scholarly journals Inception Mechanisms of Tunneling Nanotubes

Cells ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 626 ◽  
Author(s):  
Mitja Drab ◽  
David Stopar ◽  
Veronika Kralj-Iglič ◽  
Aleš Iglič

Tunneling nanotubes (TNTs) are thin membranous tubes that interconnect cells, representing a novel route of cell-to-cell communication and spreading of pathogens. TNTs form between many cell types, yet their inception mechanisms remain elusive. We review in this study general concepts related to the formation and stability of membranous tubular structures with a focus on a deviatoric elasticity model of membrane nanodomains. We review experimental evidence that tubular structures initiate from local membrane bending facilitated by laterally distributed proteins or anisotropic membrane nanodomains. We further discuss the numerical results of several theoretical and simulation models of nanodomain segregation suggesting the mechanisms of TNT inception and stability. We discuss the coupling of nanodomain segregation with the action of protruding cytoskeletal forces, which are mostly provided in eukaryotic cells by the polymerization of f-actin, and review recent inception mechanisms of TNTs in relation to motor proteins.

2022 ◽  
Vol 13 (1) ◽  
pp. 1-2
Author(s):  
Karthikeyan Pethusamy ◽  
Ruby Dhar ◽  
Arun Kumar ◽  
Subhradip Karmakar

Cell to Cell communications is the pivot for life processes. Any event that disrupts this leads to the loss of physiological function, eventually leading to cell death. Evolutionarily, cells developed an elaborate mechanism to undertake this paramount responsibility through cell surface glycocalyx, receptors, integrins, and other recognition molecules. Cells also exchange through local acting soluble mediators as well as through vesicles and exosomes. Recent development in this field led to the identification of a spectacular network of membrane process that seems to be the supremo of all that was known about cellular communications. These are called membrane nanotubes or tunneling nanotubes (TNT). Cellular communication can be subdivided into contact and contactless. The former provides more rapid and molecule transfer as compared to the latter. Tunneling nanotubes (TNTs) are a novel type of contact-based communication. TNTs are straight, thin membrane extensions connecting cells over long distances first reported in PC12 cells in 2004. TNT is believed to form from actin-based membrane protrusion. There are three different models of TNT formation. a>Protrusions from one cell grow and extend until it reaches the other cell, followed by a membrane fusion. b> Membrane protrusions grow from both cells until they meet and establish a connection c> TNT formation by cell dislodgement when cells migrate further apart from each other, and during this movement, TNT is formed. It is possible that all these three models may be operational depending on cell types and context. Tunneling nanotubes (TNT) are dynamic connections between cells, representing a novel route for cell-to-cell communication. TNT was reported in various cell types, like epithelial cells, neuronal cells, mesenchyma cells, and immune cells engaged in intercellular exchanges of molecules, subcellular organelles, and pathogen and viruses transport routes. TNT can extend up to 200 µm in length and about 50 nm to 1500 nm in diameter in macrophages. TNT can be established between similar cell types (homo-TNT) or between one cell type and another ( hetro TNT) and thus may be involved in the initiation and growth of cancer as well as dissemination of cancer cells. TNTs are also assumed to play a role in treatment resistance, e.g., in chemotherapy treatment of cancer. Recently, TNT has been used to hijack mitochondria from healthy cells by the cancer cells as a source of energy. TNT was also reported to transport miRNA and other RNA to the surrounding stroma creating an environment suitable for cancer growth. More research in this discipline is needed to understand the full function of these wonderful nanostructures.


Biology Open ◽  
2021 ◽  
Vol 10 (9) ◽  
Author(s):  
Tania Martins-Marques

ABSTRACT Well-orchestrated intercellular communication networks are pivotal to maintaining cardiac homeostasis and to ensuring adaptative responses and repair after injury. Intracardiac communication is sustained by cell–cell crosstalk, directly via gap junctions (GJ) and tunneling nanotubes (TNT), indirectly through the exchange of soluble factors and extracellular vesicles (EV), and by cell–extracellular matrix (ECM) interactions. GJ-mediated communication between cardiomyocytes and with other cardiac cell types enables electrical impulse propagation, required to sustain synchronized heart beating. In addition, TNT-mediated organelle transfer has been associated with cardioprotection, whilst communication via EV plays diverse pathophysiological roles, being implicated in angiogenesis, inflammation and fibrosis. Connecting various cell populations, the ECM plays important functions not only in maintaining the heart structure, but also acting as a signal transducer for intercellular crosstalk. Although with distinct etiologies and clinical manifestations, intercellular communication derailment has been implicated in several cardiac disorders, including myocardial infarction and hypertrophy, highlighting the importance of a comprehensive and integrated view of complex cell communication networks. In this review, I intend to provide a critical perspective about the main mechanisms contributing to regulate cellular crosstalk in the heart, which may be considered in the development of future therapeutic strategies, using cell-based therapies as a paradigmatic example. This Review has an associated Future Leader to Watch interview with the author.


2019 ◽  
Vol 20 (6) ◽  
pp. 1487 ◽  
Author(s):  
Heon-Jin Lee

Extracellular vesicles (EVs) are evolutionary well-conserved nano-sized membranous vesicles that are secreted by both prokaryotic and eukaryotic cells. Recently, they have gained great attention for their proposed roles in cell-to-cell communication, and as biomarkers for human disease. In particular, small RNAs (sRNAs) contained within EVs have been considered as candidate interspecies-communication molecules, due to their demonstrated capacity to modulate gene expression in multiple cell types and species. While research into this field is in its infancy, elucidating the mechanisms that underlie host–microbe interactions and communications promises to impact many fields of biological research, including human health and medicine. Thus, this review discussed the results of recent studies that have examined the ways in which EVs and sRNAs mediate ‘microbe–host’ and ‘host–microbe’ interspecies communication.


2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Nicole Matejka ◽  
Judith Reindl

AbstractDirect cell-to-cell communication is crucial for the survival of cells in stressful situations such as during or after radiation exposure. This communication can lead to non-targeted effects, where non-treated or non-infected cells show effects induced by signal transduction from non-healthy cells or vice versa. In the last 15 years, tunneling nanotubes (TNTs) were identified as membrane connections between cells which facilitate the transfer of several cargoes and signals. TNTs were identified in various cell types and serve as promoter of treatment resistance e.g. in chemotherapy treatment of cancer. Here, we discuss our current understanding of how to differentiate tunneling nanotubes from other direct cellular connections and their role in the stress reaction of cellular networks. We also provide a perspective on how the capability of cells to form such networks is related to the ability to surpass stress and how this can be used to study radioresistance of cancer cells.


2021 ◽  
Vol 22 (7) ◽  
pp. 3649
Author(s):  
Patricia Ramos-Ramírez ◽  
Omar Tliba

Glucocorticoids (GCs) act via the GC receptor (GR), a receptor ubiquitously expressed in the body where it drives a broad spectrum of responses within distinct cell types and tissues, which vary in strength and specificity. The variability of GR-mediated cell responses is further extended by the existence of GR isoforms, such as GRα and GRβ, generated through alternative splicing mechanisms. While GRα is the classic receptor responsible for GC actions, GRβ has been implicated in the impairment of GRα-mediated activities. Interestingly, in contrast to the popular belief that GRβ actions are restricted to its dominant-negative effects on GRα-mediated responses, GRβ has been shown to have intrinsic activities and “directly” regulates a plethora of genes related to inflammatory process, cell communication, migration, and malignancy, each in a GRα-independent manner. Furthermore, GRβ has been associated with increased cell migration, growth, and reduced sensitivity to GC-induced apoptosis. We will summarize the current knowledge of GRβ-mediated responses, with a focus on the GRα-independent/intrinsic effects of GRβ and the associated non-canonical signaling pathways. Where appropriate, potential links to airway inflammatory diseases will be highlighted.


2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Lei He ◽  
Quan Zhang ◽  
Yue Zhang ◽  
Yixian Fan ◽  
Fahu Yuan ◽  
...  

Abstract Background The coronavirus disease 2019 (COVID-19) outbreak caused by severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) has become an ongoing pandemic. Understanding the respiratory immune microenvironment which is composed of multiple cell types, together with cell communication based on ligand–receptor interactions is important for developing vaccines, probing COVID-19 pathogenesis, and improving pandemic control measures. Methods A total of 102 consecutive hospitalized patients with confirmed COVID-19 were enrolled in this study. Clinical information, routine laboratory tests, and flow cytometry analysis data with different conditions were collected and assessed for predictive value in COVID-19 patients. Next, we analyzed public single-cell RNA-sequencing (scRNA-seq) data from bronchoalveolar lavage fluid, which offers the closest available view of immune cell heterogeneity as encountered in patients with varying severity of COVID-19. A weighting algorithm was used to calculate ligand–receptor interactions, revealing the communication potentially associated with outcomes across cell types. Finally, serum cytokines including IL6, IL1β, IL10, CXCL10, TNFα, GALECTIN-1, and IGF1 derived from patients were measured. Results Of the 102 COVID-19 patients, 42 cases (41.2%) were categorized as severe. Multivariate logistic regression analysis demonstrated that AST, D-dimer, BUN, and WBC were considered as independent risk factors for the severity of COVID-19. T cell numbers including total T cells, CD4+ and CD8+ T cells in the severe disease group were significantly lower than those in the moderate disease group. The risk model containing the above mentioned inflammatory damage parameters, and the counts of T cells, with AUROCs ranged from 0.78 to 0.87. To investigate the molecular mechanism at the cellular level, we analyzed the published scRNA-seq data and found that macrophages displayed specific functional diversity after SARS-Cov-2 infection, and the metabolic pathway activities in the identified macrophage subtypes were influenced by hypoxia status. Importantly, we described ligand–receptor interactions that are related to COVID-19 serverity involving macrophages and T cell subsets by communication analysis. Conclusions Our study showed that macrophages driving ligand–receptor crosstalk contributed to the reduction and exhaustion of CD8+ T cells. The identified crucial cytokine panel, including IL6, IL1β, IL10, CXCL10, IGF1, and GALECTIN-1, may offer the selective targets to improve the efficacy of COVID-19 therapy. Trial registration: This is a retrospective observational study without a trial registration number.


2020 ◽  
Vol 21 (15) ◽  
pp. 5432 ◽  
Author(s):  
Stefano Burgio ◽  
Leila Noori ◽  
Antonella Marino Gammazza ◽  
Claudia Campanella ◽  
Mariantonia Logozzi ◽  
...  

Research for the most selective drug delivery to tumors represents a fascinating key target in science. Alongside the artificial delivery systems identified in the last decades (e.g., liposomes), a family of natural extracellular vesicles (EVs) has gained increasing focus for their potential use in delivering anticancer compounds. EVs are released by all cell types to mediate cell-to-cell communication both at the paracrine and the systemic levels, suggesting a role for them as an ideal nano-delivery system. Malignant pleural mesothelioma (MPM) stands out among currently untreatable tumors, also due to the difficulties in achieving an early diagnosis. Thus, early diagnosis and treatment of MPM are both unmet clinical needs. This review looks at indirect and direct evidence that EVs may represent both a new tool for allowing an early diagnosis of MPM and a potential new delivery system for more efficient therapeutic strategies. Since MPM is a relatively rare malignant tumor and preclinical MPM models developed to date are very few and not reliable, this review will report data obtained in other tumor types, suggesting the potential use of EVs in mesothelioma patients as well.


2020 ◽  
Vol 21 (24) ◽  
pp. 9585
Author(s):  
Melania Dovizio ◽  
Patrizia Ballerini ◽  
Rosa Fullone ◽  
Stefania Tacconelli ◽  
Annalisa Contursi ◽  
...  

Platelets contribute to several types of cancer through plenty of mechanisms. Upon activation, platelets release many molecules, including growth and angiogenic factors, lipids, and extracellular vesicles, and activate numerous cell types, including vascular and immune cells, fibroblasts, and cancer cells. Hence, platelets are a crucial component of cell–cell communication. In particular, their interaction with cancer cells can enhance their malignancy and facilitate the invasion and colonization of distant organs. These findings suggest the use of antiplatelet agents to restrain cancer development and progression. Another peculiarity of platelets is their capability to uptake proteins and transcripts from the circulation. Thus, cancer-patient platelets show specific proteomic and transcriptomic expression patterns, a phenomenon called tumor-educated platelets (TEP). The transcriptomic/proteomic profile of platelets can provide information for the early detection of cancer and disease monitoring. Platelet ability to interact with tumor cells and transfer their molecular cargo has been exploited to design platelet-mediated drug delivery systems to enhance the efficacy and reduce toxicity often associated with traditional chemotherapy. Platelets are extraordinary cells with many functions whose exploitation will improve cancer diagnosis and treatment.


2005 ◽  
Vol 49 (5) ◽  
pp. 1695-1700 ◽  
Author(s):  
Françoise Van Bambeke ◽  
Jennifer Saffran ◽  
Marie-Paule Mingeot-Leclercq ◽  
Paul M. Tulkens

ABSTRACT Oritavancin, a semisynthetic derivative of vancomycin endowed with a cationic amphiphilic character, accumulates to large extent in the lysosomes of eukaryotic cells (F. Van Bambeke, S. Carryn, C. Seral, H. Chanteux, D. Tyteca, M. P. Mingeot-Leclercq, and P. M. Tulkens, Antimicrob. Agents Chemother. 48:2853-2860, 2004). In the present study, we examined whether this accumulation could cause cell alterations in phagocytic (J774 mouse macrophages) and nonphagocytic (rat embryo fibroblasts) cells exposed to clinically meaningful (0- to 40-mg/liter) concentrations of oritavancin. Optical and electronic microscopy evidenced conspicuous alterations of the vacuolar apparatus in both cell types, characterized by the deposition of concentric lamellar structures, finely granular material, or other less-defined osmiophilic material, often deposed in giant vesicles. Biochemical studies showed an accumulation of phospholipids (1.5× control values) and free and esterified cholesterol (3 to 4× control values for total cholesterol). Accumulation of these lipids was in close relation to that of oritavancin (excess phospholipid/oritavancin and excess cholesterol/oritavancin molar ratios of 2 to 3 and 3 to 5, respectively). Cholesterol accumulation was rapid and reversible, and that of phospholipids was slower and poorly reversible. Vancomycin and teicoplanin, used as controls (50 and 100 mg/liter, respectively), did not cause any significant change in the lipid content of fibroblasts. The data therefore suggest that oritavancin has the potential to cause a mixed-lipid storage disorder in eukaryotic cells.


1984 ◽  
Vol 66 (1) ◽  
pp. 81-93
Author(s):  
F.V. Sepulveda ◽  
J.D. Pearson

We have studied the cell-to-cell passage of uridine nucleotides in two renal epithelial cell lines (LLC-PK1 and MDCK) and in porcine aortic endothelial cells (PAE). All three cell types incorporated tritiated uridine. After a 3 h incubation the radioactivity was predominantly in the form of acid-soluble compounds, mainly UTP. Prelabelled LLC-PK1 or MDCK cells were unable to transfer radioactivity to added adjacent, non-labelled cells, whereas PAE cells readily formed communicating intercellular junctions, as judged by autoradiographic analysis after a 3 h co-culture period. Cell-to-cell communication in either of the renal cell lines was not promoted by treatment with dibutyryl cyclic AMP and methylisobutylxanthine. Radioactivity incorporated into the acid-insoluble pool was not available for intercellular transfer, as assessed in experiments in which cells were prelabelled 24 h before co-culture.


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