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Satellite cells and exercise
Published in Adam P. Sharples, James P. Morton, Henning Wackerhage, Molecular Exercise Physiology, 2022
Neil R.W. Martin, Adam P. Sharples
How do dividing satellite cells decide whether to progress to differentiation or to self-renew? This is an area of active research, but it is known that the decision relies upon asymmetric cell division, which is the process by which two daughter cells adopt differing cellular fates. A group of proteins known as the Par complex are well established regulators of asymmetric cell division (27). In a satellite cell undergoing cell division (mitosis), the Par complex is localised to one side of the cell and activates p38 Mitogen-Activated Protein Kinase (p38 MAPK) signalling (28). MAPK signalling induces cell proliferation (29, 30) and turns on MyoD within the cell, such that one daughter cell becomes a bona fide myoblast, whilst the satellite cell without active p38 MAPK and MyoD returns to quiescence.
Melatonin for Prevention and Treatment of Complications Associated with Chemotherapy and Radiotherapy: Implications for Cancer Stem Cell Differentiation
Published in Paloma Tejero, Hernán Pinto, Aesthetic Treatments for the Oncology Patient, 2020
Germaine Escames, Ana Guerra-Librero, Dario Acuña-Castroviejo, Javier Florido, Laura Martinez-Ruiz, Cesar Rodríguez-Santana, Beatriz I Fernandez-Gil, Iryna Russanova
CSCs, caused by oncogenic processes, initiate the formation of tumors and metastases [2,3]. CSCs: (i) initiate malignant tumors and promote neoplastic proliferation [4]; (ii) recreate the heterogeneous phenotype of the originating tumor through asymmetric cell division [5]; (iii) have a capacity for self-reconstruction via symmetric cell division [5]; (iv) are generally slow or nondividing cells and thus are relatively resistant to radio- and chemotherapy [6]; and (v), unlike the bulk tumor population, express a distinct repertoire of biomarkers, which can be used for CSC definition and isolation [7] (Figure 12.1).
Therapeutic Targeting of the Melanoma Stem Cell Population
Published in Sanjiv S. Agarwala, Vernon K. Sondak, Melanoma, 2008
Keiran S.M. Smalley, Brijal Desai, Meenhard Herlyn
Tumors typically arise in tissues with rapid cell turnover, such as the gastrointestinal tract, the hematopoietic system, and the skin. In these organs, there is a continuous ordered cycle of cell proliferation that replaces the short-lived differentiated cells. This cell proliferation is a highly controlled process whereby a small pool of self-renewing stem cells gives rise to a population of proliferating progenitor cells that undergo limited rounds of cell division before reaching a state of terminal differentiation. In this system, only the stem cells are long-lived, and they have the unique property of being able to undergo self-renewing cell division where at least one of the progeny “daughter cells” remains as a stem cell—a process termed “asymmetric cell division.” The daughter cells then either remain as stem cells or undergo a further process of differentiation to become either a multipotent progenitor or a transient amplifying cell. It is through the generation of many transient amplifying cells that stem cells can generate large cell numbers to repopulate entire tissues (Fig. 2). As transient amplifying cells undergo multiple rounds of cell division, their progeny become progressively more differentiated and start losing their potential for further cell proliferation. This delicate balance between self-renewal and differentiation is critical in retaining the size of stem cell pool. Stem cells exist within a specialized microenvironment termed “the stem cell niche.” The niche plays a critical role in maintaining the undifferentiated state of the stem cell pool through the provision of paracrine and extracellular matrix signals.
Optogenetics in cancer drug discovery
Published in Expert Opinion on Drug Discovery, 2018
Michał Kiełbus, Jakub Czapiński, Adrian Odrzywolski, Grażyna Stasiak, Kamila Szymańska, Joanna Kałafut, Michał Kos, Krzysztof Giannopoulos, Andrzej Stepulak, Adolfo Rivero-Müller
Far too often, patients’ tumors relapse after primary neoplasias have been successfully treated. The new neoplasms usually develop from cancer stem-like cells. Cancer stem cells (CSC) are responsible for, among other things, the ‘production’ of various types of cancer cells within the tumor (asymmetric cell division) especially in early stages of tumor development [108], an evolved resistance to chemo- and radio-therapies [109]. In addition, CSC can be dormant for decades [110]. Finding CSCs targeting drugs is urgently needed, which strongly emphasizes routinely tests on CSCs in the drug discovery pipeline. Stem cell factors (especially Yamanaka’s four: OCT4, SOX2, Klf4, and c-Myc), used to produce induced pluripotent stem cells (iPSCs) [111], have been also used to convert non-tumorigenic cells, e.g. MCF-10A, fibroblasts or glioma cells, into induced stem-like cancer cells (iCSC). These iCSCs fulfilled all the conditions necessary to recognize them as CSCs: expression of stem cell markers [112], generation of tumors composed of different cell lineages after implantation in nude mice, and resistance to chemotherapeutics [113–116].
Pathophysiology of Meibomian Glands – An Overview
Published in Ocular Immunology and Inflammation, 2021
Jana Dietrich, Fabian Garreis, Friedrich Paulsen
The meibum is mainly produced by the meibocytes, which is released into the ductal system by holocrine secretion. Within the ductal system, the meibum is further modified by hydrolyzing enzymes originated from commensal bacteria.13–15 Lipid secretion is associated with the apoptosis of the meibocytes; thus, the entire cell content is secreted during this process and forms the meibum. To replenish the meibocytes that were loss due to the physiological cell turnover, each meibomian gland needs to harbor specialized stem cells. There exists varying results about the location of these stem cells. On the one hand, proliferating cells were identified by leucine-rich repeats and immunoglobulin-like domain protein 1 (Lrig1) expression or by incorporation of radioactive nucleotide [3 H]-thymidine during cell division.16,17 In these studies, proliferating putative stem cells were detected within the basal cell layer in the periphery of each acini in rat and human meibomian glands. On the other hand, label-retaining cells (LRCs), thus putative stem cells, were found to reside at the interface between the ductal epithelium and the acinus in mouse meibomian glands.18–20 Both observations could be interconnected. Slow-cycling stem cells, thus LRCs, could reside at the transition zone between the ductules and the acinus, as seen by Parfitt et al.19 A characteristic of stem cells is their ability to self-renew with the potential for asymmetric cell division.21–23 Asymmetric cell division results in one daughter cell that is identical to the original stem cell and one daughter cell that is more differentiated. The detected proliferating cells in the periphery of the meibomian acinus, as seen by Olami et al. and Xie et al.16,17 could therefore represent the more differentiated daughter cells derived from asymmetric cell division of the stem cells in the transition zone. However, this relation needs to be investigated in further experiments.