Transcription Factor CTIP2 Maintains Hair Follicle Stem Cell Pool and Contributes to Altered Expression of LHX2 and NFATC1

Developmental regulation of dermal adipose tissue by BCL11b

The distinct anatomic environment in which adipose tissues arise during organogenesis is a principle determinant of their adult expansion capacity. Metabolic disease results from a deficiency in hyperplastic adipose expansion within the dermal/subcutaneous depot; thus, understanding the embryonic origins of dermal adipose is imperative. Using single-cell transcriptomics throughout murine embryogenesis, we characterized cell populations, including Bcl11b + cells, that regulate the development of dermal white adipose tissue (dWAT). We discovered that BCL11b expression modulates the Wnt signaling microenvironment to enable adipogenic differentiation in the dermal compartment. Subcutaneous and visceral adipose arises from a distinct population of Nefl + cells during embryonic organogenesis, whereas Pi16 + /Dpp4 + fibroadipogenic progenitors support obesity-stimulated hypertrophic expansion in the adult. Together, these results highlight the unique regulatory pathways used by anatomically distinct adipose depots, with important implications for human metabolic disease.

Reprofiling synthetic glucocorticoid-induced leucine zipper fusion peptide as a novel and effective hair growth promoter

Hair is a biofilament with unique multi-dimensional values. In human, in addition to physiologic impacts, hair loss and hair related disorders can affect characteristic features, emotions, and social behaviors. Despite significant advancement, there is a dire need to explore alternative novel therapies with higher efficacy, less side effects and lower cost to promote hair growth to treat hair deficiency. Glucocorticoid-induced leucine zipper (GILZ) is a protein rapidly induced by glucocorticoids. Studies from our group and many others have suggested that a synthetic form of GILZ, TAT-GILZ, a fusion peptide of trans-activator of transcription and GILZ, can function as a potent regulator of inflammatory responses, re-establishing and maintaining the homeostasis. In this study, we investigate whether TAT-GILZ could promote and contribute to hair growth. For our pre-clinical model, we used 9-12 week-old male BALB/c and nude (athymic, nu/J) mice. We applied TAT-GILZ and/or TAT (vehicle) intradermally to depilated/hairless mice. Direct observation, histological examination, and Immunofluorescence imaging were used to assess the effects and compare different treatments. In addition, we tested two current treatment for hair loss/growth, finasteride and minoxidil, for optimal evaluation of TAT-GILZ in a comparative fashion. Our results showed, for the first time, that synthetic TAT-GILZ peptide accelerated hair growth on depilated dorsal skin of BALB/c and induced hair on the skin of athymic mice where hair growth was not expected. In addition, TAT-GILZ was able to enhance hair follicle stem cells and re-established the homeostasis by increasing counter inflammatory signals including higher regulatory T cells and glucocorticoid receptors. In conclusion, our novel findings suggest that reprofiling synthetic TAT-GILZ peptide could promote hair growth by increasing hair follicle stem cells and re-establishing homeostasis.

The Identification and Characteristics of miRNAs Related to Cashmere Fiber Traits in Skin Tissue of Cashmere Goats

microRNAs (miRNAs) are involved in the regulation of biological phenomena by down-regulating the expression of mRNAs. In this study, Liaoning cashmere (LC) goats (n = 6) and Ziwuling black (ZB) goats (n = 6) with different cashmere fiber production performances were selected. We supposed that miRNAs are responsible for the cashmere fiber trait differences. To test the hypothesis, the expression profiles of miRNAs from the skin tissue of the two caprine breeds were compared using small RNA sequencing (RNA-seq). A total of 1293 miRNAs were expressed in the caprine skin samples, including 399 known caprine miRNAs, 691 known species-conserved miRNAs, and 203 novel miRNAs. Compared with ZB goats, 112 up-regulated miRNAs, and 32 down-regulated miRNAs were found in LC goats. The target genes of the differentially expressed miRNAs were remarkably concentrated on some terms and pathways associated with cashmere fiber performance, including binding, cell, cellular protein modification process, and Wnt, Notch, and MAPK signaling pathways. The miRNA-mRNA interaction network found that 14 miRNAs selected may contribute to cashmere fiber traits regulation by targeting functional genes associated with hair follicle activities. The results have reinforced others leading to a solid foundation for further investigation of the influences of individual miRNAs on cashmere fiber traits in cashmere goats.

Integration of transcriptome sequencing and whole genome resequencing reveal candidate genes in egg production of upright and pendulous-comb chickens

Egg production performance plays an important role in the poultry industry across the world. Previous studies have shown a great difference in egg production performance between pendulous-comb (PC) and upright-comb (UC) chickens. However, there are no reports to identify potential candidate genes for egg production in PC and UC chickens. In the present study, 1,606 laying chickens were raised, and the egg laid by individual chicken was collected for 100 d. Moreover, the expression level of estrogen and progesterone hormones was measured at the start-laying and peak-laying periods of hens. Besides, 4 PC and 4 UC chickens were selected at 217 d of age to perform transcriptome sequencing (RNA-seq) and whole genome resequencing (WGS) to screen the potential candidate genes of egg production. The results showed that PC chicken demonstrated better egg production performance (P < 0.05) and higher estrogen and progesterone hormone expression levels than UC chicken (P < 0.05). RNA-seq analysis showed that 341 upregulated and 1,036 downregulated differentially expressed genes (DEGs) were identified in the ovary tissues of PC and UC chickens. These DEGs were mainly enriched in protein-related, lipid-related, and nucleic acids-related biological processes including ribosome, peptide biosynthetic process, lipid transport terms, and catalytic activity acting on RNA which can significantly affect egg production in chicken. The enrichment results of WGS analysis were consistent with RNA-seq. Further, joint analysis of WGS and RNA-seq data was utilized to screen 30 genes and CAMK1D, CLSTN2, MAST2, PIK3C2G, TBC1D1, STK3, ADGRB3, and PPARGC1A were identified as potential candidate genes for egg production in PC and UC chickens. In summary, our study provides a wealth of information for a better understanding of the genetic and molecular mechanism for the future breeding of PC and UC chickens for egg production.

Selective Ablation of BCL11A in Epidermal Keratinocytes Alters Skin Homeostasis and Accelerates Excisional Wound Healing In Vivo

Transcriptional regulator BCL11A plays a crucial role in coordinating a suite of developmental processes including skin morphogenesis, barrier functions and lipid metabolism. There is little or no reports so far documenting the role of BCL11A in postnatal adult skin homeostasis and in the physiological process of tissue repair and regeneration. The current study establishes for the first time the In Vivo role of epidermal BCL11A in maintaining adult epidermal homeostasis and as a negative regulator of cutaneous wound healing. Conditional ablation of Bcl11a in skin epidermal keratinocytes (Bcl11a^ep−/−mice) enhances the keratinocyte proliferation and differentiation program, suggesting its critical role in epidermal homeostasis of adult murine skin. Further, loss of keratinocytic BCL11A promotes rapid closure of excisional wounds both in a cell autonomous manner likely via accelerating wound re-epithelialization and in a non-cell autonomous manner by enhancing angiogenesis. The epidermis specific Bcl11a knockout mouse serves as a prototype to gain mechanistic understanding of various downstream pathways converging towards the manifestation of an accelerated healing phenotype upon its deletion.

The stem cell quiescence and niche signaling is disturbed in the hair follicle of the hairpoor mouse, an MUHH model mouse

BACKGROUND

Hair follicle stem cells (HFSC) play an essential role in the maintenance of hair homeostasis; during the hair cycle, HFSC remain quiescent for most of its duration. The hairpoor mouse (+ /Hr^Hp), an animal model of Marie-Unna hypotrichosis (MUHH), overexpresses hairless in the bulge, inner root sheath, and outer root sheath of HF and shows the same phenotype as in MUHH patients manifesting sparse hair with progression to alopecia with age. The aim of this study was to gain an understanding of the hair cycle and the status of HFSC during the hair cycle of the hairpoor mouse in order to delineate the pathogenesis of MUHH.

METHODS

H&E staining was performed in order to define the state of the hair follicle. FACS analysis and immunostaining were performed at the 1st and 2nd telogen stages for observation of the HFSC. A label retaining assay was performed to determine the quiescent state of hair follicles. qRT-PCR was performed to determine expression of factors involved in niche signaling and Wnt signaling.

RESULTS

We observed a drastic decrease in the number of hair follicles after the 1st telogen, followed by an intensified disturbance in the hair cycle with shorter anagen as well as 2nd telogen in the hairpoor mouse. A dramatic reduction in the number of CD34 expressing bulges as well as cells was observed at the telogen of the HFs, with prominent high proliferation of bulge cells, suggesting the loss of HFSC quiescence in the hairpoor mouse. The increased cell proliferation in HF was reiterated following the synchronization of the hair cycle, leading to acceleration of HF cycling. Reduced expression of Fgf18 and Bmp6, the factors involved in HFSC quiescence, was observed in the HFSC niche of the hairpoor mouse. In addition, disturbed expression of Wnt signaling molecules including Wnt7b, Wnt10b, and Sfrp1 was observed, which induced the telogen-to-anagen transition of HFs in the hairpoor mouse.

CONCLUSIONS

These results indicate that the quiescent state of HFSC is not properly maintained in the hairpoor mouse, consequently leading HFs to the completely disarrayed hair cycle. These findings may provide an understanding of an underlying mechanism for development of alopecia with age in MUHH patients.

Hair follicle-derived mesenchymal stem cells decrease alopecia areata mouse hair loss and reduce inflammation around the hair follicle

Background

Alopecia areata (AA) is a common autoimmune hair loss disease with increasing incidence. Corticosteroids are the most widely used for hair loss treatment; however, long-term usage of hormonal drugs is associated with various side effects. Mesenchymal stem cells (MSCs) therapy has been studied extensively to curb autoimmune diseases without affecting immunity against diseases.

Methods

Hair follicle-derived MSCs (HF-MSCs) were harvested from the waste material of hair transplants, isolated and expanded. The therapeutic effect of HF-MSCs for AA treatment was investigated in vitro AA-like hair follicle organ model and in vivo C3H/HeJ AA mice model.

Results

AA-like hair follicle organ in vitro model was successfully established by pre-treatment of mouse vibrissa follicles by interferon-γ (IFN-γ). The AA-like symptoms were relieved when IFN-γ induced AA in vitro model was co-cultured with HF-MSC for 2 days. In addition, when skin grafted C3H/HeJ AA mice models were injected with 10⁶ HF-MSCs once a week for 3 weeks, the transcription profiling and immunofluorescence analysis depicted that HF-MSCs treatment significantly decreased mouse hair loss and reduced inflammation around HF both in vitro and in vivo.

Conclusions

This study provides a new therapeutic approach for alopecia areata based on HF-MSCs toward its future clinical application.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02614-0.

Stem cell-intrinsic mechanisms regulating adult hair follicle homeostasis

Adult hair follicle stem cells (HFSCs) undergo dynamic and periodic molecular changes in their cellular states throughout the hair homeostatic cycle. These states are tightly regulated by cell-intrinsic mechanisms and by extrinsic signals from the microenvironment. HFSCs are essential not only for fuelling hair growth, but also for skin wound healing. Increasing evidence suggests an important role of HFSCs in organizing multiple skin components around the hair follicle, thus functioning as an organizing centre during adult skin homeostasis. Here, we focus on recent findings on cell-intrinsic mechanisms of HFSC homeostasis, which include transcription factors, histone modifications, DNA regulatory elements, non-coding RNAs, cell metabolism, cell polarity and post-transcriptional mRNA processing. Several transcription factors are now known to participate in well-known signalling pathways that control hair follicle homeostasis, as well as in super-enhancer activities to modulate HFSC and progenitor lineage progression. Interestingly, HFSCs have been shown to secrete molecules that are important in guiding the organization of several skin components around the hair follicle, including nerves, arrector pili muscle and vasculature. Finally, we discuss recent technological advances in the field such as single-cell RNA sequencing and live imaging, which revealed HFSC and progenitor heterogeneity and brought new light to understanding crosstalking between HFSCs and the microenvironment. The field is well on its way to generate a comprehensive map of molecular interactions that should serve as a solid theoretical platform for application in hair and skin disease and ageing.

Bcl11b/Ctip2 in Skin, Tooth, and Craniofacial System

Ctip2/Bcl11b is a zinc finger transcription factor with dual action (repression/activation) that couples epigenetic regulation to gene transcription during the development of various tissues. It is involved in a variety of physiological responses under healthy and pathological conditions. Its role and mechanisms of action are best characterized in the immune and nervous systems. Furthermore, its implication in the development and homeostasis of other various tissues has also been reported. In the present review, we describe its role in skin development, adipogenesis, tooth formation and cranial suture ossification. Experimental data from several studies demonstrate the involvement of Bcl11b in the control of the balance between cell proliferation and differentiation during organ formation and repair, and more specifically in the context of stem cell self-renewal and fate determination. The impact of mutations in the coding sequences of Bcl11b on the development of diseases such as craniosynostosis is also presented. Finally, we discuss genome-wide association studies that suggest a potential influence of single nucleotide polymorphisms found in the 3’ regulatory region of Bcl11b on the homeostasis of the cardiovascular system.

Transcription Factor CTIP1/ BCL11A Regulates Epidermal Differentiation and Lipid Metabolism During Skin Development

The epidermal permeability barrier (EPB) prevents organisms from dehydration and infection. The transcriptional regulation of EPB development is poorly understood. We demonstrate here that transcription factor COUP-TF-interacting protein 1 (CTIP1/BCL11A; hereafter CTIP1) is highly expressed in the developing murine epidermis. Germline deletion of Ctip1 (Ctip1^−/−) results in EPB defects accompanied by compromised epidermal differentiation, drastic reduction in profilaggrin processing, reduced lamellar bodies in granular layers and significantly altered lipid composition. Transcriptional profiling of Ctip1^−/− embryonic skin identified altered expression of genes encoding lipid-metabolism enzymes, skin barrier-associated transcription factors and junctional proteins. CTIP1 was observed to interact with genomic elements within the regulatory region of the gene encoding the differentiation-associated gene, Fos-related antigen2 (Fosl2) and lipid-metabolism-related gene, Fatty acid elongase 4 (Elvol4), and the expression of both was altered in Ctip1^−/− mice. CTIP1 appears to play a role in EPB establishment of via direct or indirect regulation of a subset of genes encoding proteins involved in epidermal differentiation and lipid metabolism. These results identify potential, CTIP1-regulated avenues for treatment of skin disorders involving EBP defects.