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Nature Neuroscience Oct 2023Oligodendrocyte precursor cells (OPCs) are a population of tissue-resident glial cells found throughout the CNS, constituting approximately 5% of all CNS cells and... (Review)
Review
Oligodendrocyte precursor cells (OPCs) are a population of tissue-resident glial cells found throughout the CNS, constituting approximately 5% of all CNS cells and persisting from development to adulthood and aging. The canonical role of OPCs is to give rise to myelinating oligodendrocytes. However, additional functions of OPCs beyond this traditional role as precursors have been suggested for a long time. In this Perspective, we provide an overview of the multiple myelination-independent functions that have been described for OPCs in the context of neuron development, angiogenesis, inflammatory response, axon regeneration and their recently discovered roles in neural circuit remodeling.
Topics: Myelin Sheath; Oligodendrocyte Precursor Cells; Axons; Nerve Regeneration; Oligodendroglia; Cell Differentiation
PubMed: 37653126
DOI: 10.1038/s41593-023-01423-3 -
Neuroscience Research Dec 2023The past 20 years of research on axon degeneration has revealed fine details on how NAD biology controls axonal survival. Extensive data demonstrate that the NAD... (Review)
Review
The past 20 years of research on axon degeneration has revealed fine details on how NAD biology controls axonal survival. Extensive data demonstrate that the NAD precursor NMN binds to and activates the pro-degenerative enzyme SARM1, so a failure to convert sufficient NMN into NAD leads to toxic NMN accumulation and axon degeneration. This involvement of NMN brings the axon degeneration field to an unexpected overlap with research into ageing and extending healthy lifespan. A decline in NAD levels throughout life, at least in some tissues, is believed to contribute to age-related functional decay and boosting NAD production with supplementation of NMN or other NAD precursors has gained attention as a potential anti-ageing therapy. Recent years have witnessed an influx of NMN-based products and related molecules on the market, sold as food supplements, with many people taking these supplements daily. While several clinical trials are ongoing to check the safety profiles and efficacy of NAD precursors, sufficient data to back their therapeutic use are still lacking. Here, we discuss NMN supplementation, SARM1 and anti-ageing strategies, with an important question in mind: considering that NMN accumulation can lead to axon degeneration, how is this compatible with its beneficial effect in ageing and are there circumstances in which NMN supplementation could become harmful?
Topics: Humans; NAD; Axons; Aging
PubMed: 36657725
DOI: 10.1016/j.neures.2023.01.004 -
Nutrients Jul 2023Dietary vitamin B3 components, such as nicotinamide and nicotinic acid, are precursors to the ubiquitous redox cofactor nicotinamide adenine dinucleotide (NAD). NAD... (Review)
Review
Dietary vitamin B3 components, such as nicotinamide and nicotinic acid, are precursors to the ubiquitous redox cofactor nicotinamide adenine dinucleotide (NAD). NAD levels are thought to decline with age and disease. While the drivers of this decline remain under intense investigation, strategies have emerged seeking to functionally maintain NAD levels through supplementation with NAD biosynthetic intermediates. These include marketed products, such as nicotinamide riboside (NR) and its phosphorylated form (NMN). More recent developments have shown that NRH (the reduced form of NR) and its phosphorylated form NMNH also increases NAD levels upon administration, although they initially generate NADH (the reduced form of NAD). Other means to increase the combined levels of NAD and NADH, NAD(H), include the inhibition of NAD-consuming enzymes or activation of biosynthetic pathways. Multiple studies have shown that supplementation with an NAD(H) precursor changes the profile of NAD(H) catabolism. Yet, the pharmacological significance of NAD(H) catabolites is rarely considered although the distribution and abundance of these catabolites differ depending on the NAD(H) precursor used, the species in which the study is conducted, and the tissues used for the quantification. Significantly, some of these metabolites have emerged as biomarkers in physiological disorders and might not be innocuous. Herein, we review the known and emerging catabolites of the NAD(H) metabolome and highlight their biochemical and physiological function as well as key chemical and biochemical reactions leading to their formation. Furthermore, we emphasize the need for analytical methods that inform on the full NAD(H) metabolome since the relative abundance of NAD(H) catabolites informs how NAD(H) precursors are used, recycled, and eliminated.
Topics: NAD; Niacinamide; Niacin; Metabolome; Oxidation-Reduction; Biomarkers
PubMed: 37447389
DOI: 10.3390/nu15133064 -
Metabolites Jul 2023Phytohormones exhibit a wide range of chemical structures, though they primarily originate from three key metabolic precursors: amino acids, isoprenoids, and lipids.... (Review)
Review
Phytohormones exhibit a wide range of chemical structures, though they primarily originate from three key metabolic precursors: amino acids, isoprenoids, and lipids. Specific amino acids, such as tryptophan, methionine, phenylalanine, and arginine, contribute to the production of various phytohormones, including auxins, melatonin, ethylene, salicylic acid, and polyamines. Isoprenoids are the foundation of five phytohormone categories: cytokinins, brassinosteroids, gibberellins, abscisic acid, and strigolactones. Furthermore, lipids, i.e., α-linolenic acid, function as a precursor for jasmonic acid. The biosynthesis routes of these different plant hormones are intricately complex. Understanding of these processes can greatly enhance our knowledge of how these hormones regulate plant growth, development, and physiology. This review focuses on detailing the biosynthetic pathways of phytohormones.
PubMed: 37623827
DOI: 10.3390/metabo13080884 -
Nature Oct 2023Transposable elements are genomic parasites that expand within and spread between genomes. PIWI proteins control transposon activity, notably in the germline. These...
Transposable elements are genomic parasites that expand within and spread between genomes. PIWI proteins control transposon activity, notably in the germline. These proteins recognize their targets through small RNA co-factors named PIWI-interacting RNAs (piRNAs), making piRNA biogenesis a key specificity-determining step in this crucial genome immunity system. Although the processing of piRNA precursors is an essential step in this process, many of the molecular details remain unclear. Here, we identify an endoribonuclease, precursor of 21U RNA 5'-end cleavage holoenzyme (PUCH), that initiates piRNA processing in the nematode Caenorhabditis elegans. Genetic and biochemical studies show that PUCH, a trimer of Schlafen-like-domain proteins (SLFL proteins), executes 5'-end piRNA precursor cleavage. PUCH-mediated processing strictly requires a 7-methyl-G cap (mG-cap) and a uracil at position three. We also demonstrate how PUCH interacts with PETISCO, a complex that binds to piRNA precursors, and that this interaction enhances piRNA production in vivo. The identification of PUCH concludes the search for the 5'-end piRNA biogenesis factor in C. elegans and uncovers a type of RNA endonuclease formed by three SLFL proteins. Mammalian Schlafen (SLFN) genes have been associated with immunity, exposing a molecular link between immune responses in mammals and deeply conserved RNA-based mechanisms that control transposable elements.
Topics: Animals; Argonaute Proteins; Caenorhabditis elegans; Caenorhabditis elegans Proteins; DNA Transposable Elements; Endoribonucleases; Holoenzymes; Piwi-Interacting RNA; RNA Cap Analogs
PubMed: 37758951
DOI: 10.1038/s41586-023-06588-2 -
Organic & Biomolecular Chemistry Dec 2023Although a ripe old discipline by now, carbene chemistry continues to flourish as both theorists and experimentalists have shown sustained interest in this area of... (Review)
Review
Although a ripe old discipline by now, carbene chemistry continues to flourish as both theorists and experimentalists have shown sustained interest in this area of research. While there are numerous ways of generating carbenes, the thermal and/or photochemical decomposition of diazo compounds and diazirines remains, by far, the most commonly used method of producing these intermediates. There is no disputing the fact that these nitrogenous precursors have served carbene researchers well, but their use is not without problems. They are often sensitive and hazardous to handle and, sometimes, the desired nitrogenous precursor simply may not be available, , for synthetic reasons, to study the particular carbene of interest. Furthermore, there is a legitimate concern that the photochemical generation of carbenes in solution from diazo compounds and diazirines may be contaminated by reactions in the excited states (RIES) of the precursors themselves. As an alternative, several laboratories, including ours, have used cyclopropanated aromatic systems to generate a wide range of carbenes. In each case, the cheleotropic extrusion of carbenes is accompanied by the formation of stable aromatic by-products such as phenanthrene, indane, naphthalene, and 1,4-dihydronaphthalene. The emergence of these "non-traditional" carbene sources, their versatility, and promise are reviewed in this work.
PubMed: 37994575
DOI: 10.1039/d3ob01525d -
Hematology/oncology Clinics of North... May 2024Cervical cancer, caused due to oncogenic types of human papillomavirus (HPV), is a leading preventable cause of cancer morbidity and mortality globally. Chronic,... (Review)
Review
Cervical cancer, caused due to oncogenic types of human papillomavirus (HPV), is a leading preventable cause of cancer morbidity and mortality globally. Chronic, persistent HPV infection-induced cervical precursor lesions, if left undetected and untreated, can progress to invasive cancer. Cervical cancer screening approaches have evolved from cytology (Papanicolaou test) to highly sensitive HPV-based molecular methods and personalized, risk-stratified, management guidelines. Innovations like self-collection of samples to increase screening access, innovative triage methods to optimize management of screen positives, and scalable and efficacious precancer treatment approaches will be key to further enhance the utility of prevention interventions.
PubMed: 38760198
DOI: 10.1016/j.hoc.2024.03.005 -
Seminars in Liver Disease Nov 2023Biliary tract cancer is a devastating malignancy of the bile ducts and gallbladder with a dismal prognosis. The study of precancerous lesions has received considerable... (Review)
Review
Biliary tract cancer is a devastating malignancy of the bile ducts and gallbladder with a dismal prognosis. The study of precancerous lesions has received considerable attention and led to a histopathological classification which, in some respects, remains an evolving field. Consequently, increasing efforts have been devoted to characterizing the molecular pathogenesis of the precursor lesions, with the aim of better understanding the mechanisms of tumor progression, and with the ultimate goal of meeting the challenges of early diagnosis and treatment. This review delves into the molecular mechanisms that initiate and promote the development of precursor lesions of intra- and extrahepatic cholangiocarcinoma and of gallbladder carcinoma. It addresses the genomic, epigenomic, and transcriptomic landscape of these precursors and provides an overview of animal and organoid models used to study them. In conclusion, this review summarizes the known molecular features of precancerous lesions in biliary tract cancer and highlights our fragmentary knowledge of the molecular pathogenesis of tumor initiation.
Topics: Humans; Bile Duct Neoplasms; Biliary Tract Neoplasms; Cholangiocarcinoma; Precancerous Conditions; Bile Ducts, Intrahepatic; Molecular Biology
PubMed: 37944999
DOI: 10.1055/a-2207-9834 -
World Journal of Clinical Cases Jun 2024The diagnosis of pancreatic cancer associates an appalling significance. Detection of preinvasive stage of pancreatic cancer will ameliorate the survival of this deadly...
The diagnosis of pancreatic cancer associates an appalling significance. Detection of preinvasive stage of pancreatic cancer will ameliorate the survival of this deadly disease. Premalignant lesions such as Intraductal Papillary Mucinous Neoplasms or Mucinous Cystic Neoplasms of the pancreas are detectable on imaging exams and this permits their management prior their invasive development. Pancreatic intraepithelial neoplasms (PanIN) are the most frequent precursors of pancreatic adenocarcinoma (PDAC), and its particular type PanIN high-grade represents the malignant non-invasive form of PDAC. Unfortunately, PanINs are not detectable on radiologic exams. Nevertheless, they can associate indirect imaging signs which would rise the diagnostic suspicion. When this suspicion is established, the patient will be enrolled in a follow-up strategy that includes performing of blood test and serial imaging test such as computed tomography or magnetic resonance imaging, which will cost in the best-case scenario a burden of healthcare systems, and potential mortality in the worst-case scenario when the patient underwent resection surgery, worthless when there is no moderate or high grade dysplasia in the final histopathology. This issue will be avoid having at its disposal a diagnostic technique capable of detecting high-grade PanIN lesions, such is the cytology of pancreatic juice obtained by nasopancreatic intubation. Herein, we review the possibility of detection of early malignant lesions before they become invasive PADC.
PubMed: 38898835
DOI: 10.12998/wjcc.v12.i17.2935 -
Genomics, Proteomics & Bioinformatics May 2024Ribonuclease P (RNase P) was first described in the 1970's as an endoribonuclease acting in the maturation of precursor transfer RNAs (tRNAs). More recent studies,... (Review)
Review
Ribonuclease P (RNase P) was first described in the 1970's as an endoribonuclease acting in the maturation of precursor transfer RNAs (tRNAs). More recent studies, however, have uncovered non-canonical roles for RNase P and its components. Here, we review the recent progress of its involvement in chromatin assembly, DNA damage response, and maintenance of genome stability with implications in tumorigenesis. The possibility of RNase P as a therapeutic target in cancer is also discussed.
Topics: Ribonuclease P; Humans; RNA, Transfer; Neoplasms; RNA Precursors; Genomic Instability; Animals; DNA Damage; RNA Processing, Post-Transcriptional; Chromatin Assembly and Disassembly
PubMed: 38862431
DOI: 10.1093/gpbjnl/qzae016