant malaria parasites. The crystal structure of hGLUT3, which shares 80% sequence similarity with hGLUT1, was resolved in complex with C3361, a moderate PfHT1-specific inhibitor, at 2.3-Å resolution. Structural comparison between the present hGLUT3-C3361 and our previously reported PfHT1-C3361 confirmed the unique inhibitor binding-induced pocket in PfHT1. We then designed small molecules to simultaneously block the orthosteric and allosteric pockets of PfHT1. Through extensive structure–activity relationship studies, the TH-PF series was identified to selectively inhibit PfHT1 over hGLUT1 and potent against multiple strains of the blood-stage P. falciparum. Our findings shed light on the next-generation chemotherapeutics with a paradigm-shifting structure-based design strategy to simultaneously target the orthosteric and allosteric sites of a transporter.

Artemisinin-resistant malaria parasites have emerged and been spreading, posing a significant public health challenge. Anti-malarial drugs with novel mechanisms of action are therefore urgently needed. In this report, we exploit a “selective starvation” strategy by selectively inhibiting Plasmodium falciparum hexose transporter 1 (PfHT1), the sole hexose transporter in Plasmodium falciparum, over human glucose transporter 1 (hGLUT1), providing an alternative approach to fight against multidrug-resistant malaria parasites. Comparison of the crystal structures of human GLUT3 and PfHT1 bound to C3361, a PfHT1-specific moderate inhibitor, revealed an inhibitor binding-induced pocket that presented a promising druggable site. We thereby designed small-molecules to simultaneously block the orthosteric and allosteric pockets of PfHT1. Through extensive structure-activity relationship (SAR) studies, the TH-PF series was identified to selectively inhibit PfHT1 over GLUT1 and potent against multiple strains of the blood-stage P. falciparum. Our findings shed light on the next-generation chemotherapeutics with a paradigm-shifting structure-based design strategy to simultaneously targeting the orthosteric and allosteric sites of a transporter.Significance statementBlocking sugar uptake in P. falciparum by selectively inhibiting the hexose transporter PfHT1 kills the blood-stage parasites without affecting the host cells, indicating PfHT1 as a promising therapeutic target. Here, we report the development of novel small-molecule inhibitors that are selectively potent to the malaria parasites over human cell lines by simultaneously targeting the orthosteric and the allosteric binding sites of PfHT1. Our findings established the basis for the rational design of next-generation anti-malarial drugs.

Nutritional screening has been recommended for hospitalized patients. The goal of this study was to compare the screening value of Nutritional Risk Screening 2002 (NRS-2002), Malnutrition Universal Screening Tool (MUST), and Malnutrition Screening Tool (MST) in inpatients with laryngeal cancer, and to identify which is the most accurate.An observational cross-sectional study of 197 laryngeal cancer patients admitted for surgery was conducted using continuous sampling. NRS-2002, MUST, and MST were used to screen the nutritional risk of patients after admission and before discharge. Diagnostic information and the length-of-hospital stay (LOS) data were extracted from the hospital HIS system.The detection rates of NRS-2002, MUST, and MST in admission or discharge patients were 14.7%/27.9%, 22.3%/26.9%, and 4.6%/11.2%, respectively. Using NRS-2002 as the reference, high sensitivity (82.8%) and a Kappa coefficient (k=0.584) were achieved using MUST in admission patients, while MST presented the lowest sensitivity (17.3%) and Kappa coefficient (k=0.208). MST maintained low sensitivity (25.5%) and Kappa coefficient (k=0.243) in discharge patients. NRS-2002 ≥3 was an independent risk factor for longer LOS in patients with laryngeal cancer (odds ratio (OR)=5.59, 95% confidence interval (CI)=1.86-16.81, p=0.002). The MUST and MST scores did not predict long LOS.Compared with NRS-2002, MUST is superior to MST in sensitivity, specificity, and Kappa coefficient. NRS-2002 better identified patients at risk for longer LOS, but a consistent conclusion was not reached with MUST and MST. Further validation in larger samples is needed.

Summary Plasmodium species, the causative agent of malaria, rely on glucose for energy supply during blood stage. Inhibition of glucose uptake thus represents a potential strategy for the development of antimalarial drugs. Here, we present the crystal structures of PfHT1, the sole hexose transporter in the genome of Plasmodium species, at resolutions of 2.6 A in complex with D-glucose and 3.7 A with a moderately selective inhibitor, C3361. Although both structures exhibit occluded conformations, binding of C3361 induces marked rearrangements that result in an additional pocket. This inhibitor-binding-induced pocket presents an opportunity for the rational design of PfHT1-specific inhibitors. Among our designed C3361 derivatives, several exhibited improved inhibition of PfHT1 and cellular potency against P. falciparum, with excellent selectivity to human GLUT1. These findings serve as a proof of concept for the development of the next-generation antimalarial chemotherapeutics by simultaneously targeting the orthosteric and allosteric sites of PfHT1.