Saturday, March 31, 2007

DNA Repair & the Timeless/Tipin Complex

Science Daily features an article entitled 'Scientists Discover Cellular 'SOS' Signal In Response To UV Skin Damage' which describes a regulatory mechanism which can slow the rate of DNA replication in order to allow for more time to repair DNA damaged by ultraviolet radiation. Regulation is attributed to two proteins known as Timeless and Tipin. The following quote is from the linked article:

"New research from the University of North Carolina at Chapel Hill School of Medicine has identified two proteins that may help protect against skin cancer.

The study, which appears in the advance online edition of the journal Molecular and Cellular Biology, indicates that two proteins, named Timeless and Tipin, form a complex that regulates the rate at which DNA is replicated after exposure to ultraviolet radiation.

Ultraviolet radiation in sunlight damages the DNA in skin cells. If left unrepaired by the cell, this damage can turn into mutations that lead to cancer. Before cells divide, they must replicate, or copy, their DNA to form new daughter cells.

If damage in the DNA is discovered even after the cell has given a "go-ahead" to replicate its DNA, the Timeless/Tipin complex sends a signal throughout the nucleus of the cell to slow the rate of replication. This slowdown may give the cell additional time to repair its DNA and potentially save itself from becoming cancerous or from dying in response to ultraviolet radiation."


DNA repair mechanisms are not limited to "toolkit" responses. In this case a regulatory function, involving the timing of replication, helps maintain genomic integrity.

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