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Advances in Genome Editing
Published in Yashwant Pathak, Gene Delivery, 2022
Extracellular vesicles are an emerging new type of biological RNA delivery mechanism that is progressively being studied. Extracellular vesicles are nanosized particles discharged into the extracellular environment by generating cells to interact with and act on remote and nearby cells. Extracellular vesicles can transport a variety of cellular material, including DNA, messenger RNA, microRNA, and proteins to specific cells (Jiang et al., 2017; Massaro et al., 2020).
Intracellular Maturation of Acute Phase Proteins
Published in Andrzej Mackiewicz, Irving Kushner, Heinz Baumann, Acute Phase Proteins, 2020
Erik Fries, E. Mathilda Sjöberg
During the assembly of a secretory protein, the first 15 to 30 amino acid residues — the signal sequence — serve to direct the synthetic machinery to the endoplasmic reticulum (ER). Further elongation results in the progressive translocation of the polypeptide into the lumen of the ER and the removal of the signal sequence.3 The secretory proteins are then transported by vesicles to the Golgi complex (GC) via a tubulo-vesicular system, usually referred to as the intermediate compartment (Figure 1).4,5
Neuroendocrine Morphology
Published in Paul V. Malven, Mammalian Neuroendocrinology, 2019
Cytological Features of Adenohypophysial Secretion. Hormones are synthesized, packaged into secretory vesicles, and secreted from adenohypophysial cells in ways that appear to be similar to those of other hormone-secreting cells. Gene transcription and RNA processing occurs in the nucleus followed by transport of the mRNA to the RER where synthesis of the prohormone occurs. The prohormone is cleaved into the products for secretion, and occasionally subunits produced from different gene transcripts are covalently linked. The secretory products are packaged into dense-core secretory vesicles in the Golgi apparatus from which they migrate to a position near the plasma membrane to await release. Release into the extracellular space occurs by exocytosis wherein (1) the membrane of the secretory vesicle fuses with the inner surface of the plasma membrane, (2) the double layer of fused membrane breaks down, and (3) the contents of the secretory vesicle enter the extracellular space. The speed of the entire process of synthesis, packaging, and exocytosis probably depends upon the intensity of stimulation of the adenohypophysial cell. Studies with strongly stimulated mammotrophs from rats suggest that the entire process can occur in as little as 50 min, but this may represent a lower limit.
Potential applications of mesenchymal stem cells and their derived exosomes in regenerative medicine
Published in Expert Opinion on Biological Therapy, 2023
Maryam Adelipour, David M. Lubman, Jeongkwon Kim
Extracellular vesicles (EVs) include a variety of vesicles that differ in size, content, and biogenesis. The three main types of extracellular vesicles are exosomes, microvesicles, and apoptotic bodies. Microvesicles and apoptotic bodies are released from living or dying cells, respectively, by outward budding of the plasma membrane. Exosomes are typically smaller than microvesicles and apoptotic bodies and are formed through the endocytic pathway [107]. Exosomes released from MSCs are being discovered as mediators for cell-free regenerative medicine. These small EVs, with sizes less than 150 nm, are produced from endosomes, created by the invagination of the plasma membrane, and released through membrane fusion. Exosomes contain two layers of phospholipids enriched in ceramide, sphingomyelin, and cholesterol. Exosomes also contain various biomolecules, including transmembrane proteins (CD63, CD9, and CD81), mRNA, microRNA, and DNA, which make them potential therapeutic agents [108,109].
Unraveling the complexity of the extracellular vesicle landscape with advanced proteomics
Published in Expert Review of Proteomics, 2022
Julia Morales-Sanfrutos, Javier Munoz
Different types of extracellular vesicles have been identified and these are often classified on the basis of their size, composition and biological origin. Advances on this regard have been mainly driven by the development of new approaches for the isolation and characterization of EVs. However, the lack of defined guidelines and criteria for the unambiguous assignment of EVs, as well as issues with the purity and heterogeneity of EVs preparations, have caused a confusing nomenclature in current literature. Indeed, classification of the EVs landscape is continuously evolving [3]. One of the major types of EVs are microvesicles (MVs), sometimes referred as ectosomes and micro-particles. MVs are lipid-bilayered particles of 100–1000 nm that originate via shedding of the plasma membrane (Figure 1A). Their biogenesis is controlled by intracellular Ca2+ levels and a set of proteins that include flippases, translocases, scramblase, actin cytoskeleton and members of the Ras family of GTPase [4], ultimately leading to the outward budding of the plasma membrane, trapping inside the intra-cellular material.
Cranial nerve involvement in varicella zoster virus after renal transplantation
Published in Baylor University Medical Center Proceedings, 2020
Jennifer Nielsen Fan, Jerry Fan, Hameed Ali
Varicella zoster virus (VZV) is a very common infection that manifests in adulthood as shingles. Its primary infection, which causes chickenpox, lies latent in the dorsal root ganglia until reactivating during a time of stress or low immunity. The characteristic finding includes a painful rash of vesicles in a dermatomal distribution, commonly on the side of the trunk or face.1 VZV reactivation can cause several other complications, such as neuralgic pain without a rash (zoster sine herpete), encephalitis, meningitis, myelopathies, vasculitis, and Guillain-Barré syndrome. Additionally, involvement can occasionally extend to the brain and cranial nerves, which presents a challenging clinical diagnosis, especially due to the lack of the characteristic rash.1,2 We present one such case.