Recent progress in hair follicle stem cell markers and their regulatory roles.

Hair follicle stem cells (HFSCs) in the bulge are a multipotent adult stem cell population. They can periodically give rise to new HFs and even regenerate the epidermis and sebaceous glands during wound healing. An increasing number of biomarkers have been used to isolate, label, and trace HFSCs in recent years. Considering more detailed data from single-cell transcriptomics technology, we mainly focus on the important HFSC molecular markers and their regulatory roles in this review.

Adenovirus-mediated Wnt5a expression inhibits the telogen-to-anagen transition of hair follicles in mice.

The canonical Wnt/ß-catenin pathway plays an important role in hair cycle induction. Wnt5a is a non-canonical Wnt family member that generally antagonizes canonical Wnt signaling in other systems. In hair follicles, Wnt5a and canonical Wnt are both expressed in cells in the telogen stage. Wnt5a has been shown to be critical for controlling hair cell fate. However, the role that Wnt5a plays in the transition from the telogen to anagen stage is unknown. In this study, using whole-mount in situ hybridization, we show that Wnt5a is produced by several other cell types, excluding dermal papilla cells, throughout the hair cycle. For example, Wnt5a is expressed in bulge and secondary hair germ cells in the telogen stage. Our studies focused on the depilated 8-week-old mouse as a synchronized model of hair growth. Interestingly, overexpression of adenovirus Wnt5a in the dorsal skin of mice led to the elongation of the telogen stage and inhibition of the initiation of the anagen stage. However, following an extended period of time, four pelage hair types grew from hairless skin that was induced by Wnt5a, and the structure of these new hair shafts was normal. Using microarray analysis and quantitative arrays, we showed that the expression of ß-catenin and some target genes of canonical Wnt signaling decreased after Wnt5a treatment. These data demonstrate that Wnt5a may inhibit the telogen stage to maintain a quiescent state of the hair follicle.

Adenovirus-mediated Wnt10b overexpression induces hair follicle regeneration.

Hair follicles periodically undergo regeneration. The balance between activators and inhibitors may determine the time required for telogen hair follicles to reenter anagen. We previously reported that Wnt10b (wingless-type mouse mammary tumor virus integration site family member 10b) could promote the growth of hair follicles in vitro. To unveil the roles of Wnt10b in hair follicle regeneration, we established an in vivo mouse model using intradermal injection. On the basis of this model, we found that Wnt10b could induce the biological switch of hair follicles from telogen to anagen when overexpressed in the skin. The induced hair follicles expressed structure markers and could cycle normally into catagen. Conversely, anagen onset was abrogated by the knockdown of Wnt10b with small interfering RNA (siRNA). The Wnt10b aberrant expression data suggest that it is one of the activators of hair follicle regeneration. The ß-catenin protein is translocated to the nucleus in Wnt10b-induced hair follicles. The biological effects of Wnt10b were abrogated when ß-catenin expression was downregulated with siRNA. These data revealed that Wnt10b might induce hair follicle regeneration in vivo via the enhanced activation of the canonical Wnt signaling pathway. To our knowledge, our data provide previously unreported insights into the regulation of hair follicle cycling and provide potential therapeutic targets for hair follicle-related diseases.

The construction of siRNA plasmid targeting mouse HIF-1alpha and in vitro study of its inhibition effect.

OBJECTIVE: To construct effective RNA-interference plasmids targeting mouse HIF-1alpha gene and testify their effects and specificities in interfering HIF-1alpha expression. METHODS: Three RNA-interference plasmids targeting mouse HIF-1alpha gene, pBS/U6/HIF-1alpha-siRNAI~III, were constructed and identified using double digestion method in the present study. RT-PCR, immunostaining and western blotting were employed to detect the expression alterations of HIF-1alpha in 293T cells following transfections of the three plasmids, respectively. The interference effect of pBS/U6/HIF1alphai-II in SH-SY5Y cell line was further investigated. RESULTS: All the three RNA-interference plasmids, especially pBS/U6/HIF1alphai-II, showed significant inhibition in HIF-1alpha expression in 293T cell line. pBS/U6/HIF1alphai-II could also inhibit HIF-1alpha expression in SH-SY5Y cell line, in a dose-dependent way. CONCLUSION: Plasmid pBS/U6/HIF1alphai-II constructed in our study can effectively and specifically inhibit HIF-1alpha expression, and its role in neural tube development and dysfunction will be further investigated. Construct of pBS/U6/HIF1alphai-II plasmid will provide a useful tool to study the role of HIF-1 pathway in embryogenesis, oncogenesis and ischemia development.