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1.
Identification of the Large-Conductance Ca2+-Regulated Potassium Channel in Mitochondria of Human Bronchial Epithelial Cells.
Sek, A, Kampa, RP, Kulawiak, B, Szewczyk, A, Bednarczyk, P
Molecules (Basel, Switzerland). 2021;(11)
Abstract
Mitochondria play a key role in energy metabolism within the cell. Potassium channels such as ATP-sensitive, voltage-gated or large-conductance Ca2+-regulated channels have been described in the inner mitochondrial membrane. Several hypotheses have been proposed to describe the important roles of mitochondrial potassium channels in cell survival and death pathways. In the current study, we identified two populations of mitochondrial large-conductance Ca2+-regulated potassium (mitoBKCa) channels in human bronchial epithelial (HBE) cells. The biophysical properties of the channels were characterized using the patch-clamp technique. We observed the activity of the channel with a mean conductance close to 285 pS in symmetric 150/150 mM KCl solution. Channel activity was increased upon application of the potassium channel opener NS11021 in the micromolar concentration range. The channel activity was completely inhibited by 1 µM paxilline and 300 nM iberiotoxin, selective inhibitors of the BKCa channels. Based on calcium and iberiotoxin modulation, we suggest that the C-terminus of the protein is localized to the mitochondrial matrix. Additionally, using RT-PCR, we confirmed the presence of α pore-forming (Slo1) and auxiliary β3-β4 subunits of BKCa channel in HBE cells. Western blot analysis of cellular fractions confirmed the mitochondrial localization of α pore-forming and predominately β3 subunits. Additionally, the regulation of oxygen consumption and membrane potential of human bronchial epithelial mitochondria in the presence of the potassium channel opener NS11021 and inhibitor paxilline were also studied. In summary, for the first time, the electrophysiological and functional properties of the mitoBKCa channel in a bronchial epithelial cell line were described.
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2.
Chemodynamic features of nanoparticles: Application to understanding the dynamic life cycle of SARS-CoV-2 in aerosols and aqueous biointerfacial zones.
Duval, JFL, van Leeuwen, HP, Norde, W, Town, RM
Advances in colloid and interface science. 2021;:102400
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Abstract
We review concepts involved in describing the chemodynamic features of nanoparticles and apply the framework to gain physicochemical insights into interactions between SARS-CoV-2 virions and airborne particulate matter (PM). Our analysis is highly pertinent given that the World Health Organisation acknowledges that SARS-CoV-2 may be transmitted by respiratory droplets, and the US Center for Disease Control and Prevention recognises that airborne transmission of SARS-CoV-2 can occur. In our theoretical treatment, the virion is assimilated to a core-shell nanoparticle, and contributions of various interaction energies to the virion-PM association (electrostatic, hydrophobic, London-van der Waals, etc.) are generically included. We review the limited available literature on the physicochemical features of the SARS-CoV-2 virion and identify knowledge gaps. Despite the lack of quantitative data, our conceptual framework qualitatively predicts that virion-PM entities are largely able to maintain equilibrium on the timescale of their diffusion towards the host cell surface. Comparison of the relevant mass transport coefficients reveals that virion biointernalization demand by alveolar host cells may be greater than the diffusive supply. Under such conditions both the free and PM-sorbed virions may contribute to the transmitted dose. This result points to the potential for PM to serve as a shuttle for delivery of virions to host cell targets. Thus, our critical review reveals that the chemodynamics of virion-PM interactions may play a crucial role in the transmission of COVID-19, and provides a sound basis for explaining reported correlations between episodes of air pollution and outbreaks of COVID-19.
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Observational cohort study of the effect of a single lubricant exposure during transvaginal ultrasound on cell-shedding from the vaginal epithelium.
O'Hanlon, DE, Brown, SE, He, X, Stennett, CA, Robbins, SJ, Johnston, ED, Wnorowski, AM, Mark, K, Ravel, J, Cone, RA, et al
PloS one. 2021;(5):e0250153
Abstract
The outer layers of the vaginal epithelium (VE) are important because they accumulate glycogen which, under optimal conditions, Lactobacillus spp. consume to grow and acidify the vaginal microenvironment with lactic acid. We hypothesized that exposure to lubricant, for example in the conduct of a transvaginal ultrasound (TVUS), may contribute to the shedding of mature epithelial cells, exposing immature cells. Cervicovaginal fluid (CVF) was sampled at four time points by menstrual cup (Softdisc™) from 50 women referred for TVUS, during which a controlled volume of lubricant was applied to the TVUS wand. Samples were collected (1) immediately before TVUS and (2) 6-12 hours, (3) within one week, and (4) two weeks after TVUS. Clinical vaginal lubricants are similar to commercial lubricants, and often have a high osmolality or pH, and contain bactericides such as methylparaben and propylparaben. The number and maturity of epithelial cells in each CVF sample were measured by quantitative and differential fluorimetry (maturity index, MI). Comparisons of cell-counts and maturity were made by paired Wilcoxon signed-rank tests. Among women with a high pre-TVUS MI (> 3), there was a decrease in median cell-count and mean MI in the sample collected 6-12 hours after TVUS (p<0.001, n = 26 and p < 0.001, n = 26, respectively). For these women, cell-count and MI remained lower in the sample collected within the subsequent week (p<0.001, n = 29 and p<0.01, n = 29, respectively), and MI remained lower in the sample collected within two weeks of TVUS (p<0.01, n = 25), compared to the pre-TVUS sample. Among participants with a low pre-TVUS MI (< 3), cell-count was higher in the sample collected within two weeks of TVUS compared to the pre-TVUS sample (p = 0.03, n = 15), but no significant changes in MI were observed. Results were similar when restricted to reproductive-age women. This preliminary data indicates hypertonic vaginal lubricants may increase vaginal epithelial cell shedding.
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Chronobiological activity of cysteinyl leukotriene receptor 1 during basal and induced autophagy in the ARPE-19 retinal pigment epithelial cell line.
Koller, A, Preishuber-Pflügl, J, Runge, C, Ladek, AM, Brunner, SM, Aigner, L, Reitsamer, H, Trost, A
Aging. 2021;(24):25670-25693
Abstract
Autophagy is an important cellular mechanism for maintaining cellular homeostasis, and its impairment correlates highly with age and age-related diseases. Retinal pigment epithelial (RPE) cells of the eye represent a crucial model for studying autophagy, as RPE functions and integrity are highly dependent on an efficient autophagic process. Cysteinyl leukotriene receptor 1 (CysLTR1) acts in immunoregulation and cellular stress responses and is a potential regulator of basal and adaptive autophagy. As basal autophagy is a dynamic process, the aim of this study was to define the role of CysLTR1 in autophagy regulation in a chronobiologic context using the ARPE-19 human RPE cell line. Effects of CysLTR1 inhibition on basal autophagic activity were analyzed at inactive/low and high lysosomal degradation activity with the antagonists zafirlukast (ZTK) and montelukast (MTK) at a dosage of 100 nM for 3 hours. Abundances of the autophagy markers LC3-II and SQSTM1 and LC3B particles were analyzed in the absence and presence of lysosomal inhibitors using western blot analysis and immunofluorescence microscopy. CysLTR1 antagonization revealed a biphasic effect of CysLTR1 on autophagosome formation and lysosomal degradation that depended on the autophagic activity of cells at treatment initiation. ZTK and MTK affected lysosomal degradation, but only ZTK regulated autophagosome formation. In addition, dexamethasone treatment and serum shock induced autophagy, which was repressed by CysLTR1 antagonization. As a newly identified autophagy modulator, CysLTR1 appears to be a key player in the chronobiological regulation of basal autophagy and adaptive autophagy in RPE cells.
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Resolving Human Lactation Heterogeneity Using Single Milk-Derived Cells, a Resource at the Ready.
Martin Carli, JF, Trahan, GD, Rudolph, MC
Journal of mammary gland biology and neoplasia. 2021;(1):3-8
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Abstract
Single cell RNA sequencing (scRNAseq) of human milk-derived cells (HMDCs) makes highly detailed analyses of the biology of human lactation possible. We explore this powerful application as an exciting tool to inspect the cellular composition of human milk. We point out some important challenges unique to this approach and highlight the importance of collaborations between biologists and well-trained bioinformaticians to utilize these data to their maximum potential. We extend this focus by discussing the first two such studies that describe HMDCs via scRNAseq and a variety of important questions in the field that warrant attention through further research. The stage is set to apply scRNAseq in human lactation biology, potentially leading to new insights regarding the molecular and cellular diversity of human secretory mammary epithelial cells.
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Intracellular Cl- Regulation of Ciliary Beating in Ciliated Human Nasal Epithelial Cells: Frequency and Distance of Ciliary Beating Observed by High-Speed Video Microscopy.
Yasuda, M, Inui, TA, Hirano, S, Asano, S, Okazaki, T, Inui, T, Marunaka, Y, Nakahari, T
International journal of molecular sciences. 2020;(11)
Abstract
Small inhaled particles, which are entrapped by the mucous layer that is maintained by mucous secretion via mucin exocytosis and fluid secretion, are removed from the nasal cavity by beating cilia. The functional activities of beating cilia are assessed by their frequency and the amplitude. Nasal ciliary beating is controlled by intracellular ions (Ca2+, H+ and Cl-), and is enhanced by a decreased concentration of intracellular Cl- ([Cl-]i) in ciliated human nasal epithelial cells (cHNECs) in primary culture, which increases the ciliary beat amplitude. A novel method to measure both ciliary beat frequency (CBF) and ciliary beat distance (CBD, an index of ciliary beat amplitude) in cHNECs has been developed using high-speed video microscopy, which revealed that a decrease in [Cl-]i increased CBD, but not CBF, and an increase in [Cl-]i decreased both CBD and CBF. Thus, [Cl-]i inhibits ciliary beating in cHNECs, suggesting that axonemal structures controlling CBD and CBF may have Cl- sensors and be regulated by [Cl-]i. These observations indicate that the activation of Cl- secretion stimulates ciliary beating (increased CBD) mediated via a decrease in [Cl-]i in cHNECs. Thus, [Cl-]i is critical for controlling ciliary beating in cHNECs. This review introduces the concept of Cl- regulation of ciliary beating in cHNECs.
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Effects of Short-Chain Fatty Acids on Human Oral Epithelial Cells and the Potential Impact on Periodontal Disease: A Systematic Review of In Vitro Studies.
Magrin, GL, Strauss, FJ, Benfatti, CAM, Maia, LC, Gruber, R
International journal of molecular sciences. 2020;(14)
Abstract
Short-chain fatty acids (SCFA), bacterial metabolites released from dental biofilm, are supposed to target the oral epithelium. There is, however, no consensus on how SCFA affect the oral epithelial cells. The objective of the present study was to systematically review the available in vitro evidence of the impact of SCFA on human oral epithelial cells in the context of periodontal disease. A comprehensive electronic search using five databases along with a grey literature search was performed. In vitro studies that evaluated the effects of SCFA on human oral epithelial cells were eligible for inclusion. Risk of bias was assessed by the University of Bristol's tool for assessing risk of bias in cell culture studies. Certainty in cumulative evidence was evaluated using GRADE criteria (grading of recommendations assessment, development, and evaluation). Of 3591 records identified, 10 were eligible for inclusion. A meta-analysis was not possible due to the heterogeneity between the studies. The risk of bias across the studies was considered "serious" due to the presence of methodological biases. Despite these limitations, this review showed that SCFA negatively affect the viability of oral epithelial cells by activating a series of cellular events that includes apoptosis, autophagy, and pyroptosis. SCFA impair the integrity and presumably the transmigration of leucocytes through the epithelial layer by changing junctional and adhesion protein expression, respectively. SCFA also affect the expression of chemokines and cytokines in oral epithelial cells. Future research needs to identify the underlying signaling cascades and to translate the in vitro findings into preclinical models.
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Regulation of mucin 1 expression and its relationship with oral diseases.
Kashyap, B, Kullaa, AM
Archives of oral biology. 2020;:104791
Abstract
OBJECTIVE The aim of this study is to describe the polymorphic mucin 1 (MUC1), and to provide an overview of the known complex and multiple functions of MUC1 in normal oral mucosa and oral mucosal lesions in compromised situations as well as exploring the challenges associated with the heterogeneous nature of MUC1. We will review the current knowledge and provide insights into the future management possibilities of using MUC1 as a therapeutic agent. METHODS A literature search of the electronic databases included MEDLINE (1966 -December 2019) and hand searches of cross-references were undertaken using terms related to mucins, MUC1. RESULTS MUC1 is a large transmembrane glycoprotein expressed on the apical surface of most of epithelial cell surfaces. Not only is it involved in lubrication, cell surface hydration, and protection against degrading enzymes, MUC1 also promotes abnormal cellular signalling, angiogenesis, anti-adhesion and tumorigenesis. Aberrant glycosylation, overexpression, loss of apical constraint are characteristics of the transformation of a normal cell to a cancerous cell. This review summarizes studies of MUC1 expression and function with a special emphasis on oral epithelial cells in normal and abnormal conditions. In addition, current knowledge of MUC1 and unexplored areas of MUC1 are presented. CONCLUSION MUC1 is an archetypical transmembrane protein, the presence of MUC1 in ectopic regions may lead to dysregulation of certain enzymes and activation of various pathways, favouring the development of inflammatory responses and tumour formation. This review examines the potential of MUC1 in the development of future therapeutics.
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Antiepithelial-Mesenchymal Transition of Herbal Active Substance in Tumor Cells via Different Signaling.
Cui, X, Lin, Q, Huang, P, Liang, Y
Oxidative medicine and cellular longevity. 2020;:9253745
Abstract
Epithelial-mesenchymal transition (EMT) is a biological process through which epithelial cells differentiate into mesenchymal cells. EMT plays an important role in embryonic development and wound healing; however, EMT also contributes to some pathological processes, such as tumor metastasis and fibrosis. EMT mechanisms, including gene mutation and transcription factor regulation, are complicated and not yet well understood. In this review, we introduce some herbal active substances that exert antitumor activity through inhibiting EMT that is induced by hypoxia, high blood glucose level, lipopolysaccharide, or other factors.
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Mucosal-Associated Invariant T Cells in Tumors of Epithelial Origin.
Zumwalde, NA, Gumperz, JE
Advances in experimental medicine and biology. 2020;:63-77
Abstract
Mucosal-associated invariant T (MAIT) cells are innate T lymphocytes that circulate in blood and also reside in mucosal tissues. Blood MAIT cells are typically highly Th1-polarized, while those in mucosal tissues include both Th1- and Th17-polarized subsets. MAIT cells mount cytokine and cytolytic responses as a result of T cell receptor (TCR)-mediated recognition of microbially derived metabolites of riboflavin (vitamin B2) presented by the MR1 antigen-presenting molecule. Additionally, MAIT cells can be activated by inflammatory cytokines produced by antigen-presenting cells (APCs) that have been exposed to pathogen-associated molecular patterns (PAMPs). Since the antigenic metabolites of riboflavin recognized by MAIT cells are produced by many microorganisms, including pathogens as well as non-pathogenic colonists, the inflammatory state of the tissue may be a key feature that determines the nature of MAIT cell responses. Under normal conditions where inflammatory cytokines are not produced, MAIT cell responses to microbial metabolites may simply serve to help maintain a healthy balance between epithelial cells and microbial colonists. In contrast, in situations where inflammatory cytokines are produced (e.g., pathogenic infection or damage to epithelial tissue), MAIT cell responses may be more potently pro-inflammatory. Since chronic inflammation and microbial drivers are associated with tumorigenesis and also trigger MAIT cell responses, the nexus of MAIT cells, local microbiomes, and epithelial cells may play an important role in epithelial carcinogenesis. This chapter reviews current information about MAIT cells and epithelial tumors, where the balance of evidence suggests that enrichment of Th17-polarized MAIT cells at tumor sites associates with poor patient prognosis. Studying the role of MAIT cells and their interactions with resident microbes offers a novel view of the biology of epithelial tumor progression and may ultimately lead to new approaches to target MAIT cells clinically.