Quercetagitrin Inhibits Tau Accumulation and Reverses Neuroinflammation and Cognitive Deficits in P301S-Tau Transgenic Mice.

Intracellular tau accumulation is a hallmark pathology of Alzheimer's disease (AD) and other tauopathies. Tau protein, in the hyperphosphorylated form, is the component of paired helical filaments (PHFs) and neurofibrillary tangles (NFTs) in AD. Blocking tau aggregation and/or phosphorylation is currently a promising strategy for AD treatment. Here, we elucidate that quercetagitrin, a natural compound derived from African marigold (Tagetes erecta), could inhibit tau aggregation and reduce tau phosphorylation at multiple disease-related sites in vitro. Moreover, the in vivo effect of quercetagitrin was assessed in P301S-tau transgenic via oral administration. The compound treatment restored the cognitive deficits and neuron loss in the mice. The formation of NFTs and tau phosphorylations in the hippocampus and cortex of the mice was also prevented by the compound. Moreover, quercetagitrin feeding displayed neuroinflammation protection through the inhibition of NF-κB activation in the mice. Together, our data reveal that quercetagitrin possesses the potential to further develop as a therapeutic medicine for AD and other tauopathies.

Proteomic Profiling of Cerebrum Mitochondria, Myelin Sheath, and Synaptosome Revealed Mitochondrial Damage and Synaptic Impairments in Association with 3 × Tg-AD Mice Model.

Alzheimer's disease (AD) is the most common age-associated dementia with complex pathological hallmarks. Mitochondrion, synaptosome, and myelin sheath appear to be vulnerable and play a key role in the pathogenesis of AD. To clarify the early mechanism associated with AD, followed by subcellular components separation, we performed iTRAQ (isobaric tags for relative and absolute quantification)-based proteomics analysis to simultaneously investigate the differentially expressed proteins (DEPs) within the mitochondria, synaptosome, and myelin sheath in the cerebrum of the 6-month-old triple transgenic AD (3 × Tg-AD) and 6-month-old wild-type (WT) mice. A large number of DEPs between the AD and WT mice were identified. Most of them are related to mitochondria and synaptic dysfunction and cytoskeletal protein change. Differential expressions of Lrpprc, Nefl, and Sirpa were verified by Western blot analysis. The results suggest that decreased energy metabolism, impaired amino acid metabolism and neurotransmitter synthesis, increase compensatory fatty acid metabolism, up-regulated cytoskeletal protein expression, and oxidative stress are the early events of AD. Among these, mitochondrial damage, synaptic dysfunction, decreased energy metabolism, and abnormal amino acid metabolism are the most significant events. The results indicate that it is feasible to separate and simultaneously perform proteomics analysis on the three subcellular components.

Phosphorylation of the overlooked tyrosine 310 regulates the structure, aggregation, and microtubule- and lipid-binding properties of Tau.

The microtubule-associated protein Tau is implicated in the pathogenesis of several neurodegenerative disorders, including Alzheimer's disease. Increasing evidence suggests that post-translational modifications play critical roles in regulating Tau's normal functions and its pathogenic properties in tauopathies. Very little is known about how phosphorylation of tyrosine residues influences the structure, aggregation, and microtubule- and lipid-binding properties of Tau. Here, we sought to determine the relative contributions of phosphorylation of one or several of the five tyrosine residues in Tau (Tyr-18, -29, -197, -310, and -394) to the regulation of its biophysical, aggregation, and functional properties. We used a combination of site-specific mutagenesis and in vitro phosphorylation by c-Abl kinase to generate Tau species phosphorylated at all five tyrosine residues, all tyrosine residues except Tyr-310 or Tyr-394 (pTau-Y310F and pTau-Y394F, respectively) and Tau phosphorylated only at Tyr-310 or Tyr-394 (4F/pTyr-310 or 4F/pTyr-394). We observed that phosphorylation of all five tyrosine residues, multiple N-terminal tyrosine residues (Tyr-18, -29, and -197), or specific phosphorylation only at residue Tyr-310 abolishes Tau aggregation and inhibits its microtubule- and lipid-binding properties. NMR experiments indicated that these effects are mediated by a local decrease in ß-sheet propensity of Tau's PHF6 domain. Our findings underscore Tyr-310 phosphorylation has a unique role in the regulation of Tau aggregation, microtubule, and lipid interactions. These results also highlight the importance of conducting further studies to elucidate the role of Tyr-310 in the regulation of Tau's normal functions and pathogenic properties.

Targeted metabolomics study of early pathological features in hippocampus of triple transgenic Alzheimer's disease male mice.

Alzheimer's disease (AD) is a serious neurodegenerative disease in people of age 65 or above. The detailed etiology and pathogenesis of AD have not been elucidated yet. In this study, the hippocampi of 2- and 6-month-old triple transgenic Alzheimer's disease male mice and age-sex-matched wild-type (WT) mice were analyzed by using targeted metabolomics approach. Compared with WT mice, 24 and 60 metabolites were found with significant differences in 2- and 6-month-old AD mice. Among these, 14 metabolites were found common while 10 metabolites showed consistent variable trends in both groups. These differential metabolites are found associated with amino acid, lipid, vitamin, nucleotide-related base, neurotransmitter and energy metabolisms, and oxidative stress. The results suggest that these differential metabolites might play a critical role in AD pathophysiology, and may serve as potential biomarkers for AD. Moreover, the results highlight the involvement of abnormal purine, pyrimidine, arginine, and proline metabolism, along with glycerophospholipid metabolism in early pathology of AD. For the first time, several differential metabolites are found to be associated with AD in this study. Targeted metabolomics can be used for rapid and accurate quantitative analysis of specific target metabolites associated with AD.

Tau N-Terminal Inserts Regulate Tau Liquid-Liquid Phase Separation and Condensates Maturation in a Neuronal Cell Model.

The microtubule-associated protein tau can undergo liquid-liquid phase separation (LLPS) to form membraneless condensates in neurons, yet the underlying molecular mechanisms and functions of tau LLPS and tau droplets remain to be elucidated. The human brain contains mainly 6 tau isoforms with different numbers of microtubule-binding repeats (3R, 4R) and N-terminal inserts (0N, 1N, 2N). However, little is known about the role of N-terminal inserts. Here we observed the dynamics of three tau isoforms with different N-terminal inserts in live neuronal cell line HT22. We validated tau LLPS in cytoplasm and found that 2N-tau forms liquid-like, hollow-shell droplets. Tau condensates became smaller in 1N-tau comparing with 2N-tau, while no obvious tau accumulated dots were shown in 0N-tau. The absence of N-terminal inserts significantly affected condensate colocalization of tau and p62. The results reveal insights into the tau LLPS assembly mechanism and functional effects of N-terminal inserts in tau.

Duckling short beak and dwarfism syndrome virus infection activates host innate immune response involving both DNA and RNA sensors.

Duckling short beak and dwarfism syndrome virus (SBDSV), a newly identified goose parvovirus, causes devastating disease in domestic waterfowl and considerable economic losses to Chinese waterfowl industry. The molecular pathogenesis of SBDSV infection, nature and dynamics of host immune responses against SBDSV infection remained elusive. In this study, we systematically explored the relative mRNA expression profiles of major innate immune-related genes in SBDSV infected duck embryo fibroblasts. We found that SBDSV infection effectively activated host innate immune responses and resulted in significant up-regulation of IFN-ß and several vital IFN-stimulated genes (ISGs). These up-regulation responses were mainly attributed to viral genomic DNA and dsRNA replication intermediates. Importantly, the expression of cGAS was significantly induced, whereas the expression of other DNA receptors including DDX41, STING, ZBP1, LSM14A and LRRFIP1 have no significant change. Furthermore, SBDSV infection also activates the up-regulation of TLR3 and inhibited the expression of TLR2 and TLR4; however, no effect was observed on the expression of TLR1, TLR5, TLR7, TLR15 and TLR21. Intriguingly, SBDSV infection significantly up-regulated the expression of RNA sensors such as MDA5 and LGP2, and resulted in a delayed but significant up-regulation of RIG-I gene. Taken together, these data indicate that host multiple sensors including DNA sensor (cGAS) and RNA sensors (TLR3, MDA5 and LGP2) are involved in recognizing a variety of different pathogen associated molecular patterns (PAMPs) including viral genomic ssDNA and dsRNA replication intermediates, which trigger an effective antiviral innate immune response.

Development of an EvaGreen based real-time RT-PCR assay for rapid detection, quantitation and diagnosis of goose calicivirus.

An unclassified calicivirus (CV) detected in geese was recently reported and proposed as a new member of the family Caliciviridae. There is limited information about the epidemiology, etiology and detection method of goose-origin CV (GCV) to date. In this study, an EvaGreen based fluorescence quantitative real-time RT-PCR assay was developed and optimized for the detection of GCVs. The assay sensitively detected GCV RNA template with a good linear standard curve. We also demonstrated the specificity and reproducibility of the detection method for GCVs. Thus, the method developed in this study will benefit the investigation of possible sporadic outbreaks of CV infections in geese, as well as epidemiological and etiological studies of GCVs.

The genomic constellation of a novel duck reovirus strain associated with hemorrhagic necrotizing hepatitis and splenitis in Muscovy ducklings in Fujian, China.

The complete sequence of a reovirus, strain NP03 associated with necrotic focus formation in the liver and spleen of Muscovy ducklings in Fujian Province, China in 2009, was determined and compared with sequences of other waterfowl and chicken-origin avian reoviruses (ARVs). Sequencing of the complete genomes of strain NP03 showed that they consisted of 23,418 bp and were divided into 10 segments, ranging from 1191 bp (S4) to 3959 bp (L1) in length, and all segments contained conserved sequences in the 5' non-coding region (GCUUUU) and 3' non-coding region (UCAUC). Pairwise sequence comparisons demonstrated that NP03 strain showed the highest similarity with novel waterfowl origin reoviruses (WRVs). The genome analysis revealed that the S1 segment of novel WRV is a tricistronic gene, encoding the overlapping open reading frames (ORFs) for p10, p18, and σC, similar to the ARV S1 gene, but distinct from classical WRV S4 genome segment, which contained two overlapping ORFs encoding p10 and σC. Phylogenetic analyses of the nucleotide sequences of all 10 segments revealed that NP03 strain was clustered together with other novel WRVs and were distinct from classical WRVs and chicken-origin ARVs. The analyses also showed possible intra-segmental reassortment events in the segments encoding λA, λB, µB, µNS, σA, and σNS between novel and classical WRVs. Potential recombination events detection in segment L1 suggests that NP03 strain may be recombinants of novel WRVs. Based on our genetic analyses, multiple reassortment events, intra-segmental recombination, and accumulation of point mutations have possibly contributed to the emergence of this novel genotype of WRV, identified in China.

A TaqMan-MGB real-time RT-PCR assay with an internal amplification control for rapid detection of Muscovy duck reovirus.

A real-time reverse transcriptase-polymerase chain reaction (RT-PCR) for the detection of Muscovy duck reovirus (MDRV) RNA in clinical samples is described. The assay is based on TaqMan-MGB technology, consisting of two primers and one probe labeled with the reporter dye 6-carboxyfluorescein that binds selectively to the sigma B-protein gene of MDRV. This technique also includes an Internal Positive Control (IPC). The real-time RT-PCR assay was able to detect MDRVs, whereas other common waterfowl-origin viral pathogens were not recognised by the established oligonucleotide set, thus showing that the test was specific for MDRV. The sensitivity of the assay was 2.83 × 101 copies/µL and was 100 times higher than that of the conventional RT-PCR. The variation coefficients of intra-assay and inter-assay were less than 1.5% which verified sufficient repeatability of this assay. The use of ß-actin mRNA as an IPC in order not to reduce the efficiency of the assay was adopted. The detection for 100 clinical samples showed that the positive rate of the established TaqMan-MGB real-time RT-PCR method was 87% (87/100), while the positive rate of the conventional RT-PCR was 83% (83/100), with the coincidence rate was 97.14%. Sensitivity and positive rate for clinical samples of TaqMan fluorescent quantitative RT-PCR were higher than conventional RT-PCR. The high specificity, sensitivity, and rapidity TaqMan-MGB real-time RT-PCR assay with the use of IPC to monitor for false negative results can make this method suitable for the pathogenic surveillance and epidemiological investigation of MDRV infection.

Muscovy Duck Reovirus Infection Disrupts the Composition of Intestinal Microbiota in Muscovy Ducklings.

Muscovy duck reovirus (MDRV) is highly pathogenic to young Muscovy ducklings. Although MDRV infection results in ducklings' acute watery diarrhea, the effect of MDRV infection on the composition of host's intestinal microbiota remains poorly understood. This study was conducted to investigate the impacts of MDRV on the composition of Muscovy ducklings' intestinal bacterial community. Three-day-old Muscovy ducklings were inoculated with either the virulent MDRV strain MW9710 or sterile Hank's solution, respectively. The cecal microbiota was analyzed between control and mock MDRV-infected ducklings using Illumina MiSeq sequencing at 6 dpi and 17 dpi, respectively. The results indicated that MDRV infection damaged the intestinal mucosa. In addition, MDRV infection caused severe perturbations of gut microbiota by decreasing microbial richness, altering the abundance of certain genera of the gut microbiota at 6 dpi. Specifically, the relative abundance of short chain fatty acids-producing bacteria (including Shuttleworthia, Streptococcus, and Ruminococcus) was reduced in MDRV-infected ducklings than those of control group, whereas, with an enrichment of Enterobacteriaceae (including Plesiomonas, Escherichia_Shigella and Proteus). Furthermore, microbiota analysis showed that the gut microbiota dysbiosis caused by MDRV infection was basically recovered at 17 dpi. Collectively, this study demonstrated that the gut microbiota of Muscovy ducklings were altered due to MDRV infection, mainly featuring as a net loss of beneficial bacteria and a compensatory proliferation of pathogenic bacteria, which may lead to severe pathology to the intestinal mucosa, and ultimately acute diarrhea. These results will provide insights into the pathology of MDRV infection.

Impacts of novel duck reovirus infection on the composition of intestinal microbiota of Muscovy ducklings.

Novel duck reovirus (NDRV) is pathogenic to young ducks, which is characterized by hemorrhagic spots and necrotic foci of the livers and necrotic foci of spleens. However, the effect of NDRV infection on the composition of the host's intestinal microbiota remains poorly understood. In this study, three-day-old Muscovy ducklings were inoculated with either the virulent NDRV strain NP03 or sterile Hank's solution. Through Illumina MiSeq sequencing, the whole cecal microbiota of healthy and NDRV infected ducklings was examined. The results showed that the gut microbiota was mainly dominated by Firmicutes, Proteobacteria and Bacteroidestes in both healthy and NDRV infected ducks. NDRV infection altered the relative abundance of bacteria. Specifically, families Ruminococcaceae and Lachnospiraceae were remarkably reduced, whereas Escherichia_Shigella belonging to family Enterobacteriaceae was significantly increased. Collectively, NDRV infection in Muscovy ducks resulted in a shift of the gut microbiota, including a net loss of probiotic bacteria with a compensatory expansion of pathogenic bacteria. These results provide new insights into the potential pathogenic mechanisms of NDRV.

Development of a duplex SYBR Green I-based quantitative real-time PCR assay for the rapid differentiation of goose and Muscovy duck parvoviruses.

BACKGROUND: Waterfowl parvoviruses, including goose parvovirus (GPV) and Muscovy duck parvovirus (MDPV), can cause seriously diseases in geese and ducks. Developing a fast and precise diagnosis assay for these two parvoviruses is particularly important. RESULTS: A duplex SYBR Green I-based quantitative real-time PCR assay was developed for the simultaneous detection and differentiation of GPV and MDPV. The assay yielded melting curves with specific single peak (Tm = 87.3 ± 0.26 °C or Tm = 85.4 ± 0.23 °C) when GPV or MDPV was evaluated, respectively. When both parvoviruses were assessed in one reaction, melting curves with specific double peaks were yielded. CONCLUSION: This duplex quantitative RT-PCR can be used to rapid identify of GPV and MDPV in field cases and artificial trials, which make it a powerful tool for diagnosing, preventing and controlling waterfowl parvovirus infections.

Recovery of Muscovy duck-origin goose parvovirus from an infectious clone containing an E-box motif (CACATG) deletion within the left terminal region.

Muscovy duck-origin goose parvovirus (MDGPV) is a causative agent of MDGPV-associated Derzsy's disease. To evalute the role of the cis-acting element E-box (CACATG) deletion on MDGPV eplication, an infectious plasmid clone p-PTΔE287, having one E-box deletion at nucleotide (nt) 287 of the left inverted terminal repeat sequence (L-ITR), was constructed by overlap extension PCR deleting the 287CACATG292 motif from the plasmid pMDGPVPT containing the full-length genome of the virulent MDGPV strain PT. The p-PTΔE287 plasmid was transfected into 9-day-old non-immune Muscovy duck embryos via the yolk sac, resulting in successful rescue of the deletion mutant virus r-PTΔE287. Compared with its parental virus PT, the virulence and the replication ability of r-PTΔE287 were reduced. In addition, we examined the ability of r-PTΔE287 to manipulate cell cycle progression. The results showed that r-PTΔE287 replication results in G0/G1 phase accumulation of infected duck embryo liver mesenchymal stem cells (BMSCs) and that this accumulation is caused by the prevention of cell cycle entry from G0/G1 phase into S phase. Taken together, introducing 287CACATG292 element deletion into MDGPV PT genomic DNA that induced rescued mutant virus (r-PTΔE287) cell cycle arrest function at the G0/G1 phase, which might inhibit MDGPV replication and virus progeny production. This study laid the foundation for further understanding of the relationship between E-box deletion in the L-ITR and MDGPV virulence.

Construction and rescue of Muscovy duck-origin goose parvovirus from an infectious clone containing an E-box deletion within the left terminal region.

To obtain a deletion mutant of Muscovy duck-origin goose parvovirus (MDGPV) and to analyze its biological characteristics, the pMDGPVPT plasmid, which contains a full-length DNA infectious clone of the MDGPV PT strain, was used in this study as the template. The E-box at nt 315 of the left inverted terminal repeat sequence (L-ITR) was deleted by overlap extension PCR to obtain the infectious recombinant plasmid p-PTΔE315. The p-PTΔE315 plasmid was transfected into 9-day-old non-immune Muscovy duck embryos via the yolk sac and the rescued deletion mutant virus r-PTΔE315 was generated. Experiments to demonstrate the novel deletion mutant virus' biological characteristics showed that r-PTΔE315 can cause typical lesions after infection of Muscovy duck embryos. Compared with its parent strain PT, the virulence of r-PTΔE315 and its proliferation ability in Muscovy duck embryos were attenuated, but its ability to replicate in MDEF cells was enhanced. This study laid the foundation for further understanding of the relationship between E-box deletion in the L-ITR and MDGPV virulence.

Isolation and characterization of a distinct duck-origin goose parvovirus causing an outbreak of duckling short beak and dwarfism syndrome in China.

Many mule duck and Cherry Valley duck flocks in different duck-producing regions of China have shown signs of an apparently new disease designated "short beak and dwarfism syndrome" (SBDS) since 2015. The disease is characterized by dyspraxia, weight loss, a protruding tongue, and high morbidity and low mortality rates. In order to characterize the etiological agent, a virus designated SBDSV M15 was isolated from allantoic fluid of dead embryos following serial passage in duck embryos. This virus causes a cytopathic effect in duck embryo fibroblast (DEF) cells. Using monoclonal antibody diagnostic assays, the SBDSV M15 isolate was positive for the antigen of goose parvovirus but not Muscovy duck parvovirus. A 348-bp (2604-2951) VP1gene fragment was amplified, and its sequence indicated that the virus was most closely related to a Hungarian GPV strain that was also isolated from mule ducks with SBDS disease. A similar disease was reproduced by inoculating birds with SBDSV M15. Together, these data indicate that SBDSV M15 is a GPV-related parvovirus causing SBDS disease and that it is divergent from classical GPV isolates.

Rational modification of protein stability by targeting surface sites leads to complicated results.

The rational modification of protein stability is an important goal of protein design. Protein surface electrostatic interactions are not evolutionarily optimized for stability and are an attractive target for the rational redesign of proteins. We show that surface charge mutants can exert stabilizing effects in distinct and unanticipated ways, including ones that are not predicted by existing methods, even when only solvent-exposed sites are targeted. Individual mutation of three solvent-exposed lysines in the villin headpiece subdomain significantly stabilizes the protein, but the mechanism of stabilization is very different in each case. One mutation destabilizes native-state electrostatic interactions but has a larger destabilizing effect on the denatured state, a second removes the desolvation penalty paid by the charged residue, whereas the third introduces unanticipated native-state interactions but does not alter electrostatics. Our results show that even seemingly intuitive mutations can exert their effects through unforeseen and complex interactions.

Tau binds to lipid membrane surfaces via short amphipathic helices located in its microtubule-binding repeats.

Tau is a microtubule-associated protein that is genetically linked to dementia and linked to Alzheimer's disease via its presence in intraneuronal neurofibrillary tangle deposits, where it takes the form of aggregated paired helical and straight filaments. Although the precise mechanisms by which tau contributes to neurodegeneration remain unclear, tau aggregation is commonly considered to be a critical component of tau-mediated pathogenicity. Nevertheless, the context in which tau aggregation begins in vivo is unknown. Tau is enriched in membrane-rich neuronal structures such as axons and growth cones, and can interact with membranes both via intermediary proteins and directly via its microtubule-binding domain (MBD). Membranes efficiently facilitate tau aggregation in vitro, and may therefore provide a physiologically relevant context for nucleating tau aggregation in vivo. Furthermore, tau-membrane interactions may potentially play a role in tau's poorly understood normal physiological functions. Despite the potential importance of direct tau-membrane interactions for tau pathology and physiology, the structural mechanisms that underlie such interactions remain to be elucidated. Here, we employ electron spin resonance spectroscopy to investigate the secondary and long-range structural properties of the MBD of three-repeat tau isoforms when bound to lipid vesicles and membrane mimetics. We show that the membrane interactions of the tau MBD are mediated by short amphipathic helices formed within each of the MBD repeats in the membrane-bound state. To our knowledge, this is the first detailed elucidation of helical tau structure in the context of intact lipid bilayers. We further show, for the first time (to our knowledge), that these individual helical regions behave as independent membrane-binding sites linked by flexible connecting regions. These results represent the first (to our knowledge) detailed structural view of membrane-bound tau and provide insights into potential mechanisms for membrane-mediated tau aggregation. Furthermore, the results may have implications for the structural basis of tau-microtubule interactions and microtubule-mediated tau aggregation.

Development and application of a multiplex PCR method for the simultaneous detection of goose parvovirus, waterfowl reovirus, and goose astrovirus in Muscovy ducks.

A multiplex polymerase chain reaction (PCR) method was developed to detect and distinguish goose parvovirus (GPV), waterfowl reovirus (WRV), and goose astrovirus (GAstV). Three pairs of primers were designed based on conserved regions in the genomic sequences of these enteric viruses and were used to specifically amplify targeted fragments of 493 bp from the viral protein 3 (VP3) gene of GPV, 300 bp from the sigma A-encoding gene of WRV, and 156 bp from the capsid protein-encoding gene of GAstV. The results showed that the primers can specifically amplify target fragments, without any cross-amplification with other viruses, indicating that the method had good specificity. A sensitivity test showed that the detection limit of the multiplex PCR method was 1 × 103 viral copies. A total of 102 field samples from Muscovy ducks with clinically suspected diseases were evaluated using the newly developed multiplex PCR method. The ratio of positive samples to total samples for GPV, WRV, and GAstV was 73.53% (75/102) for multiplex PCR and was 73.53% (75/102) for routine PCR. Seventy-five positive samples were detected by both methods, for a coincidence ratio of 100%. This multiplex PCR method can simultaneously detect GPV, WRV, and GAstV, which are associated with viral enteritis, thereby providing a specific, sensitive, efficient, and accurate new tool for clinical diagnosis and laboratory epidemiological investigations.

Selenoprotein W modulates tau homeostasis in an Alzheimer's disease mouse model.

Lower selenium levels are observed in Alzheimer's disease (AD) brains, while supplementation shows multiple benefits. Selenoprotein W (SELENOW) is sensitive to selenium changes and binds to tau, reducing tau accumulation. However, whether restoration of SELENOW has any protective effect in AD models and its underlying mechanism remain unknown. Here, we confirm the association between SELENOW downregulation and tau pathology, revealing SELENOW's role in promoting tau degradation through the ubiquitin‒proteasome system. SELENOW competes with Hsp70 to interact with tau, promoting its ubiquitination and inhibiting tau acetylation at K281. SELENOW deficiency leads to synaptic defects, tau dysregulation and impaired long-term potentiation, resulting in memory deficits in mice. Conversely, SELENOW overexpression in the triple transgenic AD mice ameliorates memory impairment and tau-related pathologies, featuring decreased 4-repeat tau isoform, phosphorylation at Ser396 and Ser404, neurofibrillary tangles and neuroinflammation. Thus, SELENOW contributes to the regulation of tau homeostasis and synaptic maintenance, implicating its potential role in AD.

Duck cGAS inhibits DNA and RNA virus replication by activating IFNs and antiviral ISGs.

Cyclic GMP-AMP Synthase (cGAS) is a pivotal adaptor of the signaling pathways involving the pattern recognition receptors and plays an important role in apoptosis and immune regulation. The cGAS function in mammals has been investigated extensively; however, the function of duck cGAS (du-cGAS) in response to viral infections is still unclear. This study aimed to clone the mallard (Anas platyrhynchos) cGAS homolog to investigate the function of duck cGAS (du-cGAS) in host antiviral innate immunity. The results showed that the open reading frame (ORF) region of the du-cGAS gene was 1296 bp, encoding 432 amino acids (aa) and exhibiting similar functional domains with its chicken counterpart. Knockdown of the endogenous du-cGAS by specific sgRNA strongly increased the replication of DNA viruses, including duck adenovirus B2 (DAdV B2) and duck short beak and dwarfism syndrome virus (SBDSV). However, the knockout did not impair the replication of novel duck reovirus (NDRV), an RNA virus. Furthermore, the mRNA expressions of type I interferon (IFNs) and vital interferon-stimulated genes (ISGs) were remarkably reduced in the du-cGAS knockout DEF cell line. Inversely, du-cGAS overexpression greatly activated the transcription of IFN-α, IFN-ß, and vital ISGs, and impaired the replication of DAdV B2, SBDSV, and NDRV in the DEF cell line. Importantly, we found that a deletion of 68 aa in the N terminus didn't impair the antiviral function of du-cGAS. Overexpressing NTase Core, C-Domain (Mab21), or Zinc-Ribbon domain independently had no antiviral effects. Generally, these results reveal that du-cGAS is a vital component of the innate immune system of ducks, with a universal antiviral activity, and provides a useful strategy for the control of waterfowl viral diseases.