User:Smbiophysics/Tunneling nanotube

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FINAL THINGS: Add part about Arp2/3 and WASP/WAVE? Or just about Arp2/3 both inhibiting and promoting TNT

Remove link from "BnL-FGF" gradient. FGF (fibroblast growth factor) is protein whose homolog in drosophila is produced by gene branchless (bnl). Add link to FGF gradient, and bnl is a gene in drosophila that produces a FGF homolog

"Streamers" could use a description to describe what it is as a nanotube structure. This section should be moved to TNT like structures, as it cannot be inferred that TNT's are inhibited by actin depolymerization.

Portland Press article for talking about Arp2/3's inhibition actually promoted more cells connected via TNT's, but less TNT's overall

Portland Press for WASP and WAVE interaction with polymerizing actin

Myopodia in article has incorrect link to pseudopods. There is no link to Myopodia so I will need to remove it.

Under Applications Section:

Tunneling nanotubes have the potential to be involved in the field of nanomedicine, as they have shown the ability to inter-cellularly transfer such treatments.

Image:

Tunelling[sic] nanotube on Wikimedia Commons add to history section -Clarify that viruses can induce TNT formation in cells, they do not form their own (Kade feedback)

-Include video on microtubule presence

-Include part about active diffusion

Edits:

Clear up image description:

A High resolution 3D live-cell fluorescence image of a tunneling nanotube (TNT) (white arrow) connecting two primary mesothelial cells. Scale bar: 20 μm.

B Depiction of a TNT (black arrow) between two cells with scanning electron microscopy. Scale bar: 10 μm.

C Fluorescently labeled F-actin (white arrow) present in TNTs between individual HPMCs. Scale bar: 20 μm.

D Scanning electron microscope image of a potential TNT precursor (black arrowhead). Insert shows a fluorescence microscopic image of filopodia-like protrusions (white arrowhead) approaching a neighboring cell. Scale bar: 2 μm.

A tunneling nanotube (TNT) or membrane nanotube is a term that has been applied to cytoskeletal protrusions that extend from the plasma membrane which enable different animal cells to connect over long distances, sometimes over 100 μm between certain types of cells.

Tunneling nanotubes that are less than 0.7 micrometers in diameter, have an actin structure and carry portions of plasma membrane between cells in both directions. Larger TNTs (>0.7 μm), contain an actin structure with microtubules and/or intermediate filaments, and can carry components of the cytoplasm such as vesicles and organelles between cells, including whole mitochondria. (reference for all three in a TNT)

The diameter of TNTs ranges from 0.05 μm to 1.5 μm and they can reach lengths of several cell diameters. There have been t'''wo types of observed TNTs: open ended and closed ended. Open ended TNTs are effectively hollow and connect the cytoplasm of two cells. Closed ended TNTs do not have continuous cytoplasm as there is a gap junction cap that only allows small molecules and ions to flow between cells.'''

These structures have shown involvement in cell-to-cell communication, transfer of nucleic acids such as mRNA and miRNA between cells in culture or in a tissue, and the spread of pathogens or toxins such as HIV and prions.

and several proteins have been implicated in their formation or inhibition, primarily those that interact with Arp2/3.

More recently, a Science article published in 2004 described structures that connected PC12 cells together, as well as other types of cell cultures. This study coined the term "tunneling nanotubes" and also showed that nanotube formation between cells is correlated with both membrane and organelle transfer. (reference already used in their paper)

The other mechanism occurs when two previously connected cells move away from one another, and TNTs remain as bridges between the two cells.

Phosphatidylserine exposure has demonstrated the ability to guide TNT formation from mesenchymal stem cells (MSCs) to a population of injured cells. Additionally, the protein S100A4 and its receptor have been shown to guide the direction of TNT growth, as p53 activates caspase 3 to cleave S100A4 in the initiating cell, thereby generating a gradient in which the target cell has higher amounts of the protein. These findings suggests that chemotactic gradients may be involved in TNT induction.

TNTs have many components, but their main inhibitors work by blocking or limiting actin formation. TNT-like structures called streamers, which are thinner versions of cytonemes, did not form when cultured with

Inhibiting Arp2/3 directly resulted in different effects depending on cell type. In human eye cells and macrophages, blocking Arp2/3 led to a decrease in TNT formation. However, such inhibition in neuronal cells resulted in an increase in the amount of cells connected via TNTs, while lowering the total amount of TNTs connecting cells.

Change subheading to "Roles in intercellular transfer" (while I won't be adding a lot, this is a general section that can be added to easier)

Add Mitochondrial Transfer as a subsubheading

Add Virus Transfer

Add Nanomedicine transfer

Interestingly, A recent study in Nature Nanotechnology has reported that cancer cells can hijack the mitochondria from immune cells via physical tunneling nanotubes

Tunneling nanotubes have been shown to propagate action potentials via their extensions of endoplasmic reticulum that propagate Ca2+ influx.

Many viruses can transfer their proteins to TNT-connected cells. Certain types, such as influenza, have even been found to transfer their genome via TNTs. Since this discovery, over two dozen types of viruses were found to transfer through and/or modulate TNT.

'''Tunneling nanotubes have the potential to be involved in the field of nanomedicine, as they have shown the ability to transfer such treatments between cells. Future applications look to either inhibit TNTs to prevent nanomedicine toxicity from reaching neighboring cells, or to promote TNT formation to increase positive effects of the medicine.'''

'''While TNT-like structures are all cytoskeletal cellular protrusions, their fundamental difference with TNTs is in the connection between two cells. TNT-like structures do not share intracellular contents such as ions or small molecules–a feature that is present in both open ended and closed ended TNTs. '''

(MOVE) Cytonemes, however, do not always connect the membrane two cells and can act solely as environmental sensor. The formation of cytonemes towards a FGF homolog gradient has been observed, suggesting that chemotactic controls may also induce the formation of TNT-like structures.

Add image about cancer cells using tunneling nanotubes