Nuclear localization of Meis1 in dermal papilla promotes hair matrix cell proliferation in the anagen phase of hair cycle

Interpretation of the Yak Skin Single-Cell Transcriptome Landscape

The morphogenesis of hair follicle structure is accompanied by the differentiation of skin tissue. Mammalian coats are produced by hair follicles. The formation of hair follicles requires signal transmission between the epidermis and dermis. However, knowledge of the transcriptional regulatory mechanism is still lacking. We used single-cell RNA sequencing to obtain 26,573 single cells from the scapular skin of yaks at hair follicle telogen and anagen stages. With the help of known reference marker genes, 11 main cell types were identified. In addition, we further analyzed the DP cell and dermal fibroblast lineages, drew a single-cell map of the DP cell and dermal fibroblast lineages, and elaborated the key genes, signals, and functions involved in cell fate decision making. The results of this study provide a very valuable resource for the analysis of the heterogeneity of DP cells and dermal fibroblasts in the skin and provide a powerful theoretical reference for further exploring the diversity of hair follicle cell types and hair follicle morphogenesis.

Double mutation of claudin‐1 and claudin‐3 causes alopecia in infant mice

Hair follicles (HFs) undergo cyclic phases of growth, regression, and rest in association with hair shafts to maintain the hair coat. Nonsense mutations in the tight junction protein claudin (CLDN)-1 cause hair loss in humans. Therefore, we evaluated the roles of CLDNs in hair retention. Among the 27 CLDN family members, CLDN1, CLDN3, CLDN4, CLDN6, and CLDN7 were expressed in the inner bulge layer, isthmus, and sebaceous gland of murine HFs. Hair phenotypes were observed in Cldn1 weaker knockdown and Cldn3-knockout (Cldn1^Δ/Δ Cldn3^-/- ) mice. Although hair growth was normal, Cldn1^Δ/Δ Cldn3^-/- mice showed striking hair loss in the first telogen. Simultaneous deficiencies in CLDN1 and CLDN3 caused abnormalities in telogen HFs, such as an aberrantly layered architecture of epithelial cell sheets in bulges with multiple cell layers, mislocalization of bulges adjacent to sebaceous glands, and dilated hair canals. Along with the telogen HF abnormalities, which shortened the hair retention period, there was an enhanced proliferation of the epithelium surrounding HFs in Cldn1^Δ/Δ Cldn3^-/- mice, causing accelerated hair regrowth in adults. Our findings suggested that CLDN1 and CLDN3 may regulate hair retention in infant mice by maintaining the appropriate layered architecture of HFs, a deficiency of which can lead to alopecia.

Meis1 Controls the Differentiation of Eye Progenitor Cells and the Formation of Posterior Poles during Planarian Regeneration

As a member of TALE family, Meis1 has been proven to regulate cell proliferation and differentiation during cell fate commitment; however, the mechanism is still not fully understood. The planarian, which has an abundance of stem cells (neoblasts) responsible for regenerating any organ after injury, is an ideal model for studying the mechanisms of tissue identity determination. Here, we characterized a planarian homolog of Meis1 from the planarian Dugesia japonica. Importantly, we found that knockdown of DjMeis1 inhibits the differentiation of neoblasts into eye progenitor cells and results in an eyeless phenotype with normal central nervous system. Furthermore, we observed that DjMeis1 is required for the activation of Wnt signaling pathway by promoting the Djwnt1 expression during posterior regeneration. The silencing of DjMeis1 suppresses the expression of Djwnt1 and results in the inability to reconstruct posterior poles. In general, our findings indicated that DjMeis1 acts as a trigger for the activation of eye and tail regeneration by regulating the differentiation of eye progenitor cells and the formation of posterior poles, respectively.

Dexpanthenol Promotes Cell Growth by Preventing Cell Senescence and Apoptosis in Cultured Human Hair Follicle Cells

Dexpanthenol (D-panthenol) is a precursor of vitamin B5 (pantothenic acid) and is widely used for dietary supplements and topical applications. D-panthenol has long been used in hair care products for the purpose of anti-hair loss, its effects and the underlying mechanisms, however, were barely reported. In this study, the effects of D-panthenol on human hair follicle cells, including dermal papilla cells (hDPCs) and outer root sheath cells (hORSCs), were investigated. D-panthenol enhanced the cell viability, increasing the cellular proliferation marker Ki67 in cultured hDPCs. The markers for apoptosis (Caspase3/9) and cell senescence (p21/p16), reported to be expressed in aged or resting phase follicles, were significantly reduced by D-panthenol. Anagen-inducing factors (ALP; β-catenin; versican), which trigger or elongate the anagen phase, were stimulated by D-panthenol. On the other hand, D-panthenol reduced TGF-β1 expressions in both mRNA and protein levels. The expression of VEGF, which is important for peripheral blood vessel activation; was up-regulated by D-panthenol treatment. In cultured hORSCs, cell proliferation and viability were enhanced, while the mRNA expression of cell senescence markers (p21/p16) was significantly down-regulated. The expressions of both VEGF and its receptor (VEGFR) were up-regulated by D-panthenol. In conclusion, our data suggest that the hair growth stimulating activity of D-panthenol was exerted by increasing the cell viability, suppressing the apoptotic markers, and elongating the anagen phase in hair follicles.

Cultivation of Hair Matrix Cells from Cashmere Goat Skins and Exemplified Applications

Simple Summary

A large scale of sequencing data pertaining to cashmere growth on cashmere goats have not been cost-effectively used due to the lack of in vitro cellular models, especially for hair matrix cells (HMCs)—the precursors of hair-forming keratinocytes, causing an enormous waste of data resources. Herein, we successfully isolated and cultivated previously unreported HMCs from cashmere goat skins and identified them morphologically and molecularly via their distinct appearance and signature genes’ expression from spatially adjacent dermal papilla cells. Through monitoring the effects of calcium and all-trans retinoic acid on HMCs using various biological techniques, we displayed that the cells are useful models to explore unsolved issues in hair fiber growth on goats. Therefore, our present success paves the road for further utilizing currently deposited data to unveil the secrets of cashmere growth and, ultimately, improve the quantity and quality of animal fibers.

Abstract

A functional interpretation of filtered candidates and predicted regulatory pathways related to cashmere growth from sequencing trials needs available cell models, especially for hair matrix cells (HMCs), whose continual proliferation and differentiation result in rapid hair growth. To fulfill such goals, we herein obtained primary goat HMCs via a microdissection-based method; optimized the selection of the culture medium and coating substances for better cell maintenance; and exemplified their usefulness through examining the effects of calcium and all-trans retinoic acid (ATRA) on cells using immunoblotting, flow cytometry, and other techniques. As a result, we successfully acquired primary and passaged goat HMCs with typical keratinocyte morphology. Calcium-free RPMI (Roswell Park Memorial Institute) 1640 and MEM (minimum Eagle’s medium) outperformed normal DMEM/F12 (Dulbecco’s modified Eagle’s medium/Nutrient Mixture F-12) on long-term cell maintenance, whereas serum-free media K-SFM and EpiLife failed to support cell growth. HMCs differed molecularly and morphologically from their neighbor dermal papilla cells on expressions of feature genes, such as HOXC13, and on characteristic keratinocyte-like appearances versus fibroblast shapes, respectively. Higher calcium concentrations significantly stimulated the expression of the genes (e.g., KRT1 and IVL) involved in keratinocyte differentiation and, promoted cell proliferation. Moreover, 10⁻⁵ M ATRA obviously boosted goat HMC expansions and changed their cell cycle distributions compared to the controls. Our study shines a light on researches exploring the mechanisms underlying the growth of cashmere.

Thymosin β4 Identified by Transcriptomic Analysis from HF Anagen to Telogen Promotes Proliferation of SHF-DPCs in Albas Cashmere Goat

Increasing cashmere yield is one of the important goals of cashmere goat breeding. To achieve this goal, we screened the key genes that can improve cashmere performance. In this study, we used the RNA raw datasets of the skin and dermal papilla cells of secondary hair follicle (SHF-DPCs) samples of hair follicle (HF) anagen and telogen of Albas cashmere goats and identified a set of significant differentially expressed genes (DEGs). To explore potential associations between gene sets and SHF growth features and to identify candidate genes, we detected functional enrichment and constructed protein-protein interaction (PPI) networks. Through comprehensive analysis, we selected Thymosin β4 (Tβ4), Rho GTPase activating protein 6 (ARHGAP6), ADAM metallopeptidase with thrombospondin type 1 motif 15, (ADAMTS15), Chordin (CHRD), and SPARC (Osteonectin), cwcv and kazal-like domains proteoglycan 1 (SPOCK1) as candidate genes. Gene set enrichment analysis (GSEA) for these genes revealed Tβ4 and ARHGAP6 have a close association with the growth and development of SHF-DPCs. However, the expression of Tβ4 in the anagen was higher than that in the telogen, so we finally chose Tβ4 as the ultimate research object. Overexpressing Tβ4 promoted and silencing Tβ4 inhibited the proliferation of SHF-DPCs. These findings suggest that Tβ4 can promote the growth and development of SHF-DPCs and indicate that this molecule may be a valuable target for increasing cashmere production.