A common ancestor for cells involved in hearing and touch

Inner ear sensory cells (left) and skin sensory cells from a one-day-old mouse. Credit: Vincent Yu/Segil Lab/USC Stem Cell

The sensory cells in the inner ear and the touch receptors in the skin actually have a lot in common, according to a new study from the USC Stem Cell laboratory of Neil Segil published in the Proceedings of the National Academy of Sciences (PNAS).

“There are striking similarities in the development of two types of specialized sensory cells: the so-called ‘hair cells’ that receive sound vibrations in the inner ear, and the Merkel cells that sense light touch at the surface of the skin,” said Segil, who is a Professor in the Department of Stem Cell Biology and Regenerative Medicine, and the USC Tina and Rick Caruso Department of Otolaryngology—Head and Neck Surgery. “Ultimately, these developmental similarities are a legacy of shared evolutionary history. This demonstrates how the story of evolutionary developmental biology, or ‘evo devo,’ also extends to what we call the ‘epigenetic level’—or how genes are regulated.”

In the study, Ph.D. student Haoze (Vincent) Yu, postdoctoral scholar Litao Tao, and their colleagues identified a shared mechanism involved in gene regulation or epigenetics, that enables stem cells and progenitor cells to differentiate into more specialized hair cells and Merkel cells.

In order to begin the process of differentiation, the right parts of a stem cell’s DNA need to be taken out of storage. Each human cell can store around six feet of DNA in its nucleus, because this DNA is wound around tiny “spools” made up of proteins called histones. These spools of DNA and histone protein are further packed together to form what are known are nucleosomes, which are stacked to create chromatin, which is the material that makes up the chromosomes.

When DNA is wound tightly into this storage configuration, the chromatin is closed and inaccessible to the protein ATOH1. This protein is a “master regulator” that can activate a network of differentiation genes in the DNA within the chromatin—but not without first gaining access.

To this end, ATOH1 stimulates the production of a second protein known as POU4F3, an aptly named “pioneer factor” with the ability to venture into new frontiers by binding to closed and inaccessible chromatin. After POU4F3 blazes a trail by binding to the closed chromatin, ATOH1 is able to move forward with engaging and activating the network of genes that drives differentiation into hair cells and Merkel cells.

Strikingly, there is significant overlap in the specific regions of chromatin that POU4F3 makes accessible to ATOH1 in hair cells and Merkel cells.

“It’s remarkable that these two cell types, which are both involved in sensing mechanical stimuli but derive from distinct parts of the embryo, both rely on the same ATOH1/POU4F3 mechanism in order to differentiate,” said Segil. “Our study suggests that this mechanism is extremely ancient, and emerged before hair cells and Merkel cells diverged from a common evolutionary ancestor—an ‘ur-mechanoreceptor’ cell type.”

Cells take sole responsibility for Merkel cell maintenance

More information:
Haoze V. Yu el al., “POU4F3 pioneer activity enables ATOH1 to drive diverse mechanoreceptor differentiation through a feed-forward epigenetic mechanism,” PNAS (2021). www.pnas.org/cgi/doi/10.1073/pnas.2105137118

Provided by
Keck School of Medicine of USC

A common ancestor for cells involved in hearing and touch (2021, July 12)
retrieved 12 July 2021
from https://phys.org/news/2021-07-common-ancestor-cells-involved.html

This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no
part may be reproduced without the written permission. The content is provided for information purposes only.

For all the latest Science News Click Here 

 For the latest news and updates, follow us on Google News

Read original article here

Denial of responsibility! TheDailyCheck is an automatic aggregator around the global media. All the content are available free on Internet. We have just arranged it in one platform for educational purpose only. In each content, the hyperlink to the primary source is specified. All trademarks belong to their rightful owners, all materials to their authors. If you are the owner of the content and do not want us to publish your materials on our website, please contact us by email – [email protected] The content will be deleted within 24 hours.