Researchers identify embryonic origin of Merkel cells

Publication in Journal of Cell Biology : researchers from ULB (IRIBHM) identify the embryonic origin of Merkel cells. Their research continue on an extremely aggressive cancer, the Merkel cell carcinoma

Merkel cells are neuroendocrine cells located in the skin epidermis that mediate touch sensation. Since their first identification by Frederich Merkel in 1875, the embryonic origin of Merkel cells remain matters of intense controversy. Merkel cells present many characteristics of neuronal cells such as factors involved in neuronal cell fate determination factors, neuro-peptides and many components of the synaptic machinery suggesting they arise from neuronal cells. On the other hand, Merkel cells also express charcteristics of epitelial cells suggesting that they may arise from the epithelial cells of the skin. 

In a recent study, Alexandra Van Keymeulen and Guilhem Mascré in the laboratory of Cedric Blanpain, IRIBHM, ULB used new genetic experiments to determine their embryonic origin, the mechanisms that specify these cells during embryonic development and that maintain these cells during adult life. They demonstrated that Merkel cells originate from embryonic epidermal progenitors and not from neural crest cells as it has been previously suggested. They also show that Merkel cells undergo a slow but significant turnover during adult life that is ensured by epidermal stem cells. Finally, they showed that a proneural factor named Atoh1/Math1 is required in embryonic epidermal progenitors for Merkel cell specification. The ablation of this proneural factor in epidermal cells provides the first animal model completely deficient for Merkel cells.

This study opens many new exciting areas of research. It offers new ways to define the role of Merkel cells in sensory perception and open new avenues to define the cell at the origin and mechanisms leading to the formation of Merkel cell carcinoma, a poorly understood and extremely aggressive cancer in humans with rising incidence especially in aging and immunocompromised patients. The researcher at ULB, IRIBHM, in collaboration with Dr Hassan, VIB, KUL, now are trying to generate the first animal models of this devastating cancer. This work also provide new cues to understand how it is possible to generate neuron like cells from skin cells, which may be useful in the future to generate bona fide neurons from skin cells, a highly accessible tissue. 

This study has been published and makes the cover of the Journal Cell Biology of the October 5th issue and is accompained by an editoral highlight.