The bitter end: T2R bitter receptor agonists elevate nuclear calcium and induce apoptosis in non-ciliated airway epithelial cells

Bitter taste receptors (T2Rs) localize to airway motile cilia and initiate innate immune responses in retaliation to bacterial quorum sensing molecules (acyl-homoserine lactones and quinolones). Activation of T2Rs leads to calcium-driven NO production that increases cilia beating and directly kills bacteria. Several airway diseases, including chronic rhinosinusitis, COPD, and cystic fibrosis, are characterized by epithelial remodeling, including loss of motile cilia and/or squamous metaplasia. To understand the function of T2Rs within the altered landscape of airway disease, we studied T2Rs in non-ciliated airway cell lines and primary cells de-differentiated to a squamous phenotype. In differentiated cells, T2Rs localize to cilia, however in de-differentiated, non-ciliated cells they localize to the nucleus. Cilia and nuclear import utilize many shared proteins, thus in the absence of motile cilia some T2Rs may target to the nucleus. T2R agonists selectively elevated both nuclear and mitochondrial calcium through a G-protein-coupled receptor, phospholipase C, and InsP3 receptor-dependent mechanism. Additionally, T2R agonists decreased nuclear cAMP, increased nitric oxide, and increased cGMP, consistent with T2R signaling. Furthermore, exposure to T2R agonists led to nuclear calcium-induced mitochondrial depolarization and caspase activation. T2R agonists induced apoptosis in primary bronchial and nasal cells differentiated at air-liquid interface but then induced to a squamous phenotype by apical submersion. Air-exposed well-differentiated cells did not die. This T2R-induced apoptosis may be a last-resort defense against infection, possibly when bacteria have breached the epithelial barrier and reach non-ciliated cells below. However, it may also increase susceptibility of de-differentiated or remodeled epithelia to damage by bacterial metabolites. Moreover, the T2R-activated apoptosis pathway occurs in airway cancer cells. T2Rs may thus contribute to microbiome-tumor cell crosstalk in airway cancers. T2R agonists may also be useful topical therapeutics (e.g., delivered by nasal rinse or nebulizer) for activating airway cancer cell apoptosis without killing surrounding differentiated tissue.

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Critical role of p63 in the development of a normal esophageal and tracheobronchial epithelium

AJP Cell Physiology ◽

10.1152/ajpcell.00226.2003 ◽

2004 ◽

Vol 287 (1) ◽

pp. C171-C181 ◽

Cited By ~ 183

Author(s):

Yaron Daniely ◽

Grace Liao ◽

Darlene Dixon ◽

R. Ilona Linnoila ◽

Adriana Lori ◽

...

Keyword(s):

Stem Cells ◽

Progenitor Cells ◽

Squamous Metaplasia ◽

Critical Role ◽

Basal Layer ◽

Cell Types ◽

Basal Cells ◽

Ciliated Cells ◽

Differentiated Cells ◽

Unique Cell

The trachea and esophagus originate from the foregut endoderm during early embryonic development. Their epithelia undergo a series of changes involving the differentiation of stem cells into unique cell types and ultimately forming the mature epithelia. In this study, we monitored the expression of p63 in the esophagus and the trachea during development and examined in detail morphogenesis in p63−/− mice. At embryonic day 15.5 (E15.5), the esophageal and tracheobronchial epithelia contain two to three layers of cells; however, only the progenitor cells express p63. These progenitor cells differentiate first into ciliated cells (p63−/β-tubulin IV+) and after birth into mature basal cells (p63+/K14+/K5+/BS-I-B4+). In the adult pseudostratified, columnar tracheal epithelium, K14+/K5+/BS-I-B4+ basal cells stain most intensely for p63, whereas ciliated and mucosecretory cells are negative. In stratified squamous esophageal epithelium and during squamous metaplasia in the trachea, cells in the basal layer stain strongest for p63, whereas p63 staining declines progressively in transient amplifying and squamous differentiated cells. Generally, p63 expression is restricted to human squamous cell carcinomas, and adenocarcinomas and Barrett's metaplasia do not stain for p63. Examination of morphogenesis in newborn p63−/− mice showed an abnormal persistence of ciliated cells in the esophagus. Significantly, in both tissues, lack of p63 expression results in the development of a highly ordered, columnar ciliated epithelium deficient in basal cells. These observations indicate that p63 plays a critical role in the development of normal esophageal and tracheobronchial epithelia and appears to control the commitment of early stem cells into basal cell progeny and the maintenance of basal cells.

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Glutathione peroxidase-1 regulates ASK1-dependent apoptosis via interaction with TRAF2 in RIPK3-negative cancer cells

Experimental & Molecular Medicine ◽

10.1038/s12276-021-00642-7 ◽

2021 ◽

Author(s):

Sunmi Lee ◽

Eun-Kyung Lee ◽

Dong Hoon Kang ◽

Jiyoung Lee ◽

Soo Hyun Hong ◽

...

Keyword(s):

Glutathione Peroxidase ◽

Cancer Cells ◽

Mammalian Cells ◽

Apoptosis Pathway ◽

Glutathione Peroxidase 1 ◽

Peroxidase Enzyme ◽

Thioredoxin 1 ◽

Sequential Activation ◽

Induced Apoptosis

AbstractGlutathione peroxidase (GPx) is a selenocysteine-containing peroxidase enzyme that defends mammalian cells against oxidative stress, but the role of GPx signaling is poorly characterized. Here, we show that GPx type 1 (GPx1) plays a key regulatory role in the apoptosis signaling pathway. The absence of GPx1 augmented TNF-α-induced apoptosis in various RIPK3-negative cancer cells by markedly elevating the level of cytosolic H2O2, which is derived from mitochondria. At the molecular level, the absence of GPx1 led to the strengthened sequential activation of sustained JNK and caspase-8 expression. Two signaling mechanisms are involved in the GPx1-dependent regulation of the apoptosis pathway: (1) GPx1 regulates the level of cytosolic H2O2 that oxidizes the redox protein thioredoxin 1, blocking ASK1 activation, and (2) GPx1 interacts with TRAF2 and interferes with the formation of the active ASK1 complex. Inducible knockdown of GPx1 expression impaired the tumorigenic growth of MDA-MB-231 cells (>70% reduction, P = 0.0034) implanted in mice by promoting apoptosis in vivo. Overall, this study reveals the apoptosis-related signaling function of a GPx family enzyme highly conserved in aerobic organisms.

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TGF-β1 increases permeability of ciliated airway epithelia via redistribution of claudin 3 from tight junction into cell nuclei

Pflügers Archiv - European Journal of Physiology ◽

10.1007/s00424-020-02501-2 ◽

2021 ◽

Author(s):

Carolin Schilpp ◽

Robin Lochbaum ◽

Peter Braubach ◽

Danny Jonigk ◽

Manfred Frick ◽

...

Keyword(s):

Time Course ◽

Atopic Asthma ◽

Ciliated Cells ◽

Cell Nuclei ◽

Tissue Remodelling ◽

Similar Time ◽

Airway Epithelia ◽

Epithelial Integrity ◽

Motile Cilia ◽

Tgf Β1

AbstractTGF-β1 is a major mediator of airway tissue remodelling during atopic asthma and affects tight junctions (TJs) of airway epithelia. However, its impact on TJs of ciliated epithelia is sparsely investigated. Herein we elaborated effects of TGF-β1 on TJs of primary human bronchial epithelial cells. We demonstrate that TGF-β1 activates TGF-β1 receptors TGFBR1 and TGFBR2 resulting in ALK5-mediated phosphorylation of SMAD2. We observed that TGFBR1 and -R2 localize specifically on motile cilia. TGF-β1 activated accumulation of phosphorylated SMAD2 (pSMAD2-C) at centrioles of motile cilia and at cell nuclei. This triggered an increase in paracellular permeability via cellular redistribution of claudin 3 (CLDN3) from TJs into cell nuclei followed by disruption of epithelial integrity and formation of epithelial lesions. Only ciliated cells express TGF-β1 receptors; however, nuclear accumulations of pSMAD2-C and CLDN3 redistribution were observed with similar time course in ciliated and non-ciliated cells. In summary, we demonstrate a role of motile cilia in TGF-β1 sensing and showed that TGF-β1 disturbs TJ permeability of conductive airway epithelia by redistributing CLDN3 from TJs into cell nuclei. We conclude that the observed effects contribute to loss of epithelial integrity during atopic asthma.

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Cell cycle arrest and apoptosis induction by Juniperus communis extract in esophageal squamous cell carcinoma through activation of p53‐induced apoptosis pathway

Food Science & Nutrition ◽

10.1002/fsn3.2084 ◽

2020 ◽

Author(s):

Chia‐Yu Li ◽

Shan‐Chih Lee ◽

Wen‐Lin Lai ◽

Kai‐Fu Chang ◽

Xiao‐Fan Huang ◽

...

Keyword(s):

Cell Cycle ◽

Squamous Cell Carcinoma ◽

Esophageal Squamous Cell Carcinoma ◽

Cell Carcinoma ◽

Cell Cycle Arrest ◽

Apoptosis Induction ◽

Apoptosis Pathway ◽

Juniperus Communis ◽

Cycle Arrest ◽

Induced Apoptosis

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Characterization of Endoplasmic Reticulum (ER) in Human Pluripotent Stem Cells Revealed Increased Susceptibility to Cell Death upon ER Stress

Cells ◽

10.3390/cells9051078 ◽

2020 ◽

Vol 9 (5) ◽

pp. 1078

Author(s):

Tae Won Ha ◽

Ji Hun Jeong ◽

HyeonSeok Shin ◽

Hyun Kyu Kim ◽

Jeong Suk Im ◽

...

Keyword(s):

Stem Cells ◽

Endoplasmic Reticulum ◽

Er Stress ◽

Pluripotent Stem Cells ◽

Meta Analysis ◽

Embryonic Stem ◽

Structural Features ◽

Human Pluripotent Stem Cells ◽

Differentiated Cells ◽

Induced Apoptosis

Human pluripotent stem cells (hPSCs), such as embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), have a well-orchestrated program for differentiation and self-renewal. However, the structural features of unique proteostatic-maintaining mechanisms in hPSCs and their features, distinct from those of differentiated cells, in response to cellular stress remain unclear. We evaluated and compared the morphological features and stress response of hPSCs and fibroblasts. Compared to fibroblasts, electron microscopy showed simpler/fewer structures with fewer networks in the endoplasmic reticulum (ER) of hPSCs, as well as lower expression of ER-related genes according to meta-analysis. As hPSCs contain low levels of binding immunoglobulin protein (BiP), an ER chaperone, thapsigargin treatment sharply increased the gene expression of the unfolded protein response. Thus, hPSCs with decreased chaperone function reacted sensitively to ER stress and entered apoptosis faster than fibroblasts. Such ER stress-induced apoptotic processes were abolished by tauroursodeoxycholic acid, an ER-stress reliever. Hence, our results revealed that as PSCs have an underdeveloped structure and express fewer BiP chaperone proteins than somatic cells, they are more susceptible to ER stress-induced apoptosis in response to stress.

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Depletion of Survivin suppresses docetaxel-induced apoptosis in HeLa cells by facilitating mitotic slippage

Scientific Reports ◽

10.1038/s41598-021-81563-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Teng-Long Han ◽

Hang Sha ◽

Jun Ji ◽

Yun-Tian Li ◽

Deng-Shan Wu ◽

...

Keyword(s):

Hela Cells ◽

Spindle Assembly Checkpoint ◽

Spindle Assembly ◽

Clonogenic Survival ◽

Mitotic Arrest ◽

Apoptosis Pathway ◽

Mitotic Slippage ◽

Intrinsic Apoptosis Pathway ◽

Apoptosis Protein ◽

Induced Apoptosis

AbstractThe anticancer effects of taxanes are attributed to the induction of mitotic arrest through activation of the spindle assembly checkpoint. Cell death following extended mitotic arrest is mediated by the intrinsic apoptosis pathway. Accordingly, factors that influence the robustness of mitotic arrest or disrupt the apoptotic machinery confer drug resistance. Survivin is an inhibitor of apoptosis protein. Its overexpression is associated with chemoresistance, and its targeting leads to drug sensitization. However, Survivin also acts specifically in the spindle assembly checkpoint response to taxanes. Hence, the failure of Survivin-depleted cells to arrest in mitosis may lead to taxane resistance. Here we show that Survivin depletion protects HeLa cells against docetaxel-induced apoptosis by facilitating mitotic slippage. However, Survivin depletion does not promote clonogenic survival of tumor cells but increases the level of cellular senescence induced by docetaxel. Moreover, lentiviral overexpression of Survivin does not provide protection against docetaxel or cisplatin treatment, in contrast to the anti-apoptotic Bcl-xL or Bcl-2. Our findings suggest that targeting Survivin may influence the cell response to docetaxel by driving the cells through aberrant mitotic progression, rather than directly sensitizing cells to apoptosis.

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New Cyclic Diarylheptanoids from Platycarya strobilacea

Molecules ◽

10.3390/molecules25246034 ◽

2020 ◽

Vol 25 (24) ◽

pp. 6034

Author(s):

Wen-bing Ding ◽

Rui-yuan Zhao ◽

Guan-hua Li ◽

Bing-lei Liu ◽

Hua-liang He ◽

...

Keyword(s):

Nitric Oxide ◽

Pc12 Cells ◽

Stem Bark ◽

No Production ◽

Electronic Circular Dichroism ◽

Pheochromocytoma Pc12 ◽

Pheochromocytoma Pc12 Cells ◽

Induced Apoptosis ◽

Circular Dichroïsm

Five new cyclic diarylheptanoids (platycary A–E, compounds 1–5) and three previously identified analogues (i.e., phttyearynol (compound 6), myricatomentogenin (compound 7), and juglanin D (compound 8)) were isolated from the stem bark of Platycarya strobilacea. The structures of these compounds were determined using NMR, HRESIMS, and electronic circular dichroism (ECD) data. The cytotoxicity of compounds 1–5 and their ability to inhibit nitric oxide (NO) production, as well as protect against the corticosterone-induced apoptosis of Pheochromocytoma (PC12) cells, were evaluated in vitro using the appropriate bioassays. Compounds 1 and 2 significantly inhibited the corticosterone-induced apoptosis of PC12 cells at a concentration of 20 μΜ.

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Effects of the cationic protein poly-L-arginine on airway epithelial cellsin vitro

Mediators of Inflammation ◽

10.1080/09622935020138172 ◽

2002 ◽

Vol 11 (3) ◽

pp. 141-148 ◽

Cited By ~ 27

Author(s):

Shahida Shahana ◽

Caroline Kampf ◽

Godfried M. Roomans

Keyword(s):

Electron Microscopy ◽

Epithelial Cells ◽

Cell Membrane ◽

Cell Damage ◽

Membrane Damage ◽

Light And Electron Microscopy ◽

Airway Epithelial Cells ◽

Airway Epithelial ◽

Cationic Protein ◽

Induced Apoptosis

Background: Allergic asthma is associated with an increased number of eosinophils in the airway wall. Eosinophils secrete cationic proteins, particularly major basic protein (MBP).Aim: To investigate the effect of synthetic cationic polypeptides such as poly-L-arginine, which can mimic the effect of MBP, on airway epithelial cells.Methods: Cultured airway epithelial cells were exposed to poly-L-arginine, and effects were determined by light and electron microscopy.Results: Poly-L-arginine induced apoptosis and necrosis. Transmission electron microscopy showed mitochondrial damage and changes in the nucleus. The tight junctions were damaged, as evidenced by penetration of lanthanum. Scanning electron microscopy showed a damaged cell membrane with many pores. Microanalysis showed a significant decrease in the cellular content of magnesium, phosphorus, sodium, potassium and chlorine, and an increase in calcium. Plakoglobin immunoreactivity in the cell membrane was decreased, indicating a decrease in the number of desmosomes.Conclusions: The results point to poly-L-arginine induced membrane damage, resulting in increased permeability, loss of cell-cell contacts and generalized cell damage.

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