New mechanisms causing greying hair and baldness uncovered

Scientists have shown how a gene and protein cause greying and hair loss in mice.

Though 'accidentally' discovered by scientists researching a form of cancer, the findings pose a new avenue of research into balding and greying hair.

'Although this project was started in an effort to understand how certain kinds of tumours form, we ended up learning why hair turns grey and discovering the identity of the cell that directly gives rise to hair,' said Dr Lu Le of Harold C. Simmons Comprehensive Cancer Center at the University of Texas Southwestern.

Dr Le and his team were investigating precursor cells (stem cells) in hair follicles using mice, as part of their research into neurofibromatosis, a rare genetic disease where tumours grow along nerve cells. A strain of genetically engineered mice they were using developed grey hair early in life, and they decided to investigate why.

They discovered a protein known as KROX20, usually associated with nerve development, is found in the precursor cells which eventually form the hair shaft. When the researchers deleted the KROX20-producing cells in mice, the mice did not grow hair and became bald.

The production of KROX20 in precursor cells also triggers the expression of stem cell factor (SCF) protein. The team found when they silenced the SCF gene, the hair of the mice turned white.

Dr Le said that scientists already knew that stem cells in hair follicles were involved in making hair, and that SCF is important for pigmented cells. However, it was not known that the precursor cells produce KROX20, nor how they contribute to the growth of hair as they spread through the follicles, and which follicle cells produce SCF.

The team next intend to find out if KROX20 and the SCF gene are involved in the ageing process and lead to the graying and hair thinning seen in older people, or to male pattern baldness.

The study was published in Genes & Development.