New study resolves the mysterious origin of Merkel cells

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New study resolves the mysterious origin of Merkel cells

http://www.eurekalert.org/pub_releases/2009-09/rup-nsr092209.php

A new study resolves a 130-year-old mystery over the developmental origin of

specialized skin cells involved in touch sensation. The findings will appear in

the October 5, 2009 issue of the Journal of Cell Biology (online September 28).

First described in 1875, Merkel cells are neuroendocrine cells that reside in

the vertebrate epidermis, passing mechanical stimuli on to sensory neurons. In

mice, they are mainly found in the paws and around the whiskers but, because

they express proteins characteristic of both epithelial and neuronal cells,

scientists have long debated whether Merkel cells develop from the epidermis or

neural crest.

Van Keymeulen et al. traced the lineage of Merkel cells by fluorescently

labeling cells derived from either epidermal or neural crest progenitors. This

revealed that Merkel cells originally emerge from the embryonic epidermis. In

addition, epidermal stem cells in adult mouse skin replenish the Merkel cell

population as they slowly die off over time. The researchers also found that a

transcription factor called Atoh1 is required for epidermal progenitors to

differentiate into Merkel cells—mice lacking Atoh1 in their skin failed to

develop any of the mechanotransducing cells.

Atoh1 acts as a tumor suppressor to prevent an aggressive skin cancer called

Merkel cell carcinoma, says senior author Cédric Blanpain. His team now wants to

investigate the precise function of the transcription factor in Merkel cell

differentiation, as well as the signaling pathways that regulate the process.