Stages Of Hair Follicle Cycle Research Articles

Autophagy induces hair follicle stem cell activation and hair follicle regeneration by regulating glycolysis

BackgroundHair follicle stem cells (HFSCs) typically remain quiescent and are activated only during the transition from telogen to anagen to ensure that the hair follicle enters a new cycle. The metabolic behavior of stem cells in tissues is regulated by macroautophagy/autophagy, and changes in HFSC metabolism directly affect their activation and maintenance. However, the role of autophagy in the regulation of HFSC metabolism and function remains unclear.MethodsBack skin samples were obtained from mice at different hair follicle cycle stages, and immunofluorescence staining was used to monitor autophagy in HFSCs. Mouse and human hair follicles were treated with rapamycin (Rapa, an autophagy activator) or 3-methyladenine (3-MA, an autophagy inhibitor). The effects of autophagy on the hair follicle cycle and HFSC were investigated by imaging, cell proliferation staining, and HFSC-specific marker staining. The influence and mechanism of autophagy on HFSC metabolism were explored using RNA sequencing, real-time polymerase chain reaction, immunohistochemical staining, and detection of lactate and glucose concentrations. Finally, the influence of autophagy-induced glycolysis on HFSC and the hair follicle cycle was verified by stem cell characteristics and in vivo functional experiments.ResultsAutophagy in HFSC was highest during the transition from telogen to anagen. Inhibiting autophagy with 3-MA led to early entry into catagen and prolonged telogen, whereas Rapa promoted autophagy and hair growth. Autophagy activated HFSC by increasing the expression and activity of HFSC lactate dehydrogenase (Ldha), thereby transforming HFSC metabolism into glycolysis. Inhibition of Ldha expression counteracted the effects of autophagy.ConclusionsAutophagy activated HFSC by promoting the transition from HFSC metabolism to glycolysis, ultimately initiating the hair follicle cycle and promoting hair growth.Graphical

Transcriptome-based selection and validation of optimal house-keeping genes for skin research in goats (Capra hircus)

BackgroundIn quantitative real-time polymerase chain reaction (qRT-PCR) experiments, accurate and reliable target gene expression results are dependent on optimal amplification of house-keeping genes (HKGs). RNA-seq technology offers a novel approach to detect new HKGs with improved stability. Goat (Capra hircus) is an economically important livestock species and plays an indispensable role in the world animal fiber and meat industry. Unfortunately, uniform and reliable HKGs for skin research have not been identified in goat. Therefore, this study seeks to identify a set of stable HKGs for the skin tissue of C. hircus using high-throughput sequencing technology.ResultsBased on the transcriptome dataset of 39 goat skin tissue samples, 8 genes (SRP68, NCBP3, RRAGA, EIF4H, CTBP2, PTPRA, CNBP, and EEF2) with relatively stable expression levels were identified and selected as new candidate HKGs. Commonly used HKGs including SDHA and YWHAZ from a previous study, and 2 conventional genes (ACTB and GAPDH) were also examined. Four different experimental variables: (1) different development stages, (2) hair follicle cycle stages, (3) breeds, and (4) sampling sites were used for determination and validation. Four algorithms (geNorm, NormFinder, BestKeeper, and ΔCt method) and a comprehensive algorithm (ComprFinder, developed in-house) were used to assess the stability of each HKG. It was shown that NCBP3 + SDHA + PTPRA were more stably expressed than previously used genes in all conditions analysis, and that this combination was effective at normalizing target gene expression. Moreover, a new algorithm for comprehensive analysis, ComprFinder, was developed and released.ConclusionThis study presents the first list of candidate HKGs for C. hircus skin tissues based on an RNA-seq dataset. We propose that the NCBP3 + SDHA + PTPRA combination could be regarded as a triplet set of HKGs in skin molecular biology experiments in C. hircus and other closely related species. In addition, we also encourage researchers who perform candidate HKG evaluations and who require comprehensive analysis to adopt our new algorithm, ComprFinder.

The balance of Bmp6 and Wnt10b regulates the telogen-anagen transition of hair follicles

BackgroundThe periodic growth of hair follicles is regulated by the balance of activators and inhibitors. The BMP signaling pathway plays an important role during hair follicle regeneration, but the exact BMP protein that controls this process has not been revealed.MethodsThe expression of BMP6 was determined via in situ hybridization and immunofluorescence. The in vivo effect of BMP6 overexpression was studied by using a previously established adenovirus injection model. The hair follicle regeneration was assessed by gross observation, H&E staining and 5-bromo-2-deoxyuridine (BrdU) tracing. The expression patterns of BMP6 signaling and Wnt10b signaling in both AdBMP6-treated and AdWnt10b-treated skins were determined by in situ hybridization and immunofluorescence.ResultsBMP6 was expressed differently in the stages of hair follicle cycle. The telogen-anagen transition of hair follicles was inhibited by adenovirus-mediated overexpression of BMP6. In the in vivo model, the BMP6 signaling was inhibited by Wnt10b and the Wnt10b signaling was inhibited by BMP6. The activation of hair follicle stem cells (HFSCs) was also competitively regulated by Wnt10b and BMP6.ConclusionsCombined with previously reported data of Wnt10b, our findings indicate that BMP6 and Wnt10b are major inhibitors and activators respectively and their balance regulates the telogen-anagen transition of hair follicles. To the best of our knowledge, our data provide previously unreported insights into the regulation of hair follicle cycling and provide new clues for the diagnosis and therapies of hair loss.

Regulation of hair follicle development by exosomes derived from dermal papilla cells

BackgroundDermal papilla cells (DPCs) play a critical role in the regulation of hair follicle (HF) growth, formation, and cycling. DPCs are thought to regulate HF growth through a paracrine mechanism, in which exosomes may play a critical role. MethodsDPC-Exos were cutaneously injected into HFs at different HF cycle stages and the effects were evaluated by histological and immunohistochemical analyses. The effects of DPC-Exos on proliferation, migration, and cell cycle status of outer root sheath cells (ORSCs) were evaluated. After treatment of DPC-Exos, changes in mRNA and protein levels of β-catenin and Sonic hedgehog (Shh) in ORSCs were detected. ResultsDPC-Exos were approximately 105 nm in diameter and expressed tumor susceptibility gene 101, cluster of differentiation (CD)9, and CD63. Injection of DPC-Exos accelerated the onset of HF anagen and delayed catagen in mice. Immunohistochemical analyses revealed that β-catenin and Shh levels were upregulated in the skin. In vitro, DPC-Exo treatment enhanced ORSC proliferation and migration, and stimulated the expression of β-catenin and Shh. ConclusionDPC-Exos contribute to the regulation of HF growth and development, and provide a potential avenue for the treatment of hair loss.

A lncRNA-H19 transcript from secondary hair follicle of Liaoning cashmere goat: Identification, regulatory network and expression regulated potentially by its promoter methylation

The H19 transcript (imprinted maternally expressed transcript) is well-known as long noncoding RNA (lncRNA), and it is thought to be associated with the inductive capacity of dermal papilla cells for hair-follicle reconstruction. In this study, we isolated and characterized a lncRNA-H19 transcript from the secondary hair follicle of Liaoning cashmere goat. Also, we investigated its transcriptional pattern and methylation status of H19 gene in secondary hair follicle of this breed during different stages of hair follicle cycle. Nucleotide composition analysis indicated that guanine (G) and cytosine (C) are the dominant nucleotides in the lncRNA-H19 transcript of Liaoning cashmere goat with the highest frequency distribution (11.25%) of GG nucleotide pair. The regulatory network showed that lncRNA-H19 transcript appears to have remarkably diverse regulatory relationships with its related miRNAs and the potential target genes. In secondary hair follicle, the relative expression of lncRNA-H19 transcript at the anagen phase is significantly higher than that at both telogen and catagen phases suggesting that lncRNA-H19 transcript might play essential roles in the formation and growth of cashmere fiber of goat. Methylation analysis indicated that the methylation of the promoter region of H19 gene most likely participates in its transcriptional suppression in secondary hair follicle of Liaoning cashmere goat.

Molecular characterization, expression and methylation status analysis of BMP4 gene in skin tissue of Liaoning cashmere goat during hair follicle cycle

Bone morphogenetic protein 4 (BMP4) is a member of the bone morphogenetic protein family (BMPs). It is involved in the development and cycle of hair follicle, as well as, is thought to be a potential candidate gene for cashmere traits in goats. In the present study, we isolated and characterized a full-length open reading frame (ORF) of BMP4 cDNA from the skin tissue of Liaoning cashmere goat, and investigated the transcriptional pattern and methylation status of BMP4 gene in skin tissue of this breed during different stages of hair follicle cycle. The sequence analysis indicated that the isolated cDNA was 1264-bp in length containing a complete ORF of 1230-bp. It encoded a precursor peptide of 409 amino acids with a signal peptide of 19 amino acids. The structural analysis indicated that goat BMP4 contains typical TGF-β propeptide and TGF-β domains. In skin tissue, BMP4 is generally transcribed in an ascendant pattern from anagen to telogen. The methylation level of 5' flanking regulatory region of BMP4 gene might be involved in its mRNA expression in skin tissue: a higher BMP4 methylation level in skin coincides with a lower expression of BMP4 mRNA. These results from the present work provided a foundation for further insight into the functional and regulatory characteristics of BMP4 in the development and cycle of hair follicle in Liaoning Cashmere goat.

Cone of skin exists in rat: A "hypertrophic scarring free" animal.

Cone of skin is deemed to be related to hypertrophic scarring and absent in such traditionally "hypertrophic scarring and keloid free" animals as rat. The purpose of our study is to determine whether the cone of skin exists in rat. If it was, why it was ignored, and what was the meaning of it. The depilation of left dorsum of 32 male Sprague-Dawley rats was performed using a wax/rosin mixture. Skin samples were harvested on 0 d, 3 d, 9 d, 15 d, 21 d, 27 d, 33 d, and 39 d after depilation and stained by hematoxylin and eosin methods. Light microscopic observation of the dermis-fat interface was studied at 25× magnification. It was observed that, "dome" like fat tissue bulged up into the dermis from 3 d to 27 d and hair follicle bulged down into the "dome" like fat tissue from 15 d to 27 d and a "cone" like structure was seen. Cone of skin exists in rat in certain stages of hair follicle cycle, which is a valuable addition to the scientific literature and might be a challenge to the relation between cone of skin and hypertrophic scarring. Anat Rec, 299:1140-1144, 2016. © 2016 Wiley Periodicals, Inc.

Regulatory effect of β-catenin on proliferation of hair follicle stem cells involves PI3K/Akt pathway

Summary β-catenin signaling is required for hair follicle development and regeneration which are involved in the resuscitation of hair follicle stem cells (HFSCs). To further characterize the role of β-catenin in the regulation of proliferation of HFSCs, the β-catenin expression was measured in the defined stages of hair follicle cycle and the proliferative potency was determined by using an in vitro cell growth assay. Our results showed that activation of β-catenin correlated with HFSCs proliferation, which appeared to be mediated by the nuclear translocation of stabilized β-catenin and the activation of responsible cell cycle genes (cyclin D1 and p21). In addition, PI3K/Akt pathway was also involved in the HFSCs proliferation, partly regulated by β-catenin signaling pathway. These results demonstrate that β-catenin is an essential factor in the regulation of HFSCs proliferation via PI3K/Akt pathway and might be a potential therapeutic target for the regulation of the yield of keratinocytes from HFSCs.

Analysis of the expression pattern of involucrin in human scalp skin and hair follicles: hair cycle-associated alterations

Involucrin is a structural component of the keratinocyte cornified envelope that is expressed early in the keratinocyte differentiation process. It is a component of the initial envelope scaffolding and considered as a marker for keratinocyte terminal differentiation. The expression pattern of involucrin in human scalp skin and hair follicle cycle stages is not fully explored. This study addresses this issue and tests the hypothesis that "the expression of involucrin undergoes hair follicle cycle-dependent changes". A total of 50 normal human scalp skin biopsies were examined (healthy females, 51-62years) using immunofluorescence staining methods and real-time PCR analysis. In each case, 50 hair follicles were analyzed (35, 10 and 5 follicles in anagen, catagen and telogen, respectively). Involucrin was prominently expressed in the human scalp skin and hair follicles, on both gene and protein levels. The protein expression showed hair follicle cycle-associated changes i.e. a very strong expression during early and mature anagen, intermediate to strong expression during catagen and prominent decline in the telogen phase. The expression value of involucrin in both anagen and catagen was statistically significantly higher than that of telogen hair follicles (p<0.001). This study provides the first morphologic indication that involucrin is differentially expressed in the human scalp skin and hair follicles and reports that involucrin expression pattern undergoes hair cycle-dependent changes. The clinical ramifications of these findings are open for further investigations.

Expression patterns of the glial cell line–derived neurotrophic factor, neurturin, their cognate receptors GFRα-1, GFRα-2, and a common signal transduction element c-Ret in the human skin hair follicles

Glial cell line-derived neurotrophic factor (GDNF) and a related family member, neurturin (NTN), and their cognate receptors (GFRalpha-1 and GFRalpha-2, for GDNF and NTN, respectively) are distal members of the transforming growth factor-beta superfamily. They are involved in the control of murine hair follicle (HF) cycling. This study tests the hypothesis that GDNF and NTN, and their cognate receptors, are expressed in the human HF and their expression varies in the different stages of the HF cycle. The expression pattern of these proteins was examined in human HF by immunofluorescence, immunoalkalinephosphatase staining methods, and reverse transcription-polymerase chain reaction (GDNF). The functional effects (GDNF and NTN) were examined in organ culture of the microdissected HFs. GDNF, NTN, GFRalpha-1, GFRalpha-2, and c-Ret proteins were weakly expressed in catagen and telogen HFs. In contrast, they were strongly expressed in the epithelial and mesenchymal compartments of the anagen HF. GDNF gene was transcribed, both in the human scalp skin and in the isolated anagen HFs (reverse transcription-polymerase chain reaction). In HF organ culture, GDNF (but not NTN) increased the number of the proliferating HF keratinocytes (Ki 67 + cells). GDNF partially protected HFs from transforming growth factor-beta2-induced premature catagen transition. None. GDNF, NTN, GFRalpha-1, GFRalpha-2, and c-Ret proteins are differentially expressed in the different stages of HF cycle. GFRalpha-mediated signaling involves c-Ret and may play a role in human HF biology.