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Brain Communications 2024Amyotrophic lateral sclerosis is an age-dependent cell type-selective degenerative disease. Genetic studies indicate that amyotrophic lateral sclerosis is part of a...
Amyotrophic lateral sclerosis is an age-dependent cell type-selective degenerative disease. Genetic studies indicate that amyotrophic lateral sclerosis is part of a spectrum of disorders, ranging from spinal muscular atrophy to frontotemporal dementia that share common pathological mechanisms. Amyotrophic lateral sclerosis Type 8 is a familial disease caused by mis-sense mutations in . VAPB is localized to the cytoplasmic surface of the endoplasmic reticulum, where it serves as a docking point for cytoplasmic proteins and mediates inter-organelle interactions with the endoplasmic reticulum membrane. A gene knock-in model of amyotrophic lateral sclerosis Type 8 based on the mutation and gene deletion has been generated in rats. These animals display a range of age-dependent phenotypes distinct from those previously reported in mouse models of amyotrophic lateral sclerosis Type 8. A loss of motor neurones in and animals is indicated by a reduction in the number of large choline acetyl transferase-staining cells in the spinal cord. animals exhibit a relative increase in cytoplasmic TDP-43 levels compared with the nucleus, but no large protein aggregates. Concomitant with these spinal cord pathologies , and animals exhibit age-dependent changes in paw placement and exerted pressures when traversing a CatWalk apparatus, consistent with a somatosensory dysfunction. Extramotor dysfunction is reported in half the cases of motor neurone disease, and this is the first indication of an associated sensory dysfunction in a rodent model of amyotrophic lateral sclerosis. Different rodent models may offer complementary experimental platforms with which to understand the human disease.
PubMed: 38846532
DOI: 10.1093/braincomms/fcae184 -
F1000Research 2021Antimalarial drug resistance is a major challenge hampering malaria control and elimination. About three-quarters of Eritrea's population resides in the malaria-endemic...
BACKGROUND
Antimalarial drug resistance is a major challenge hampering malaria control and elimination. About three-quarters of Eritrea's population resides in the malaria-endemic western lowlands of the country. , the leading causative parasite species, has developed resistance to basically all antimalarials. Continued surveillance of drug resistance using genetic markers provides important molecular data for treatment policies which complements clinical studies, and strengthens control efforts. This study sought to genotype point mutations associated with resistance to sulfadoxine-pyrimethamine and artemisinin, in dried-blood spots from three hospitals in the western lowlands of Eritrea.
METHODS
Dried-blood spot samples were collected from patients visiting Adi Quala, Keren and Gash Barka Hospitals, between July and October, 2014. The patients were followed up after treatment with first line artesunate-amodiaquine, and dried-blood spots were collected on day three after treatment. Nested polymerase chain reaction and Sanger sequencing techniques were employed to genotype point mutations in the (PF3D7_0417200), (PF3D7_0810800) and (PF3D7_1343700) partial gene regions.
RESULTS
Sequence data analyses of PCR-positive isolates found wild-type artemisinin haplotypes associated with resistance (Y493Y, R539R, I543I) in three isolates, whereas four mutant antifolate haplotypes associated with resistance were observed in six isolates. These included the triple-mutant (S108N, C59R, N51I) haplotype, the double-mutant (N51I, S108N) haplotype, the single-mutant (K540E) haplotype, and the mixed-mutant (S108N, N51I + K540E) haplotype. Other findings observed were, a rare non-synonymous V45A mutation in four isolates, and a synonymous R449R in one isolate.
CONCLUSIONS
The mutant antifolate haplotypes observed indicate a likely existence of full SP resistance. Further studies can be carried out to estimate the prevalence of SP resistance. The wild-type artemisinin haplotypes observed suggest artemisinin is still an effective treatment. Continuous monitoring of point mutations associated with delayed parasite clearance in ART clinical studies is recommended.
PubMed: 38840941
DOI: 10.12688/f1000research.54195.3 -
International Journal of Medical... Jun 2024Staphylococcus aureus is a notorious pathogen responsible for various severe diseases. Due to the emergence of drug-resistant strains, the prevention and treatment of S....
Staphylococcus aureus is a notorious pathogen responsible for various severe diseases. Due to the emergence of drug-resistant strains, the prevention and treatment of S. aureus infections have become increasingly challenging. Vancomycin is considered to be one of the last-resort drugs for treating most methicillin-resistant S. aureus (MRSA), so it is of great significance to further reveal the mechanism of vancomycin resistance. VraFG is one of the few important ABC (ATP-binding cassette) transporters in S. aureus that can form TCS (two-component systems)/ABC transporter modules. ABC transporters can couple the energy released from ATP hydrolysis to translocate solutes across the cell membrane. In this study, we obtained a strain with decreased vancomycin susceptibility after serial passaging and selection. Subsequently, whole-genome sequencing was performed on this laboratory-derived strain MWA2 and a novel single point mutation was discovered in vraF gene, leading to decreased sensitivity to vancomycin and daptomycin. Furthermore, the mutation reduces autolysis of S. aureus and downregulates the expression of lytM, isaA, and atlA. Additionally, we observed that the mutant has a less net negative surface charge than wild-type strain. We also noted an increase in the expression of the dlt operon and mprF gene, which are associated with cell surface charge and serve to hinder the binding of cationic peptides by promoting electrostatic repulsion. Moreover, this mutation has been shown to enhance hemolytic activity, expand subcutaneous abscesses, reflecting an increased virulence. This study confirms the impact of a point mutation of VraF on S. aureus antibiotic resistance and virulence, contributing to a broader understanding of ABC transporter function and providing new targets for treating S. aureus infections.
Topics: Virulence; Staphylococcal Infections; Anti-Bacterial Agents; Vancomycin; Animals; ATP-Binding Cassette Transporters; Bacterial Proteins; Staphylococcus aureus; Microbial Sensitivity Tests; Vancomycin Resistance; Whole Genome Sequencing; Daptomycin; Mice; Autolysis; Humans; Point Mutation; Mutation; Female
PubMed: 38838390
DOI: 10.1016/j.ijmm.2024.151624 -
OncoTargets and Therapy 2024The third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), osimertinib, is an effective first-line therapy for patients with common...
Characterization of Patients with Mutation-Positive NSCLC Following Emergence of the Osimertinib Resistance Mutations, L718Q or G724S: A Multicenter Retrospective Observational Study in France.
PURPOSE
The third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), osimertinib, is an effective first-line therapy for patients with common mutation-positive non-small cell lung cancer (NSCLC). However, almost all patients become resistant to treatment. In some patients, emergence of tertiary mutations is implicated as a resistance mechanism. This study describes patients with NSCLC who acquired the rare mutations, L718Q or G724S, following EGFR TKI treatment.
PATIENTS AND METHODS
This was a retrospective, observational study undertaken in France from Feb-Nov 2021, in patients with mutation-positive NSCLC with an acquired L718Q or G724S mutation. Primary objectives were description of tumor characteristics, progression, and progression under treatment.
RESULTS
Nine eligible patients were identified. Acquired resistance to initial EGFR TKI treatment was associated with T790M emergence in six patients, who then received osimertinib monotherapy. Overall, eight patients received osimertinib monotherapy treatment at some point (average treatment duration: 18.3 months). Following the emergence of L718Q or G724S, patients received chemotherapy (n = 4; two of whom subsequently received afatinib), nivolumab (n = 2), afatinib (n = 2), or immunochemotherapy (n = 1). In the four patients who received afatinib after identification of L718Q or G724S, 2 achieved a partial response, one had stable disease and one had progressive disease. Treatment duration was 1.6-31.7 months. In patients with controlled disease (n = 3), progression-free survival was 6.1-31.7 months. Two of these patients had previously received osimertinib.
CONCLUSION
Currently, there is no consensus regarding the treatment of mutation-positive NSCLC following emergence of the osimertinib resistance mutations, L718Q or G724S. Afatinib appears to be a promising treatment option in this setting.
PubMed: 38836187
DOI: 10.2147/OTT.S448909 -
MBio Jun 2024Group III hybrid histidine kinases are fungal-specific proteins and part of the multistep phosphorelay, representing the initial part of the high osmolarity glycerol...
UNLABELLED
Group III hybrid histidine kinases are fungal-specific proteins and part of the multistep phosphorelay, representing the initial part of the high osmolarity glycerol (HOG) pathway. TcsC, the corresponding kinase in was expected to be a cytosolic protein but is targeted to the nucleus. Activation of TcsC by the antifungal fludioxonil has lethal consequences for the fungus. The agent triggers a fast and TcsC-dependent activation of SakA and later on a redistribution of TcsC to the cytoplasm. High osmolarity also activates TcsC, which then exits the nucleus or concentrates in spot-like, intra-nuclear structures. The sequence corresponding to the N-terminal 208 amino acids of TcsC lacks detectable domains. Its loss renders TcsC cytosolic and non-responsive to hyperosmotic stress, but it has no impact on the antifungal activity of fludioxonil. A point mutation in one of the three putative nuclear localization sequences, which are present in the N-terminus, prevents the nuclear localization of TcsC, but not its ability to respond to hyperosmotic stress. Hence, this striking intracellular localization is no prerequisite for the role of TcsC in the adaptive response to hyperosmotic stress, instead, TcsC proteins that are present in the nuclei seem to modulate the cell wall composition of hyphae, which takes place in the absence of stress. The results of the present study underline that the spatiotemporal dynamics of the individual components of the multistep phosphorelay is a crucial feature of this unique signaling hub.
IMPORTANCE
Signaling pathways enable pathogens, such as , to respond to a changing environment. The TcsC protein is the major sensor of the high osmolarity glycerol (HOG) pathway of and it is also the target of certain antifungals. Insights in its function are therefore relevant for the pathogenicity and new therapeutic treatment options. TcsC was expected to be cytoplasmic, but we detected it in the nucleus and showed that it translocates to the cytoplasm upon activation. We have identified the motif that guides TcsC to the nucleus. An exchange of a single amino acid in this motif prevents a nuclear localization, but this nuclear targeting is no prerequisite for the TcsC-mediated stress response. Loss of the N-terminal 208 amino acids prevents the nuclear localization and renders TcsC unable to respond to hyperosmotic stress demonstrating that this part of the protein is of crucial importance.
PubMed: 38832777
DOI: 10.1128/mbio.01184-24 -
Scientific Reports Jun 2024Dermatophytes show a wide geographic distribution and are the main causative agents of skin fungal infections in many regions of the world. Recently, their resistance to...
Dermatophytes show a wide geographic distribution and are the main causative agents of skin fungal infections in many regions of the world. Recently, their resistance to antifungal drugs has led to an obstacle to effective treatment. To address the lack of dermatophytosis data in Iraq, this study was designed to investigate the distribution and prevalence of dermatophytes in the human population and single point mutations in squalene epoxidase gene (SQLE) of terbinafine resistant isolates. The identification of 102 dermatophytes isolated from clinical human dermatophytosis was performed through morphological and microscopic characteristics followed by molecular analysis based on ITS and TEF-1α sequencing. Phylogeny was achieved through RAxML analysis. CLSI M38-A2 protocol was used to assess antifungal susceptibility of the isolates to four major antifungal drugs. Additionally, the presence of point mutations in SQLE gene, which are responsible for terbinafine resistance was investigated. Tinea corporis was the most prevalent clinical manifestation accounting for 37.24% of examined cases of dermatophytosis. Based on ITS, T. indotineae (50.98%), T. mentagrophytes (19.61%), and M. canis (29.41%) was identified as an etiologic species. T. indotineae and T. mentagrophytes strains were identified as T. interdigitale based on TEF-1α. Terbinafine showed the highest efficacy among the tested antifungal drugs. T. indotineae and T. mentagrophytes showed the highest resistance to antifungal drugs with MICs of 2-4 and 4 μg/mL, while M. canis was the most susceptible species. Three of T. indotineae isolates showed mutations in SQLE gene PheLeu substitution. A non-previously described point mutation, PheLeu was identified in T. indotineae and mutations LysAsn, PheLeu and LeuPhe were diagnosed in T. mentagrophytes XVII. The results of mutation analysis showed that PheLeu was a destabilizing mutation; protein stability has decreased with variations in pH, and point mutations affected the interatomic interaction, resulting in bond disruption. These results could help to control the progression of disease effectively and make decisions regarding the selection of appropriate drugs for dermatophyte infections.
Topics: Humans; Antifungal Agents; Iraq; Point Mutation; Tinea; Drug Resistance, Fungal; Microbial Sensitivity Tests; Male; Arthrodermataceae; Female; Squalene Monooxygenase; Adult; Phylogeny; Terbinafine; Middle Aged; Adolescent; Young Adult; Child; Fungal Proteins; Aged
PubMed: 38830918
DOI: 10.1038/s41598-024-63425-w -
MicroPublication Biology 2024SLX4 is an interactor and activator of structure-specific exonuclease that helps resolve tangled recombination intermediates arising at stalled replication forks. It is...
SLX4 is an interactor and activator of structure-specific exonuclease that helps resolve tangled recombination intermediates arising at stalled replication forks. It is one of the many factors that assist with homologous recombination, the major mechanism for restarting replication. SLX4 mutations have been reported in many cancers but a pan cancer map of all the mutations has not been undertaken. Here, using data from the Catalogue of Somatic Mutations in Cancers (COSMIC), we show that mutations occur in almost every cancer and many of them truncate the protein which should severely alter the function of the enzyme. We identified a frequent R1779W point mutation that occurs in the SLX4 domain required for heterodimerization with its partner, SLX1. In silico protein structure analysis of this mutation shows that it significantly alters the protein structure and is likely to destabilize the interaction with SLX1. Although this brief communication is limited to only analysis, it identifies certain high frequency SLX4 mutations in human cancers that would warrant further studies. Additionally, these mutations may be potentially actionable for drug therapies.
PubMed: 38828439
DOI: 10.17912/micropub.biology.001216 -
The American Journal of Case Reports Jun 2024BACKGROUND Various resistance mechanisms of the epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) have been reported, and approximately half of the...
BACKGROUND Various resistance mechanisms of the epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) have been reported, and approximately half of the cases show a T790M point mutation as resistance to EGFR-TKI. In addition, 3-14% of cases of non-small cell lung cancer transform into small cell lung carcinoma (SCLC) during treatment. However, there are few reported cases in which 2 mechanisms of resistance have been observed simultaneously. This report describes a 66-year-old man with initial presentation of stage IIA right-sided lung adenocarcinoma with EGFR gene exon 21 L858R mutation and 3 years of stable disease. During treatment with erlotinib, the patient developed SCLC and adenocarcinoma with EGFR exon 21 L858R and exon 20 T790M mutation. CASE REPORT A 66-year-old man underwent right pneumonectomy plus nodal dissection 2a for right hilar lung cancer and was diagnosed with an EGFR exon21 L858R mutated lung adenocarcinoma. Three years later, pleural dissemination was observed in the right chest wall. Although erlotinib was continued for 52 months, new metastases to the right ribs were detected. Chest wall tumor resection was performed. Based on the World Health Organization classification, the patient was diagnosed with combined SCLC, with EGFR exon21 L858R and exon20 T790M mutation. The patient received 4 cycles of carboplatin plus etoposide, 14 cycles of amrubicin, and 2 cycles of irinotecan. Chemotherapy continued for 25 months. CONCLUSIONS Long-term survival was achieved by chemotherapy after transformation. Since EGFR mutation-positive lung cancer shows a variety of acquired resistances, it is important to consider the treatment strategy of performing re-biopsy.
Topics: Aged; Humans; Male; Adenocarcinoma; Adenocarcinoma of Lung; Drug Resistance, Neoplasm; ErbB Receptors; Erlotinib Hydrochloride; Lung Neoplasms; Mutation; Small Cell Lung Carcinoma; Tyrosine Kinase Inhibitors
PubMed: 38822519
DOI: 10.12659/AJCR.943466 -
Human Genomics May 2024Although CDKN2A alteration has been explored as a favorable factor for tumorigenesis in pan-cancers, the association between CDKN2A point mutation (MUT) and intragenic...
BACKGROUND
Although CDKN2A alteration has been explored as a favorable factor for tumorigenesis in pan-cancers, the association between CDKN2A point mutation (MUT) and intragenic deletion (DEL) and response to immune checkpoint inhibitors (ICIs) is still disputed. This study aims to determine the associations of CDKN2A MUT and DEL with overall survival (OS) and response to immune checkpoint inhibitors treatment (ICIs) among pan-cancers and the clinical features of CDKN2A-altered gastric cancer.
METHODS
This study included 45,000 tumor patients that underwent tumor sequencing across 33 cancer types from four cohorts, the MSK-MetTropism, MSK-IMPACT, OrigiMed2020 and TCGA cohorts. Clinical outcomes and genomic factors associated with response to ICIs, including tumor mutational burden, copy number alteration, neoantigen load, microsatellite instability, tumor immune microenvironment and immune-related gene signatures, were collected in pan-cancer. Clinicopathologic features and outcomes were assessed in gastric cancer. Patients were grouped based on the presence of CDKN2A wild type (WT), CDKN2A MUT, CDKN2A DEL and CDKN2A other alteration (ALT).
RESULTS
Our research showed that CDKN2A-MUT patients had shorter survival times than CDKN2A-WT patients in the MSK MetTropism and TCGA cohorts, but longer OS in the MSK-IMPACT cohort with ICIs treatment, particularly in patients having metastatic disease. Similar results were observed among pan-cancer patients with CDKN2A DEL and other ALT. Notably, CDKN2A ALT frequency was positively related to tumor-specific objective response rates to ICIs in MSK MetTropism and OrigiMed 2020. Additionally, individuals with esophageal carcinoma or stomach adenocarcinoma who had CDKN2A MUT had poorer OS than patients from the MSK-IMPACT group, but not those with adenocarcinoma. We also found reduced levels of activated NK cells, T cells CD8 and M2 macrophages in tumor tissue from CDKN2A-MUT or DEL pan-cancer patients compared to CDKN2A-WT patients in TCGA cohort. Gastric cancer scRNA-seq data also showed that CDKN2A-ALT cancer contained less CD8 T cells but more exhausted T cells than CDKN2A-WT cancer. A crucial finding of the pathway analysis was the inhibition of three immune-related pathways in the CDKN2A ALT gastric cancer patients, including the interferon alpha response, inflammatory response, and interferon gamma response.
CONCLUSIONS
This study illustrates the CDKN2A MUT and DEL were associated with a poor outcome across cancers. CDKN2A ALT, on the other hand, have the potential to be used as a biomarker for choosing patients for ICI treatment, notably in esophageal carcinoma and stomach adenocarcinoma.
Topics: Humans; Stomach Neoplasms; Cyclin-Dependent Kinase Inhibitor p16; Tumor Microenvironment; Male; Female; Immune Checkpoint Inhibitors; Middle Aged; Biomarkers, Tumor; Aged; Prognosis; DNA Copy Number Variations; Mutation; Microsatellite Instability
PubMed: 38822443
DOI: 10.1186/s40246-024-00615-7 -
Biochemical and Biophysical Research... Sep 2024Excitation-contraction coupling in skeletal muscle myofibers depends upon Ca release from the sarcoplasmic reticulum through the ryanodine receptor/Ca-release channel...
Excitation-contraction coupling in skeletal muscle myofibers depends upon Ca release from the sarcoplasmic reticulum through the ryanodine receptor/Ca-release channel RyR1. The RyR1 contains ∼100 Cys thiols of which ∼30 comprise an allosteric network subject to posttranslational modification by S-nitrosylation, S-palmitoylation and S-oxidation. However, the role and function of these modifications is not understood. Although aberrant S-nitrosylation of multiple unidentified sites has been associated with dystrophic diseases, malignant hyperthermia and other myopathic syndromes, S-nitrosylation in physiological situations is reportedly specific to a single (1 of ∼100) Cys in RyR1, Cys in a manner gated by pO. Using mice expressing a form of RyR1 with a Cys→Ala point mutation to prevent S-nitrosylation at this site, we showed that Cys was the principal target of endogenous S-nitrosylation during normal muscle function. The absence of Cys S-nitrosylation suppressed stimulus-evoked Ca release at physiological pO (at least in part by altering the regulation of RyR1 by Ca/calmodulin), eliminated pO coupling, and diminished skeletal myocyte contractility in vitro and measures of muscle strength in vivo. Furthermore, we found that abrogation of Cys S-nitrosylation resulted in a developmental defect reflected in diminished myofiber diameter, altered fiber subtypes, and altered expression of genes implicated in muscle development and atrophy. Thus, our findings establish a physiological role for pO-coupled S-nitrosylation of RyR1 in skeletal muscle contractility and development and provide foundation for future studies of RyR1 modifications in physiology and disease.
Topics: Ryanodine Receptor Calcium Release Channel; Animals; Muscle, Skeletal; Mice; Calcium; Cysteine; Protein Processing, Post-Translational; Muscle Development; Mice, Transgenic; Calcium Signaling
PubMed: 38820626
DOI: 10.1016/j.bbrc.2024.150163