Biology subjects

Cao, X.

Publications and source records attributed to Cao, X..

At least 109 records · Page 6Linked to original sources

bioRxiv2024

p300/CBP degradation is required to disable the active AR enhanceosome in prostate cancer

Prostate cancer is an exemplar of an enhancer-binding transcription factor-driven disease. The androgen receptor (AR) enhanceosome complex comprised of chromatin and epigenetic coregulators assembles at enhancer elements to drive disease progression. The paralog lysine acetyltransferases p300 and CBP deposit histone marks that are associated with enhancer activation. Here, we demonstrate that p300/CBP are determinant cofactors of the active AR enhanceosome in prostate cancer. Histone H2B N-terminus multisite lysine acetylation (H2BNTac), which is exclusively reliant on p300/CBP catalytic function, marked active enhancers and was notably elevated in prostate cancer lesions relative to the adjacent benign epithelia. Degradation of p300/CBP rapidly depleted acetylation marks associated with the active AR enhanceosome, which was only partially phenocopied by inhibition of their reader bromodomains. Notably, H2BNTac was effectively abrogated only upon p300/CBP degradation, which led to a stronger suppression of p300/CBP-dependent oncogenic gene programs relative to bromodomain inhibition or the inhibition of its catalytic domain. In vivo experiments using an orally active p300/CBP proteolysis targeting chimera (PROTAC) degrader (CBPD-409) showed that p300/CBP degradation potently inhibited tumor growth in preclinical models of castration-resistant prostate cancer and synergized with AR antagonists. While mouse p300/CBP orthologs were effectively degraded in host tissues, prolonged treatment with the PROTAC degrader was well tolerated with no significant signs of toxicity. Taken together, our study highlights the pivotal role of p300/CBP in maintaining the active AR enhanceosome and demonstrates how target degradation may have functionally distinct effects relative to target inhibition, thus supporting the development of p300/CBP degraders for the treatment of advanced prostate cancer.

cancer biology↗

bioRxiv2024

CDK12 Loss Promotes Prostate Cancer Development While Exposing Vulnerabilities to Paralog-Based Synthetic Lethality

Biallelic loss of cyclin-dependent kinase 12 (CDK12) defines a unique molecular subtype of metastatic castration-resistant prostate cancer (mCRPC). It remains unclear, however, whether CDK12 loss per se is sufficient to drive prostate cancer development--either alone, or in the context of other genetic alterations--and whether CDK12-mutant tumors exhibit sensitivity to specific pharmacotherapies. Here, we demonstrate that tissue-specific Cdk12 ablation is sufficient to induce preneoplastic lesions and robust T cell infiltration in the mouse prostate. Allograft-based CRISPR screening demonstrated that Cdk12 loss is positively associated with Trp53 inactivation but negatively associated with Pten inactivation--akin to what is observed in human mCRPC. Consistent with this, ablation of Cdk12 in prostate organoids with concurrent Trp53 loss promotes their proliferation and ability to form tumors in mice, while Cdk12 knockout in the Pten-null prostate cancer mouse model abrogates tumor growth. Bigenic Cdk12 and Trp53 loss allografts represent a new syngeneic model for the study of androgen receptor (AR)-positive, luminal prostate cancer. Notably, Cdk12/Trp53 loss prostate tumors are sensitive to immune checkpoint blockade. Cdk12-null organoids (either with or without Trp53 co-ablation) and patient-derived xenografts from tumors with CDK12 inactivation are highly sensitive to inhibition or degradation of its paralog kinase, CDK13. Together, these data identify CDK12 as a bona fide tumor suppressor gene with impact on tumor progression and lends support to paralog-based synthetic lethality as a promising strategy for treating CDK12-mutant mCRPC.

cancer biology↗

bioRxiv2024

Targeting PIKfyve-driven lipid homeostasis as a metabolic vulnerability in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) subsists in a nutrient-deregulated microenvironment, making it particularly susceptible to treatments that interfere with cancer metabolism1 2. For example, PDAC utilizes and is dependent on high levels of autophagy and other lysosomal processes3-5. Although targeting these pathways has shown potential in preclinical studies, progress has been hampered by the challenge of identifying and characterizing favorable targets for drug development6. Here, we characterize PIKfyve, a lipid kinase integral to lysosomal functioning7, as a novel and targetable vulnerability in PDAC. In human patient and murine PDAC samples, we discovered that PIKFYVE is overexpressed in PDAC cells compared to adjacent normal cells. Employing a genetically engineered mouse model, we established the essential role of PIKfyve in PDAC progression. Further, through comprehensive metabolic analyses, we found that PIKfyve inhibition obligated PDAC to upregulate de novo lipid synthesis, a relationship previously undescribed. PIKfyve inhibition triggered a distinct lipogenic gene expression and metabolic program, creating a dependency on de novo lipid metabolism pathways, by upregulating genes such as FASN and ACACA. In PDAC, the KRAS-MAPK signaling pathway is a primary driver of de novo lipid synthesis, specifically enhancing FASN and ACACA levels. Accordingly, the simultaneous targeting of PIKfyve and KRAS-MAPK resulted in the elimination of tumor burden in a syngeneic orthotopic model and tumor regression in a xenograft model of PDAC. Taken together, these studies suggest that disrupting lipid metabolism through PIKfyve inhibition induces synthetic lethality in conjunction with KRAS-MAPK-directed therapies for PDAC.

cancer biology↗

bioRxiv2024

Cas1 mediates the interference stage in a phage-encoded CRISPR-Cas system

CRISPR-Cas systems are prokaryotic adaptive immune systems against invading phages and other mobile genetic elements, which function in three stages: adaptation, expression and interference. Interestingly, phages were also found to encode CRISPR-Cas systems to antagonize their hosts and establish infection. The Vibrio cholerae-infecting ICP1 phage was the first discovered phage with a functional CRISPR-Cas system against an antiphage region in the host genome. Nevertheless, this system lacks a domain essential for recruitment of helicase-nuclease Cas2/3 during target DNA cleavage, and how this system accomplishes the interference stage remains unknown. Here, surprisingly, we found that Cas1, a highly conserved component known to exclusively work in the adaptation stage, also mediates the interference stage through connecting Cas2/3 to the DNA bound-Cascade (Csy) complex of the ICP1 CRISPR-Cas system. A series of structures of Csy, Csy-dsDNA, Cas1-Cas2/3 and Csy-dsDNA-Cas1-Cas2/3 complexes collectively reveal the whole process of Cas1-mediated target DNA cleavage by the ICP1 CRISPR-Cas system. Together, these data support an unprecedented model in which Cas1 mediates the interference stage in a phage-encoded CRISPR-Cas system and also shed light on a unique model of primed adaptation.

microbiology↗

bioRxiv2024

Development of an orally bioavailable mSWI/SNF ATPase degrader and acquired mechanisms of resistance in prostate cancer

Mammalian switch/sucrose non-fermentable (mSWI/SNF) ATPase degraders have been shown to be effective in enhancer-driven cancers by functioning to impede oncogenic transcription factor chromatin accessibility. Here, we developed AU-24118, a first-in-class, orally bioavailable proteolysis targeting chimera (PROTAC) degrader of mSWI/SNF ATPases (SMARCA2 and SMARCA4) and PBRM1. AU-24118 demonstrated tumor regression in a model of castration-resistant prostate cancer (CRPC) which was further enhanced with combination enzalutamide treatment, a standard of care androgen receptor (AR) antagonist used in CRPC patients. Importantly, AU-24118 exhibited favorable pharmacokinetic profiles in preclinical analyses in mice and rats, and further toxicity testing in mice showed a favorable safety profile. As acquired resistance is common with targeted cancer therapeutics, experiments were designed to explore potential mechanisms of resistance that may arise with long-term mSWI/SNF ATPase PROTAC treatment. Prostate cancer cell lines exposed to long-term treatment with high doses of a mSWI/SNF ATPase degrader developed SMARCA4 bromodomain mutations and ABCB1 overexpression as acquired mechanisms of resistance. Intriguingly, while SMARCA4 mutations provided specific resistance to mSWI/SNF degraders, ABCB1 overexpression provided broader resistance to other potent PROTAC degraders targeting bromodomain-containing protein 4 (BRD4) and AR. The ABCB1 inhibitor, zosuquidar, reversed resistance to all three PROTAC degraders tested. Combined, these findings position mSWI/SNF degraders for clinical translation for patients with enhancer-driven cancers and define strategies to overcome resistance mechanisms that may arise. Significance StatementThe mSWI/SNF complex is a promising therapeutic target for enhancer-driven cancers. PROTACs, which enable the targeting of "undruggable" proteins, often face the challenge of achieving oral bioavailability. Here, we present AU-24118, a first-in-class, orally bioavailable mSWI/SNF ATPase dual degrader with remarkable efficacy in in vitro and in vivo models. Additionally, our study describes two distinct mechanisms of resistance to PROTAC degraders, providing crucial insights into potential challenges facing their clinical application. These findings are critical for advancing PROTAC-based therapies to clinical settings as targeted therapies for cancers.

cancer biology↗

bioRxiv2024

PIKfyve controls dendritic cell function and tumor immunity

The modern armamentarium for cancer treatment includes immunotherapy and targeted therapy, such as protein kinase inhibitors. However, the mechanisms that allow cancer-targeting drugs to effectively mobilize dendritic cells (DCs) and affect immunotherapy are poorly understood. Here, we report that among shared gene targets of clinically relevant protein kinase inhibitors, high PIKFYVE expression was least predictive of complete response in patients who received immune checkpoint blockade (ICB). In immune cells, high PIKFYVE expression in DCs was associated with worse response to ICB. Genetic and pharmacological studies demonstrated that PIKfyve ablation enhanced DC function via selectively altering the alternate/non-canonical NF-{kappa}B pathway. Both loss of Pikfyve in DCs and treatment with apilimod, a potent and specific PIKfyve inhibitor, restrained tumor growth, enhanced DC-dependent T cell immunity, and potentiated ICB efficacy in tumor-bearing mouse models. Furthermore, the combination of a vaccine adjuvant and apilimod reduced tumor progression in vivo. Thus, PIKfyve negatively controls DCs, and PIKfyve inhibition has promise for cancer immunotherapy and vaccine treatment strategies.

cancer biology↗

bioRxiv2024

NSD2 is a requisite subunit of the AR/FOXA1 neo-enhanceosome in promoting prostate tumorigenesis

The androgen receptor (AR) is a ligand-responsive transcription factor that binds at enhancers to drive terminal differentiation of the prostatic luminal epithelia. By contrast, in tumors originating from these cells, AR chromatin occupancy is extensively reprogrammed to drive hyper-proliferative, metastatic, or therapy-resistant phenotypes, the molecular mechanisms of which remain poorly understood. Here, we show that the tumor-specific enhancer circuitry of AR is critically reliant on the activity of Nuclear Receptor Binding SET Domain Protein 2 (NSD2), a histone 3 lysine 36 di-methyltransferase. NSD2 expression is abnormally gained in prostate cancer cells and its functional inhibition impairs AR trans-activation potential through partial off-loading from over 40,000 genomic sites, which is greater than 65% of the AR tumor cistrome. The NSD2-dependent AR sites distinctly harbor a chimeric AR-half motif juxtaposed to a FOXA1 element. Similar chimeric motifs of AR are absent at the NSD2-independent AR enhancers and instead contain the canonical palindromic motifs. Meta-analyses of AR cistromes from patient tumors uncovered chimeric AR motifs to exclusively participate in tumor-specific enhancer circuitries, with a minimal role in the physiological activity of AR. Accordingly, NSD2 inactivation attenuated hallmark cancer phenotypes that were fully reinstated upon exogenous NSD2 re-expression. Inactivation of NSD2 also engendered increased dependency on its paralog NSD1, which independently maintained AR and MYC hyper-transcriptional programs in cancer cells. Concordantly, a dual NSD1/2 PROTAC degrader, called LLC0150, was preferentially cytotoxic in AR-dependent prostate cancer as well as NSD2-altered hematologic malignancies. Altogether, we identify NSD2 as a novel subunit of the AR neo-enhanceosome that wires prostate cancer gene expression programs, positioning NSD1/2 as viable paralog co-targets in advanced prostate cancer.

cancer biology↗

bioRxiv2024

Spherical Echo-Planar Time-resolved Imaging (sEPTI) for rapid 3D quantitative T2* and Susceptibility imaging

PurposeTo develop a 3D spherical EPTI (sEPTI) acquisition and a comprehensive reconstruction pipeline for rapid high-quality whole-brain submillimeter T2* and QSM quantification. MethodsFor the sEPTI acquisition, spherical k-space coverage is utilized with variable echo-spacing and maximum kx ramp-sampling to improve efficiency and incoherency when compared to existing EPTI approaches. For reconstruction, an iterative rank-shrinking B0 estimation and odd-even high-order phase correction algorithms were incorporated into the reconstruction to better mitigate artifacts from field imperfections. A physics-informed unrolled network was utilized to boost the SNR, where 1-mm and 0.75-mm isotropic whole-brain imaging were performed in 45 and 90 seconds, respectively. These protocols were validated through simulations, phantom, and in vivo experiments. Ten healthy subjects were recruited to provide sufficient data for the unrolled network. The entire pipeline was validated on additional 5 healthy subjects where different EPTI sampling approaches were compared. Two additional pediatric patients with epilepsy were recruited to demonstrate the generalizability of the unrolled reconstruction. ResultssEPTI achieved 1.4 x faster imaging with improved image quality and quantitative map precision compared to existing EPTI approaches. The B0 update and the phase correction provide improved reconstruction performance with lower artifacts. The unrolled network boosted the SNR, achieving high-quality T2* and QSM quantification with single average data. High-quality reconstruction was also obtained in the pediatric patient using this network. ConclusionsEPTI achieved whole-brain distortion-free multi-echo imaging and T2* and QSM quantification at 0.75 mm in 90 seconds which has the potential to be useful for wide clinical applications.

bioengineering↗

bioRxiv2024

Efficient cloning of genes for wheat yield component traits from QTLs via sequencing of the RIL population

In wheat (Triticum aestivum L.), yield component traits (YCTs) are the most important yield traits. Only several genes for YCTs have been originally cloned. The efficient cloning of genes for YCTs directly from wheat remains a challenge. Here, we proposed a strategy for cloning genes from quantitative trait loci (QTLs) by sequencing of recombinant inbred lines (RILs) (QTL-Seq-RIL). Using the TN18 x LM6 RIL population as an example, we identified 138 candidate unigenes (CUGs) for YCTs from 77 stable QTLs. The average of CUGs per QTL was 1.8, which enabled us to confirm the CUGs directly. We have confirmed seven CUGs, TaIFABPL, TaDdRp, TaRLK, TaTD, TaTFC3, TaKMT and TaSPL17, via the CRISPR/Cas9 system. Of these, six genes were found firstly to regulate YCTs in crops except for TaSPL17. Five CUGs (include TaSPL17) for which orthologous genes have been cloned previously with the same or similar agronomic functions. It is to say, 11 CUGs were preliminarily validated using a single RIL population. QTL-Seq-RIL provides an efficient method for rapid gene cloning using existing RIL populations.

plant biology↗

bioRxiv2024

Large-scale multi-omics analyses identified root-microbiome associations underlying plant nitrogen nutrition

The microbiome determines the performance and fitness of the host plant. Nevertheless, the causal interaction between host genetic variation, gene regulation and the impact of the microbiome on the host phenotype remain unknown. Here we generated 1,341 paired root transcriptome, rhizosphere microbiome and root ionome samples and performed a multi-omics analyses of the host-microbe association at the root-soil interface using 175 rapeseeds (Brassica napus L.) resequenced ecotypes at two field environments. We observed the highest statistically explained variance for root nitrogen uptake among natural ionomic variation by overall transcriptome-wide gene expression and microbial abundance variation. Moreover, we identified significant genome-wide associations for 203 highly heritable amplicon sequence variants (ASVs) at multiple genetic loci regulated by eQTL hotspots associated with nitrogen metabolism components. These associations involved a central bacterial genus (Sphingopyxis), which plays a dominant role on gene regulatory effect on its variation regulated by eQTL hotspots. In addition, we performed high-throughput bacterial cultivation from rapeseed roots and subjected Sphingopyxis to whole genome sequencing. Finally, targeted metabolite profiling and confocal imaging assays demonstrated a host-microbiome regulatory effect on Sphingopyxis established by lateral root development and plant nitrogen nutrition. In summary, our integrative approach reveals the genetic basis of host-microbiome trait associations in the transcriptional, nutritional and environmental domains and suggests that the microbiome might have causal effects on root development with implications towards the breeding of nutrient-efficient crops.

plant biology↗

bioRxiv2024

Targeting the mSWI/SNF Complex in POU2F-POU2AF Transcription Factor-Driven Malignancies

The POU2F3-POU2AF2/3 (OCA-T1/2) transcription factor complex is the master regulator of the tuft cell lineage and tuft cell-like small cell lung cancer (SCLC). Here, we found that the POU2F3 molecular subtype of SCLC (SCLC-P) exhibits an exquisite dependence on the activity of the mammalian switch/sucrose non-fermentable (mSWI/SNF) chromatin remodeling complex. SCLC-P cell lines were sensitive to nanomolar levels of a mSWI/SNF ATPase proteolysis targeting chimera (PROTAC) degrader when compared to other molecular subtypes of SCLC. POU2F3 and its cofactors were found to interact with components of the mSWI/SNF complex. The POU2F3 transcription factor complex was evicted from chromatin upon mSWI/SNF ATPase degradation, leading to attenuation of downstream oncogenic signaling in SCLC-P cells. A novel, orally bioavailable mSWI/SNF ATPase PROTAC degrader, AU-24118, demonstrated preferential efficacy in the SCLC-P relative to the SCLC-A subtype and significantly decreased tumor growth in preclinical models. AU-24118 did not alter normal tuft cell numbers in lung or colon, nor did it exhibit toxicity in mice. B cell malignancies which displayed a dependency on the POU2F1/2 cofactor, POU2AF1 (OCA-B), were also remarkably sensitive to mSWI/SNF ATPase degradation. Mechanistically, mSWI/SNF ATPase degrader treatment in multiple myeloma cells compacted chromatin, dislodged POU2AF1 and IRF4, and decreased IRF4 signaling. In a POU2AF1-dependent, disseminated murine model of multiple myeloma, AU-24118 enhanced survival compared to pomalidomide, an approved treatment for multiple myeloma. Taken together, our studies suggest that POU2F-POU2AF-driven malignancies have an intrinsic dependence on the mSWI/SNF complex, representing a therapeutic vulnerability.

cancer biology↗

bioRxiv2024

Identification and classification of the genomes of novel Microviruses in a poultry slaughterhouse

Microviridae is a family of phages with circular ssDNA genomes and they are widely found in various environments and organisms. In this study, Virome techniques were employed to explore potential members of Microviridae in poultry slaughterhouse, leading to the identification of 98 novel and complete microvirus genomes. Using a similarity clustering network classification approach, these viruses were found to belong to at least 6 new subfamilies within Microviridae and 3 higher-level taxonomic units. Analysis of their genomes found that the genome size, GC content and genome structure of these new taxa showed evident regularities, validating the rationality of our classification method. Compared with the 19 families classified by previous researchers for microviruses dataset, our method can divide microviruses into about 45 more detailed clusters, which may serve as a new standard for classifying Microviridae members. Furthermore, addressing the scarcity of host information for microviruses, this study significantly broadened their host range and discovered over 20 possible new hosts, including important pathogenic bacteria such as Helicobacter pylori and Vibrio cholerae, as well as different taxa demonstrated differential host specificity. The findings of this study effectively expand the diversity of the Microviridae, providing new insights for their classification and identification. Additionally, it offers a novel perspective for monitoring and controlling pathogenic microorganisms in poultry slaughterhouse environments.

microbiology↗

bioRxiv2024

Comparison and Evaluation of Neutralization of Clinically Frequently Used Antimicrobial Agents Using Three Different Culture Media in Simulated Blood Cultures

The performance of BACT/ALERT FA/FN Plu (France) blood culture containing a novel resin, DL (China) blood culture containing common resin, and adsorbent-free Thermo (USA) blood culture relying on dilution for antimicrobial neutralization at %peak serum concentration was evaluated by measuring the recovery of organisms and time to detection (TTD) in nine simulated microorganism-antimicrobial combination blood cultures.There was a significant difference in recovery rates between the aerobic media: 35/40 (87.5%) for BACT/ALERT media, 15/35 (42.9%) for DL media, and 5/40 (12.5%) for Thermo media; whereas, there was no statistical difference in TTD between FA Plus media and DL aerobic media. The recovery rates of the anaerobic media were 32/35 (91.4%) for BACT/ALERT media, 1/35 (2.9%) for DL media, and 5/35 (14.3%) for Thermo media, with significant differences only between BACT/ALERT FN Plus media and the others. Among the seven main antimicrobial categories, only BACT/ALERT FA/FN Plus culture media showed high recovery of microorganisms, except for carbapenems. The DL culture media exhibited a relatively high recovery rate of piperacillin/tazobactam, levofloxacin, and gentamicin only in aerobic media, and Thermo media only displayed the recovery of gentamicin.BACT/ALERT FA/FN Plus culture media with novel resin showed absolute advantages over DL and Thermo culture media and, thus, can be selectively applied clinically with prior use of antimicrobials before pathogen detection. DL culture media containing common resin outperformed adsorbent-free dilution-based Thermo culture media, which can be a backup option. We should focus on improving the neutralization of carbapenems with low efficiency in all three media.

microbiology↗

bioRxiv2023

Broad H3K4me3 Domain Is Associated with Spatial Coherence during Mammalian Embryonic Development

It is well known that the chromatin states play a major role in cell-fate decision and cell-identity maintenance; however, the spatial variation of chromatin states in situ remains poorly characterized. Here, by leveraging recently available spatial-CUT&Tag data, we systematically characterized the global spatial organization of the H3K4me3 profiles in a mouse embryo. Our analysis identified a subset of genes with spatially coherent H3K4me3 patterns, which together delineate the tissue boundaries. The spatially coherent genes are strongly enriched with tissue-specific transcriptional regulators. Remarkably, their corresponding genomic loci are marked by broad H3K4me3 domains, which is distinct from the typical H3K4me3 signature. Spatial transition across tissue boundaries is associated with continuous shortening of the broad H3K4me3 domains as well as expansion of H3K27me3 domains. Our analysis reveals a strong connection between the genomic and spatial variation of chromatin states, which may play an important role in embryonic development.

systems biology↗

bioRxiv2023

Gain of chromosome region 1q31.3 in human iPSCs confers growth advantage and alters contraction in derivative cardiomyocytes

hPSCs can acquire chromosomal aberrations such as copy number variations during prolonged maintenance in vitro, conferring growth advantages. However, the effect of these culture-acquired mutations on the phenotypes of the differentiated hPSCs is largely unstudied. Here, we identified mosaicism in a hPSC line in which some cells showed a gain of chromosome 1q31.3. We subcloned the wild-type and variant hPSCs and could maintain both as stable lines. While both variant and wildtype lines differentiated efficiently to cardiomyocytes (hPSC-CMs), molecular analysis revealed the variant hPSC-CMs had increased expression of TNNT2, a gene encoding one of the major sarcomere proteins mediating cardiomyocyte contractility and located within the gained chromosome 1q region. Moreover, the variant hPSC-CMs showed altered contraction kinetics. Together these results highlight the importance of careful monitoring of chromosome aberrations in hPSC lines as these could have confounding effects in various applications such as disease modelling and drug discovery.

cell biology↗

bioRxiv2023

E3 ligase ASB3 downregulates antiviral innate immunity by targeting MAVS for ubiquitin-proteasomal degradation

E3 ubiquitin ligases are very important to regulate antiviral immunity during viral infection. Here, we discovered that Ankyrin repeat and SOCS box-containing protein 3 (ASB3), an E3 ligase, are upregulated in the presence of RNA viruses, particularly Influenza A virus (IAV). Notably, overexpression of ASB3 inhibits type I IFN (IFN-I) responses induced by Sendai virus (SeV) and H9N2, and ablation of ASB3 restores SeV and H9N2 infection-mediated transcription of IFN-{beta} and its downstream interferon-stimulated genes (ISGs). Interestingly, animals lacking ASB3 showed a decreased susceptibility to H9N2 and PR8 infections. Mechanistically, ASB3 interacts with MAVS and directly mediates K48-linked polyubiquitination and degradation of MAVS at K297, thereby inhibiting the phosphorylation levels of TBK1 and IRF3, downregulating downstream antiviral signaling. These findings establish ASB3 as a critical negative regulator in controlling the activation of antiviral signaling and describe a novel function of ASB3 that has not been previously reported. IMPORTANCEIAV is a significant zoonotic pathogen that causes infections of the respiratory system. Hosts have evolved multiple strategies to defend against IAV infection. However, not all host proteins play an active defense role. In this study, we found that the E3 ligase ASB3 regulates antiviral immunity by manipulating MAVS stability. Briefly, overexpression of ASB3 degrades MAVS, thereby promoting viral replication. In contrast, ASB3 deletion restores MAVS expression, upregulating IFN-I responses. Additional research revealed that ASB3 mediates the K48-linked polyubiquitination of MAVS at K297, resulting in ASB3 being degraded via the ubiquitin-proteasome pathway. These findings reveal, for the first time, a novel mechanism by which ASB3 negatively regulates antiviral immunity and provides a potential target for anti-IAV drug development.

immunology↗

bioRxiv2023

AhR ligands from LGG metabolites promote piglet intestinal ILC3 activation and IL-22 secretion to inhibit PEDV infection

In maintaining organismal homeostasis, gut immunity plays a crucial role. The coordination between the microbiota and the immune system through bidirectional interactions regulates the impact of microorganisms on the host. Our research focused on understanding the relationship between substantial changes in jejunal intestinal flora and metabolites and intestinal immunity during porcine epidemic diarrhea virus (PEDV) infection in piglets. We discovered that Lactobacillus rhamnosus GG (LGG) could effectively prevent PEDV infection in piglets. Further investigation revealed that LGG metabolites interact with type 3 innate lymphoid cells (ILC3) in the jejunum of piglets through the aryl hydrocarbon receptor (AhR). This interaction promotes the activation of ILC3 cells and the production of interleukin-22 (IL-22). Subsequently, IL-22 facilitates the proliferation of IPEC-J2 cells and activates the STAT3 signaling pathway, thereby preventing PEDV infection. Moreover, the AhR receptor exerts its influence on various cell types within organoids, including intestinal stem cells (ISCs), Paneth cells, and enterocytes, fostering their growth and development, suggesting a broad impact of AhR on intestinal health. In conclusion, our study demonstrates the ability of LGG to modulate intestinal immunity and effectively prevent PEDV infection in piglets. These findings highlight the potential application of LGG as a preventive measure against viral infections in livestock.

immunology↗

bioRxiv2023

Single phage proteins sequester TIR- and cGAS-generated signaling molecules

Prokaryotic anti-phage immune systems use TIR (toll/interleukin-1 receptor) and cGAS (cyclic GMP-AMP synthase) enzymes to produce 1-3/1-2 glycocyclic ADPR (gcADPR) and cyclid di-/tri-nucleotides (CDNs and CTNs) signaling molecules that limit phage replication, respectively 1-3. However, how phages neutralize these common systems is largely unknown. Here, we show that Thoeris anti-defense proteins Tad1 4 and Tad2 5 both have anti-CBASS activity by simultaneously sequestering CBASS cyclic oligonucleotides. Strikingly, apart from binding Thoeris signals 1-3 and 1-2 gcADPR, Tad1 also binds numerous CBASS CDNs/CTNs with high affinity, inhibiting CBASS systems using these molecules in vivo and in vitro. The hexameric Tad1 has six binding sites for CDNs or gcADPR, which are independent from two high affinity binding sites for CTNs. Tad2 also sequesters various CDNs in addition to gcADPR molecules, inhibiting CBASS systems using these CDNs. However, the binding pockets for CDNs and gcADPR are different in Tad2, whereby a tetramer can bind two CDNs and two gcADPR molecules simultaneously. Taken together, Tad1 and Tad2 are both two-pronged inhibitors that, alongside anti-CBASS protein 2, establish a paradigm of phage proteins that flexibly sequester a remarkable breadth of cyclic nucleotides involved in TIR- and cGAS-based anti-phage immunity.

microbiology↗