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International Journal of Molecular... Jun 2024Chronic obstructive pulmonary disease (COPD) is commonly caused from smoking cigarettes that induce biological stress responses. Previously we found disorganized...
Chronic obstructive pulmonary disease (COPD) is commonly caused from smoking cigarettes that induce biological stress responses. Previously we found disorganized endoplasmic reticulum (ER) in fibroblasts from COPD with different responses to chemical stressors compared to healthy subjects. Here, we aimed to investigate differences in stress-related gene expressions within lung cells from COPD and healthy subjects. Bronchoalveolar lavage (BAL) cells were collected from seven COPD and 35 healthy subjects. Lung fibroblasts were derived from 19 COPD and 24 healthy subjects and exposed to cigarette smoke extract (CSE). Gene and protein expression and cell proliferation were investigated. Compared to healthy subjects, we found lower gene expression of CHOP in lung fibroblasts from COPD subjects. Exposure to CSE caused inhibition of lung fibroblast proliferation in both groups, though the changes in ER stress-related gene expressions (ATF6, IRE1, PERK, ATF4, CHOP, BCL2L1) and genes relating to proteasomal subunits mostly occurred in healthy lung fibroblasts. No differences were found in BAL cells. In this study, we have found that lung fibroblasts from COPD subjects have an atypical ER stress gene response to CSE, particularly in genes related to apoptosis. This difference in response to CSE may be a contributing factor to COPD progression.
Topics: Humans; Pulmonary Disease, Chronic Obstructive; Fibroblasts; Endoplasmic Reticulum Stress; Male; Female; Middle Aged; Lung; Bronchoalveolar Lavage Fluid; Aged; Cell Proliferation; Gene Expression Regulation; Cells, Cultured; Apoptosis; Case-Control Studies
PubMed: 38928305
DOI: 10.3390/ijms25126600 -
International Journal of Molecular... Jun 2024Integrin αβ mediates platelet aggregation by binding the Arginyl-Glycyl-Aspartic acid (RGD) sequence of fibrinogen. RGD binding occurs at a site topographically...
Integrin αβ mediates platelet aggregation by binding the Arginyl-Glycyl-Aspartic acid (RGD) sequence of fibrinogen. RGD binding occurs at a site topographically proximal to the α and β subunits, promoting the conformational activation of the receptor from bent to extended states. While several experimental approaches have characterized RGD binding to αβ integrin, applying computational methods has been significantly more challenging due to limited sampling and the need for a priori information regarding the interactions between the RGD peptide and integrin. In this study, we employed all-atom simulations using funnel metadynamics (FM) to evaluate the interactions of an RGD peptide with the α and β subunits of integrin. FM incorporates an external history-dependent potential on selected degrees of freedom while applying a funnel-shaped restraint potential to limit RGD exploration of the unbound state. Furthermore, it does not require a priori information about the interactions, enhancing the sampling at a low computational cost. Our FM simulations reveal significant molecular changes in the β subunit of integrin upon RGD binding and provide a free-energy landscape with a low-energy binding mode surrounded by higher-energy prebinding states. The strong agreement between previous experimental and computational data and our results highlights the reliability of FM as a method for studying dynamic interactions of complex systems such as integrin.
Topics: Oligopeptides; Platelet Glycoprotein GPIIb-IIIa Complex; Protein Binding; Humans; Molecular Dynamics Simulation; Blood Platelets; Binding Sites; Integrin beta3
PubMed: 38928286
DOI: 10.3390/ijms25126580 -
International Journal of Molecular... Jun 2024Obesity and metabolic syndrome alter serum lipid profiles. They also increase vulnerability to viral infections and worsen the survival rate and symptoms after...
Obesity and metabolic syndrome alter serum lipid profiles. They also increase vulnerability to viral infections and worsen the survival rate and symptoms after infection. How serum lipids affect influenza virus proliferation is unclear. Here, we investigated the effects of lysophosphatidylcholines on influenza A virus (IAV) proliferation. IAV particles in the culture medium were titrated using extraction-free quantitative PCR, and viral RNA and protein levels were assessed using real-time PCR and Western blot, respectively. RNA sequencing data were analyzed using PCA and heatmap analysis, and pathway analysis was performed using the KEGG mapper and PathIN tools. Statistical analysis was conducted using SPSS21.0. LPC treatment of THP-1 cells significantly increased IAV proliferation and IAV RNA and protein levels, and saturated LPC was more active in IAV RNA expression than unsaturated LPC was. The functional analysis of genes affected by LPCs showed that the expression of genes involved in IAV signaling, such as suppressor of cytokine signaling 3 (SOCS3), phosphoinositide-3-kinase regulatory subunit 3 (PI3K) and AKT serine/threonine kinase 3 (AKT3), Toll-like receptor 7 (TKR7), and interferon gamma receptor 1 (IFNGR1), was changed by LPC. Altered influenza A pathways were linked with MAPK and PI3K/AKT signaling. Treatment with inhibitors of MAPK or PI3K attenuated viral gene expression changes induced by LPCs. The present study shows that LPCs stimulated virus reproduction by modifying the cellular environment to one in which viruses proliferated better. This was mediated by the MAPK, JNK, and PI3K/AKT pathways. Further animal studies are needed to confirm the link between LPCs from serum or the respiratory system and IAV proliferation.
Topics: Humans; Lysophosphatidylcholines; Virus Replication; MAP Kinase Signaling System; Influenza A virus; Macrophages; THP-1 Cells; Cell Differentiation; Influenza, Human; Signal Transduction; Animals
PubMed: 38928244
DOI: 10.3390/ijms25126538 -
International Journal of Molecular... Jun 2024Hypoxia-inducible factor 1-alpha (HIF1A) is a key transcription factor aiding tumor cells' adaptation to hypoxia, regulated by the prolyl hydroxylase family (EGLN1-3) by...
Hypoxia-inducible factor 1-alpha (HIF1A) is a key transcription factor aiding tumor cells' adaptation to hypoxia, regulated by the prolyl hydroxylase family (EGLN1-3) by directing toward degradation pathways. DNA methylation potentially influences EGLN and HIF1A levels, impacting cellular responses to hypoxia. We examined 96 HNSCC patients and three cell lines, analyzing gene expression of , , , , and at the mRNA level and EGLN1 protein levels. Methylation levels of and were assessed through high-resolution melting analysis. Bioinformatics tools were employed to characterize associations between and expression and methylation. We found significantly higher mRNA levels of , , , , and ( = 0.021; < 0.0001; < 0.0001; = 0.004, and < 0.0001, respectively) genes in tumor tissues compared to normal ones and downregulation of the mRNA level in tumor tissues ( = 0.0013). In HNSCC patients with hypermethylation of in normal tissue, we noted a reduction in mRNA levels compared to tumor tissue ( = 0.04). In conclusion, the differential expression of and genes in HNSCC tumors compared to normal tissues influences patients' overall survival, highlighting their role in tumor development. Moreover, DNA methylation could be responsible for suppression in the normal tissues of HNSCC patients.
Topics: Humans; DNA Methylation; Hypoxia-Inducible Factor 1, alpha Subunit; Squamous Cell Carcinoma of Head and Neck; Female; Head and Neck Neoplasms; Male; Gene Expression Regulation, Neoplastic; Cell Line, Tumor; Hypoxia-Inducible Factor-Proline Dioxygenases; Middle Aged; Prolyl Hydroxylases; Aged; Carcinogenesis; Adult
PubMed: 38928200
DOI: 10.3390/ijms25126495 -
International Journal of Molecular... Jun 2024Arc (also known as Arg3.1) is an activity-dependent immediate early gene product enriched in neuronal dendrites. Arc plays essential roles in long-term potentiation,...
Arc (also known as Arg3.1) is an activity-dependent immediate early gene product enriched in neuronal dendrites. Arc plays essential roles in long-term potentiation, long-term depression, and synaptic scaling. Although its mechanisms of action in these forms of synaptic plasticity are not completely well established, the activities of Arc include the remodeling of the actin cytoskeleton, the facilitation of AMPA receptor (AMPAR) endocytosis, and the regulation of the transcription of AMPAR subunits. In addition, Arc has sequence and structural similarity to retroviral Gag proteins and self-associates into virus-like particles that encapsulate mRNA and perhaps other cargo for intercellular transport. Each of these activities is likely to be influenced by Arc's reversible self-association into multiple oligomeric species. Here, we used mass photometry to show that Arc exists predominantly as monomers, dimers, and trimers at approximately 20 nM concentration in vitro. Fluorescence fluctuation spectroscopy revealed that Arc is almost exclusively present as low-order (monomer to tetramer) oligomers in the cytoplasm of living cells, over a 200 nM to 5 μM concentration range. We also confirmed that an α-helical segment in the N-terminal domain contains essential determinants of Arc's self-association.
Topics: Protein Multimerization; Humans; Cytoskeletal Proteins; Nerve Tissue Proteins; Animals
PubMed: 38928159
DOI: 10.3390/ijms25126454 -
Genes May 2024Human T-cell leukemia virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia/lymphoma. The oncogene product Tax of HTLV-I is thought to play crucial roles...
Human T-cell leukemia virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia/lymphoma. The oncogene product Tax of HTLV-I is thought to play crucial roles in leukemogenesis by promoting proliferation of the virus-infected cells through activation of growth-promoting genes. These genes code for growth factors and their receptors, cytokines, cell adhesion molecules, growth signal transducers, transcription factors and cell cycle regulators. We show here that Tax activates the gene coding for coactivator-associated arginine methyltransferase 1 (CARM1), which epigenetically enhances gene expression through methylation of histones. Tax activated the gene and increased protein expression, not only in human T-cell lines but also in normal peripheral blood lymphocytes (PHA-PBLs). Tax increased R17-methylated histone H3 on the target gene , concomitant with increased expression of CARM1. Short hairpin RNA (shRNA)-mediated knockdown of CARM1 decreased Tax-mediated induction of and gene expression, reduced E2F activation and inhibited cell cycle progression. Tax acted via response elements in intron 1 of the gene, through the NF-κB pathway. These results suggest that Tax-mediated activation of the gene contributes to leukemogenic target-gene expression and cell cycle progression, identifying the first epigenetic target gene for Tax-mediated trans-activation in cell growth promotion.
Topics: Humans; Protein-Arginine N-Methyltransferases; Gene Products, tax; Human T-lymphotropic virus 1; Cyclin D2; Transcriptional Activation; Interleukin-2 Receptor alpha Subunit; NF-kappa B; Histones; Epigenesis, Genetic; Jurkat Cells
PubMed: 38927636
DOI: 10.3390/genes15060698 -
Genes May 2024A 23-month-old neutered male dog of unknown ancestry presented with a history of progressive neurological signs that included anxiety, cognitive impairment, tremors,...
A 23-month-old neutered male dog of unknown ancestry presented with a history of progressive neurological signs that included anxiety, cognitive impairment, tremors, seizure activity, ataxia, and pronounced visual impairment. The clinical signs were accompanied by global brain atrophy. Due to progression in the severity of disease signs, the dog was euthanized at 26 months of age. An examination of the tissues collected at necropsy revealed dramatic intracellular accumulations of autofluorescent inclusions in the brain, retina, and cardiac muscle. The inclusions were immunopositive for subunit c of mitochondrial ATP synthase, and their ultrastructural appearances were similar to those of lysosomal storage bodies that accumulate in some neuronal ceroid lipofuscinosis (NCL) diseases. The dog also exhibited widespread neuroinflammation. Based on these findings, the dog was deemed likely to have suffered from a form of NCL. A whole genome sequence analysis of the proband's DNA revealed a homozygous C to T substitution that altered the intron 3-exon 4 splice site of . Other mutations in cause NCL diseases in humans and animals, including dogs. The CLN6 protein was undetectable with immunolabeling in the tissues of the proband. Based on the clinical history, fluorescence and electron-microscopy, immunohistochemistry, and molecular genetic findings, the disorder in this dog was classified as an NCL resulting from the absence of the CLN6 protein. Screening the dog's genome for a panel of breed-specific polymorphisms indicated that its ancestry included numerous breeds, with no single breed predominating. This suggests that the disease variant is likely to be present in other mixed-breed dogs and at least some ancestral breeds, although it is likely to be rare since other cases have not been reported to date.
Topics: Neuronal Ceroid-Lipofuscinoses; Animals; Dogs; Male; Dog Diseases; RNA Splice Sites; Membrane Proteins; Mitochondrial Proton-Translocating ATPases; Brain; Mutation
PubMed: 38927597
DOI: 10.3390/genes15060661 -
Biomedicines Jun 2024The complex regulation of traction forces (TF) produced during cellular migration remains poorly understood. We have previously found that calpain 4 (Capn4), the small...
The complex regulation of traction forces (TF) produced during cellular migration remains poorly understood. We have previously found that calpain 4 (Capn4), the small non-catalytic subunit of the calpain 1 and 2 proteases, regulates the production of TF independent of the proteolytic activity of the larger subunits. Capn4 was later found to facilitate tyrosine phosphorylation and secretion of the lectin-binding protein galectin-3 (Gal3). In this study, recombinant Gal3 (rGal3) was added to the media-enhanced TF generated by mouse embryonic fibroblasts (MEFs). Extracellular Gal3 also rescued defects in the distribution, morphology, and adhesive strength of focal adhesions present in MEF cells. Surprisingly, extracellular Gal3 does not influence mechanosensing. c-Abl kinase was found to affect Gal3 secretion and the production of TF through phosphorylation of Y107 on Gal3. Our study also suggests that Gal3-mediated regulation of TF occurs through signaling pathways triggered by β1 integrin but not by focal adhesion kinase (FAK) Y397 autophosphorylation. Our findings provide insights into the signaling mechanism by which Capn4 and secreted Gal3 regulate cell migration through the modulation of TF distinctly independent from a mechanosensing mechanism.
PubMed: 38927454
DOI: 10.3390/biomedicines12061247 -
Biomolecules Jun 2024Antithrombin (AT) is a critical regulator of the coagulation cascade by inhibiting multiple coagulation factors including thrombin and FXa. Binding of heparinoids to...
Molecular Mechanisms of the Impaired Heparin Pentasaccharide Interactions in 10 Antithrombin Heparin Binding Site Mutants Revealed by Enhanced Sampling Molecular Dynamics.
Antithrombin (AT) is a critical regulator of the coagulation cascade by inhibiting multiple coagulation factors including thrombin and FXa. Binding of heparinoids to this serpin enhances the inhibition considerably. Mutations located in the heparin binding site of AT result in thrombophilia in affected individuals. Our aim was to study 10 antithrombin mutations known to affect their heparin binding in a heparin pentasaccharide bound state using two molecular dynamics (MD) based methods providing enhanced sampling, GaMD and LiGaMD2. The latter provides an additional boost to the ligand and the most important binding site residues. From our GaMD simulations we were able to identify four variants (three affecting amino acid Arg47 and one affecting Lys114) that have a particularly large effect on binding. The additional acceleration provided by LiGaMD2 allowed us to study the consequences of several other mutants including those affecting Arg13 and Arg129. We were able to identify several conformational types by cluster analysis. Analysis of the simulation trajectories revealed the causes of the impaired pentasaccharide binding including pentasaccharide subunit conformational changes and altered allosteric pathways in the AT protein. Our results provide insights into the effects of AT mutations interfering with heparin binding at an atomic level and can facilitate the design or interpretation of in vitro experiments.
Topics: Heparin; Molecular Dynamics Simulation; Binding Sites; Humans; Antithrombins; Mutation; Protein Binding; Oligosaccharides
PubMed: 38927061
DOI: 10.3390/biom14060657 -
Biomolecules May 2024The exosome multiprotein complex plays a critical role in RNA processing and degradation. This system governs the regulation of mRNA quality, degradation in the...
The exosome multiprotein complex plays a critical role in RNA processing and degradation. This system governs the regulation of mRNA quality, degradation in the cytoplasm, the processing of short noncoding RNA, and the breakdown of RNA fragments. We determined two crystal structures of exosome components from (): one with a resolution of 2.3 Å that reveals the central components (Rrp41 and Rrp42), and another with a resolution of 3.5 Å that displays the whole exosome (Rrp41, Rrp42, and Rrp4). The fundamental exosome structure revealed the presence of a heterodimeric complex consisting of Rrp41 and Rrp42. The structure comprises nine subunits, with Rrp41 and Rrp42 arranged in a circular configuration, while Rrp4 is located at the apex. The RNA degradation capabilities of the Rrp4:41:42 complex were verified by RNA degradation assays, consistent with prior findings in other archaeal exosomes. The resemblance between archaeal exosomes and bacterial PNPase suggests a common mechanism for RNA degradation. Despite sharing comparable topologies, the surface charge distributions of Rrp4 and other archaea structures are surprisingly distinct. Different RNA breakdown substrates may be responsible for this variation. These newfound structural findings enhance our comprehension of RNA processing and degradation in biological systems.
Topics: Thermoplasma; Exosomes; Crystallography, X-Ray; Archaeal Proteins; Models, Molecular; Protein Subunits; Exosome Multienzyme Ribonuclease Complex; RNA Stability
PubMed: 38927025
DOI: 10.3390/biom14060621