Extracellular proteoglycan decorin maintains human hair follicle stem cells.

Hair follicle stem cells (HFSC) are localized in the bulge region of the hair follicle and play a role in producing hair. Recently, it has been shown that the number of HFSC decreases with age, which is thought to be a cause of senile alopecia. Therefore, maintaining HFSC may be key for the prevention of age-related hair loss, but the regulatory mechanisms of HFSC and the effects of aging on them are largely unknown.

Laminin-332 regulates differentiation of human interfollicular epidermal stem cells.

Interfollicular epidermal stem cells (IFE-SCs) have self-renewal and differentiation potentials, and maintain epidermal homeostasis. Stem cells in vivo are regulated by the surrounding environment called niche to function properly, however, IFE-SC niche components are not fully understood. In order to elucidate the mechanisms of keeping epidermal homeostasis and of skin aging, and also to develop new therapeutic technologies for skin diseases, we searched for niche factors that regulate IFE-SCs.

Accelerated differentiation of melanocyte stem cells contributes to the formation of hyperpigmented maculae.

It has been reported that the abnormal regulation of melanocyte stem cells (McSCs) causes hair greying; however, little is known about the role of McSCs in skin hyperpigmentation such as solar lentigines (SLs). To investigate the involvement of McSCs in SLs, the canonical Wnt signalling pathway that triggers the differentiation of McSCs was analysed in UVB-induced delayed hyperpigmented maculae in mice and human SL lesions. After inducing hyperpigmented maculae on dorsal skin of F1 mice of HR-1× HR/De, which was formed long after repeated UVB irradiation, the epidermal Wnt1 expression and the number of nuclear β-catenin-positive McSCs were increased as compared to non-irradiated control mice.

ZIP2 protein, a zinc transporter, is associated with keratinocyte differentiation.

Zinc is essential for the proper functioning of various enzymes and transcription factors, and its homeostasis is rigorously controlled by zinc transporters (SLC39/ZIP, importers; SLC30/ZnT, exporters). Skin disease is commonly caused by a zinc deficiency. Dietary and inherited zinc deficiencies are known to cause alopecia and the development of vesicular or pustular dermatitis.

Comprehensive analysis of melanogenesis and proliferation potential of melanocyte lineage in solar lentigines.

Background: Solar lentigines (SLs) are characterized by hyperpigmented macules, commonly seen on sun-exposed areas of the skin. Although it has been reported that an increase in the number of melanocytes and epidermal melanin content was observed in the lesions, the following questions remain to be answered: (1) Is acceleration of melanogenesis in the epidermis caused by an increased number of melanocytes or the high melanogenic potential of each melanocyte? (2) Why does the number of melanocytes increase?

Objective: To elucidate the pathogenic mechanism of SLs by investigating the number, melanogenic potential and proliferation status of the melanocyte lineage in healthy skin and SL lesions.

Methods: Immunostaining for melanocyte lineage markers (tyrosinase, MART-1, MITF, and Frizzled-4) and a proliferation marker, Ki67, was performed on skin sections, and the obtained images were analyzed by image analysis software.

Analysis of the effects of hydroquinone and arbutin on the differentiation of melanocytes.

Hydroquinone (HQ) is a chemical compound that inhibits the functions of melanocytes and has long been known for its skin-whitening effect. According to previous studies, the Tyrosinase (Tyr) activity inhibitory effect and melanocyte-specific cell toxicity are known depigmenting mechanisms; however, details of the underlying mechanisms are unknown. Arbutin (Arb) is also known for its Tyr activity inhibitory effect and is commonly used as a skin-whitening agent.

Lignin Induces ES Cells to Differentiate into Neuroectodermal Cells through Mediation of the Wnt Signaling Pathway.

Embryonic stem cells (ES cells) are characterized by their pluripotency and infinite proliferation potential. Ever since ES cells were first established in 1981, there have been a growing number of studies aimed at clinical applications of ES cells. In recent years, various types of differentiation inducement systems using ES cells have been established.

Wnt/β-catenin and kit signaling sequentially regulate melanocyte stem cell differentiation in UVB-induced epidermal pigmentation.

UV radiation is a well-known inducer of epidermal pigmentation that is utilized in therapy for vitiligo, one of the skin depigmentation disorders. Although it has been reported that melanocyte stem cells (McSCs) play essential roles in hair pigmentation, the relationship between McSCs and epidermal pigmentation remains unclear. Repetitive UVB irradiation on the dorsal skin of F1 mice of HR-1 × HR/De caused apparent epidermal pigmentation, and it was characterized by increase in the number of melanocytes.

Major amino acids in collagen hydrolysate regulate the differentiation of mouse embryoid bodies.

To take advantage of the therapeutic potential of embryonic stem cells (ESCs), it is necessary to regulate their differentiation in response to defined factors. In this study, in order to explore novel molecules that regulate the differentiation of ESCs, we investigated whether collagen hydrolysate, collagen-characteristic amino acids, glycine (Gly), l-proline and trans-4-hydroxy-l-proline (l-Hyp); or dipeptides, proline-hydroxyproline and hydroxyproline-glycine regulate the differentiation of mouse embryoid bodies (EBs). We identified that treatment with collagen hydrolysate or Gly repressed the expression of the mesendodermal markers, Brachyury and Foxa2 in EBs and maintained the undifferentiated state of mESCs in a feeder-free monolayer culture.

Bimodal effect of retinoic acid on melanocyte differentiation identified by time-dependent analysis.

Retinoic acid (RA) is considered to control melanocytes; however, its precise mechanism remains unclear because of a bimodal effect, which promotes or inhibits melanin synthesis depending on the cell type, culture condition of melanocytes and skin conditions. In this study, we examined the effects of RA throughout each stage of differentiation of melanocytes using a mouse embryonic stem cell culture system to induce melanocytes. The results showed that RA has significantly different effects depending on the stage of differentiation of melanocytes.

Melanocyte stem cells express receptors for canonical Wnt-signaling pathway on their surface.

It has been reported that melanocytes play important roles in skin and hair pigmentation and are differentiated from melanocyte stem cells (MSCs) residing in the bulge area of hair follicles. Recently, interest has been growing in MSCs because regulation of the upstream of differentiated melanocytes is essential for the determination of skin and hair pigmentation; however, their precise characteristics remain to be elucidated. The aim of this study is to explore cell-surface markers expressed on MSCs in order to understand their characteristics.