The Cell Secret Immune System

It was thought until very recently that once a virus had breached a cell’s membrane only luck affected its passage to the nucleus but scientists have just discovered this exciting immune response inside the cell. Any adenovirus that has got this far, still has this new level of defense to contend with: Trim 21. Trim 21 is a small protein that resides in the cytoplasm of most cells in our bodies. It is believed to gather along the internal highway systems of the cell waiting for any cargo tagged by antibodies. Once it detects antibodies it will bind to them and kick-start the proteolysis cycle.

The proteolysis cycle starts when Trim 21 fixes to an antibody and begins to attract ubiquitin proteins. The ubiquitin proteins form a chain, which in turn attracts proteasomes – the cell’s recycling machines - telling them to devour the tagged body. The proteasome shreds the antibody and anything it’s attached to. In this case - the invading adenovirus.

There is also evidence to suggest that the amount of Trim21 is increased in cells that have received ‘warning signs’ of infection. This discovery heralds new potential cures for the common cold. If scientists are able to develop a drug that increases levels of Trim 21 without an infection – then our bodies would find it easier to fight diseases like the common cold.

Release date: 18 Oct 2012

4 minutes

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