Human Counterpart Research Articles

METB-03. SOLID PEDIATRIC TUMORS IN MICE REVEAL MODEL-SPECIFIC GLOBAL DNA METHYLATION AND CNV PROFILES CORRESPONDING TO HUMAN COUNTERPARTS

Abstract BACKGROUND The analysis and comparison of global DNA methylation patterns has become a gold standard in modern neuropathology. For human central nervous system (CNS) tumors and other cancers, the research community has collected thousands of methylation profiles, leading to the discovery and definition of numerous molecularly distinct tumor types and subtypes. Although reliable preclinical mouse models are essential for the understanding of tumor development and the validation of therapeutic approaches, such DNA methylation analyses have so far not been systematically performed for murine tumors owing to technical limitations. METHODS We employed the Illumina Bead Chip 285k mouse methylation array to profile ~500 samples covering 90 different mouse models representing 33 pediatric solid tumor types, including CNS tumors and sarcomas from 18 laboratories. We compared DNA methylation profiles of these models between each other and to human CNS tumors, performed immune cell deconvolution and conducted an in-depth analysis of copy number variants (CNVs) during tumor evolution. RESULTS Unsupervised clustering showed that mouse models form groups of their presumed tumor types. Using a tailor-made cross-species analysis based on syntenic CpG sites, we found that most tumors also group with their corresponding human counterparts. Immune cell deconvolution revealed distinct tumor microenvironments that showed clear similarities to human tumors. We further identified recurrent, model-specific CNVs that are syntenic to genomic aberrations in respective human tumors, suggesting an essential role of CNVs during tumor initiation or maintenance. CONCLUSION We provide a global resource of well characterized pediatric solid cancer models representing numerous different tumor types. Our comparative analyses reveal novel molecular model characteristics and validate their reliability as human disease models. Our data provide new biological insights into immune composition, tumor cell identities and tumor development by identifying model-specific CNV profiles.

Outdated and re-configured: Challenging linear conceptualizations of ageing through the case of revived obsolete technologies

Taking as a starting point the conventional view of ageing as a linear process beginning in a youthful and productive stage but gradually deteriorating, this paper shifts the usual anthropocentric focal point towards technological artifacts which do not conform to this typical view. More specifically, three examples of technologies previously considered obsolete, but which have seen a revival in the last decade, are presented: the so-called dumbphones, analogue cameras, and vinyl players. Although very different at first glance, the three cases of these revived technologies show a similar evolution trajectory which breaks from the typical view of ageing in technological artifacts. Instead, they indicate how their revival does not simply entail a reconsideration of their initial value (such as it is often the case with antiques or heirlooms), but a transformation, hybridisation, and re-envisioned purpose.To this effect, the agential realism theory is applied to show how the revival of technological artifacts and practices once considered outdated attempts to dissolve binaries such as old/new, young/old, or slow/fast. Furthermore, such artifacts reveal trajectories of ageing that are unlike their human counterparts, but which can make way for new manners of articulating issues pertaining to ageing as a process in humans as well.The contribution of the paper lies in illustrating how adopting a non-linear view of ageing and fundamentally questioning its inherent binaries has the capacity to produce a much-needed nuanced view of ageing in humans, non-humans, and their sociomaterial entanglements.

MODL-15. CHARACTERIZATION OF SPONTANEOUS CANINE HIGH-GRADE GLIOMA MODELS AS CLINICALLY-RELEVANT SURROGATES OF PEDIATRIC HIGH-GRADE GLIOMA

Abstract BACKGROUND High-grade glioma (HGG) occurring spontaneously in canines shows histological and genetic resemblance to pediatric high-grade glioma (PHGG). Both canine HGG and PHGG are treated with combinations of surgical resection, radiation therapy, and/or chemotherapy, but outcomes for both groups are poor. Studying canine HGG both serves companion dogs and provides an orthogonal preclinical model of PHGG. METHODS Canine HGG lines J3T, SDT3G, and G06A were characterized and compared with H3K27M-mutant PHGG lines DIPG7, DIPG13, and BT245 using neurosphere dilution assay and drug screening with all FDA-approved anti-cancer agents. J3T and SDT3G were orthotopically implanted into mice and monitored using MRI and bioluminescence. RESULTS Like PHGG, the canine lines J3T and SDT3G were highly sensitive to proteasome and XPO1 inhibition; compared to PHGG, the canine lines were most sensitive to protein translation inhibitors and DNA intercalators. Canine HGG lines were not as sensitive to other targeted inhibitors effective in PHGG. Compared to PHGG cell lines, canine cell lines had greater variance in self-renewal capability. J3T and SDT3G were also injected into the cortex of immunodeficient mice. Bioluminescent signal confirmed J3T engraftment one week post-surgery with rapid tumor growth, while SDT3G presented initial engraftment by MRI two weeks post-surgery but did not exhibit sustained growth. DISCUSSION Canine HGG and PHGG showed similar sensitivity to proteasome and XPO1 inhibition; they differed in self-renewal capability and susceptibility to other anti-cancer agents. This could be because canine target proteins often differ from their human counterparts and thus may respond differently to targeted medications designed for humans. Overall, canine HGG provides a novel, primary, immunocompetent surrogate that resembles PHGG and may provide a step for clinical investigation between xenograft models and PHGG trials and/or opportunities for co-clinical trials.

Dissecting the abilities of murine Siglecs to interact with gangliosides

Siglecs are cell surface receptors whose functions are tied to the binding of their sialoglycan ligands. Recently, we developed an optimized liposome formulation and used it to investigate the binding of human Siglecs (hSiglec) against a panel of gangliosides. Animal models, more specifically murine models, are used to understand human biology, however, species-specific differences can complicate the interpretation of the results. Herein, we used our optimized liposome formulation to dissect the interactions between murine Siglecs (mSiglecs) and gangliosides to assess the appropriateness of mSiglecs as a proxy to better understand the biological roles of hSiglec-ganglioside interactions. Using our optimized liposome formulation, we found that ganglioside binding is generally conserved between mice and humans with mSiglec-1, -E, -F, and -15 binding multiple gangliosides like their human counterparts. However, in contrast to the hSiglecs, we observed little to no binding between the mSiglecs and ganglioside GM1a. Detailed analysis of mSiglec-1 interacting with GM1a and its structural isomer, GM1b, suggests that mSiglec-1 preferentially binds α2-3-linked sialic acids presented from the terminal galactose residue. The ability of mSiglecs to interact or not interact with gangliosides, particularly GM1a, has implications for using mice to study neurodegenerative diseases, infections, and cancer, where interactions between Siglecs and glycolipids have been proposed to modulate these human diseases.

Identification of Small Molecule Inhibitors Targeting Phosphoserine Phosphatase: A Novel Target for the Development of Antiamoebic Drugs.

Amoebiasis, a widespread disease caused by the protozoan parasite Entamoeba histolytica, poses challenges due to the adverse effects of existing antiamoebic drugs and rising drug resistance. Novel targeted drugs are in need of the hour to combat the prevalence of this disease. Given the significance of cysteine for Entamoeba survival, the rate-determining step in the serine (the sole substrate of cysteine synthesis) biosynthetic pathway, i.e., the conversion of 3-phosphoserine to l-serine catalyzed by phosphoserine phosphatase (PSP), emerges as a promising drug target. Our previous study unveils the essential role of EhPSP in amoebas' survival, particularly under oxidative stress, by increasing cysteine production. The study also revealed that EhPSP differs significantly from its human counterpart, both structurally and biochemically, highlighting its potential as a viable target for developing new antiamoebic drugs. In the present study, employing in silico screening of vast natural and synthetic small chemical compound libraries, we identified 21 potential EhPSP inhibitor molecules. Out of the 21 compounds examined, only five could inhibit the catalytic activity of EhPSP. The inhibition capability of these five compounds was subsequently validated by in silico binding free energy calculations, SPR-based real-time binding studies, and molecular simulations to assess the stability of the EhPSP-inhibitor complexes. By identifying the five potential inhibitors that can target cysteine synthesis via EhPSP, our findings establish EhPSP as a drug candidate that can serve as a foundation for antiamoebic drug research.

The effect of human versus virtual influencers: The roles of destination types and self-referencing processes

Social media influencers are increasingly recognized for their ability to influence tourists’ decision-making processes. The emergent phenomenon of virtual influencers presents an unprecedented challenge to their human counterparts, reshaping the dynamics of the tourism industry. It remains a challenge to integrate various forms of destination advertising and harmonize the approaches of both human and virtual influencers to effectively attract tourists. This study addresses this gap by investigating the effectiveness of human and virtual influencers in endorsing natural versus cultural destinations. Adopting source credibility theory, we conduct five empirical studies. Our findings reveal that virtual influencers boost visit intentions for cultural destinations, while human influencers do so for natural destinations. Credibility and self-referencing play a serially mediating role in this process. Furthermore, this study explores the moderating role of tourists’ preference for uniqueness. This research offers valuable insights for tourism industry managers aiming to harness the power of virtual influencers effectively.

Discovery and Characterization of the ddx41 Gene in Atlantic Salmon: Evolutionary Implications, Structural Functions, and Innate Immune Responses to Piscirickettsia salmonis and Renibacterium salmoninarum Infections.

The innate immune response in Salmo salar, mediated by pattern recognition receptors (PRRs), is crucial for defending against pathogens. This study examined DDX41 protein functions as a cytosolic/nuclear sensor for cyclic dinucleotides, RNA, and DNA from invasive intracellular bacteria. The investigation determined the existence, conservation, and functional expression of the ddx41 gene in S. salar. In silico predictions and experimental validations identified a single ddx41 gene on chromosome 5 in S. salar, showing 83.92% homology with its human counterpart. Transcriptomic analysis in salmon head kidney confirmed gene transcriptional integrity. Proteomic identification through mass spectrometry characterized three unique peptides with 99.99% statistical confidence. Phylogenetic analysis demonstrated significant evolutionary conservation across species. Functional gene expression analysis in SHK-1 cells infected by Piscirickettsia salmonis and Renibacterium salmoninarum indicated significant upregulation of DDX41, correlated with increased proinflammatory cytokine levels and activation of irf3 and interferon signaling pathways. In vivo studies corroborated DDX41 activation in immune responses, particularly when S. salar was challenged with P. salmonis, underscoring its potential in enhancing disease resistance. This is the first study to identify the DDX41 pathway as a key component in S. salar innate immune response to invading pathogens, establishing a basis for future research in salmonid disease resistance.

KR158 Spheres Harboring Slow-Cycling Cells Recapitulate High-Grade Glioma Features in an Immunocompetent System.

Glioblastoma (GBM) poses a significant challenge in clinical oncology due to its aggressive nature, heterogeneity, and resistance to therapies. Cancer stem cells (CSCs) play a critical role in GBM, particularly in treatment resistance and tumor relapse, emphasizing the need to comprehend the mechanisms regulating these cells. Also, their multifaceted contributions to the tumor microenvironment (TME) underline their significance, driven by their unique properties. This study aimed to characterize glioblastoma stem cells (GSCs), specifically slow-cycling cells (SCCs), in an immunocompetent murine GBM model to explore their similarities with their human counterparts. Using the KR158 mouse model, we confirmed that SCCs isolated from this model exhibited key traits and functional properties akin to human SCCs. KR158 murine SCCs, expanded in the gliomasphere assay, demonstrated sphere forming ability, self-renewing capacity, positive tumorigenicity, enhanced stemness and resistance to chemotherapy. Together, our findings validate the KR158 murine model as a framework to investigate GSCs and SCCs in GBM pathology, and explore specifically the SCC-immune system communications, understand their role in disease progression, and evaluate the effect of therapeutic strategies targeting these specific connections.

Peroxisome biogenesis factor PEX14 is crucial for survival and fecundity of female brown planthopper, Nilaparvata lugens (Stål)

Peroxisomes are ubiquitous cellular organelles participating in a variety of critical metabolic reactions. PEX14 is an essential peroxin responsible for peroxisome biogenesis. In this study, we identified the human PEX14 homolog in the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae). N. lugens PEX14 (NlPEX14) showed significant topological similarity to its human counterpart. It is expressed throughout all developmental stages, with the highest expression observed in adult insects. Down-regulation of NlPEX14 through injection of NlPEX14-specific double-strand RNA impaired nymphal development. Moreover, females subjected to dsNlPEX14 treatment exhibited a significantly reduced lifespan. Additionally, we found abnormal ovarian development and a significant decrease in the number of eggs laid in NlPEX14-downregulated females. Further experiments support that the shortening of lifespan and the decrease in female fecundity can be attributed, at least partially, to the accumulation of fatty acids and reduced expression of vitellogenin. Together, our study reveals an indispensable function of NlPEX14 for insect reproduction and establishes a causal connection between the phenotypes and peroxisome biogenesis, shedding light on the importance of peroxisomes in female fecundity.

Immunohistochemical Expression Levels of Epidermal Growth Factor Receptor, Cyclooxygenase-2, and Ki-67 in Canine Cutaneous Squamous Cell Carcinomas

Squamous cell carcinoma (SCC) stands as the second most prevalent skin cancer in dogs, primarily attributed to UV radiation exposure. Affected areas typically include regions with sparse hair and pale or depigmented skin. The significance of spontaneous canine cutaneous SCC as a model for its human counterpart is underscored by its resemblance. This study assesses the expression of key markers—Epidermal Growth Factor Receptor (EGFR), Cyclooxygenase-2 (Cox-2), and Ki-67—in canine cutaneous SCC. Our objective is to investigate the association between their expression levels and classical clinicopathological parameters, unraveling the intricate relationships among these molecular markers. In our retrospective analysis of 37 cases, EGFR overexpression manifested in 43.2% of cases, while Cox-2 exhibited overexpression in 97.3%. The EGFR, Cox-2 overexpression, and Ki-67 proliferation indices, estimated through immunohistochemistry, displayed a significant association with the histological grade, but only EGFR labeling is associated with the presence of lymphovascular emboli. The Ki-67 labeling index expression exhibited an association with EGFR and Cox-2. These findings propose that EGFR, Cox-2, and Ki-67 hold promise as valuable markers in canine SCC. EGFR, Cox-2, and Ki-67 may serve as indicators of disease progression, offering insights into the malignancy of a lesion. The implications extend to the potential therapeutic targeting of EGFR and Cox-2 in managing canine SCC. Further exploration of these insights is warranted due to their translational relevance and the development of targeted interventions in the context of canine SCC.

Understanding the influence of AI autonomy on AI explainability levels in human-AI teams using a mixed methods approach

An obstacle to effective teaming between humans and AI is the agent’s "black box" design. AI explanations have proven benefits, but few studies have explored the effects that explanations can have in a teaming environment with AI agents operating at heightened levels of autonomy. We conducted two complementary studies, an experiment and participatory design sessions, investigating the effect that varying levels of AI explainability and AI autonomy have on the participants’ perceived trust and competence of an AI teammate to address this research gap. The results of the experiment were counter-intuitive, where the participants actually perceived the lower explainability agent as both more trustworthy and more competent. The participatory design sessions further revealed how a team’s need to know influences when and what teammates need explained from AI teammates. Based on these findings, several design recommendations were developed for the HCI community to guide how AI teammates should share decision information with their human counterparts considering the careful balance between trust and competence in human-AI teams.

Identifying, Diagnosing, and Grading Malignant Peripheral Nerve Sheath Tumors in Genetically Engineered Mouse Models.

Patients with the autosomal dominant tumor susceptibility syndrome neurofibromatosis type 1 (NF1) commonly develop plexiform neurofibromas (PNs) that subsequently transform into highly aggressive malignant peripheral nerve sheath tumors (MPNSTs). Understanding the process by which a PN transforms into an MPNST would be facilitated by the availability of genetically engineered mouse (GEM) models that accurately replicate the PN-MPNST progression seen in humans with NF1. Unfortunately, GEM models with Nf1 ablation do not fully recapitulate this process. This led us to develop P0-GGFβ3 mice, a GEM model in which overexpression of the Schwann cell mitogen neuregulin-1 (NRG1) in Schwann cells results in the development of PNs that progress to become MPNSTs with high frequency. However, to determine whether tumorigenesis and neoplastic progression in P0-GGFβ3 mice accurately model the processes seen in NF1 patients, we had to first prove that the pathology of P0-GGFβ3 peripheral nerve sheath tumors recapitulates the pathology of their human counterparts. Here, we describe the specialized methodologies used to accurately diagnose and grade peripheral nervous system neoplasms in GEM models, using P0-GGFβ3 and P0-GGFβ3;Trp53+/- mice as an example. We describe the histologic, immunohistochemical, and histochemical methods used to diagnose PNs and MPNSTs, how to distinguish these neoplasms from other tumor types that mimic their pathology, and how to grade these neoplasms. We discuss the establishment of early-passage cultures from GEM MPNSTs, how to characterize these cultures using immunocytochemistry, and how to verify their tumorigenicity by establishing allografts. Collectively, these techniques characterize the pathology of PNs and MPNSTs that arise in GEM models and critically compare the pathology of these murine tumors to their human counterparts.

Exploratory screening for micro-RNA biomarkers in canine multicentric lymphoma.

Lymphoma is one of the most frequent hematopoietic tumors in dogs and shares similar features with human counterparts. MicroRNAs (miRNA, small non-coding RNAs) are pivotal in gene regulation fine tuning and cancer hallmarks are influenced by their aberrant expression. Consequently, miRNA biomarkers may assist predicting therapeutic response and clinical outcome by providing less-invasive novel diagnostics tools. The aim of this study was to detect dysregulated miRNAs in lymphomatous lymph node tissues in comparison to lymph node material or PBMCs from healthy control dogs. Potential significant differences in miRNA expression profiles between four lymphoma entities were evaluated. A customized PCR array was utilized to profile 89 canine target miRNAs. Quantification was performed using qPCR, relative expression was determined by the delta-delta Ct method, and p-values were calculated with student's t-test. In the 14 diffuse large B-cell lymphoma (DLBCL) patients, 28 and 24 different miRNAs were significantly dysregulated compared to lymph node material or PBMCs. Sixteen miRNAs occurred in both control groups, with 12 miRNAs being down- and four miRNAs being upregulated. The six peripheral T-cell lymphoma (PTCL) samples showed 24 and 25 dysregulated miRNAs when compared to the healthy controls. A combined analysis of DLBCL and PTCL samples revealed seven shared and 19 differently expressed miRNAs. Potential biomarkers in T- and B-cell lymphoma could be the miRNA-17/92 cluster and miRNA-181-family together with miRNA-34a and miRNA-150. Diagnostic utility of potential biomarkers must be validated in larger, prospective cohorts of canine lymphoma cases and in higher numbers of physiological patient material.

Algorithmic Decision Making: Can Artificial Intelligence and the Metaverse Provide Technological Solutions to Modernise the United Kingdom’s Legal Services and Criminal Justice?

Artificial intelligence (AI), machine learning (ML) and deep learning (DL) have had a profound impact on various sectors including Banking (Fin Tech), Health (HealthTech) and Charitable Fundraising (Charity Tech). The ‘natural’ ability of an AI system to independently perform and, often, outthink its human-counter parts by developing ‘intelligence’(simulating human intelligence) through its own experiences and processing deep layers of information i.e., complex representations of data, and learn has resulted in astounding improvements in the completion of tasks that are complex and technical, time-consuming.AI, with the ease of working with the most granular level of detail, can identify people and objects, recognise voices, uncover patterns and, in advance, screen for problems. Yet, RegTech (or LawTech/LegalTech) has not seen the same level of advancement. AI can provide solutions and enormous economic, political, and social benefits – in terms of public service administration. The purpose of this article is to explore advents in AI (ML and DL) and whether the criminal justice system, in the United Kingdom (UK), which is heavily overburdened, could benefit from some of the advances that have taken place in other sectors and jurisdictions, and whether automation and algorithmic decision making could be used to modernise it. This research draws on domestic and international published law, regulation, and literature, and isset out in six parts, the first partre views the position of the criminal justice system i.e., issues, part two then looks at relative technological advancements in AI, and the Metaverse. Part three explores current advents in AI relating to RegTech (LawTech/LegalTech) and how, if at all, the CJS can use this technology. Part four explores what aspects of the U.K.’s CJS would be fit for automation. Part five focuses on those matters pertaining to AI that pose problems in relation to matters in part 4 i.e., AI discrimination and bias, and explores safeguarding and mitigation including the requirement for explanation as set out in the GDPR. Part six concludes the discussion with some recommendations, as at, January 2024. It is suggested that AI and algorithmic decision making, with the correct legal framework and safeguards in place, could assist in modernising the CJS focussed legal functions, services in law firms, innovating for the next decade. This work is original and timely given the increased debate relating to how AI can assist in modernising the U.K.’s CJS, the global criminal justice challenges, solutions, and what, if any, role the Metaverse can play.

Cdc48/p97 segregase: Spotlight on DNA-protein crosslinks

The ATP-dependent molecular chaperone Cdc48 (in yeast) and its human counterpart p97 (also known as VCP), are essential for a variety of cellular processes, including the removal of DNA-protein crosslinks (DPCs) from the DNA. Growing evidence demonstrates in the last years that Cdc48/p97 is pivotal in targeting ubiquitinated and SUMOylated substrates on chromatin, thereby supporting the DNA damage response. Along with its cofactors, notably Ufd1-Npl4, Cdc48/p97 has emerged as a central player in the unfolding and processing of DPCs. This review introduces the detailed structure, mechanism and cellular functions of Cdc48/p97 with an emphasis on the current knowledge of DNA-protein crosslink repair pathways across several organisms. The review concludes by discussing the potential therapeutic relevance of targeting p97 in DPC repair.

A Preliminary Evaluation of the Prognostic Role of HER-2 and HER-3 Immunohistochemical Expression in Canine Melanomas.

Canine melanoma is a malignant and aggressive neoplasm showing clinical, histological, and molecular features similar to the human counterpart. In human medicine, epidermal growth factor receptors (EGFRs) have already been suggested as prognostic markers and potential therapeutic targets in cutaneous melanoma. The aim of this study was to evaluate the expression of HER-2 and HER-3 in canine melanomas by immunohistochemistry and correlate their expression to the clinicopathological parameters of the examined tumors. Thirty-seven canine melanoma samples were recruited. Data regarding signalment and clinical parameters were also collected. The population was composed of 18 cutaneous, 16 oral/mucosal, and three digital/foot pad melanomas. Histopathological investigations were carried out to analyze histological type, ulceration, and mitotic count. On each sample, immunohistochemistry was performed using an anti-Melan-A or anti-Melanoma antigen, i.e., anti-HER-2 and anti-HER-3 antibodies. HER-2 and HER-3 positivity were classified using already established scoring criteria and a statistical analysis was carried out. The results highlighted that HER-2 expression was observed in 48.6% of the samples and HER-3 expression in 18.9%. The highest HER 2 score (3+) was recorded in 16.2% of the samples, while the coexpression of the two receptors was detected in 13.5% of the samples. A statistically significant association (p < 0.05) was observed between the expression of HER-2 and HER-3 and the presence of ulceration in oromucosal tumors. This work confirms the expression of HER-2 and HER-3 in canine melanomas and suggests a putative association with negative prognostic parameters. Further studies are necessary to strengthen these data by increasing the samples size and combining pathological examinations with molecular biology in the investigation of EGFR family receptors.

Selected humanization of yeast U1 snRNP leads to global suppression of pre-mRNA splicing and mitochondrial dysfunction in the budding yeast.

The recognition of the 5' splice site (5' ss) is one of the earliest steps of pre-mRNA splicing. To better understand, the mechanism and regulation of 5' ss recognition, we selectively humanized components of the yeast U1 (yU1) snRNP to reveal the function of these components in 5' ss recognition and splicing. We targeted U1C and Luc7, two proteins that interact with and stabilize the yU1 snRNA and the 5' ss RNA duplex. We replaced the zinc-finger (ZnF) domain of yeast U1C (yU1C) with its human counterpart, which resulted in a cold-sensitive growth phenotype and moderate splicing defects. We next added an auxin-inducible degron to yeast Luc7 (yLuc7) protein (to mimic the lack of Luc7Ls in human U1 snRNP). We found that Luc7-depleted yU1 snRNP resulted in the concomitant loss of Prp40 and Snu71 (two other essential yU1 snRNP proteins), and further biochemical analyses suggest a model of how these three proteins interact with each other in the U1 snRNP. The loss of these proteins resulted in a significant growth retardation accompanied by a global suppression of pre-mRNA splicing. The splicing suppression led to mitochondrial dysfunction as revealed by a release of Fe2+ into the growth medium and an induction of mitochondrial reactive oxygen species. Together, these observations indicate that the human U1C ZnF can substitute that of yeast, Luc7 is essential for the incorporation of the Luc7-Prp40-Snu71 trimer into yU1 snRNP, and splicing plays a major role in the regulation of mitochondrial function in yeast.

Catalytic specificity and crystal structure of cystathionine γ-lyase from Pseudomonas aeruginosa

The escalating drug resistance among microorganisms underscores the urgent need for innovative therapeutic strategies and a comprehensive understanding of bacteria's defense mechanisms against oxidative stress and antibiotics. Among the recently discovered barriers, the endogenous production of hydrogen sulfide (H2S) via the reverse transsulfuration pathway, emerges as a noteworthy factor. In this study, we have explored the catalytic capabilities and crystal structure of cystathionine γ-lyase from Pseudomonas aeruginosa (PaCGL), a multidrug-opportunistic pathogen chiefly responsible for nosocomial infections. In addition to a canonical l-cystathionine hydrolysis, PaCGL efficiently catalyzes the production of H2S using l-cysteine and/or l-homocysteine as alternative substrates. Comparative analysis with the human enzyme and counterparts from other pathogens revealed distinct structural features within the primary enzyme cavities. Specifically, a distinctly folded entrance loop could potentially modulate the access of substrates and/or inhibitors to the catalytic site. Our findings offer significant insights into the structural evolution of CGL enzymes across different pathogens and provide novel opportunities for developing specific inhibitors targeting PaCGL.

The Positively Charged Cluster in the N-terminal Disordered Region may Affect Prion Protein Misfolding: Cryo-EM Structure of Hamster PrP(23–144) Fibrils

Prions, the misfolding form of prion proteins, are contagious proteinaceous macromolecules. Recent studies have shown that infectious prion fibrils formed in the brain and non-infectious fibrils formed from recombinant prion protein in a partially denaturing condition have distinct structures. The amyloid core of the in vitro-prepared non-infectious fibrils starts at about residue 160, while that of infectious prion fibrils formed in the brain involves a longer sequence (residues ∼90–230) of structural conversion. The C-terminal truncated prion protein PrP(23–144) can form infectious fibrils under certain conditions and cause disease in animals. In this study, we used cryogenic electron microscopy (cryo-EM) to resolve the structure of hamster sHaPrP(23-144) fibrils prepared at pH 3.7. This 2.88 Å cryo-EM structure has an amyloid core covering residues 94–144. It comprises two protofilaments, each containing five β-strands arranged as a long hairpin plus an N-terminal β-strand. This N-terminal β-strand resides in a positively charged cluster region (named PCC2; sequence 96–111), which interacts with the turn region of the opposite protofilaments’ hairpin to stabilize the fibril structure. Interestingly, this sHaPrP(23–144) fibril structure differs from a recently reported structure formed by the human or mouse counterpart at pH 6.5. Moreover, sHaPrP(23–144) fibrils have many structural features in common with infectious prions. Whether this structure is infectious remains to be determined. More importantly, the sHaPrP(23–144) structure is different from the sHaPrP(108–144) fibrils prepared in the same fibrillization buffer, indicating that the N-terminal disordered region, possibly the positively charged cluster, influences the misfolding pathway of the prion protein.

In Case You Haven't Heard…

Can dogs be depressed? According to Veterinarians.org, researchers in the 1980s found that canines can go through behavioral changes for various reasons, prompting them to experience extreme emotions, just like their human counterparts, People recently reported. Information shared on Veterinarians.org noted that some of the main signs of depression in dogs include “reduced activity levels and a desire to play,” plus “clinginess or social withdrawal” and “a loss or change in appetite.” “Excessive licking that brings comfort” and “uncharacteristic whining or howling” are other signs of canine depression, according to the organization. A big cause of depression in dogs, the organization noted, can be from experiencing a loss, which can range from that of a human companion or another pet living in the same home. Dogs can also be affected by environmental changes, such as the addition of a new pet or baby, or from something such as a change in scenery from moving, per Veterinarians.org. Dog trainers can help protect against depression in dogs by helping rid a pet of “established and unwanted behaviors through conditioning or positive reinforcement.” Veterinarians will sometimes medicate dogs with prescription drugs, similar to ones that humans take for depression, including Zoloft and Xanax. When prescribed, these medications may take up to four to six weeks to kick in and show effective changes, according to Veterinarians.org.