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Mysterious tunnels between cells: How do tunneling nanotubes help cells transmit signals to each other?
At the forefront of biotechnology, scientists are exploring how cells establish connections to transmit signals. These unique structures, Tunneling Nanotubes (TNTs), are becoming important players in cell communication. These tiny cellular protrusions can not only build bridges between cells, but also easily transfer a variety of molecules, including nucleic acids and organic matter, and even complete mitochondria.
Tunneling nanotubes range in diameter from 0.05 microns to 1.5 microns and can connect distances of more than 100 microns.
The formation of TNT has attracted widespread attention from scientists. These structures are mainly divided into two types: open end and closed end. The open-ended TNT directly connects the cytoplasm of the two cells, while the closed end has a junction that allows only small molecules and ions to enter. Such connections allow cells to exchange signals and substances efficiently.
Formation mechanism and induction
There are currently several hypotheses about the formation mechanism of TNT. The two most common mechanisms involve the formation of a bridge by protrusions of the cell's cytoplasm, and the retention of a bridge when two cells move while originally connected. These protrusions are controlled by a variety of molecules, and interactions between cells also play a key role.
Some studies have shown that direct contact between cells is an important condition for the formation of TNT bridges.
Experts point out that certain stimuli (such as bacteria or mechanical stimulation) can trigger the flow of calcium in the endoplasmic reticulum, thereby activating the formation of TNTs. This process occurs at speeds of up to 35 micrometers per second, highlighting TNTs' ability to rapidly communicate between cells.
Inhibition and Function
Although TNTs play a key role in cellular interactions, their formation can be affected by a range of inhibitory factors. For example, the commonly used F-actin depolymerizing agent cytochalasin B can effectively inhibit the formation of TNTs but does not destroy existing structures. These inhibitory mechanisms have given scientists a deeper understanding of the complexity of signaling within cells.
The role of cell-cell signaling
TNTs are not only a physical connection, but also function in cell signaling. Existing research has shown that entire mitochondria can be transferred from one cell to another via TNTs, a process that is particularly important in recovery after a heart attack. Damaged cardiomyocytes can acquire healthy mitochondria through TNT to restore function, which has great application potential in regenerative medicine.
TNT has been found to be able to deliver a variety of viruses, including HIV and SARS-CoV-2, revealing its importance in pathological conditions.
Future Outlook
With a deeper understanding of TNT function and its role in cellular communication, scientists hope to apply these findings to the field of nanomedicine. On the one hand, scientists are trying to prevent the toxic spread of medical treatments by inhibiting TNTs, and on the other hand, they are also considering how to enhance the therapeutic effects by promoting the formation of TNTs.
The potential of these tiny structures for human health cannot be underestimated. What discoveries can we expect in future research that will change our understanding and approach to disease treatment?
