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An Overview of Parasite Diversity
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
Helminths seem not to have elaborate mechanisms for antigenic variation but do have complex and resilient surface coats adorned with a variety of surface proteins encoded by expanded gene families. Surface glycoproteins may be bound by components of the host innate immune system like lectins, sending inhibitory signals in the process. Glycosyltransferase enzymes, expanded in both nematodes and tapeworms, can modify parasite surface glycoproteins, potentially altering immune recognition. Some surface molecules like tetraspanins exist in expanded gene families and are also of interest because they can be included in small extracellular vesicles produced by parasites that may be delivered to, enter and affect host cells.
The Emerging Role of Exosome Nanoparticles in Regenerative Medicine
Published in Harishkumar Madhyastha, Durgesh Nandini Chauhan, Nanopharmaceuticals in Regenerative Medicine, 2022
Zahra Sadat Hashemi, Mahlegha Ghavami, Saeed Khalili, Seyed Morteza Naghib
It should be noted that the biogenesis pathway of exosomes and their distinction fromother cell-derived vesicles were identified due to the existence of lysosomal surface protein (LAMP), tetraspanins (CD81, CD9, and CD63), heat shock proteins (Hsc70), and also some fusion proteins such as Annexin, CD9, and flotillin in the exosomal membrane (Caby et al. 2005; Andaloussi et al. 2013; Conde-Vancells et al. 2008; Mohammadpour and Majidzadeh-A 2020). The transport (ESCRT) process requires the endosomal sorting complex, which is a collection of proteins necessary for formation and sorting of cargo into exosomes.
Retinal stem cell research
Published in A Peyman MD Gholam, A Meffert MD Stephen, D Conway MD FACS Mandi, Chiasson Trisha, Vitreoretinal Surgical Techniques, 2019
Henry Klassen, Michael J Young, Robert Ritch, Julia E Richards, Teresa Borrάs, Leonard A Levin
CNS stem or progenitor cells also express many less specific markers. These include the intermediate filament protein vimentin, the proliferation marker Ki-67, the cell cycle protein cyclin D1, and various forms of the surface adhesion molecule NCAM (neural cell adhesion molecule, CD56), as well as the surface markers CD9 and CD81, both of which are members of the tetraspanin family of transmembrane proteins.5 While it seems increasingly likely that no single unique marker for NSCs will be identified, the use of multiple positive and negative markers in combination may provide a way around this problem. Undoubtedly, a more comprehensive understanding of cellular transcriptional activity will allow investigators to better resolve the ontogenetic status of cells of interest.
Exosomes-based cell-free cancer therapy: a novel strategy for targeted therapy
Published in Immunological Medicine, 2021
Exosome biogenesis initiates within the endosomal system and is tightly regulated. Exosomes correspond to the intraluminal vesicles (ILVs) of MVBs. During the process of exosome biogenesis, endosomal membrane invaginates to generate ILVs in the lumen of the MVBs [10]. In most cells, MVBs fuse with lysosomes where their content is degraded. However, MVBs can also directly fuse with the plasma membrane to release ILVs into the extracellular space. The ESCRT machinery is important in this process. It is composed of approximately ∼30 proteins that are assembled into four complexes (numbered from ESCRT-0 to –3) The ESCRT-0 complex recruits proteins for internalization, whereas ESCRT-1 and –2 complexes determine the budding process and promote formation of ILVs and MVBs in the intracellular compartment [11]. In the final stage, ESCRT-3 complex along with ATPase VPS4, promotes membrane cleavage to free ILVs in the inner lumen space of MVBs [12]. Recently, an ESCRT-independent mechanism has been proposed suggesting that MVB biogenesis can occur without ESCRTs. Tetraspanins are exosomal transmembrane proteins, which are involved in releasing exosomes, independent of the ESCRT machinery. Fusion of MVBs with the plasma membrane releases ILVs as exosomes into the extracellular space. Exosome biogenesis partakes in unique cytosolic components including DNA, mRNA, miRNA and other non-coding RNAs from cell, depending on the physiological state of the parent cell. The ubiquitous production of exosomes by all cell types and their unique content has generated excitement for their potential as therapeutic tool [13].
Novel therapeutic targets for cancer metastasis
Published in Expert Review of Anticancer Therapy, 2020
Konstantin Stoletov, Perrin H. Beatty, John D. Lewis
CTCs use a plethora of molecular and cellular motility mechanisms to overcome or evade host intrinsic obstacles to metastasis [83]. One mechanism is to form CTC tetraspanin-integrin adhesion mediated aggregates with host platelets [5,84]. Podoplanin is the tumor cell surface-expressed factor that induces aggregation in order to protect CTCs from environmental shear stresses and helps the CTCs evade host immune cells [80]. Expression of podoplanin on the surface of CTCs also enhances the release of transforming growth factor-β (TGF-β) from the aggregated platelets, which then activates cancer cell invasive behavior such as epithelial-mesenchymal transition (EMT) [80]. Podoplanin-induced EMT instigates the rapid adhesion and cytoskeletal protein rearrangements needed for extravasation from the vasculature and colonization of metastatic lesions into the surrounding tissue [10,21]. When a TGF-β blocking antibody was administered to mice with metastatic cancer, podoplanin-induced EMT and metastasis were suppressed, suggesting that the podoplanin-triggered release of TGF-β was necessary for successful secondary site lesion formation. Blocking the TGF-β signaling pathway may be one way to effectively block distant site metastasis [80].
The involvement of liquid crystals in multichannel implanted neurostimulators, hearing and ENT infections, and cancer
Published in Acta Oto-Laryngologica, 2019
Chouard Claude-Henri, Christiane Binot, Jean-François Sadoc
We previously stressed the essential role of nanodomains known as lipid rafts in neurodegenerative, infectious, and oncologic processes [17,18]. This concept of lipid rafts has broadened in recent decades. Tetraspanin-enriched microdomains are involved in ENT pathophysiology. Tetraspanins are transmembrane glycoproteins able to associate with one another and with other proteins. Six tetraspanins (Tspan 5, 10, 14, 15, 17, 33) of the Tspan 8 subfamily interact directly with ADAM10 metalloprotease [70]. This is anchored in the plasma membrane and induces proteolytic cleavage of the ectodomain of various surface molecules, and turns out to play an essential role in Notch pathway signaling activation, which is up-regulated by Tspan5 and 4 and down-regulated by Tspan15. Tspan15 is a down-regulator acting upstream of gamma secretase. Single-molecule studies show that membrane zones are reorganized during this regulation process, notably modifying the dynamics of ADAM10 and its interactions with tetraspanins.