Revealing the structure and organization of intercellular tunneling nanotubes (TNTs) by STORM imaging† † Electronic supplementary information (ESI) available. See https://doi.org/10.1039/d2na00415a
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ABSTRACT:
SUBMITTER: Huang L
PROVIDER: S-EPMC9552758 | biostudies-literature | 2022 Sep
REPOSITORIES: biostudies-literature
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Project description:Intercellular communication plays a critical role in the ever-evolving landscape of invasive cancers. Recent studies have elucidated the potential role of tunneling nanotubes (TNTs) in this function. TNTs are long, filamentous, actin-based cell protrusions that mediate direct cell-to-cell communication between malignant cells. In this study, we investigated the formation of TNTs in response to variable concentrations of the chemotherapeutic drug doxorubicin, which is used extensively in the treatment of cancer patients. Doxorubicin stimulated an increased formation of TNTs in pancreatic cancer cells, and this occurred in a dose-dependent fashion. Furthermore, TNTs facilitated the intercellular redistribution of this drug between connected cells in both pancreatic and ovarian cancer systems in vitro. To provide supportive evidence for the relevance of TNTs in pancreatic cancer in vivo, we performed multiphoton fluorescence microscopy and imaged TNTs in tumor specimens resected from three human patients with pancreatic adenocarcinoma, and one with neuroendocrine carcinoma. In sum, TNT formation was upregulated in aggressive forms of pancreatic carcinoma, was further stimulated after chemotherapy exposure, and acted as a novel method for drug efflux. These findings implicate TNTs as a potential novel mechanism of drug resistance in chemorefractory forms of cancer.
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Project description:Tunneling nanotubes (TNTs) are F-actin-based membrane tubes, and can form between cultured cells and within vital tissues. TNTs mediate intercellular communications that range from electrical signaling to the transfer of organelles. Following peripheral nerve injury, the orchestrated intercellular communications among neural and non-neural cells are required for effective nerve regeneration. It remains unknown whether TNTs exist between neural cells in the peripheral nerve system and how TNTs affect neural regeneration. To address these interesting questions, we investigated the transfer of neurotropic factors, membrane protein, cytoplasmic protein, mitochondria and RNA in functional TNTs formed between cultured Schwann cells (SCs). TNT-like structures were increased not only in cultured SCs after exposure to serum depletion but also in longitudinal sections of proximal sciatic nerve stump harvested after rat peripheral nerve transection. Meanwhile, downregulation of Rab8a or Rab11a in cultured SCs inhibited the formation of functional TNTs and vesicle transfer and led to decrease in cell migration, increase in SCs apoptosis. Likewise, knockdown of Rab8a or Rab11a in primary SCs also suppressed axonal outgrowth from co-cultured dorsal root ganglion (DRG) neurons. Overall, our results suggested that the gene of Rab8a or Rab11a might be involved in the formation of TNTs structures in the peripheral nerve system, while TNTs structures were likely to affect peripheral nerve regeneration through the regulation of neural cell communications.
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Project description:Tunneling nanotubes (TNTs) are thin channel-like structures connecting distant cells, providing a route for intercellular communication. In this study, we investigated the physical properties, including the cytoskeletal components, length and diameter, of the TNTs formed by HEK293T, U87 MG, and U251 cell lines. We found that organelles such as lysosomes, mitochondria, and Golgi bodies can be transported through TNTs, indicating that TNTs can mediate material transport. Moreover, we investigated the transport of the Tau protein and β-amyloid (Aβ), which are both closely related to Alzheimer's disease (AD) pathology, through TNTs. The results showed that TNTs formed by various neuronal cell lines can mediate the transport of different forms of the Tau protein and fluorescently labeled Aβ and that this transport is bidirectional, with different velocities in various cell lines. Our results confirmed the transport of the Tau protein and Aβ between cells and provided a possible explanation for the cascade of cell death in specific brain regions during the progression of AD. Our findings suggest new possibilities for the treatment of AD.
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Project description:Tunneling nanotubes (TNTs) are thin F-actin based membranous structures that form continuous cytoplasmic bridges between cells over distances ranging from several hundred nm up to 100 µm. They allow cell-to-cell communication by facilitating the transfer of different cargoes directly from cytoplasma to cytoplasma of the connected cells, including organelles (lysosomes, mitochondria), micro or mRNAs, pathogens, and misfolded proteins (for example prion proteins, tau or α-synuclein aggregates). TNTs could play major roles in various diseases, including neurodegenerative diseases or cancers of different types. TNT formation is highly dynamic and depends on cellular stresses and actin regulators. However, the mechanisms of TNT formation and TNT molecular components and regulators are still poorly understood. Because of their size, of some common components, of the ability to transfer cellular material to remote cells and because TNTs are fragile and easily broken and released in cell culture supernatants (where EVs are also found), TNTs were difficult to distinguish from EVs for their composition and function. With the goal of identifying structural components of TNTs, beside actin filaments, and possibly markers and regulators of these structures, we established a protocol of purification from U2OS cultured cells, allowing to separate TNTs from extracellular vesicles (EVs) and from cell bodies. We obtained the full composition of TNTs, compared to EVs.
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