Expression of miRNA-1-3p and its target gene in hair follicle cycle development of Liaoning Cashmere goat

MicroRNA exerts an important regulatory role in almost all the biological process, including hair follicle development in Liaoning Cashmere goat. In order to improve the Cashmere performance of goat, the regulatory role of microRNA in hair follicle cycle has drawn hotspot attention. However, the molecular mechanisms of miRNA-1-3p involved in hair follicle development are poorly understood. In this study, we found that miRNA-1-3p was less expressed in anagen stage of hair follicle cycle of Cashmere goat than that in telogen stage by using RT-qPCR and immunoblotting analysis, in contrast to the expression pattern of FGF14. The Dual-Luciferase reporter assay was employed to verify the relationship between miRNA-1-3p and FGF14. The results showed that miRNA-1-3p specifically binds to the 3'UTR of FGF14 mRNA, and FGF14 is the target gene of miR-1-3p. In conclusion, this study shows that miRNA-1-3p may regulate hair follicle development in Liaoning Cashmere goats by targeting FGF14.

Gender-Difference in Hair Length as Revealed by Crispr-Based Production of Long-Haired Mice with Dysfunctional FGF5 Mutations

Fibroblast growth factor 5 (FGF5) is an important molecule required for the transition from anagen to catagen phase of the mammalian hair cycle. We previously reported that Syrian hamsters harboring a 1-bp deletion in the Fgf5 gene exhibit excessive hair growth in males. Herein, we generated Fgf5 mutant mice using genome editing via oviductal nucleic acid delivery (GONAD)/improved GONAD (i-GONAD), an in vivo genome editing system used to target early embryos present in the oviductal lumen, to study gender differences in hair length in mutant mice. The two lines (Fgf5go-malc), one with a 2-bp deletion (c.552_553del) and the other with a 1-bp insertion (c.552_553insA) in exon 3 of Fgf5, were successfully established. Each mutation was predicted to disrupt a part of the FGF domain through frameshift mutation (p.Glu184ValfsX128 or p.Glu184ArgfsX128). Fgf5go-malc1 mice had heterogeneously distributed longer hairs than wild-type mice (C57BL/6J). Notably, this change was more evident in males than in females (p < 0.0001). Immunohistochemical analysis revealed the presence of FGF5 protein in the dermal papilla and outer root sheath of the hair follicles from C57BL/6J and Fgf5go-malc1 mice. Histological analysis revealed that the prolonged anagen phase might be the cause of accelerated hair growth in Fgf5go-malc1 mice.

Cucurbitacin promotes hair growth in mice by inhibiting the expression of fibroblast growth factor 18

BACKGROUND

The inhibition of fibroblast growth factor 18 (FGF18) promotes the transition of hair follicles (HFs) from the telogen phase to the anagen phase. Cucurbitacin has been shown to have a good effect in promoting hair cell growth. This study explored the potential effect of cucurbitacin on hair growth and its effect on FGF18 expression in mice.

METHODS

Male C57BL/6J mice were randomly divided into the following two groups: (I) the vehicle group; and (II) the cucurbitacin group. Matrix cream and cucurbitacin cream were applied to the depilated skin on the back of the vehicle group mice and the cucurbitacin group mice, respectively. On days 3, 6, 9, 12, 15, and 18, the hair growth in the depilated dorsal skin of the mice was recorded with a digital camera and a HF detector, and the HF cycle status of the mice was observed by hematoxylin and eosin (H&E) staining. In addition, the level of FGF18 messenger ribonucleic acid (mRNA) in the dorsal skin was measured on days 15 and 18 by quantitative real-time polymerase chain reaction (qRT-PCR), while the level of FGF18 protein was measured by western blot and immunofluorescence staining.

RESULTS

The dorsal skin to which the cucurbitacin cream was applied began to darken on day 6 and grew hairs on day 9, which was 3 days earlier than the dorsal skin to which the matrix cream was applied. The H&E staining revealed a transition from the telogen phase to the anagen phase 3 days earlier for the cucurbitacin cream-treated skin than the matrix cream-treated skin. In addition, the skin treated with cucurbitacin cream also showed a significant decrease in FGF18 mRNA as seen by qRT-PCR, and reduced FGF18 protein levels as detected by western blot and immunofluorescence staining compared to the skin treated with matrix cream only.

CONCLUSIONS

Cucurbitacin significantly reduced the levels of FGF18 mRNA and protein in the dorsal skin of mice to accelerate the HFs to enter the anagen phase earlier, thereby promoting the regeneration of hair. Thus, cucurbitacin can be considered a new and valuable agent for the development of anti-hair loss products.

DNA Methylation Mediates lncRNA2919 Regulation of Hair Follicle Regeneration

Hair follicles (HFs) are organs that periodically regenerate during the growth and development of mammals. Long non-coding RNAs (lncRNAs) are non-coding RNAs with crucial roles in many biological processes. Our previous study identified that lncRNA2919 is highly expressed in catagen during the HF cycle. In this study, the in vivo rabbit model was established using intradermal injection of adenovirus-mediated lncRNA2919. The results showed that lncRNA2919 decreased HF depth and density and contributed to HF regrowth, thereby indicating that lncRNA2919 plays a negative role in HF regeneration. Moreover, methylation levels of the lncRNA2919 promoter at different HF cycle stages were detected through bisulfite sequencing. The key CpG site that negatively correlates with lncRNA2919 expression during the HF cycle was identified. 5-Aza-dc-induced demethylation upregulated lncRNA2919 expression, and the core promoter region of lncRNA2919 was verified on the basis of luciferase activity. Furthermore, we found that DNA methylation could prevent the binding of EGR1 to the lncRNA2919 promoter region, thereby affecting the transcriptional expression of lncRNA2919. Collectively, DNA methylation inhibits the transcriptional expression of lncRNA2919, which plays a vital role in the HF cycle and HF regrowth. These findings contribute to the basic theory of epigenetics in HF biology and provide references for further research in HF disease treatment and animal wool production.

Suppression of FGF5 and FGF18 Expression by Cholesterol-Modified siRNAs Promotes Hair Growth in Mice

FGF5 and FGF18 are key factors in the regulation of the hair follicle cycle. FGF5 is overexpressed during the late anagen phase and serves as a crucial regulatory factor that promotes the anagen-to-catagen transition in the hair follicle cycle. FGF18, which is overexpressed during the telogen phase, mainly regulates the hair follicle cycle by maintaining the telogen phase and inhibiting the entry of hair follicles into the anagen phase. The inhibition of FGF5 may prolong the anagen phase, whereas the inhibition of FGF18 may promote the transition of the hair follicles from the telogen phase to the anagen phase. In the present study, we used siRNA to suppress FGF5 or FGF18 expression as a way to inhibit the activity of these genes. Using qPCR, we showed that FGF5-targeting siRNA modified by cholesterol was more effective than the same siRNA bound to a cell-penetrating peptide at suppressing the expression of FGF5 both in vitro and in vivo. We then investigated the effects of the cholesterol-modified siRNA targeting either FGF5 or FGF18 on the hair follicle cycle in a depilated area of the skin on the back of mice. The cholesterol-modified siRNA, delivered by intradermal injection, effectively regulated the hair follicle cycle by inhibiting the expression of FGF5 and FGF18. More specifically, intradermal injection of a cholesterol-modified FGF5-targeted siRNA effectively prolonged the anagen phase of the hair follicles, whereas intradermal injection of the cholesterol-modified FGF18-targeted siRNA led to the mobilization of telogen follicles to enter the anagen phase earlier. The inhibitory effect of the cholesterol-modified FGF18-targeted siRNA on FGF18 expression was also evaluated for a topically applied siRNA. Topical application of a cream containing the cholesterol-modified FGF18-targeted siRNA on a depilated area of the skin of the back of mice revealed comparable inhibition of FGF18 expression with that observed for the same siRNA delivered by intradermal injection. These findings suggested that alopecia could be prevented and hair regrowth could be restored either through the intradermal injection of cholesterol-modified siRNA targeting FGF5 or FGF18 or the topical application of FGF18 siRNA.

Effects of UV Induced-Photoaging on the Hair Follicle Cycle of C57BL6/J Mice

Purpose

To study the changes in the hair follicle cycle and related stem cells induced by photoaging to establish a mouse model of senescence in hair follicles.

Methods

There were 54 C57BL6/J mice randomly divided into three groups. The UVA group and the UVB group underwent photoaging induced by UV lamps for 8 weeks. Changes in skin and the hair follicle cycle were compared by physical signs, dermoscopy, and hematoxylin and eosin and Masson's staining in each group. Western blot, immunohistochemistry, and RT-qPCR were carried out to test canonical proteins and gene expression of the Wnt signaling pathway in the samples. Immunofluorescence was chosen to show variations in the stem cells related to the hair follicle cycle.

Results

There were more gray hairs in the UVA group than the other groups (P<0.05). Both diameter of the hair shaft and depth of hair root were significantly decreased in the UV groups (P<0.05). Stem cells and melanocytes of the hair follicles were reduced in the UVA group. UV, especially UVB, up-regulated the expression of the Wnt signaling pathway and prolonged anagen and telogen phases in the hair follicles, compared with the control group (P<0.05).

Conclusion

By decreasing the number of stem cells related to hair follicles, UVA induces hair follicle photoaging characterized by hair follicle miniaturization and gray hairs. UV up-regulated the expression of the Wnt signaling pathway, and the hair follicle cycle was significantly prolonged by UVB.

Identification of Key Pathways and Genes Related to the Development of Hair Follicle Cycle in Cashmere Goats

The development of hair follicle in cashmere goats shows significant periodic change, as with mice and humans. However, for cashmere goat with double-coat, the periodic change may be due to other regulatory molecules and signal pathways. To understand the mechanism of periodic development of hair follicle, we performed a weighted gene coexpression network analysis (WGCNA) to mine key genes and establish an interaction network by utilizing the NCBI public dataset. Ten coexpression modules, including 7689 protein-coding genes, were constructed by WGCNA, six of which are considered to be significantly related to the development of the hair follicle cycle. A functional enrichment analysis for each model showed that they are closely related to ECM- receptor interaction, focal adhesion, PI3K-Akt signaling pathway, estrogen signaling pathway, and so on. Combined with the analysis of differential expressed genes, 12 hub genes from coexpression modules were selected as candidate markers, i.e., COL1A1, C1QTNF6, COL1A2, AQP3, KRTAP3-1, KRTAP11-1, FA2H, NDUFS5, DERL2, MRPL14, ANTKMT and XAB2, which might be applied to improve cashmere production.

Participation of Somatic Stem Cells, Labeled by a Unique Antibody (A3) Recognizing both N-glycan and Peptide, to Hair Follicle Cycle and Cutaneous Wound Healing in Rats

A monoclonal antibody (A3) was generated by using rat malignant fibrous histiocytoma (MFH) cells as the antigen. Generally, MFH is considered to be a sarcoma derived from undifferentiated mesenchymal cells. Molecular biological analyses using the lysate of rat MFH cells revealed that A3 is a conformation specific antibody recognizing both N-glycan and peptide. A3-labeled cells in bone marrow were regarded as somatic stem cells, because the cells partly coexpressed CD90 and CD105 (both immature mesenchymal markers). In the hair follicle cycle, particularly the anagen, the immature epithelial cells (suprabasal cells) near the bulge and some immature mesenchymal cells in the disassembling dermal papilla and regenerating connective tissue sheath/hair papilla reacted to A3. In the cutaneous wound-healing process, A3-labeled epithelial cells participated in re-epithelialization in the wound bed, and apparently, the labeled cells were derived from the hair bulge; in addition, A3-labeled immature mesenchymal cells in the connective tissue sheath of hair follicles at the wound edge showed the expansion of the A3 immunolabeling. A3-labeled immature epithelial and mesenchymal cells contributed to morphogenesis in the hair cycle and tissue repair after a cutaneous wound. A3 could become a unique antibody to identify somatic stem cells capable of differentiating both epithelial and mesenchymal cells in rat tissues.

TGF-β and HSP70 profiles during transformation of yak hair follicles from the anagen to catagen stage

Transforming growth factor-β (TGF-β) and heat shock protein 70 (HSP70) are important for the hair follicle (HF) cycle, but it is unclear whether they participate in HF regression in yak skin. In this study, we investigated the role of TGF-β, TGF-βRII, and HSP70 in the transition from anagen to catagen of HFs. The results showed that TGF-β2 transcription was significantly higher than that of TGF-β1 and TGF-β3 in the same periods. Meanwhile, the expressions of TGF-β2, TGF-βRII, and caspase-3 were higher in the catagen phase than that in mid-anagen, and some TGF-βRII-positive HF cells were terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL)-positive. Moreover, the HSP70 protein levels in mid-anagen were higher than those in late-anagen and catagen. These results suggested that TGF-β2 plays a major role in catagen induction in yak HFs, which might be achieved via TGF-βRII-mediated apoptosis in HF epithelial cells. In contrast, HSP70 might protect epithelial cells from apoptosis and ultimately inhibit HF regression. In conclusion, TGF-β2 has positive effects, whereas HSP70 has negative effects, on catagen induction.

Systematic Analysis of Non-coding RNAs Involved in the Angora Rabbit (Oryctolagus cuniculus) Hair Follicle Cycle by RNA Sequencing

The hair follicle (HF) cycle is a complicated and dynamic process in mammals, associated with various signaling pathways and gene expression patterns. Non-coding RNAs (ncRNAs) are RNA molecules that are not translated into proteins but are involved in the regulation of various cellular and biological processes. This study explored the relationship between ncRNAs and the HF cycle by developing a synchronization model in Angora rabbits. Transcriptome analysis was performed to investigate ncRNAs and mRNAs associated with the various stages of the HF cycle. One hundred and eleven long non-coding RNAs (lncRNAs), 247 circular RNAs (circRNAs), 97 microRNAs (miRNAs), and 1,168 mRNAs were differentially expressed during the three HF growth stages. Quantitative real-time PCR was used to validate the ncRNA transcriptome analysis results. Gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses provided information on the possible roles of ncRNAs and mRNAs during the HF cycle. In addition, lncRNA-miRNA-mRNA and circRNA-miRNA-mRNA ceRNA networks were constructed to investigate the underlying relationships between ncRNAs and mRNAs. LNC_002919 and novel_circ_0026326 were found to act as ceRNAs and participated in the regulation of the HF cycle as miR-320-3p sponges. This research comprehensively identified candidate regulatory ncRNAs during the HF cycle by transcriptome analysis, highlighting the possible association between ncRNAs and the regulation of hair growth. This study provides a basis for systematic further research and new insights on the regulation of the HF cycle.

The Role of Immature and Mature Adipocytes in Hair Cycling

Hair follicles (HFs) strongly interact with adipocytes within the dermal white adipose tissue (dWAT), suggesting a strong physiological dependence on the content of immature and mature adipocytes in this layer. This content is regulated by the proliferation and differentiation of adipocyte precursors, as well as by dedifferentiation of mature existing adipocytes. Spatially, long-range interactions between HFs and dWAT involve the exchange of extracellular vesicles which are differentially released by precursors, preadipocytes, and mature adipocytes. Different exogenous factors, including light irradiation, are likely to modify the release of adipocyte-derived exosomes in dWAT, which can lead to aberrations of the HF cycle. Consequently, dWAT should be considered as a potential target for the modulation of hair growth.

Bimodal behaviour of interfollicular epidermal progenitors regulated by hair follicle position and cycling

Interfollicular epidermal (IFE) homeostasis is a major physiological process allowing maintenance of the skin barrier function. Despite progress in our understanding of stem cell populations in different hair follicle compartments, cellular mechanisms of IFE maintenance, in particular, whether a hierarchy of progenitors exists within this compartment, have remained controversial. We here used multicolour lineage tracing with Brainbow transgenic labels activated in the epidermis to track individual keratinocyte clones. Two modes of clonal progression could be observed in the adult murine dorsal skin. Clones attached to hair follicles showed rapid increase in size during the growth phase of the hair cycle. On the other hand, clones distant from hair follicles were slow cycling, but could be mobilized by a proliferative stimulus. Reinforced by mathematical modelling, these data support a model where progenitor cycling characteristics are differentially regulated in areas surrounding or away from growing hair follicles. Thus, while IFE progenitors follow a non-hierarchical mode of development, spatiotemporal control by their environment can change their potentialities, with far-reaching implications for epidermal homeostasis, wound repair and cancer development.

Expression of decorin throughout the murine hair follicle cycle: hair cycle dependence and anagen phase prolongation

Decorin is a prototypical member of the small leucine-rich proteoglycan (SLRP) family, which is involved in numerous biological processes. The role of decorin, as a representative SLRP, in hair follicle morphogenesis has not been elucidated. We present our initial findings on decorin expression patterns during induced murine hair follicle (HF) cycles. It was found that decorin expression is exclusively restricted to the epidermis, outer root sheath and sebaceous glands during the anagen phase, which correlates with the upregulation of decorin mRNA and protein expression in depilated murine dorsal skin. Furthermore, we used a functional approach to investigate the effects of recombinant human decorin (rhDecorin) via cutaneous injection into HFs at various murine hair cycle stages. The local injection of rhDecorin (100 μg/ml) into the hypodermis of depilated C57BL/6 mice at anagen delayed catagen progression. In contrast, rhDecorin injection during the telogen phase caused the premature onset of anagen, as demonstrated by the assessment of the following parameters: (i) hair shaft length, (ii) follicular bulbar diameter, (iii) hair follicle cycling score and (iv) follicular phase percentage. Taken together, our results suggest that decorin may modulate follicular cycling and morphogenesis. In addition, this study also provides insight into the molecular control mechanisms governing hair follicular epithelial-mesenchymal interactions.

Cyclosporine A increases hair follicle growth by suppressing apoptosis-inducing factor nuclear translocation: a new mechanism

Cyclosporine A (CsA) enhances hair growth through caspase-dependent pathways by retarding anagen-to-catagen phase transition in the hair follicle growth cycle. Whether apoptosis-inducing factor (AIF), a protein that induces caspase-independent apoptosis, can regulate the hair follicle cycle in response to CsA is currently unclear. Here, we show that the pro-hair growth properties of CsA are in part due to blockage of AIF nuclear translocation. We first isolate hair follicles from murine dorsal skin. We then used Western blot, immunohistochemistry and immunofluorescence to evaluate the expression and localization of AIF in hair follicles. We also determined whether modulation of AIF was responsible for the effects of CsA at the anagen-to-catagen transition. AIF was expressed in hair follicles during the anagen, catagen and telogen phases. There was significant nuclear translocation of AIF as hair follicles transitioned from anagen to late catagen phase; this was inhibited by CsA, likely due to reduced cyclophilin A expression and attenuated AIF release from mitochondria. However, we note that AIF translocation was not completely eliminated, which likely explains why the transition to catagen phase was severely retarded by CsA, rather than being completely inhibited. We speculate that blockade of the AIF signalling pathway is a critical event required for CsA-dependent promotion of hair growth in mice. The study of AIF-related signalling pathways may provide insight into hair diseases and suggest potential novel therapeutic strategies.

Eiger triggers death from afar

Cells undergoing programmed cell death release signals that can trigger the death of cells at remote locations.

Apoptotic cells can induce non-autonomous apoptosis through the TNF pathway

Apoptotic cells can produce signals to instruct cells in their local environment, including ones that stimulate engulfment and proliferation. We identified a novel mode of communication by which apoptotic cells induce additional apoptosis in the same tissue. Strong induction of apoptosis in one compartment of the Drosophila wing disc causes apoptosis of cells in the other compartment, indicating that dying cells can release long-range death factors. We identified Eiger, the Drosophila tumor necrosis factor (TNF) homolog, as the signal responsible for apoptosis-induced apoptosis (AiA). Eiger is produced in apoptotic cells and, through activation of the c-Jun N-terminal kinase (JNK) pathway, is able to propagate the initial apoptotic stimulus. We also show that during coordinated cell death of hair follicle cells in mice, TNF-α is expressed in apoptotic cells and is required for normal cell death. AiA provides a mechanism to explain cohort behavior of dying cells that is seen both in normal development and under pathological conditions.

DOI:http://dx.doi.org/10.7554/eLife.01004.001

The tissues of developing organisms can be shaped by apoptosis, a form of regulated cell killing. Although this process can occur in individual cells, apoptotic signals may also dictate the ‘communal death’ of many cells simultaneously. This occurs frequently in animal development: in human fetuses, for example, cells in the hand are directed to die to remove webbing between the fingers.

Apoptosis has been thought to resemble a form of silent suicide by cells, but more recent work suggests that apoptotic cells can also transmit signals. Now, Pérez-Garijo et al. find that these cells can stimulate other cells to die in both fruit flies and mice.

In fruit flies, apoptosis is activated by proteins known as Grim, Hid and Reaper. To explore whether apoptotic cells could communicate with other cells, Pérez-Garijo et al. created ‘undead’ cells in which one of these proteins was turned on, but other downstream proteins (that are responsible for the cellular execution phase of apoptosis) had been turned off: these cells were undergoing apoptosis, but could not complete the process and die.

Strikingly, undead cells in the posterior (back) region of the wing imaginal disc—the tissue in the larva that gives rise to the wing in the adult fruit fly—could trigger apoptosis in cells in the anterior (front) half. Pérez-Garijo et al. found that the JNK pathway activated apoptosis in anterior cells. In fruit flies, the Eiger protein turns on this pathway; when Eiger was absent from posterior cells in the wing imaginal disc, apoptosis in anterior cells ceased, indicating that Eiger might signal at long range.

Eiger is related to a protein called TNF that has been implicated in cycles of destruction and renewal of hair follicles in mice. Pérez-Garijo et al. found that TNF is produced by apoptotic cells in hair follicles, and that blocking TNF inhibits the death of other cells in the same cohort: this suggests that a common mechanism could regulate the communal death of cells in flies and mammals. These studies therefore shed light on a conserved pathway in the modulation of tissue development.

DOI:http://dx.doi.org/10.7554/eLife.01004.002