UC San Diego Biologists Discover a Protein Link to Wound Healing

MARCH 24, 2009
By: Kim McDonald


Two infant mice side by side, one is normal and the other has skin five times thicker than normal



"Not only does the loss of this protein, caspase 8, stimulate inflammation, which brings in a rush of cells designed to stop microbes from infecting the wound," said Colin Jamora, an assistant professor of biology at UCSD who headed the research team. "But it also stimulates the production of stem cells that provide the materials to help close the wound. That's important, because in the initial stages of a wound the protective barrier provided by the skin is broken and the internal body is exposed to microbes and environmental toxins."

The discovery occurred by accident when Jamora, who studies the stem cell progenitors of skin cells and hair follicles, was asked by a colleague-Steve Hedrick, a professor of biology at UCSD-whether he wanted to examine a mutant mouse with unusually thick skin that had been genetically engineered in his laboratory. Hedrick's team had knocked out the gene in the epidermis necessary for the production of caspase 8.

The skin is the largest organ in the mammalian body. The average adult human, according to Jamora, has six pounds of skin that spans approximately 21 square feet. What's more, our skin is constantly being replaced because skin cells have a short lifespan and are genetically programmed to die.


"But what was actually happening was not that the skin cells were living longer, but that the lack of caspase 8 was stimulating more skin cells to divide, which was unexpected," said Jamora. "And when we looked further, we also found that there was inflammation going on in the skin of these mice. Those two things led us to suspect that the loss of caspase 8 can trigger a normal wound-healing response in the absence of any trauma to the skin."




The team of UCSD researchers that contributed to this study included members of the Jamora lab-Pedro Lee, Dai-Jen Lee, Carol Chan and Shih-Wei Chen-in collaboration with Irene Ch'en from the laboratory of Steve Hedrick.






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  • As Reported by the Xinhua News Agency