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Nature Communications Jun 2024Glucagon, a hormone released from pancreatic α-cells, is critical for maintaining euglycemia and plays a key role in the pathophysiology of diabetes. To stimulate the...
Glucagon, a hormone released from pancreatic α-cells, is critical for maintaining euglycemia and plays a key role in the pathophysiology of diabetes. To stimulate the development of new classes of therapeutic agents targeting glucagon release, key α-cell signaling pathways that regulate glucagon secretion need to be identified. Here, we focused on the potential importance of α-cell G signaling on modulating α-cell function. Studies with α-cell-specific mouse models showed that activation of α-cell G signaling causes a marked increase in glucagon secretion. We also found that intra-islet adenosine plays an unexpected autocrine/paracrine role in promoting glucagon release via activation of α-cell G-coupled A adenosine receptors. Studies with α-cell-specific Gα knockout mice showed that α-cell G also plays an essential role in stimulating the activity of the Gcg gene, thus ensuring proper islet glucagon content. Our data suggest that α-cell enriched G-coupled receptors represent potential targets for modulating α-cell function for therapeutic purposes.
Topics: Glucagon; Animals; Glucagon-Secreting Cells; Signal Transduction; Mice, Knockout; Mice; GTP-Binding Protein alpha Subunits, Gs; Adenosine; Receptor, Adenosine A2A; Male; Mice, Inbred C57BL; Islets of Langerhans
PubMed: 38879678
DOI: 10.1038/s41467-024-49537-x -
Die Pharmazie Jun 2024In this study, we hypothesized that lixisenatide (LIX) and ticagrelor (TIC) could have a protective effect against type 2 diabetes mellitus (T2DM)-induced vascular...
Ameliorative effect of lixisenatide on diabetic cardiovascular damage and its enhancement via ticagrelor co-administration in rats: possible role of eNOS and NrF₂ /HO-1 signaling.
In this study, we hypothesized that lixisenatide (LIX) and ticagrelor (TIC) could have a protective effect against type 2 diabetes mellitus (T2DM)-induced vascular damage. Furthermore, we explored the possible additional protective effect of co-administering LIX and TIC in the treatment regimen. 50 male rats were divided into five groups, each comprising 10 rats: C (control), D (T2DM rats), D + LIX (T2DM rats treated with LIX for 4 weeks), D + TIC (T2DM rats treated with TIC for 4 weeks), and D + LIX + TIC (T2DM rats treated with LIX + TIC for 4 weeks). : The D group showed an increase in body weight, blood glucose, hemostatic model assessment for insulin resistance (HOMA-IR), aorta reactive oxygen species (ROS), and nuclear factor kappa B (NF-κ B), along with a reduction in serum insulin, aorta superoxide dismutase (SOD), glutathione reduced (GSH), nuclear factor erythroid-2 (NrF₂), hemeoxygenase-1 (HO-1), and endothelial nitric oxide synthase (eNOS). Deterioration in the aorta histopathological condition, coupled with a noticeable impairment in vascular reactivity compared to the C group, was observed. A single administration of LIX showed a reduction in body weight, blood glucose, HOMA-IR, aorta ROS, and NF-κ B, accompanied by an increase in serum insulin, aorta SOD, GSH, NrF₂, HO-1, and eNOS. Amelioration in the aorta histopathological condition and improved vascular reactivity compared to the D group were reported. Similarly, a single administration of TIC showed a reduction in aorta ROS and NF-κ B, along with an increase in aorta SOD, GSH, NrF₂, HO-1, and eNOS. A slight amelioration was detected in the aorta histopathological condition, with improved vascular reactivity compared to the D group. The combined administration of LIX and TIC showed a reduction in aorta ROS and NF-κ B, along with an increase in aorta GSH, SOD, HO-1, and eNOS. This was combined with evident amelioration in the aorta histopathological condition and noticeable improvement in vascular reactivity compared to the single treatment with either LIX or TIC group. : The present study introduces clear evidence that the administration of LIX and TIC can improve metabolic and vascular complications of T2DM through modulating eNOS and NrF₂ /HO-1 signaling. The combined administration of LIX and TIC produced more significant effects than a single treatment.
Topics: Animals; Male; Nitric Oxide Synthase Type III; Rats; Signal Transduction; Ticagrelor; Peptides; NF-E2-Related Factor 2; Diabetes Mellitus, Experimental; Reactive Oxygen Species; Blood Glucose; Insulin Resistance; Diabetes Mellitus, Type 2; Rats, Sprague-Dawley; Heme Oxygenase (Decyclizing); NF-kappa B; Hypoglycemic Agents; Heme Oxygenase-1; Insulin; Oxidative Stress; Superoxide Dismutase; Drug Synergism; Glucagon-Like Peptide-2 Receptor
PubMed: 38877681
DOI: 10.1691/ph.2024.4509 -
Proceedings of the National Academy of... Jun 2024Human bocavirus 1 (HBoV1) is a human parvovirus that causes lower respiratory tract infections in young children. It contains a single-stranded (ss) DNA genome of ~5.5...
Human bocavirus 1 (HBoV1) is a human parvovirus that causes lower respiratory tract infections in young children. It contains a single-stranded (ss) DNA genome of ~5.5 kb that encodes a small noncoding RNA of 140 nucleotides known as bocavirus-encoded small RNA (BocaSR), in addition to viral proteins. Here, we determined the secondary structure of BocaSR in vivo by using DMS-MaPseq. Our findings reveal that BocaSR undergoes N6-methyladenosine (m6A) modification at multiple sites, which is critical for viral DNA replication in both dividing HEK293 cells and nondividing cells of the human airway epithelium. Mechanistically, we found that m6A-modified BocaSR serves as a mediator for recruiting Y-family DNA repair DNA polymerase (Pol) η and Pol κ likely through a direct interaction between BocaSR and the viral DNA replication origin at the right terminus of the viral genome. Thus, this report represents direct involvement of a viral small noncoding RNA in viral DNA replication through m6A modification.
Topics: Humans; Adenosine; Virus Replication; DNA-Directed DNA Polymerase; DNA Replication; DNA, Viral; HEK293 Cells; RNA, Viral; Human bocavirus; Genome, Viral; Parvoviridae Infections
PubMed: 38875150
DOI: 10.1073/pnas.2320782121 -
Nucleic Acids Research Jun 2024Recent findings in cell biology have rekindled interest in Z-DNA, the left-handed helical form of DNA. We report here that two minimally modified nucleosides, 2'F-araC...
Recent findings in cell biology have rekindled interest in Z-DNA, the left-handed helical form of DNA. We report here that two minimally modified nucleosides, 2'F-araC and 2'F-riboG, induce the formation of the Z-form under low ionic strength. We show that oligomers entirely made of these two nucleosides exclusively produce left-handed duplexes that bind to the Zα domain of ADAR1. The effect of the two nucleotides is so dramatic that Z-form duplexes are the only species observed in 10 mM sodium phosphate buffer and neutral pH, and no B-form is observed at any temperature. Hence, in contrast to other studies reporting formation of Z/B-form equilibria by a preference for purine glycosidic angles in syn, our NMR and computational work revealed that sequential 2'F…H2N and intramolecular 3'H…N3' interactions stabilize the left-handed helix. The equilibrium between B- and Z- forms is slow in the 19F NMR time scale (≥ms), and each conformation exhibited unprecedented chemical shift differences in the 19F signals. This observation led to a reliable estimation of the relative population of B and Z species and enabled us to monitor B-Z transitions under different conditions. The unique features of 2'F-modified DNA should thus be a valuable addition to existing techniques for specific detection of new Z-binding proteins and ligands.
PubMed: 38874502
DOI: 10.1093/nar/gkae508 -
Methods in Molecular Biology (Clifton,... 2024Recent advancements in detection and mapping methods have enabled researchers to uncover the biological importance of RNA chemical modifications, which play a vital role...
Recent advancements in detection and mapping methods have enabled researchers to uncover the biological importance of RNA chemical modifications, which play a vital role in post-transcriptional gene regulation. Although numerous types of RNA modifications have been identified in higher eukaryotes, only a few have been extensively studied for their biological functions. Of these, N-methyladenosine (mA) is the most prevalent and important mRNA modification that influences various aspects of RNA metabolism, including mRNA stability, degradation, splicing, alternative polyadenylation, export, and localization, as well as translation. Thus, they have implications for a variety of biological processes, including growth, development, and stress responses. The mA deposition or removal on transcripts is dynamic and is altered in response to internal and external cues. Because this mark can alter gene expression under stress conditions, it is essential to identify the transcripts that can acquire or lose this epitranscriptomic mark upon exposure to stress conditions. Here we describe a step-by-step protocol for identifying stress-responsive transcriptome-wide mA changes using RNA immunoprecipitation followed by high-throughput sequencing (MeRIP-seq).
Topics: Adenosine; Stress, Physiological; Transcriptome; Gene Expression Regulation, Plant; RNA, Plant; High-Throughput Nucleotide Sequencing; RNA, Messenger; Gene Expression Profiling; Arabidopsis; Sequence Analysis, RNA; Immunoprecipitation; Plants; RNA Processing, Post-Transcriptional
PubMed: 38869786
DOI: 10.1007/978-1-0716-3973-3_3 -
Frontiers in Immunology 2024Immunotherapy for hematological malignancies is a rapidly advancing field that has gained momentum in recent years, primarily encompassing chimeric antigen receptor... (Review)
Review
Immunotherapy for hematological malignancies is a rapidly advancing field that has gained momentum in recent years, primarily encompassing chimeric antigen receptor T-cell (CAR-T) therapies, immune checkpoint inhibitors, and other modalities. However, its clinical efficacy remains limited, and drug resistance poses a significant challenge. Therefore, novel immunotherapeutic targets and agents need to be identified. Recently, N6-methyladenosine (m6A), the most prevalent RNA epitope modification, has emerged as a pivotal factor in various malignancies. Reportedly, m6A mutations influence the immunological microenvironment of hematological malignancies, leading to immune evasion and compromising the anti-tumor immune response in hematological malignancies. In this review, we comprehensively summarize the roles of the currently identified m6A modifications in various hematological malignancies, with a particular focus on their impact on the immune microenvironment. Additionally, we provide an overview of the research progress made in developing m6A-targeted drugs for hematological tumor therapy, to offer novel clinical insights.
Topics: Humans; Tumor Microenvironment; Hematologic Neoplasms; Adenosine; Animals; Immunotherapy
PubMed: 38868768
DOI: 10.3389/fimmu.2024.1374390 -
The Journal of Physiological Sciences :... Jun 2024Hibernation and torpor are not passive responses caused by external temperature drops and fasting but are active brain functions that lower body temperature. A...
Hibernation and torpor are not passive responses caused by external temperature drops and fasting but are active brain functions that lower body temperature. A population of neurons in the preoptic area was recently identified as such active torpor-regulating neurons. We hypothesized that the other hypothermia-inducing maneuvers would also activate these neurons. To test our hypothesis, we first refined the previous observations, examined the brain regions explicitly activated during the falling phase of body temperature using c-Fos expression, and confirmed the preoptic area. Next, we observed long-lasting hypothermia by reactivating torpor-tagged Gq-expressing neurons using the activity tagging and DREADD systems. Finally, we found that about 40-60% of torpor-tagged neurons were activated by succeeding isoflurane anesthesia and by icv administration of an adenosine A1 agonist. Isoflurane-induced and central adenosine-induced hypothermia is, at least in part, an active process mediated by the torpor-regulating neurons in the preoptic area.
Topics: Animals; Preoptic Area; Isoflurane; Adenosine; Neurons; Male; Anesthetics, Inhalation; Body Temperature; Hypothermia; Torpor; Mice; Proto-Oncogene Proteins c-fos
PubMed: 38867187
DOI: 10.1186/s12576-024-00927-2 -
Cellular and Molecular Life Sciences :... Jun 2024Pulmonary hypertension (PH) is characterized by vascular remodeling predominantly driven by a phenotypic switching in pulmonary artery smooth muscle cells (PASMCs)....
Pulmonary hypertension (PH) is characterized by vascular remodeling predominantly driven by a phenotypic switching in pulmonary artery smooth muscle cells (PASMCs). However, the underlying mechanisms for this phenotypic alteration remain incompletely understood. Here, we identified that RNA methyltransferase METTL3 is significantly elevated in the lungs of hypoxic PH (HPH) mice and rats, as well as in the pulmonary arteries (PAs) of HPH rats. Targeted deletion of Mettl3 in smooth muscle cells exacerbated hemodynamic consequences of hypoxia-induced PH and accelerated pulmonary vascular remodeling in vivo. Additionally, the absence of METTL3 markedly induced phenotypic switching in PASMCs in vitro. Mechanistically, METTL3 depletion attenuated mA modification and hindered the processing of pri-miR-143/145, leading to a downregulation of miR-143-3p and miR-145-5p. Inhibition of hnRNPA2B1, an mA mediator involved in miRNA maturation, similarly resulted in a significant reduction of miR-143-3p and miR-145-5p. We demonstrated that miR-145-5p targets Krüppel-like factor 4 (KLF4) and miR-143-3p targets fascin actin-bundling protein 1 (FSCN1) in PASMCs. The decrease of miR-145-5p subsequently induced an upregulation of KLF4, which in turn suppressed miR-143/145 transcription, establishing a positive feedback circuit between KLF4 and miR-143/145. This regulatory circuit facilitates the persistent suppression of contractile marker genes, thereby sustaining PASMC phenotypic switch. Collectively, hypoxia-induced upregulation of METTL3, along with mA mediated regulation of miR-143/145, might serve as a protective mechanism against phenotypic switch of PASMCs. Our results highlight a potential therapeutic strategy targeting mA modified miR-143/145-KLF4 loop in the treatment of PH.
Topics: Kruppel-Like Factor 4; Animals; MicroRNAs; Pulmonary Artery; Kruppel-Like Transcription Factors; Myocytes, Smooth Muscle; Mice; Adenosine; Methyltransferases; Rats; Phenotype; Male; Hypertension, Pulmonary; Muscle, Smooth, Vascular; Mice, Inbred C57BL; Vascular Remodeling; Rats, Sprague-Dawley; Humans
PubMed: 38866991
DOI: 10.1007/s00018-024-05304-1 -
Nature Communications Jun 2024Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease due to gradual motoneurons (MN) degeneration. Among the processes associated to ALS...
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease due to gradual motoneurons (MN) degeneration. Among the processes associated to ALS pathogenesis, there is the formation of cytoplasmic inclusions produced by aggregation of mutant proteins, among which the RNA binding protein FUS. Here we show that, in neuronal cells and in iPSC-derived MN expressing mutant FUS, such inclusions are significantly reduced in number and dissolve faster when the RNA mA content is diminished. Interestingly, stress granules formed in ALS conditions showed a distinctive transcriptome with respect to control cells, which reverted to similar to control after mA downregulation. Notably, cells expressing mutant FUS were characterized by higher mA levels suggesting a possible link between mA homeostasis and pathological aggregates. Finally, we show that FUS inclusions are reduced also in patient-derived fibroblasts treated with STM-2457, an inhibitor of METTL3 activity, paving the way for its possible use for counteracting aggregate formation in ALS.
Topics: RNA-Binding Protein FUS; Amyotrophic Lateral Sclerosis; Humans; Motor Neurons; Induced Pluripotent Stem Cells; Cytoplasmic Granules; Fibroblasts; Adenosine; Methyltransferases; Mutation; Inclusion Bodies; Stress Granules; Transcriptome
PubMed: 38866783
DOI: 10.1038/s41467-024-49416-5 -
Proceedings of the National Academy of... Jun 2024The fat mass and obesity-associated fatso (FTO) protein is a member of the Alkb family of dioxygenases and catalyzes oxidative demethylation of N-methyladenosine (mA),...
The fat mass and obesity-associated fatso (FTO) protein is a member of the Alkb family of dioxygenases and catalyzes oxidative demethylation of N-methyladenosine (mA), N-methyladenosine (mA), 3-methylthymine (mT), and 3-methyluracil (mU) in single-stranded nucleic acids. It is well established that the catalytic activity of FTO proceeds via two coupled reactions. The first reaction involves decarboxylation of alpha-ketoglutarate (αKG) and formation of an oxyferryl species. In the second reaction, the oxyferryl intermediate oxidizes the methylated nucleic acid to reestablish Fe(II) and the canonical base. However, it remains unclear how binding of the nucleic acid activates the αKG decarboxylation reaction and why FTO demethylates different methyl modifications at different rates. Here, we investigate the interaction of FTO with 5-mer DNA oligos incorporating the mA, mA, or mT modifications using solution NMR, molecular dynamics (MD) simulations, and enzymatic assays. We show that binding of the nucleic acid to FTO activates a two-state conformational equilibrium in the αKG cosubstrate that modulates the O accessibility of the Fe(II) catalyst. Notably, the substrates that provide better stabilization to the αKG conformation in which Fe(II) is exposed to O are demethylated more efficiently by FTO. These results indicate that i) binding of the methylated nucleic acid is required to expose the catalytic metal to O and activate the αKG decarboxylation reaction, and ii) the measured turnover of the demethylation reaction (which is an ensemble average over the entire sample) depends on the ability of the methylated base to favor the Fe(II) state accessible to O.
Topics: Alpha-Ketoglutarate-Dependent Dioxygenase FTO; Ketoglutaric Acids; Iron; Humans; Substrate Specificity; Adenosine; Protein Conformation; Uracil; Molecular Dynamics Simulation; Thymine
PubMed: 38865275
DOI: 10.1073/pnas.2404457121