Cell: Significant progress! Explain the real causes of chicken skin.

!--:page title"--27 July 2020 /prNewswire/ -- --- if you ever wondered why we're going to get goosebumps, there are a lot of people who think about chicken skins like you--- Charles Darwin, who thought about chicken skins in his evolutionary books.chicken skinmay protect furry animals from the cold, but we humans don't seem to benefit much from this reaction, so why is it preserved in evolution? In a new study of mice, researchers from research institutions such as Harvard University in the United States and Taiwan University of China found the cause: the type of cells that cause the skins of the chicken is also important for regulating stem cells that regenerate hair follicles and hairs.under the skin, the muscles that produce chicken skins by contracting --- a smooth muscle --- called arrector pili muscle is necessary to connect sympathetic nerves with hair follicle stem cells.sympathetic nerve's response to the cold is to shrink the vertical hair muscle in a short period of time and cause goose bumps, and promote hair follicle stem cell activation and new hair growth in the long term.these findings give researchers a better understanding of how different types of cells interact, linking stem cell activity to changes in the outside environment.related findings were published online July 16, 2020 in the journal Cell, with the title "Cell Type Promoting Goosebumps Form a Niche to Regulate Hair Follicle Stem Cells."picture from Cell, 2020, doi: 10.1016/j.cell.2020.06.031. "We've always been interested in understanding how stem cell behavior is regulated by external stimuli," said Ya-Chieh Hsu, co-author of thepaper and an associate professor of stem cell and regenerative biology at Harvard University.skin is a fascinating system: it has a variety of stem cells surrounded by different cell types around it, and it is the intersection of our body and the outside world.its stem cells may respond to various stimuli from the microenvironment , the entire body, and even the external environment.in this study, we identified an interesting two-component microenvironment (dual-component niche), which regulates stem cells not only in a stable state, but also in terms of stem cell behavior according to external temperature changes." Many organs of a system that regulates hair growth are made up of three types of tissue: epithelial (epithelium), mesenchyme, and nerve.in the skin, the three tissues are assembled in a special arrangement.sympathetic nerves are part of our nervous system, which controls the balance of the body and our response to external stimuli.sympathetic nerves are connected to a tiny smooth muscle in the interstitial (i.e., the vertical muscle mentioned earlier).this smooth muscle is also connected to hair follicle stem cells, which are epithelial stem cells that are essential for hair follicle regeneration and wound repair. The link between thesympathetic nerves and this smooth muscle is well known because they are the cellular basis of the skins produced by the chicken skin: the cold triggers nerve signals from sympathetic neurons, which react by shrinking and causing hair to rise. However, when examining the skin at very high resolution using an electron microscope, the researchers found that sympathetic nerves were not only connected to this smooth muscle, but also directly linked to hair follicle stem cells. in fact, nerve fibers are wrapped around hair follicle stem cells like a ribbon. "We can really see how sympathetic nerves and hair follicle stem cells interact at the superstructure level, " says Hsu. neurons tend to regulate excitable cells, just as other neurons or muscles interact with synapses. However, we were surprised to find that they form synaptic structures with hair follicle stem cells, after all, hair follicle stem cells are not typical targets for neurons. "Next, the researchers confirmed that sympathetic nerves do act on hair follicle stem cells, " . sympathetic nervous system usually remains low-level activation to maintain the body's balance. the researchers found that this low level of neural activity left hair follicle stem cells in a state ready to regenerate. in long-term cold conditions, the sympathetic nerve sits at a higher level of activation, releasing more neurotransmitters, allowing hair follicle stem cells to activate quickly, regenerate hair follicles, and grow new hairs. the researchers also looked at what maintains the connection between sympathetic nerves and hair follicle stem cells. when they remove the smooth muscles connected to the hair follicles, the sympathetic nerves replindicate and the connection between the sympathetic nerves and the hair follicle stem cells is lost, suggesting that the smooth muscles are the necessary support structure for connecting the sympathetic nerves to the hair follicles. how this system is produced, in addition to studying hair follicles in fully formed states, the researchers also studied how the system initially produced --- smooth muscles and sympathetic nerves first reached the hair follicles. "We found that this signal came from the developing follicleites themselves," said Yulia Shwartz, a postdoctoral researcher at Hsu Labs who co-authored the paper . a protein it secretes that regulates the formation of smooth muscles, which then attract sympathetic nerves. in adulthood, this interaction reverses, with sympathetic nerves and smooth muscles regulating hair follicle stem cells to regenerate new hair follicles. this is shutting down the entire cycle -- the developing hair follicles are building their own microenvironment. " response to the environment through these experiments, the researchers identified a two-component system that regulates hair follicle stem cells. sympathetic nerves activate the signalcomponents of hair follicle stem cells through neurotransmitters, while smooth muscles are the structural components that make nerve fibers directly connected to hair follicle stem cells. "You can regulate hair follicle stem cells in many different ways, and they are wonderful models for studying tissue regeneration," Shwartz said. this particular response is useful for conjuging tissue regeneration with external changes such as temperature. this is a two-tiered response: chicken skin squirming is a quick way to provide some relief in a short period of time. But when the cold lasts, it's a good mechanism for letting hair follicle stem cells know maybe it's time to regenerate new fur. the "!--/ewebeditor": !--webeditor: page title" -- in the future, the researchers will explore how the external environment affects stem cells in the skin, whether in steady state or in repair conditions, such as wound healing. "We live in a changing environment," says Hsu. Because the skin is always in contact with the outside world, this gives us the opportunity to study the mechanisms by which stem cells in our bodies combine tissue production with changing needs, which is essential for organisms to thrive in this dynamic world. "( Bioon.com):1.Yulia Shwartz et al. Cell Types Promoting Goosebumps Form a Niche to Regulate Hair Follicle Stem Cells. Cell, 2020, doi: 10.1016/j.cell.2020.06.031.2.The real reason reason behind goosebumps.