The pigment melanin, which is responsible for skin and hair color in mammals, is produced in specialized cells called melanocytes and then distributed to other cells. But not every cell in the complex layers of skin becomes pigmented. The question of how melanin is delivered to appropriate locations may have been answered by a study from researchers at the Massachusetts General Hospital (MGH) Cutaneous Biology Research Center (CBRC).
“Pigment recipient cells essentially tell melanocytes where to deposit melanin, and the pattern of those recipients determines pigment patterns,” says Janice Brissette, PhD, who led the study. “Recipient cells act like the outlines in a child’s coloring book; as recipient cells develop, they form a ‘picture’ that is initially colorless but is then ‘colored in’ by the melanocytes.” The report appears in the Sept. 7 issue of Cell.
In humans, melanin is deposited in both the skin and the hair; but in some other mammals such as mice, melanin is primarily deposited in the coat, leaving the skin beneath the coat unpigmented. Melanocytes deposit melanin via cellular extensions called dendrites that reach out to other cells in the epidermis (the outer layer of skin) or the hair follicles. But the mechanism determining whether melanin is delivered to a particular cell has been unknown.
The MGH-CBRC researchers theorized that a mouse gene known as Foxn1 might play a role. Lack of Foxn1 is responsible for so-called ‘nude mice,’ which have hair that is so brittle it breaks off, resulting in virtually total hairlessnes, and other defects of the skin. A similar phenomenon exists in humans with inactivation of the corresponding gene.
When the researchers developed a strain of transgenic mice in which Foxn1 is misexpressed in cells that do not usually contain melanin, they found those normally colorless areas became pigmented. Examining the skin of the transgenic mice revealed that melanocytes were contacting and delivering melanin to the cells in which Foxn1 was abnormally activated. No pigment was observed in the corresponding tissues of normal mice. Examination of human skin samples showed that the human version of Foxn1 was also expressed in cells known to be pigment recipients. Further experiments revealed that Foxn1 signals melanocytes through a protein called Fgf2, levels of which rise as Foxn1 espression increases.
“Foxn1 makes epithelial cells into pigment recipients, which attract melanocytes and stimulate pigment transfer, engineering their own pigmentation,” says Brissette, an associate professor of Dermatology at Harvard Medical School. She and her colleagues note that the Foxn1/Fgf2 pathway probably has additional functions in the skin and that it is probably not the only pathway responsible for the targeting of pigment.
“We know that Foxn1 and Fgf2 act in concert with other factors and function within a larger network of genes. Our next step will be to identify other genes that can confer the pigment recipient phenotype or control the targeting of pigment,” Brissette adds. Her research may eventually be relevant to disorders such as vitiligo – in which pigment disappears from patches of skin – age spots, the greying of hair and even the deadly melanocyte-based skin cancer melanoma.
Emily Parker | EurekAlert!
First time-lapse footage of cell activity during limb regeneration
25.10.2016 | eLife
Phenotype at the push of a button
25.10.2016 | Institut für Pflanzenbiochemie
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
25.10.2016 | Earth Sciences
25.10.2016 | Power and Electrical Engineering
25.10.2016 | Process Engineering