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Unveiling the dance of evolution: Pla-mediated cleavage of Ymt modulates the virulence dynamics of .MBio Jul 2024has recently evolved into a highly lethal flea-borne pathogen through the pseudogenization of extensive genes and the acquisition of exogenous plasmids. Particularly...
UNLABELLED
has recently evolved into a highly lethal flea-borne pathogen through the pseudogenization of extensive genes and the acquisition of exogenous plasmids. Particularly noteworthy are the newly acquired pPCP1 and pMT1 plasmids, which encode the virulence determinants Pla and murine toxin (Ymt), crucial for subcutaneous infection and survival within flea vector of , respectively. This study reveals that Pla can cleave Ymt at K299 both and expressing Ymt displays enhanced biofilm formation and increased blood survival, indicating significant roles of Pla-mediated Ymt cleavage in these phenotypes. Intriguingly, although both the ancestral form of Pla and the prevalent Pla-I259T variant in modern strains are capable of cleaving Ymt at K299, the cleavage efficiency of Pla-I259T is only half that of the ancestral variant. In subcutaneous infection, mice infected with ΔK299A show significantly prolonged survival compared to those infected with Δ. Similarly, infection with ΔI259T also results in extended survival compared to Δ infection. These data demonstrate that the I259T substitution of Pla mitigates the enhanced virulence of in mice caused by Pla-mediated Ymt cleavage, thereby prolonging the survival period of infected animals and potentially conferring advantages on the transmission of to the next host. These findings deepen our understanding of the intricate interplay between two newly acquired plasmids and shed light on the positive selection of the Pla-I259T mutation, providing new insights into the virulence dynamics and transmission mechanisms of .
IMPORTANCE
The emergence of as a highly lethal pathogen is driven by extensive gene pseudogenization and acquisition of exogenous plasmids pPCP1 and pMT1. However, the interplay between these two plasmids during evolution remains largely unexplored. Our study reveals intricate interactions between Ymt and Pla, two crucial virulence determinants encoded on these plasmids. Pla-mediated cleavage of Ymt significantly decreases survival in mouse blood and enhances its virulence in mice. The prevalent Pla-I259T variant in modern strains displays reduced Ymt cleavage, thereby extending the survival of infected animals and potentially increasing strain transmissibility. Our findings shed light on the nuanced evolution of , wherein reduced cleavage efficiency is a positive selection force, shaping the pathogen's natural trajectory.
PubMed: 38958447
DOI: 10.1128/mbio.01075-24 -
Microbiology Spectrum Jul 2024To monitor the resistance rate and gain a deeper understanding of the resistance mechanisms, we conducted over a 2-year surveillance focusing on the associated with the...
To monitor the resistance rate and gain a deeper understanding of the resistance mechanisms, we conducted over a 2-year surveillance focusing on the associated with the clinical usage of ceftazidime-avibactam (CZA) in a teaching hospital. A total of 4,641 . isolates were screened to identify the CZA resistance through antimicrobial susceptibility testing. Comprehensive analyses, including homology analysis, conjugation experiments, clone assays, and whole genome sequencing, were furtherly performed on the CZA-resistant strains. In total, four CZA-resistant (CZA-R-Kp) strains were separated from four patients, in which three of them received CZA treatment during the hospitalization, accounting for a 4% (3/75) resistance development rate of under CZA stress. All CZA-R-Kp isolates were found to possess variants of . The identified mutations included , , and a novel variant designated as , all of which were located in the Ω loop of the KPC enzyme. These mutations were found to impact the amino acid sequence and spatial structure of the enzyme's active center, consequently affecting KPC carbapenemase activity. This study underscores the importance of active surveillance to monitor the emergence of resistance to CZA, highlighting the need for ongoing research to develop effective strategies for combating antimicrobial resistance. Understanding the mechanisms behind resistance is crucial in maintaining the efficacy of CZA, a vital tool in the battle against multidrug-resistant infections.IMPORTANCEAs an effective drug for the treatment of carbapenem-resistant , ceftazidime-avibactam (CZA) began to develop resistance in recent years and showed an increasing trend. In order to effectively monitor the resistance rate of CZA and understand its resistance mechanism, we monitored for more than 2 years to find CZA-resistant strains. Through comprehensive analysis of the selected CZA-resistant strains, it was found that all the CZA-resistant strains had mutation, which could affect the activity of KPC carbapenemase. This study highlights the importance of proactive surveillance to monitor the emergence of CZA resistance, which highlights the need for ongoing research to develop effective strategies to combat antimicrobial resistance. Understanding the mechanisms behind resistance is critical to maintaining the effectiveness of CZA, an important tool in the fight against multidrug-resistant infections.
PubMed: 38958437
DOI: 10.1128/spectrum.00258-24 -
Developmental Dynamics : An Official... Jul 2024Primary cilia are antenna-like sensory organelles that are evolutionarily conserved in nearly all modern eukaryotes, from the single-celled green alga, Chlamydomonas... (Review)
Review
Primary cilia are antenna-like sensory organelles that are evolutionarily conserved in nearly all modern eukaryotes, from the single-celled green alga, Chlamydomonas reinhardtii, to vertebrates and mammals. Cilia are microtubule-based cellular projections that have adapted to perform a broad range of species-specific functions, from cell motility to detection of light and the transduction of extracellular mechanical and chemical signals. These functions render cilia essential for organismal development and survival. The high conservation of cilia has allowed for discoveries in C. reinhardtii to inform our understanding of the basic biology of mammalian primary cilia, and to provide insight into the genetic etiology of ciliopathies. Over the last two decades, a growing number of studies has revealed that multiple aspects of ciliary homeostasis are regulated by the actin cytoskeleton, including centrosome migration and positioning, vesicle transport to the basal body, ectocytosis, and ciliary-mediated signaling. Here, we review actin regulation of ciliary homeostasis, and highlight conserved and divergent mechanisms in C. reinhardtii and mammalian cells. Further, we compare the disease manifestations of patients with ciliopathies to those with mutations in actin and actin-associated genes, and propose that primary cilia defects caused by genetic alteration of the actin cytoskeleton may underlie certain birth defects.
PubMed: 38958410
DOI: 10.1002/dvdy.724 -
Cancer Investigation Jul 2024Myeloproliferative neoplasms (MPN) are hematological diseases associated with genetic driver mutations in the JAK2, CALR, and MPL genes and exacerbated oncoinflammatory...
Myeloproliferative neoplasms (MPN) are hematological diseases associated with genetic driver mutations in the JAK2, CALR, and MPL genes and exacerbated oncoinflammatory . Analyzing public microarray data from polycythemia vera (n = 41), essential thrombocythemia (n = 21), and primary myelofibrosis (n = 9) patients' peripheral blood by approaches, we found that pro-inflammatory and monocyte-related genes were differentially expressed in MPN patients' transcriptome. Genes related to cell activation, secretion of pro-inflammatory and pro-angiogenic mediators, activation of neutrophils and platelets, coagulation, and interferon pathway were upregulated in monocytes compared to controls. Together, our results suggest that molecular alterations in monocytes may contribute to oncoinflammation in MPN.
PubMed: 38958254
DOI: 10.1080/07357907.2024.2371371 -
International Journal of Cancer Jul 2024In patients with non-small cell lung cancer (NSCLC), oncogenic variants present in <5% of cases are considered rare, the predominant of which include human epidermal... (Review)
Review
In patients with non-small cell lung cancer (NSCLC), oncogenic variants present in <5% of cases are considered rare, the predominant of which include human epidermal growth factor receptor 2 (HER2) mutations, mesenchymal-epithelial transition (MET) alterations, c-ros oncogene 1 (ROS1) rearrangements, rearrangement during transfection (RET) fusions, v-raf mouse sarcoma virus oncogene homolog B1 (BRAF) mutations, and neurotrophic troponin receptor kinase (NTRK) fusions. Brain metastases (BMs) occur in approximately 10%-50% of patients with NSCLC harboring rare genetic variants. The recent advent of small-molecule tyrosine kinase inhibitors and macromolecular antibody-drug conjugates (ADCs) has conferred marked survival benefits to patients with NSCLC harboring rare driver alterations. Despite effective brain lesion control for most targeted agents and promising reports of intracranial remission associated with novel ADCs, BM continues to be a major therapeutic challenge. This review discusses the recent advances in the treatment of NSCLC with rare genetic variants and BM, with a particular focus on intracranial efficacy, and explores future perspectives on how best to treat these patients.
PubMed: 38958227
DOI: 10.1002/ijc.35070 -
Personalized Medicine Jul 2024We report the case of an 87-year-old female patient who was diagnosed with metastatic non-small-cell lung cancer harboring exon 14 skipping mutation ( ex14) and PD-L1...
We report the case of an 87-year-old female patient who was diagnosed with metastatic non-small-cell lung cancer harboring exon 14 skipping mutation ( ex14) and PD-L1 expression of 60%. A first-line treatment with atezolizumab was started with primary resistance. Then, a second-line treatment with capmatinib, a selective type Ib MET tyrosine kinase inhibitor, was started, achieving a partial response. The patient is still alive and on treatment with capmatinib 300 mg twice daily after 20 months, with a good tolerability and no evidence of disease progression.In summary, our patient experienced a long-lasting response (>18 months) with capmatinib as second-line treatment. Further analyses evaluating the efficacy and tolerability of MET tyrosine kinase inhibitors are warranted, especially in the elderly, a non-small-cell lung cancer population whose tumors could more frequently harbor ex14 mutation.
PubMed: 38958204
DOI: 10.1080/17410541.2024.2369493 -
Molecular Genetics & Genomic Medicine Jul 2024Marfan syndrome (MFS) is a hereditary connective tissue disorder involving multiple systems, including ophthalmologic abnormalities. Most cases are due to heterozygous...
BACKGROUND
Marfan syndrome (MFS) is a hereditary connective tissue disorder involving multiple systems, including ophthalmologic abnormalities. Most cases are due to heterozygous mutations in the fibrillin-1 gene (FBN1). Other associated genes include LTBP2, MYH11, MYLK, and SLC2A10. There is significant clinical overlap between MFS and other Marfan-like disorders.
PURPOSE
To expand the mutation spectrum of FBN1 gene and validate the pathogenicity of Marfan-related genes in patients with MFS and ocular manifestations.
METHODS
We recruited 318 participants (195 cases, 123 controls), including 59 sporadic cases and 88 families. All patients had comprehensive ophthalmic examinations showing ocular features of MFS and met Ghent criteria. Additionally, 754 cases with other eye diseases were recruited. Panel-based next-generation sequencing (NGS) screened mutations in 792 genes related to inherited eye diseases.
RESULTS
We detected 181 mutations with an 84.7% detection rate in sporadic cases and 87.5% in familial cases. The overall detection rate was 86.4%, with FBN1 accounting for 74.8%. In cases without FBN1 mutations, 23 mutations from seven Marfan-related genes were identified, including four pathogenic or likely pathogenic mutations in LTBP2. The 181 mutations included 165 missenses, 10 splicings, three frameshifts, and three nonsenses. FBN1 accounted for 53.0% of mutations. The most prevalent pathogenic mutation was FBN1 c.4096G>A. Additionally, 94 novel mutations were detected, with 13 de novo mutations in 14 families.
CONCLUSION
We expanded the mutation spectrum of the FBN1 gene and provided evidence for the pathogenicity of other Marfan-related genes. Variants in LTBP2 may contribute to the ocular manifestations in MFS, underscoring its role in phenotypic diversity.
Topics: Humans; Marfan Syndrome; Female; Male; Fibrillin-1; Adult; Child; High-Throughput Nucleotide Sequencing; Adolescent; Mutation; Middle Aged; Child, Preschool; Eye Diseases; Pedigree; East Asian People; Adipokines
PubMed: 38958168
DOI: 10.1002/mgg3.2482 -
Molecular Genetics & Genomic Medicine Jul 2024Pompe Disease (PD) is a metabolic myopathy caused by variants in the GAA gene, resulting in deficient enzymatic activity. We aimed to characterize the clinical features...
BACKGROUND
Pompe Disease (PD) is a metabolic myopathy caused by variants in the GAA gene, resulting in deficient enzymatic activity. We aimed to characterize the clinical features and related genetic variants in a series of Mexican patients.
METHODS
We performed a retrospective study of clinical records of patients diagnosed with LOPD, IOPD or pseudodeficiency.
RESULTS
Twenty-nine patients were included in the study, comprising these three forms. Overall, age of symptom onset was 0.1 to 43 years old. The most frequent variant identified was c.-32-13T>G, which was detected in 14 alleles. Among the 23 different variants identified in the GAA gene, 14 were classified as pathogenic, 5 were likely pathogenic, and 1 was a variant of uncertain significance. Two variants were inherited in cis arrangement and 2 were pseudodeficiency-related benign alleles. We identified two novel variants (c.1615 G>A and c.1076-20_1076-4delAAGTCGGCGTTGGCCTG).
CONCLUSION
To the best of our knowledge, this series represent the largest phenotypic and genotypic characterization of patients with PD in Mexico. Patients within our series exhibited a combination of LOPD and IOPD associated variants, which may be related to genetic diversity within Mexican population. Further population-wide studies are required to better characterize the incidence of this disease in Mexican population.
Topics: Humans; Glycogen Storage Disease Type II; Male; Female; Child, Preschool; Child; Adult; alpha-Glucosidases; Infant; Mexico; Adolescent; Mutation; Age of Onset; Phenotype; Retrospective Studies; Genetic Association Studies; Alleles; Young Adult
PubMed: 38958145
DOI: 10.1002/mgg3.2480 -
The Journal of Physical Chemistry. B Jul 2024The herpesvirus entry mediator (HVEM) and its ligand LIGHT play crucial roles in immune system regulation, including T-cell proliferation, B-cell differentiation, and...
The herpesvirus entry mediator (HVEM) and its ligand LIGHT play crucial roles in immune system regulation, including T-cell proliferation, B-cell differentiation, and immunoglobulin secretion. However, excessive T-cell activation can lead to chronic inflammation and autoimmune diseases. Thus, inhibiting the HVEM-LIGHT interaction emerges as a promising therapeutic strategy for these conditions and in preventing adverse reactions in organ transplantation. This study focused on designing peptide inhibitors, targeting the HVEM-LIGHT interaction, using molecular dynamics (MD) simulations of 65 peptides derived from HVEM. These peptides varied in length and disulfide-bond configurations, crucial for their interaction with the LIGHT trimer. By simulating 31 HVEM domain variants, including the full-length protein, we assessed conformational changes upon LIGHT binding to understand the influence of HVEM segments and disulfide bonds on the binding mechanism. Employing multitrajectory microsecond-scale, all-atom MD simulations and molecular mechanics with generalized Born and surface area (MM-GBSA) binding energy estimation, we identified promising CRD2 domain variants with high LIGHT affinity. Notably, point mutations in these variants led to a peptide with a single disulfide bond (C58-C73) and a K54E substitution, exhibiting the highest binding affinity. The importance of the CRD2 domain and Cys58-Cys73 disulfide bond for interrupting HVEM-LIGHT interaction was further supported by analyzing truncated CRD2 variants, demonstrating similar binding strengths and mechanisms. Further investigations into the binding mechanism utilized steered MD simulations at various pulling speeds and umbrella sampling to estimate the energy profile of HVEM-based inhibitors with LIGHT. These comprehensive analyses revealed key interactions and different binding mechanisms, highlighting the increased binding affinity of selected peptide variants. Experimental circular dichroism techniques confirmed the structural properties of these variants. This study not only advances our understanding of the molecular basis of HVEM-LIGHT interactions but also provides a foundation for developing novel therapeutic strategies for immune-related disorders. Furthermore, it sets a gold standard for peptide inhibitor design in drug development due to its systematic approach.
PubMed: 38958133
DOI: 10.1021/acs.jpcb.4c02255 -
Journal of the American Heart... Jul 2024Thoracic aortic aneurysm (TAA) is associated with significant morbidity and mortality. Although individuals with family histories of TAA often undergo clinical molecular...
BACKGROUND
Thoracic aortic aneurysm (TAA) is associated with significant morbidity and mortality. Although individuals with family histories of TAA often undergo clinical molecular genetic testing, adults with nonsyndromic TAA are not typically evaluated for genetic causes. We sought to understand the genetic contribution of both germline and somatic mosaic variants in a cohort of adult individuals with nonsyndromic TAA at a single center.
METHODS AND RESULTS
One hundred eighty-one consecutive patients <60 years who presented with nonsyndromic TAA at the Massachusetts General Hospital underwent deep (>500×) targeted sequencing across 114 candidate genes associated with TAA and its related functional pathways. Samples from 354 age- and sex-matched individuals without TAA were also sequenced, with a 2:1 matching. We found significant enrichments for germline (odds ratio [OR], 2.44, =4.6×10 [95% CI, 1.67-3.58]) and also somatic mosaic variants (OR, 4.71, =0.026 [95% CI, 1.20-18.43]) between individuals with and without TAA. Likely genetic causes were present in 24% with nonsyndromic TAA, of which 21% arose from germline variants and 3% from somatic mosaic alleles. The 3 most frequently mutated genes in our cohort were (encoding Filamin A), (encoding Notch receptor 3), and (encoding Fibrillin-1). There was increased frequency of both missense and loss of function variants in TAA individuals.
CONCLUSIONS
Likely contributory dominant acting genetic variants were found in almost one quarter of nonsyndromic adults with TAA. Our findings suggest a more extensive genetic architecture to TAA than expected and that genetic testing may improve the care and clinical management of adults with nonsyndromic TAA.
PubMed: 38958128
DOI: 10.1161/JAHA.123.033232