Neural circuit basis of placebo pain relief.

Placebo effects are notable demonstrations of mind-body interactions1,2. During pain perception, in the absence of any treatment, an expectation of pain relief can reduce the experience of pain-a phenomenon known as placebo analgesia3-6. However, despite the strength of placebo effects and their impact on everyday human experience and the failure of clinical trials for new therapeutics7, the neural circuit basis of placebo effects has remained unclear. Here we show that analgesia from the expectation of pain relief is mediated by rostral anterior cingulate cortex (rACC) neurons that project to the pontine nucleus (rACC→Pn)-a precerebellar nucleus with no established function in pain. We created a behavioural assay that generates placebo-like anticipatory pain relief in mice. In vivo calcium imaging of neural activity and electrophysiological recordings in brain slices showed that expectations of pain relief boost the activity of rACC→Pn neurons and potentiate neurotransmission in this pathway. Transcriptomic studies of Pn neurons revealed an abundance of opioid receptors, further suggesting a role in pain modulation. Inhibition of the rACC→Pn pathway disrupted placebo analgesia and decreased pain thresholds, whereas activation elicited analgesia in the absence of placebo conditioning. Finally, Purkinje cells exhibited activity patterns resembling those of rACC→Pn neurons during pain-relief expectation, providing cellular-level evidence for a role of the cerebellum in cognitive pain modulation. These findings open the possibility of targeting this prefrontal cortico-ponto-cerebellar pathway with drugs or neurostimulation to treat pain.

Notch1 regulates hepatic thrombopoietin production.

ABSTRACT: Notch signaling regulates cell-fate decisions in several developmental processes and cell functions. However, the role of Notch in hepatic thrombopoietin (TPO) production remains unclear. We noted thrombocytopenia in mice with hepatic Notch1 deficiency and so investigated TPO production and other features of platelets in these mice. We found that the liver ultrastructure and hepatocyte function were comparable between control and Notch1-deficient mice. However, the Notch1-deficient mice had significantly lower plasma TPO and hepatic TPO messenger RNA levels, concomitant with lower numbers of platelets and impaired megakaryocyte differentiation and maturation, which were rescued by addition of exogenous TPO. Additionally, JAK2/STAT3 phosphorylation was significantly inhibited in Notch1-deficient hepatocytes, consistent with the RNA-sequencing analysis. JAK2/STAT3 phosphorylation and TPO production was also impaired in cultured Notch1-deficient hepatocytes after treatment with desialylated platelets. Consistently, hepatocyte-specific Notch1 deletion inhibited JAK2/STAT3 phosphorylation and hepatic TPO production induced by administration of desialylated platelets in vivo. Interestingly, Notch1 deficiency downregulated the expression of HES5 but not HES1. Moreover, desialylated platelets promoted the binding of HES5 to JAK2/STAT3, leading to JAK2/STAT3 phosphorylation and pathway activation in hepatocytes. Hepatocyte Ashwell-Morell receptor (AMR), a heterodimer of asialoglycoprotein receptor 1 [ASGR1] and ASGR2, physically associates with Notch1, and inhibition of AMR impaired Notch1 signaling activation and hepatic TPO production. Furthermore, blockage of Delta-like 4 on desialylated platelets inhibited hepatocyte Notch1 activation and HES5 expression, JAK2/STAT3 phosphorylation, and subsequent TPO production. In conclusion, our study identifies a novel regulatory role of Notch1 in hepatic TPO production, indicating that it might be a target for modulating TPO level.

Single-cell transcriptome analyses reveal critical roles of RNA splicing during leukemia progression.

Leukemogenesis is proposed to be a multistep process by which normal hematopoietic stem and progenitor cells are transformed into full-blown leukemic cells, the details of which are not fully understood. Here, we performed serial single-cell transcriptome analyses of preleukemic and leukemic cells (PLCs) and constructed the cellular and molecular transformation trajectory in a Myc-driven acute myeloid leukemia (AML) model in mice, which represented the transformation course in patients. We found that the Myc targets were gradually up-regulated along the trajectory. Among them were splicing factors, which showed stage-specific prognosis for AML patients. Furthermore, we dissected the detailed gene network of a tipping point for hematopoietic stem and progenitor cells (HSPCs) to generate initiating PLCs, which was characterized by dramatically increased splicing factors and unusual RNA velocity. In the late stage, PLCs acquired explosive heterogeneity through RNA alternative splicing. Among them, the Hsp90aa1hi subpopulation was conserved in both human and mouse AML and associated with poor prognosis. Exon 4 skipping of Tmem134 was identified in these cells. While the exon skipping product Tmem134ß promoted the cell cycle, full-length Tmem134α delayed tumorigenesis. Our study emphasized the critical roles of RNA splicing in the full process of leukemogenesis.

Impact of the RNA allosteric effect triggered by single nucleotide polymorphisms on the splicing process.

The susceptibility single nucleotide polymorphisms (SNPs) obtained by genome-wide association studies leave some thorny questions, such as prioritization, false positives and unknown pathogenesis. Previous studies suggested that genetic variation may perturb the RNA secondary structure, influence protein recruitment and binding and ultimately affect splicing processes. Therefore, exploring the perturbation of SNPs to structure-function correlations may provide an effective bridge toward understanding the genetic contribution to diseases. Here, aiming to decipher the regulatory mechanism of myopia susceptibility variants, we systematically evaluated the roles of SNP-induced structural changes during splicing. In addition, 7.53% of myopia-related SNPs exhibited significant global structural changes, 19.53% presented noteworthy local structural disturbance and there were wide-ranging structural perturbations in the splice-related motifs. We established a comprehensive evaluation system for structural disturbance in the splicing-related motifs and gave the priority ranking for the SNPs at RNA structural level. These high-priority SNPs were revealed to widely disturb the molecular interaction properties between splicing-related proteins and pre-mRNAs by HDOCK. Moreover, mini-gene assays confirmed that structural perturbation could influence splicing efficiency through structural remodelling. This study deepens our understanding of the potential molecular regulatory mechanisms of susceptible SNPs in myopia and contributes to personalized diagnosis, personalized medicine, disease-risk prediction and functional verification study by guiding the prioritization of the susceptibility SNPs.

Transcription factor WRKY75 maintains auxin homeostasis to promote tomato defense against Pseudomonas syringae.

The hemibiotrophic bacterial pathogen Pseudomonas syringae infects a range of plant species and causes enormous economic losses. Auxin and WRKY transcription factors play crucial roles in plant responses to P. syringae, but their functional relationship in plant immunity remains unclear. Here, we characterized tomato (Solanum lycopersicum) SlWRKY75, which promotes defenses against P. syringae pv. tomato (Pst) DC3000 by regulating plant auxin homeostasis. Overexpressing SlWRKY75 resulted in low free indole-3-acetic acid (IAA) levels, leading to attenuated auxin signaling, decreased expansin transcript levels, upregulated expression of PATHOGENESIS-RELATED GENES (PRs) and NONEXPRESSOR OF PATHOGENESIS-RELATED GENE 1 (NPR1), and enhanced tomato defenses against Pst DC3000. RNA interference-mediated repression of SlWRKY75 increased tomato susceptibility to Pst DC3000. Yeast one-hybrid, electrophoretic mobility shift assays, and luciferase activity assays suggested that SlWRKY75 directly activates the expression of GRETCHEN HAGEN 3.3 (SlGH3.3), which encodes an IAA-amido synthetase. SlGH3.3 enhanced tomato defense against Pst DC3000 by converting free IAA to the aspartic acid (Asp)-conjugated form IAA-Asp. In addition, SlWRKY75 interacted with a tomato valine-glutamine (VQ) motif-containing protein 16 (SlVQ16) in vivo and in vitro. SlVQ16 enhanced SlWRKY75-mediated transcriptional activation of SlGH3.3 and promoted tomato defense responses to Pst DC3000. Our findings illuminate a mechanism in which the SlVQ16-SlWRKY75 complex participates in tomato pathogen defense by positively regulating SlGH3.3-mediated auxin homeostasis.

Identifying STRN3-RARA as a new fusion gene for acute promyelocytic leukemia.

Here we report a new fusion gene, STRN3-RARA, in acute promyelocytic leukemia (APL). It cooperates with UTX deficiency to drive full-blown APL in mice. Although STRN3-RARA leukemia quickly relapses after all-trans retinoic acid treatment, it can be restrained by cepharanthine.

Phylogenomics of Bivalvia Using Ultraconserved Elements (UCEs) Reveal New Topologies for Pteriomorphia and Imparidentia.

Despite significant advances in phylogenetics over the past decades, the deep relationships within Bivalvia (phylum Mollusca) remain inconclusive. Previous efforts based on morphology or several genes have failed to resolve many key nodes in the phylogeny of Bivalvia. Advances have been made recently using transcriptome data, but the phylogenetic relationships within Bivalvia historically lacked consensus, especially within Pteriomorphia and Imparidentia. Here, we inferred the relationships of key lineages within Bivalvia using matrices generated from specifically designed ultraconserved elements (UCEs) with 16 available genomic resources and 85 newly sequenced specimens from 55 families. Our new probes (Bivalve UCE 2k v.1) for target sequencing captured an average of 849 UCEs with 1085-bp in mean length from in vitro experiments. Our results introduced novel schemes from six major clades (Protobranchina, Pteriomorphia, Palaeoheterodonta, Archiheterodonta, Anomalodesmata and Imparidentia), though some inner nodes were poorly resolved, such as paraphyletic Heterodonta in some topologies potentially due to insufficient taxon sampling. The resolution increased when analyzing specific matrices for Pteriomorphia and Imparidentia. We recovered three Pteriomorphia topologies different from previously published trees, with the strongest support for ((Ostreida + (Arcida + Mytilida)) + (Pectinida + (Limida + Pectinida))). Limida were nested within Pectinida, warranting further studies. For Imparidentia, our results strongly supported the new hypothesis of (Galeommatida + (Adapedonta + Cardiida)), while the possible non-monophyly of Lucinida was inferred but poorly supported. Overall, our results provide important insights into the phylogeny of Bivalvia and show that target enrichment sequencing of UCEs can be broadly applied to study both deep and shallow phylogenetic relationships.

Foraging in a non-foraging task: Fitness maximization explains human risk preference dynamics under changing environment.

Changes in risk preference have been reported when making a series of independent risky choices or non-foraging economic decisions. Behavioral economics has put forward various explanations for specific changes in risk preference in non-foraging tasks, but a consensus regarding the general principle underlying these effects has not been reached. In contrast, recent studies have investigated human economic risky choices using tasks adapted from foraging theory, which require consideration of past choices and future opportunities to make optimal decisions. In these foraging tasks, human economic risky choices are explained by the ethological principle of fitness maximization, which naturally leads to dynamic risk preference. Here, we conducted two online experiments to investigate whether the principle of fitness maximization can explain risk preference dynamics in a non-foraging task. Participants were asked to make a series of independent risky economic decisions while the environmental richness changed. We found that participants' risk preferences were influenced by the current and past environments, making them more risk-averse during and after the rich environment compared to the poor environment. These changes in risk preference align with fitness maximization. Our findings suggest that the ethological principle of fitness maximization might serve as a generalizable principle for explaining dynamic preferences, including risk preference, in human economic decision-making.

Low-intensity ultrasound ameliorates brain organoid integration and rescues microcephaly deficits.

Human brain organoids represent a remarkable platform for modelling neurological disorders and a promising brain repair approach. However, the effects of physical stimulation on their development and integration remain unclear. Here, we report that low-intensity ultrasound significantly increases neural progenitor cell proliferation and neuronal maturation in cortical organoids. Histological assays and single-cell gene expression analyses revealed that low-intensity ultrasound improves the neural development in cortical organoids. Following organoid grafts transplantation into the injured somatosensory cortices of adult mice, longitudinal electrophysiological recordings and histological assays revealed that ultrasound-treated organoid grafts undergo advanced maturation. They also exhibit enhanced pain-related gamma-band activity and more disseminated projections into the host brain than the untreated groups. Finally, low-intensity ultrasound ameliorates neuropathological deficits in a microcephaly brain organoid model. Hence, low-intensity ultrasound stimulation advances the development and integration of brain organoids, providing a strategy for treating neurodevelopmental disorders and repairing cortical damage.

KLF15 suppresses stemness of pancreatic cancer by decreasing USP21-mediated Nanog stability.

The existence of cancer stem cells (CSCs) in pancreatic ductal adenocarcinoma (PDAC) is considered to be the key factor for metastasis and chemoresistance. Thus, novel therapeutic strategies for eradicating CSCs are urgently needed. Here we aimed to explore the role of KLF15 in stemness and the feasibility of using KLF15 to inhibit CSCs and improve chemotherapy sensitivity in PDAC. In this study, we report that KLF15 is negatively associated with poor survival and advanced pathological staging of PDAC. Moreover, tumorous KLF15 suppresses the stemness of PDAC by promoting the degradation of Nanog, and KLF15 directly interacts with Nanog, inhibiting interaction between Nanog with USP21. We also demonstrate that the KLF15/Nanog complex inhibit the stemness in vivo and in PDX cells. Tazemetostat suppresses stemness and sensitizes PDAC cells to gemcitabine by promoting KLF15 expression in PDAC. In summary, the findings of our study confirm the value of KLF15 level in diagnosis and prognosis of PDAC, it is the first time to explore the inhibition role of KLF15 in stemness of PDAC and the regulation mechanism of Nanog, contributing to provide a new therapeutic strategy that using Tazemetostat sensitizes PDAC cells to gemcitabine by promoting KLF15 expression for PDAC.

Why is there no service to support taxonomy?

Increasing complexity and specialisation of modern sciences has led to increasingly collaborative publications, as well as the involvement of commercial services. Modern integrative taxonomy likewise depends on many lines of evidence and is increasingly complex, but the trend of collaboration lags and various attempts at 'turbo taxonomy' have been unsatisfactory. We are developing a taxonomic service in the Senckenberg Ocean Species Alliance to provide fundamental data for new species descriptions. This will also function as a hub to connect a global network of taxonomists, assembling an alliance of scientists working on potential new species to tackle both the extinction and inclusion crises we face today. The current rate of new species descriptions is simply too slow; the discipline is often dismissed as old fashioned, and there is a crisis level need for taxonomic descriptions to come to grips with the scale of Anthropocene biodiversity loss. Here, we envision how the process of describing and naming species would benefit from a service supporting the acquisition of descriptive data. Also see the video abstract here: https://youtu.be/E8q3KJor_F8.

AFF4 regulates cellular adipogenic differentiation via targeting autophagy.

Transcriptional elongation is a universal and critical step during gene expression. The super elongation complex (SEC) regulates the rapid transcriptional induction by mobilizing paused RNA polymerase II (Pol II). Dysregulation of SEC is closely associated with human diseases. However, the physiological role of SEC during development and homeostasis remains largely unexplored. Here we studied the function of SEC in adipogenesis by manipulating an essential scaffold protein AF4/FMR2 family member 4 (AFF4), which assembles and stabilizes SEC. Knockdown of AFF4 in human mesenchymal stem cells (hMSCs) and mouse 3T3-L1 preadipocytes inhibits cellular adipogenic differentiation. Overexpression of AFF4 enhances adipogenesis and ectopic adipose tissue formation. We further generate Fabp4-cre driven adipose-specific Aff4 knockout mice and find that AFF4 deficiency impedes adipocyte development and white fat depot formation. Mechanistically, we discover AFF4 regulates autophagy during adipogenesis. AFF4 directly binds to autophagy-related protein ATG5 and ATG16L1, and promotes their transcription. Depleting ATG5 or ATG16L1 abrogates adipogenesis in AFF4-overepressing cells, while overexpression of ATG5 and ATG16L1 rescues the impaired adipogenesis in Aff4-knockout cells. Collectively, our results unveil the functional importance of AFF4 in regulating autophagy and adipogenic differentiation, which broaden our understanding of the transcriptional regulation of adipogenesis.

Regenerative failure of intrahepatic biliary cells in Alagille syndrome rescued by elevated Jagged/Notch/Sox9 signaling.

Despite the robust healing capacity of the liver, regenerative failure underlies numerous hepatic diseases, including the JAG1 haploinsufficient disorder, Alagille syndrome (ALGS). Cholestasis due to intrahepatic duct (IHD) paucity resolves in certain ALGS cases but fails in most with no clear mechanisms or therapeutic interventions. We find that modulating jag1b and jag2b allele dosage is sufficient to stratify these distinct outcomes, which can be either exacerbated or rescued with genetic manipulation of Notch signaling, demonstrating that perturbations of Jag/Notch signaling may be causal for the spectrum of ALGS liver severities. Although regenerating IHD cells proliferate, they remain clustered in mutants that fail to recover due to a blunted elevation of Notch signaling in the distal-most IHD cells. Increased Notch signaling is required for regenerating IHD cells to branch and segregate into the peripheral region of the growing liver, where biliary paucity is commonly observed in ALGS. Mosaic loss- and-gain-of-function analysis reveals Sox9b to be a key Notch transcriptional effector required cell autonomously to regulate these cellular dynamics during IHD regeneration. Treatment with a small-molecule putative Notch agonist stimulates Sox9 expression in ALGS patient fibroblasts and enhances hepatic sox9b expression, rescues IHD paucity and cholestasis, and increases survival in zebrafish mutants, thereby providing a proof-of-concept therapeutic avenue for this disorder.

Novel mutation in EFEMP1 identified from two Chinese POAG families differentially activated endoplasmic reticulum stress markers and induced glaucoma in mouse.

Primary open-angle glaucoma (POAG) is the most common type of glaucoma. Using whole-exome sequencing, we identified two independent families diagnosed as POAG from the China with a novel EFEMP1 variant (Exon3, c.175A>C p.Met59Leu); Three previously reported variants c.1160G>A p.R387Q, c.1189T>C p.Y397H, and c.1429C>T p.R477C in EFEPM1 from 55 sporadic POAG individuals were also identified. The variant c.175A>C p.Met59Leu co-segregated with the disease phenotype within the families. Immunoprecipitation and western blot assays showed that all three EFEMP1 mutants (p.Met59Leu, pArg140Trp, pArg345Trp) increased intracellular protein aggregations, and pMet59Leu and pArg140Arg also enhanced their extracellular proteins secretion, compared to WT in HEK293T. The differential regulations to endoplasmic reticulum (ER) stress markers ATF4, GPR78/94, and CHOP, and differential phosphorylation activations to CREB at Ser133, AKT at Ser473, p44/42 at Thr202/Tyr204, and STAT3 at Tyr705, were also detected among the mutants and WT. Finally, we revealed a significant increment of intraocular pressure and obvious reduction of RGC cells at the sixth week following intravitreal injection of adenovirus 5 (Ad5) expressing in pMet59Leu compared to WT and GFP controls. Together, variant c.175A>C p.Met59Leu in EFEMP1 is pathogenic and different mutants in EFEMP1 triggered distinct signaling pathways, explaining the reason of mutation-dependent disease phenotypes of EFEMP1.

Decoding Biomechanical Cues Based on DNA Sensors.

Biological systems perceive and respond to mechanical forces, generating mechanical cues to regulate life processes. Analyzing biomechanical forces has profound significance for understanding biological functions. Therefore, a series of molecular mechanical techniques have been developed, mainly including single-molecule force spectroscopy, traction force microscopy, and molecular tension sensor systems, which provide indispensable tools for advancing the field of mechanobiology. DNA molecules with a programmable structure and well-defined mechanical characteristics have attached much attention to molecular tension sensors as sensing elements, and are designed for the study of biomechanical forces to present biomechanical information with high sensitivity and resolution. In this work, a comprehensive overview of molecular mechanical technology is presented, with a particular focus on molecular tension sensor systems, specifically those based on DNA. Finally, the future development and challenges of DNA-based molecular tension sensor systems are looked upon.

The HEPS synchrotron unleashes new medical frontiers.

The High Energy Photon Source (HEPS) in Beijing achieved a beam energy of 6 GeV. This milestone enables groundbreaking advances in health sciences and various research fields, promising new insights into biological and quantum processes.

Venetoclax overcomes resistance to all-trans retinoic acid in a variant acute promyelocytic leukemia with TNRC18::RARA fusion.

Acute promyelocytic leukemia (APL) is generally driven by PML::RARA, but approximately 2% of variant APL patients do not contain this fusion gene and pose challenges in diagnosis and treatment. Here, we reported an aggressive APL patient with variant TNRC18::RARA fusion gene, who was resistant to standard differentiation induction therapy consisting of all-trans retinoic acid (ATRA) and arsenic trioxide but achieved complete remission with venetoclax plus ATRA. Mechanistically, venetoclax possesses synergistic effects in ATRA-induced TNRC18::RARA-positive cell differentiation.

Differential heat-response characteristics of two plastid isoforms of triose phosphate isomerase in tomato.

Heat stress causes dysfunction of the carbon-assimilation metabolism. As a member of Calvin-Benson-Bassham (CBB) cycle, the chloroplast triose phosphate isomerases (TPI) catalyse the interconversion of glyceraldehyde 3-phosphate (GAP) and dihydroxyacetone phosphate (DHAP). The tomato (Solanum lycopersicum) genome contains two individual SlTPI genes, Solyc10g054870 and Solyc01g111120, which encode the chloroplast-located proteins SlTPI1 and SlTPI2, respectively. The tpi1 and tpi2 single mutants had no visible phenotypes, but the leaves of their double mutant lines tpi1tpi2 had obviously reduced TPI activity and displayed chlorotic variegation, dysplasic chloroplasts and lower carbon-assimilation efficiency. In addition to altering carbon metabolism, proteomic data showed that the loss of both SlTPI1 and SlTPI2 severely affected photosystem proteins, reducing photosynthetic capacity. None of these phenotypes was evident in the tpi1 or tpi2 single mutants, suggesting that SlTPI1 and SlTPI2 are functionally redundant. However, the two proteins differed in their responses to heat stress; the protein encoded by the heat-induced SlTPI2 showed a higher level of thermotolerance than that encoded by the heat-suppressed SlTPI1. Notably, heat-induced transcription factors, SlWRKY21 and SlHSFA2/7, which negatively regulated SlTPI1 expression and positively regulated SlTPI2 expression, respectively. Our findings thus reveal that SlTPI1 and SlTPI2 have different thermostabilities and expression patterns in response to heat stress, which have the potential to be applied in thermotolerance strategies in crops.

Motion-robust free-running volumetric cardiovascular MRI.

PURPOSE: To present and assess an outlier mitigation method that makes free-running volumetric cardiovascular MRI (CMR) more robust to motion. METHODS: The proposed method, called compressive recovery with outlier rejection (CORe), models outliers in the measured data as an additive auxiliary variable. We enforce MR physics-guided group sparsity on the auxiliary variable, and jointly estimate it along with the image using an iterative algorithm. For evaluation, CORe is first compared to traditional compressed sensing (CS), robust regression (RR), and an existing outlier rejection method using two simulation studies. Then, CORe is compared to CS using seven three-dimensional (3D) cine, 12 rest four-dimensional (4D) flow, and eight stress 4D flow imaging datasets. RESULTS: Our simulation studies show that CORe outperforms CS, RR, and the existing outlier rejection method in terms of normalized mean square error and structural similarity index across 55 different realizations. The expert reader evaluation of 3D cine images demonstrates that CORe is more effective in suppressing artifacts while maintaining or improving image sharpness. Finally, 4D flow images show that CORe yields more reliable and consistent flow measurements, especially in the presence of involuntary subject motion or exercise stress. CONCLUSION: An outlier rejection method is presented and tested using simulated and measured data. This method can help suppress motion artifacts in a wide range of free-running CMR applications.

Biological characterization of the phage lysin AVPL and its efficiency against Aerococcus viridans-induced mastitis in a murine model.

Aerococcus viridans (A. viridans) is an important opportunistic zoonotic pathogen that poses a potential threat to the animal husbandry industry, such as cow mastitis, due to the widespread development of multidrug-resistant strains. Phage lysins have emerged as a promising alternative antibiotic treatment strategy. However, no lysins have been reported to treat A. viridans infections. In this study, the critical active domain and key active sites of the first A. viridans phage lysin AVPL were revealed. AVPL consists of an N-terminal N-acetylmuramoyl-L-alanine amidase catalytic domain and a C-terminal binding domain comprising two conserved LysM. H40, N44, E52, W68, H147, T157, F60, F64, I77, N92, Q97, H159, V160, D161, and S42 were identified as key sites for maintaining the activity of the catalytic domain. The LysM motif plays a crucial role in binding AVPL to bacterial cell wall peptidoglycan. AVPL maintains stable activity in the temperature range of 4-45°C and pH range of 4-10, and its activity is independent of the presence of metal ions. In vitro, the bactericidal effect of AVPL showed efficient bactericidal activity in milk samples, with 2 µg/mL of AVPL reducing A. viridans by approximately 2 Log10 in 1 h. Furthermore, a single dose (25 µg) of lysin AVPL significantly reduces bacterial load (approximately 2 Log10) in the mammary gland of mice, improves mastitis pathology, and reduces the concentration of inflammatory cytokines (TNF-α, IL-1ß, and IL-6) in mammary tissue. Overall, this work provides a novel alternative therapeutic drug for mastitis induced by multidrug-resistant A. viridans. IMPORTANCE: A. viridans is a zoonotic pathogen known to cause various diseases, including mastitis in dairy cows. In recent years, there has been an increase in antibiotic-resistant or multidrug-resistant strains of this pathogen. Phage lysins are an effective approach to treating infections caused by multidrug-resistant strains. This study revealed the biological properties and key active sites of the first A. viridans phage lysin named AVPL. AVPL can effectively kill multidrug-resistant A. viridans in pasteurized whole milk. Importantly, 25 µg AVPL significantly alleviates the symptoms of mouse mastitis induced by A. viridans. Overall, our results demonstrate the potential of lysin AVPL as an antimicrobial agent for the treatment of mastitis caused by A. viridans.