Hairless controls hair fate decision via Wnt/β-catenin signaling

An optimized force-triggered density gradient sedimentation method for isolation of pelage follicle dermal papilla cells from neonatal mouse skin

BACKGROUND

The dermal papilla cells are a specialized population of mesenchymal cells located at the base of the hair follicle (HF), which possess the capacity to regulate HF morphogenesis and regeneration. However, lack of cell-type specific surface markers restricts the isolation of DP cells and application for tissue engineering purposes.

METHODS

We describe a novel force-triggered density gradient sedimentation (FDGS) method to efficiently obtain purified follicular DP-spheres cells from neonatal mouse back skin, utilizing only centrifugation and optimized density gradients.

RESULTS

Expression of characteristic DP cell markers, alkaline phosphatase, β-catenin, versican, and neural cell adhesion molecules, were confirmed by immunofluorescence. Further, the patch assays demonstrated that DP cells maintained their hair regenerative capacity in vivo. Compared with current methods, including microdissection and fluorescence-activated cell sorting, the FDGS technique is simpler and more efficient for isolating DP cells from neonatal mouse skin.

CONCLUSIONS

The FDGS method will improve the research potential of neonatal mouse pelage-derived DP cells for tissue engineering purposes.

The Histone Demethylase HR Suppresses Breast Cancer Development through Enhanced CELF2 Tumor Suppressor Activity

The hairless (HR) gene encodes a transcription factor with histone demethylase activity that is essential for development and tissue homeostasis. Previous studies suggest that mutational inactivation of HR promotes tumorigenesis. To investigate HR mutations in breast cancer, we performed targeted next-generation sequencing using DNA isolated from primary breast cancer tissues. We identified HR somatic mutations in approximately 15% of the patient cohort (n = 85), compared with 23% for BRCA2, 13% for GATA3, 7% for BRCA1, and 3% for PTEN in the same patient cohort. We also found an average 23% HR copy number loss in breast cancers. In support of HR's antitumor functions, HR reconstitution in HR-deficient human breast cancer cells significantly suppressed tumor growth in orthotopic xenograft mouse models. We further demonstrated that HR's antitumor activity was at least partly mediated by transcriptional activation of CELF2, a tumor suppressor with RNA-binding activity. Consistent with HR's histone demethylase activity, pharmacologic inhibition of histone methylation suppressed HR-deficient breast cancer cell proliferation, migration and tumor growth. Taken together, we identified HR as a novel tumor suppressor that is frequently mutated in breast cancer. We also showed that pharmacologic inhibition of histone methylation is effective in suppressing HR-deficient breast tumor growth and progression.

Circadian effects on UV-induced damage and mutations

Skin cancer is the most diagnosed type of cancer in the United States, and while most of these malignancies are highly treatable, treatment costs still exceed $8 billion annually. Over the last 50 years, the annual incidence of skin cancer has steadily grown; therefore, understanding the environmental factors driving these types of cancer is a prominent research-focus. A causality between ultraviolet radiation (UVR) exposure and skin cancer is well-established, but exposure to UVR alone is not necessarily sufficient to induce carcinogenesis. The emerging field of circadian biology intersects strongly with the physiological systems of the mammalian body and introduces a unique opportunity for analyzing mechanisms of homeostatic disruption. The circadian clock refers to the approximate 24-hour cycle, in which protein levels of specific clock-controlled genes (CCGs) fluctuate based on the time of day. Though these CCGs are tissue specific, the skin has been observed to have a robust circadian clock that plays a role in its response to UVR exposure. This in-depth review will detail the mechanisms of the circadian clock and its role in cellular homeostasis. Next, the skin's response to UVR exposure and its induction of DNA damage and mutations will be covered - with an additional focus placed on how the circadian clock influences this response through nucleotide excision repair. Lastly, this review will discuss current models for studying UVR-induced skin lesions and perturbations of the circadian clock, as well as the impact of these factors on human health.

Functional hair follicle regeneration: an updated review

The hair follicle (HF) is a highly conserved sensory organ associated with the immune response against pathogens, thermoregulation, sebum production, angiogenesis, neurogenesis and wound healing. Although recent advances in lineage-tracing techniques and the ability to profile gene expression in small populations of cells have increased the understanding of how stem cells operate during hair growth and regeneration, the construction of functional follicles with cycling activity is still a great challenge for the hair research field and for translational and clinical applications. Given that hair formation and cycling rely on tightly coordinated epithelial-mesenchymal interactions, we thus review potential cell sources with HF-inducive capacities and summarize current bioengineering strategies for HF regeneration with functional restoration.

Randomized trial of electrodynamic microneedling combined with 5% minoxidil topical solution for treating androgenetic alopecia in Chinese males and molecular mechanistic study of the involvement of the Wnt/β-catenin signaling pathway

Background: Treatment of androgenetic alopecia (AGA) with concurrent electrodynamic microneedling and 5% minoxidil may further stimulate hair growth.Objectives: To evaluate the efficacy of microneedling combined with 5% minoxidil in Chinese male AGA patients and to explore the underlying mechanisms.Methods: Seventy-one male volunteers with AGA completed the entire trial and follow-up. The first group (n = 23) received only 5% minoxidil twice daily for 24 weeks; the second group (n = 23) received only microneedle therapy every 3 weeks for eight treatments; and the third group (n = 25) received the combination treatment for a total of 24 weeks. Changes in hair density and diameter were evaluated before and after treatment every 3 weeks, and patients were followed up at 6 months after the final treatment. In the combination group, a PCR array was used to detect the expression of molecules in the Wnt/β-catenin pathway within the hair loss sites on top of the head before and after treatment and within the scalp tissues from non-hair loss sites on top of the head. The tissues were obtained by punches in the most severe area of hair loss on top of the head and in the adjacent normal hair area without hair loss. Real-time quantitative PCR and western blotting were used to further examine changes in the differentially expressed molecules identified by PCR array (FZD3) and in molecules in the Wnt/β-catenin signaling pathway closely related to hair growth (β-catenin and LEF-1).Results: Compared to single minoxidil or single microneedle treatment, the combination therapy showed superior therapeutic effects clinically, with further upregulation of FZD3, β-catenin, and LEF-1 expression levels at both mRNA and protein levels in the treated areas.Conclusions: Microneedling combined with 5% minoxidil can improve AGA, and the underlying mechanism may involve activation of the Wnt/β-catenin signaling pathway.

Trps1-deficient transplanted skin gave rise to a substantial amount of hair: Trps1 is unnecessary for hair development

Trps1 is considered as an important gene involved in the interactions between the epithelial and mesenchymal cells during hair follicle morphogenesis. The number of hair follicles in Trps1 Knockout (KO) newborn mouse skin was significantly lower than that in wild-type (WT) newborn skin. To gain insight into the functional role of Trps1 in hair development, we transplanted Trps1 KO newborn mouse skin on the backs of nude mice and examined hair growth at day 42 after transplantation. Surprisingly, transplanted skin from Trps1 KO newborn mice gave rise to a substantial amount of hair, although the hair was softer than that of WT mice. Histological examination revealed that the diameter of both hair follicles and hair shafts were significantly lower, whereas the density of hair follicles showed no significant difference between the Trps1 KO and WT mice. We introduce mouse hair follicles as a fascinating model to study the functions of Trps1 in mouse hair growth and pathology. This model suggests that the function of Trps1 is unnecessary for the development of normal hair follicles and hair shafts, although the loss of Trps1 affects the diameters of hair follicles and hair shaft.