Expression pattern and role of klotho in human hair follicles

Abstract

The klotho gene, known as an “aging-suppressor” gene, increases the life span when it is over-expressed but hastens aging when it is disrupted in mice. Klotho-deficient mice display a complex phenotype reminiscent of human aging, including skin atrophy and hair loss. To date, klotho expression has only been detected in a few human tissues and cell lines. However, it is unclear whether klotho is expressed in human hair follicles and is correlated with hair growth.The purpose of the current study was to investigate the expression and effects of klotho in human hair follicles, and the functional roles of klotho in human hair growth.We examined klotho expression patterns in human hair follicle units from young as well as aged donors. Furthermore, we examined the functional roles of klotho on human hair growth using klotho siRNA and klotho recombinant protein.Interestingly, klotho was expressed in human hair follicle units at both gene and protein levels. In hair follicles, prominent klotho expression was mainly observed in the outermost regions of outer root sheath and hair bulb matrix cells. Quantification of klotho protein expression in young and aged donors showed that klotho expression decreased with aging. In human hair follicle organ culture, klotho silencing promoted premature catagen induction and inhibited human hair growth. Klotho protein prolonged human hair growth and inhibited transforming growth factor- β1 (TGF-β1) induced hair apoptosis.These results indicate that klotho might be an important regulatory factor for human hair growth and hair cycle change.