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Microbial products, such as lipopolysaccharide (LPS), can elicit efficient innate immune responses against invading pathogens. However, priming with LPS can induce a form of innate immune memory, termed innate immune "tolerance", which blunts subsequent NF‐κB signaling. Although epigenetic and transcriptional reprogramming has been shown to play a role in innate immune memory, the involvement of post‐translational regulation remains unclear. Here, we report that ubiquitin‐specific protease 3 (USP3) participates in establishing "tolerance" innate immune memory through non‐transcriptional feedback. Upon NF‐κB signaling activation, USP3 is stabilized and exits the nucleus. The cytoplasmic USP3 specifically removes the K63‐linked polyubiquitin chains on MyD88, thus negatively regulating TLR/IL1β‐induced inflammatory signaling activation. Importantly, cytoplasmic translocation is a prerequisite step for USP3 to deubiquitinate MyD88. Additionally, LPS priming could induce cytoplasmic retention and faster and stronger cytoplasmic translocation of USP3, enabling it to quickly shut down NF‐κB signaling upon the second LPS challenge. This work identifies a previously unrecognized post‐translational feedback loop in the MyD88–USP3 axis, which is critical for inducing normal "tolerance" innate immune memory. Synopsis: USP3 controls innate immune signaling and inflammatory responses by regulating the NF‐κB pathway through the deubiquitination of MyD88. LPS‐priming‐induced cytoplasmic translocation and retention of USP3 are essential for establishing normal "tolerance" innate immune memory.USP3 strongly inhibits the TLRs/IL1β‐induced inflammatory response and NF‐κB signaling by directly targeting MyD88.Upon NF‐κB pathway activation, USP3 is stabilized and moves out of the nucleus to deubiquitinate MyD88 in the cytoplasm.LPS‐priming induces cytoplasmic retention of USP3, resulting in the rapid deubiquitination of MyD88.Cytoplasmic USP3 allows for the robust suppression of NF‐κB signaling upon subsequent challenge with various TLR ligands.Deficiency of USP3 severely disrupts the establishment of normal innate immune tolerance both in vitro and in vivo. [ABSTRACT FROM AUTHOR]

Cyclic GMP‐AMP synthase (cGAS) and stimulator of interferon genes (STING) play critical roles in the innate immunity against infectious diseases and are required to link pathogen DNA sensing to immune responses. However, the mechanisms by which cGAS‐STING‐induced cytokines suppress the adaptive immune response against malaria infections remain poorly understood. Here, cGAS‐STING signaling is identified to play a detrimental role in regulating anti‐malaria immunity. cGAS or STING deficiency in mice markedly prolongs mouse survival during lethal malaria Plasmodium yoelii nigeriensis N67C infections by reducing late interleukin (IL)‐6 production. Mechanistically, cGAS/STING recruits myeloid differentiation factor 88 (MyD88) and specifically induces the p38‐dependent signaling pathway for late IL‐6 production, which, in turn, expands CD11b+Ly6Chi proinflammatory monocytes to inhibit immunity. Moreover, the blockage or ablation of the cGAS‐STING‐MyD88‐p38‐IL‐6 signaling axis or the depletion of CD11b+Ly6Chi proinflammatory monocytes provides mice a significant survival benefit during N67C and other lethal malaria‐strain infections. Taken together, these findings identify a previously unrecognized detrimental role of cGAS‐STING‐MyD88‐p38 axis in infectious diseases through triggering the late IL‐6 production and proinflammatory monocyte expansion and provide insight into how targeting the DNA sensing pathway, dysregulated cytokines, and proinflammatory monocytes enhances immunity against infection. [ABSTRACT FROM AUTHOR]

Abstract: The RIG‐I‐like receptors (RLRs) are critical for protection against RNA virus infection, and their activities must be stringently controlled to maintain immune homeostasis. Here, we report that leucine‐rich repeat containing protein 25 (LRRC25) is a key negative regulator of RLR‐mediated type I interferon (IFN) signaling. Upon RNA virus infection, LRRC25 specifically binds to ISG15‐associated RIG‐I to promote interaction between RIG‐I and the autophagic cargo receptor p62 and to mediate RIG‐I degradation via selective autophagy. Depletion of either LRRC25 or ISG15 abrogates RIG‐I‐p62 interaction as well as the autophagic degradation of RIG‐I. Collectively, our findings identify a previously unrecognized role of LRRC25 in type I IFN signaling activation by which LRRC25 acts as a secondary receptor to assist RIG‐I delivery to autophagosomes for degradation in a p62‐dependent manner. [ABSTRACT FROM AUTHOR]

The purpose of our study was to develop and evaluate a novel integrin αvβ3-specific delivery carrier for transfection of siRNA in malignant tumors. We adopted arginine-glycine-aspartate (RGD) motif as a tissue target for specific recognition of integrin ανβ3. A chimaeric peptide was synthesized by adding nonamer arginine residues (9-arginine [9R]) at the carboxy terminus of cyclic-RGD dimer, designated as c(RGD)2-9R, to enable small interfering RNA (siRNA) binding. To test the applicability of the delivery carrier in vivo, c(RGD)2-9R was labeled with radionuclide of technetium-99m. Biodistribution and γ-camera imaging studies were performed in HepG2 xenograft-bearing nude mice. As results, an optimal 10:1 molar ratio of 99mTc-c(RGD)2-9R to siRNA was indicated by the electrophoresis on agarose gels. 99mTc-c(RGD)2-9R/siRNA remained stable under a set of conditions in vitro. For in vivo study, tumor radioactivity uptake of 99mTc-c(RGD)2-9R/siRNA in nude mice bearing HepG2 xenografts was significantly higher than that of control probe ( P < .05). The xenografts were clearly visualized at 4 hours till 6 hours noninvasively after intravenous injection of 99mTc-c(RGD)2-9R/siRNA, while the xenografts were not visualized at any time after injection of control probe. It was concluded that c(RGD)2-9R could be an effective siRNA delivery carrier. Technetium-99m radiolabeled-delivery carrier represents a potential imaging strategy for RNAi-based therapy. [ABSTRACT FROM AUTHOR]

Autophagy, mediated by a number of autophagy-related ( ATG) proteins, plays an important role in the bulk degradation of cellular constituents. Beclin-1 (also known as Atg6 in yeast) is a core protein essential for autophagic initiation and other biological processes. The activity of Beclin-1 is tightly regulated by multiple post-translational modifications, including ubiquitination, yet the molecular mechanism underpinning its reversible deubiquitination remains poorly defined. Here, we identified ubiquitin-specific protease 19 ( USP19) as a positive regulator of autophagy, but a negative regulator of type I interferon ( IFN) signaling. USP19 stabilizes Beclin-1 by removing the K11-linked ubiquitin chains of Beclin-1 at lysine 437. Moreover, we found that USP19 negatively regulates type I IFN signaling pathway, by blocking RIG-I- MAVS interaction in a Beclin-1-dependent manner. Depletion of either USP19 or Beclin-1 inhibits autophagic flux and promotes type I IFN signaling as well as cellular antiviral immunity. Our findings reveal novel dual functions of the USP19-Beclin-1 axis by balancing autophagy and the production of type I IFNs. [ABSTRACT FROM AUTHOR]

To increase efficiency of water and nitrogen (N) fertilizer use, this study was conducted with a split-root pot experiment to investigate the effects of different forms of N fertilizer on root growth, photosynthesis, instantaneous water use efficiency (IWUE), and yield of tomato ( Lycopersicon esculentum L.) under alternate partial root-zone irrigation (APRI). Three irrigation modes comprised conventional irrigation (CI) and two kinds of APRI, i.e., APRI with water content in the drying soil compartment controlled at ≥ 60% or 40% of the water-holding capacity (APRI-60, APRI-40). Two N forms included ammonium-N and nitrate-N supplied as calcium nitrate or ammonium sulfate, respectively. The results show that APRI-60 enhanced root growth and increased leaf IWUE with a slight yield reduction compared with CI regardless of the N form supplied. In contrast, APRI-40 significantly decreased root growth and inhibited photosynthesis, thereby resulting in a significant yield loss. In addition, at the flowering stage tomato plants grew better with ammonium-N than nitrate-N supply; however, at the fruit expansion stage and maturity stage, the tomato plants had a higher biomass accumulation and yield with nitrate-N than ammonium-N supply. Therefore, the application of APRI should consider the soil water condition coupled with an appropriate N form. In the present study, APRI controlled at ≥ 60% of the water-holding capacity (WHC) for the drying soil side with nitrate-N supply was the best water-fertilizer supply for tomato cultivation. [ABSTRACT FROM AUTHOR]

Targeting and visualization of human telomerase reverse transcriptase (hTERT) represents a promising approach for providing diagnostic value. The uptake kinetics and imaging results of 99mTc-hTERT antisense oligonucleotides (ASON) in hTERT-expressing cells were examined in vitro and in vivo. The pharmacokinetics and acute toxicity studies of 99mTc-hTERT ASON were also performed. The labeling efficiencies of radiolabeled oligonucleotide reached 76 ± 5%, the specific activity was up to 1850 kBq/µg, and the radiochemical purity was above 96%. Radioactivity accumulated to a higher concentration in hTERT-expressing cells with antisense probe than with sense control ( p < 0.05). Lipid carrier incorporation significantly increased the transmembrane delivery of radiolabeled probes ( p < 0.05). hTERT-expressing xenografts in nude mice were clearly visualized at 6 h postinjection of the antisense probe but not the sense control probe. However, liposome did not increase the radioactivity accumulation of probes in tumors for either antisense or sense probe ( p > 0.05). Radioactivity counts per minute versus time profiles for 99mTc-hTERT ASON were biphasic, indicative of a three-compartment model. The pharmacokinetics parameters of half-life of distribution ( T1/2 α), half-life of elimination ( T1/2 β), total apparent volume of distribution (Vd), and total rate of clearance were 2.04 ± 0.48 min, 24 ± 4.8 min, 109.83 ± 17.20 mL, and 3.19 ± 0.17 mL/min, respectively. The acute toxicity study results showed the safe application of 99mTc-hTERT ASON in vivo. This study provides further evidences that 99mTc-hTERT ASON should be developed as a safe, potential molecular image-guided diagnostic agent. [ABSTRACT FROM AUTHOR]