Objective    To investigate β-catenin expression changes in hair follicle melanocyte lineage cells during the hair cycle.     Methods    RT-PCR

Western blot analysis

β-gal staining

and immunohistochemistry with paraffin section were adopted to detect the amount and distribution changes of melanocyte lineage cells in Dct-Lac-Z CD1 mouse hair follicles

and to identify β-catenin expression and distribution at mRNA and protein levels.     Results    Western blotting and RT-PCR results exhibited the protein and mRNA expression levels of β-catenin in the hair cycle [early anagen (P4 and P29)>medium anagen (P8)>telogen (

P23)>catagen (p18)

]

. Significant differences were found between β-catenin expression levels of the four phases (

P

<

0.05)

using one-way analysis of variance. Immunohistochemistry results showed that among melanocyte lineage cells

β-catenin was strongly expressed in activated melanoblasts

melanocyte stem cells (MSCs)

and melanocytes in differentiation

and was weakly expressed in resting MSCs and differentiated melanocytes.     Conclusion    Upregulation of β-catenin can promote melanocyte lineage cell differentiation in hair follicles. The periodic change of β-catenin expression may be the basis of periodic generation of hair pigments.