Debate Resolved on Human Cell Shut-Down Mechanisms

The investigators, from the University of Liverpool (UK), published their findings April 2012 in the journal Proceeding of the National Academy of Sciences of the USA (PNAS), may contribute to future research on how scientists could modify this shut-down process to ensure that viruses and other pathogens do not enter the cells of the body and cause harm.

Earlier studies had shown that when cells divide, they cannot execute any other task apart from this one. They cannot, for example, take in food and fluids at the same time as managing the important process of dividing into “daughter cells” to replicate the body’s genetic data. Instead, cells, shut-down the intake of food and fluid during cell division, and for many years it was thought that they did this by preventing a receptor from moving nutrients through the cell membrane.

Recently, scientists have provided evidence to suggest that this hypothesis may be wrong. Scientists have contended that the cell does not shut down the processes that allow food and fluid to enter the cell as previously believed, but rather the receptors that transport this fuel are absent altogether during cell division, allowing the cell to focus on the one task of dividing.

Studies at Liverpool, however, have now shown that the original concept, first documented in 1965, is accurate. The receptors are present and able to transport food and fluid during cell division, but the mechanism that allows them through the membrane of the cell shuts-down until cell division is complete.

Dr. Stephen Royle, from the University’s Institute of Translational Medicine, explained, “We know that cells in the body do not have the ability to multitask during cell division. It can only focus on the job of dividing and not on other important tasks such as uptake of nutrients. If we think of the cell membrane like a dock at a port and the receptors as a boat delivering cargo, we have shown that the boat, or receptor, is present but the dock, or membrane, does not allow it to unload or go any further. Viruses and pathogens use the same route into cells as nutrients, so the next stage of this work is to identify the trigger for this shutdown process, so that we understand whether this on/off switch can be manipulated to prevent harmful infections passing through the cell membrane. This is a long way in the future, but this work puts us closer to understanding how the cells in the body work.”

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