What are the roles of exosomes in gene expression?

Exosomes play a crucial role in gene expression by transporting RNA and proteins that can alter cellular functions.

Exosomes are tiny vesicles, about 30-150 nanometres in diameter, that are released by cells into the extracellular environment. They are formed inside the cell in an area called the endosome. When the endosome matures, it forms multivesicular bodies (MVBs) that contain many small vesicles. These MVBs can either be broken down by lysosomes or they can fuse with the cell membrane and release the vesicles, now called exosomes, into the extracellular space.

Exosomes are not just cellular waste products; they carry a cargo of molecules from their cell of origin. This cargo can include proteins, lipids, and various types of RNA, including messenger RNA (mRNA), microRNA (miRNA), and long non-coding RNA (lncRNA). These molecules can be taken up by other cells and can influence their function. For example, the mRNA can be translated into protein, and the miRNA and lncRNA can regulate gene expression.

The role of exosomes in gene expression is particularly interesting. They can transport miRNA and lncRNA from one cell to another. These types of RNA do not code for proteins, but they can regulate gene expression in the recipient cell. For example, miRNA can bind to mRNA and prevent it from being translated into protein, effectively silencing the gene. LncRNA can also regulate gene expression, although the mechanisms are less well understood.

Exosomes can therefore alter the gene expression profile of the recipient cell, influencing its behaviour. This has been shown in various contexts, such as cancer, where tumour cells can release exosomes that influence the behaviour of other cells in their environment. For example, they can promote angiogenesis (the formation of new blood vessels), which helps to supply the tumour with nutrients, or they can suppress the immune response, helping the tumour to evade detection.

In summary, exosomes play a crucial role in gene expression by transporting RNA and proteins that can alter cellular functions. They are an important part of the communication between cells, and their role in health and disease is a topic of ongoing research.