Niche Stem Cell - How to Affect the Environment and not be Affected?

The ability of stem cells to self-renew and concomitantly generate cells that are committed to undergo differentiation, requires the presence of mitogenic signals (signals that promote cell division) provided by the microenvironment called the niche. Remarkably, the cells that constitute the niche remain dormant despite their exposure to the same signals. The mechanism that allows the niche cells to ignore the mitogenic signals and remain dormant is poorly understood. Researchers from the Azrieli Faculty of Medicine at Bar-Ilan University, led by Dr. David Enshell-Seijffers, used a model of hair follicles in order to investigate this important mechanism. The researchers demonstrated that the Hdac1 and Hdac2 enzymes in the niche cells of the hair follicles are required, to maintain the quiescent state by suppressing the expression of the cell cycle genes, and in addition, protect the niche cells from apoptosis (cell death). Furthermore, the Hdac1 and Hdac2 enzymes play a role in orchestrating the hair cycle clock - in their absence, Wnt signaling is reduced not only in niche cells but also in the vicinity of the niche cells. As a result, the hair growth phase is shortened. This study's groundbreaking results, published in the prestigious journal Nature Communications, not only provide insight into the molecular mechanism that sustains the function of the niche stem cell in a persistently changing microenvironment, but also unveil how the same mechanism allows these cells to affect their microenvironment.

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