https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6055137/
Skin is a large peripheral organ densely populated by SCs. It contains a huge number of hair follicles (HFs) that undergo repetitive cycles of regeneration consisting of growth (anagen), regression (catagen), and rest (telogen) phases (22).
Activation of each new regeneration cycle is fueled by HF stem cells (HFSCs) residing in the so-called “bulge” and “secondary hair germ” niche compartments (23, 24).
When HFSC activity is suppressed, entrance to anagen is prohibited (25–29). HFSC activity has been shown to be regulated by intrinsic intracellular factors as well as by the signals from the local and systemic environments (1, 26, 30–35).
In addition to these internal regulatory factors, HF regeneration can be altered by external cues (1, 36).
Therefore, HFs provide an opportunity for interrogating the mechanisms by which tissue SCs communicate with the outer environment and how changes in the external environment are perceived and transmitted to an internal SC niche.
Using the HF regeneration paradigm, we uncovered a noncircadian neural circuit that activates HFSCs in response to light stimulation through retinal ipRGCs.
Skin is a large peripheral organ densely populated by SCs. It contains a huge number of hair follicles (HFs) that undergo repetitive cycles of regeneration consisting of growth (anagen), regression (catagen), and rest (telogen) phases (22).
Activation of each new regeneration cycle is fueled by HF stem cells (HFSCs) residing in the so-called “bulge” and “secondary hair germ” niche compartments (23, 24).
When HFSC activity is suppressed, entrance to anagen is prohibited (25–29). HFSC activity has been shown to be regulated by intrinsic intracellular factors as well as by the signals from the local and systemic environments (1, 26, 30–35).
In addition to these internal regulatory factors, HF regeneration can be altered by external cues (1, 36).
Therefore, HFs provide an opportunity for interrogating the mechanisms by which tissue SCs communicate with the outer environment and how changes in the external environment are perceived and transmitted to an internal SC niche.
Using the HF regeneration paradigm, we uncovered a noncircadian neural circuit that activates HFSCs in response to light stimulation through retinal ipRGCs.