Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientist discover the cellular roots of graying hair

27.12.2004


Findings could shed new light on malignant melanoma



Few things about growing older are as inevitable and obvious as "going gray," yet scientists have been unable to explain the precise cause of this usually unwelcome transformation.

In a report posted today on the Web site of the journal Science, researchers from Dana-Farber Cancer Institute and Children’s Hospital Boston say they have found the cellular cause of graying hair while investigating the origins of malignant melanoma, the potentially deadly skin cancer.


The scientists traced the loss of hair color to the gradual dying off of adult stem cells that form a reservoir that spawns a continuous supply of new pigment-manufacturing cells, called melanocytes, that give hair its youthful hues. Not only do the non-specialized stem cells become depleted: They also progressively make errors, turning into fully committed pigment cells in the wrong place within the hair follicle, where they are useless for coloring hair.

The new findings won’t lead to a scientific alternative to hair dyes any time soon, if ever, even if they do solve a longstanding puzzle about the underlying mechanism of graying. Of more interest to the researchers is the pattern of cellular signals that triggers the death of pigment stem cells, since melanoma is dangerous for the opposite reason –melanocytes proliferate uncontrollably to form tumors and are hard to kill with treatment.

"Preventing the graying of hair is not our goal," emphasizes David E. Fisher, MD, PhD, director of the Dana-Farber Program in Melanoma, and senior author of the Science paper. "Our goal is to prevent or treat melanoma, and to the extent this research is revealing the life cycles of melanocytes, which are the cells that become cancerous in melanoma, we would love to identify a signal that would make a melanoma cell stop growing."

Fisher and the report’s lead author, Emi K. Nishimura, MD, PhD, also of the melanoma program, are in the Department of Pediatric Oncology at Children’s Hospital Boston as well as at Dana-Farber. The second author, Scott R. Granter, MD, is a pathologist at Brigham and Women’s Hospital.

The American Cancer Society expects about 55,100 people to be diagnosed with melanoma, the most serious form of skin cancer, in 2004, with an estimated 7.910 deaths. Melanoma can be cured when it is detected and treated early, but if the lesion penetrates deeply into the skin it is often fatal. Sun exposure is a major risk factor in the disease, which has been increasing in the past several decades.

Melanocytes, which manufacture and store the pigment that combines with hair-making cells called keratinocytes to color the hair, are specialized cells spawned by colorless melanocyte stem cells. These cells were discovered by Nishimura in 2002.

A pool of undifferentiated melanocyte stem cells resides in the hair follicle, and during the hair’s grow-and-rest cycle, the stem cells give rise to color-making melanocytes that journey to the bottom of the hair follicle: That is where they tint the keratinocytes with the person’s characteristic hue.

By studying mice at progressively older intervals, Fisher and his colleagues discovered that as the rodents aged and their hair began turning gray, the numbers of stem cells diminished in proportion to the loss of color. The scientists were surprised to observe that, at the same time and the same rate, differentiated, pigmented melanocytes were showing up in the follicle at the location where the stem cells resided. Since they were in the wrong place, the pigmented cells likely did nothing to maintain the mice’s hair color.

To see if the cells behaved the same way in humans, the investigators examined human scalp tissue taken at increasing ages, and determined that the same pattern occurred.

Since cell survival in general is influenced by an "anti-death" gene called Bcl2, Fisher’s team analyzed mice lacking this gene. In a dramatic fashion, the mice lost their melanocyte stem cells shortly after birth and quickly went gray. It may be that people who gray prematurely have mutations that knock out Bcl2 activity, Fisher says.

"This tells us there is a requirement for Bcl2 in normal hair follicle cycling," adds Fisher. "So the question is: what in the hair follicle is signaling the stem cells that is absent when aging occurs and the stem cells die off? Now we have a much more refined way of dissecting that signaling pathway in melanoma. Eventually we hope to tap into this death pathway, thereby using drugs to mimic the aging process, to successfully treat melanoma."

The team also made mice lacking a gene, MITF that regulates Bcl2. These mice also went gray, but more gradually than did the mice that had no Bcl2. The loss of MITF activity, the investigators say, appears to be implicated in the mistaken differentiation of melanocyte stem cells that accompanies the stem cells’ depletion. MITF, they conclude, seems to play a crucial role in maintaining the supply of stem cells within the hair follicle, and graying is the result of "incomplete maintenance of melanocyte stem cells."

Janet Haley Dubow | EurekAlert!
Further information:
http://www.dfci.harvard.edu

More articles from Life Sciences:

nachricht How molecules teeter in a laser field
18.01.2019 | Forschungsverbund Berlin

nachricht Discovery of enhanced bone growth could lead to new treatments for osteoporosis
18.01.2019 | University of California - Los Angeles

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Ten-year anniversary of the Neumayer Station III

The scientific and political community alike stress the importance of German Antarctic research

Joint Press Release from the BMBF and AWI

The Antarctic is a frigid continent south of the Antarctic Circle, where researchers are the only inhabitants. Despite the hostile conditions, here the Alfred...

Im Focus: Ultra ultrasound to transform new tech

World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles

The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.

Im Focus: Flying Optical Cats for Quantum Communication

Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.

In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...

Im Focus: Nanocellulose for novel implants: Ears from the 3D-printer

Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.

It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:

Im Focus: Elucidating the Atomic Mechanism of Superlubricity

The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.

One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Our digital society in 2040

16.01.2019 | Event News

11th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Aachen, 3-4 April 2019

14.01.2019 | Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

 
Latest News

Additive manufacturing reflects fundamental metallurgical principles to create materials

18.01.2019 | Materials Sciences

How molecules teeter in a laser field

18.01.2019 | Life Sciences

The cytoskeleton of neurons has been found to be involved in Alzheimer's disease

18.01.2019 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>