Two genes not previously linked with the immune system have been shown by University of California-Los Angeles researchers to play a role in directing progenitor stem cells to fight infection.

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Progenitor cells are usually stored in a “standby mode” until being differentiated in response to stress, infection or disease.

Progenitor cells are described as being the link between stem cells and the “fully differentiated” cells of organs, tissues and the blood system.

“Differentiation” is the process by which progenitor cells mature into cells required by the environment that produced the progenitor cell.

Progenitor cells are usually stored in a “standby mode” until being differentiated in response to stress, infection or disease.

In the new study, researchers looked at two genes – named Yorkie and Scalloped – that have been previously identified in stem cells but not in the blood system.

The team discovered that the genes are necessary for “lineage specifying cells” – a newly defined cell type that works as a switch to activate the differentiation process of progenitor cells.

In a fruit fly study, the researchers found that if the progenitor cells did not receive the signal from the lineage specifying cells, the fly would be unable to make differentiated cells to fight infection.

The scientists say this means that the fly’s ability to fight infection and pathogens in the blood system is directly related to the new lineage specifying cell type in which Yorkie and Scalloped are implicated.

Study co-author Dr. Julian Martinez-Agosto, associate professor of human genetics at University of California-Los Angeles (UCLA), describes the team’s findings:

The beauty of this study is that we now have a system in which we can investigate how a signaling cell uses these two genes Yorkie and Scalloped, which have never before been shown in blood, to direct specific cells to be made.

It can help us to eventually answer the question of how our body knows how to make specific cell types that can fight infection. Looking at the functionality of these genes and their effect on the immune response has great potential for accelerating the development of new targeted therapies.”

Next, Dr. Martinez-Agosto and colleagues will attempt to replicate their fruit fly findings in mammals. Co-author Dr. Gabriel Ferguson, a postdoctoral fellow at UCLA, says that the molecular machinery of fruit flies, mice and humans share much in common at a biochemical level.

The UCLA team believe that their work – the results of which are published in the journal Current Biology – lays the groundwork for an improved understanding of the role of progenitor cells. “This study can further our shared understanding of how the microenvironment can regulate the differentiation and fate of a progenitor or stem cell,” Dr. Ferguson says.

In February of this year, researchers at the University of Chicago reported in the journal Nature that they had identified progenitor cells in the fetal liver and adult bone marrow of mice.

“Scientists tend to look for immune cells in the blood, lymph nodes or spleen,” said study author Albert Bendelac, PhD, professor of pathology at the University of Chicago. “That is precisely where you would not find these cells. Once they mature they directly go to tissues, such as the gut or the skin. You seldom see them in blood.”