Roles of testosterone in the growth of keratinocytes through bald frontal dermal papilla cells

Transcriptome Analysis Reveals an Inhibitory Effect of Dihydrotestosterone-Treated 2D- and 3D-Cultured Dermal Papilla Cells on Hair Follicle Growth

Dermal papillae are a target of androgen action in patients with androgenic alopecia, where androgen acts on the epidermis of hair follicles in a paracrine manner. To mimic the complexity of the dermal papilla microenvironment, a better culture model of human dermal papilla cells (DPCs) is needed. Therefore, we evaluated the inhibitory effect of dihydrotestosterone (DHT)-treated two-dimensional (2D)- and 3D-cultured DPCs on hair follicle growth. 2D- and 3D-cultured DPC proliferation was inhibited after co-culturing with outer root sheath (ORS) cells under DHT treatment. Moreover, gene expression levels of β-catenin and neural cell adhesion molecules were significantly decreased and those of cleaved caspase-3 significantly increased in 2D- and 3D-cultured DPCs with increasing DHT concentrations. ORS cell proliferation also significantly increased after co-culturing in the control-3D model compared with the control-2D model. Ki67 downregulation and cleaved caspase-3 upregulation in DHT-treated 2D and 3D groups significantly inhibited ORS cell proliferation. Sequencing showed an increase in the expression of genes related to extracellular matrix synthesis in the 3D model group. Additionally, the top 10 hub genes were identified, and the expression of nine chemokine-related genes in DHT-treated DPCs was found to be significantly increased. We also identified the interactions between transcription factor (TF) genes and microRNAs (miRNAs) with hub genes and the TF-miRNA coregulatory network. Overall, the findings indicate that 3D-cultured DPCs are more representative of in vivo conditions than 2D-cultured DPCs and contribute to our understanding of the molecular mechanisms underlying androgen-induced alopecia.

Review of Hair Follicle Dermal Papilla cells as in vitro screening model for hair growth

Hair disorders such as hair loss (alopecia) and androgen dependent, excessive hair growth (hirsutism, hypertrichosis) may impact the social and psychological well-being of an individual. Recent advances in understanding the biology of hair have accelerated the research and development of novel therapeutic and cosmetic hair growth agents. Preclinical models aid in dermocosmetic efficacy testing and claim substantiation of hair growth modulators. The in vitro models to investigate hair growth utilize the hair follicle Dermal Papilla cells (DPCs), specialized mesenchymal cells located at the base of hair follicle that play essential roles in hair follicular morphogenesis and postnatal hair growth cycles. In this review, we have compiled and discussed the extensively reported literature citing DPCs as in vitro model to study hair growth promoting and inhibitory effects. A variety of agents such as herbal and natural extracts, growth factors and cytokines, platelet-rich plasma, placental extract, stem cells and conditioned medium, peptides, hormones, lipid-nanocarrier, light, electrical and electromagnetic field stimulation, androgens and their analogs, stress-serum and chemotherapeutic agents etc. have been examined for their hair growth modulating effects in DPCs. Effects on DPCs' activity were determined from untreated (basal) or stress induced levels. Cell proliferation, apoptosis and secretion of growth factors were included as primary end-point markers. Effects on a wide range of biomolecules and mechanistic pathways that play key role in the biology of hair growth were also investigated. This consolidated and comprehensive review summarizes the up-to-date information and understanding regarding DPCs based screening models for hair growth and may be helpful for researchers to select the appropriate assay system and biomarkers. This review highlights the pivotal role of DPCs in the forefront of hair research as screening platforms by providing insights into mechanistic action at cellular level, which may further direct the development of novel hair growth modulators.

Induction of transforming growth factor-beta 1 by androgen is mediated by reactive oxygen species in hair follicle dermal papilla cells

The progression of androgenetic alopecia is closely related to androgen-inducible transforming growth factor (TGF)-β1 secretion by hair follicle dermal papilla cells (DPCs) in bald scalp. Physiological levels of androgen exposure were reported to increase reactive oxygen species (ROS) generation. In this study, rat vibrissae dermal papilla cells (DP-6) transfected with androgen receptor showed increased ROS production following androgen treatment. We confirmed that TGF-β1 secretion is increased by androgen treatment in DP-6, whereas androgeninducible TGF-β1 was significantly suppressed by the ROSscavenger, N-acetyl cysteine. Therefore, we suggest that induction of TGF-β1 by androgen is mediated by ROS in hair follicle DPCs. [BMB Reports 2013; 46(9): 460-464]

Differences in Expression of Specific Biomarkers Distinguish Human Beard from Scalp Dermal Papilla Cells

Androgen exposure stimulates the growth of beard hair follicles. The follicle dermal papilla appears to be the site of androgen action; however, the molecular mechanisms that regulate this process are not well understood. In an attempt to identify genes that contribute to the androgen-responsive phenotype, we compared gene expression patterns in unstimulated and androgen-treated cultured human dermal papilla cells isolated from beard (androgen-sensitive) and occipital scalp (androgen-insensitive) hair follicles. Through this analysis, we identified three genes that are expressed at significantly higher levels in beard dermal papilla cells. One of these genes, sfrp-2 has been identified as a dermal papilla signature gene in mouse pelage follicles. Two of these genes, mn1 and atp1beta1, have not been studied in the hair follicle. A fourth, fibulin-1d, was slightly upregulated in beard dermal papilla cells. The differences in the expression of these genes in cultured beard and scalp dermal papilla cells reflected similar differences in microdissected dermal papilla isolated from intact beard and scalp follicles. Our findings introduce potentially novel signaling pathways in dermal papilla cells. In addition, this study supports that cultured dermal papilla cells provide a cell-based model system that is reflective of the biology of in vivo hair follicle cells.

Perifollicular Fibrosis: Pathogenetic Role in Androgenetic Alopecia

Androgenetic alopecia (AGA) is a dihydrotestosterone (DHT)-mediated process, characterized by continuous miniaturization of androgen reactive hair follicles and accompanied by perifollicular fibrosis of follicular units in histological examination. Testosterone (T: 10(-9)-10(-7) M) treatment increased the expression of type I procollagen at mRNA and protein level. Pretreatment of finasteride (10(-8) M) inhibited the T-induced type I procollagen expression at mRNA (40.2%) and protein levels (24.9%). T treatment increased the expression of transforming growth factor-beta 1 (TGF-beta1) at protein levels by 81.9% in the human scalp dermal fibroblasts (DFs). Pretreatment of finasteride decreased the expression of TGF-beta1 protein induced by an average of T (30.4%). The type I procollagen expression after pretreatment of neutralizing TGF-beta1 antibody (10 microg/ml) was inhibited by an average of 54.3%. Our findings suggest that T-induced TGF-beta1 and type I procollagen expression may contribute to the development of perifollicular fibrosis in the AGA, and the inhibitory effects on T-induced procollagen and TGF-beta1 expression may explain another possible mechanism how finasteride works in AGA.

Role of androgen in mesenchymal epithelial interactions in human hair follicle

Human hair follicles, which are distributed in various and specific sites of the body, appear to have an inherited susceptibility for androgen-dependent growth. Beard, axillary, and frontal scalp dermal papilla cells (DPC) were recently shown to possess the characteristics of androgen target cells. These DPC show strong expression of androgen receptors, and the expression of type II 5alpha reductase is restricted to beard and frontal scalp DPC. These findings suggest that DPC mediate the signals of androgen to follicular epithelial cells in a paracrine fashion. We developed an in vitro co-culture system using DPC and keratinocytes (KC) to characterize the mode of androgen action in human hair follicles. Androgen significantly stimulated the proliferation of KC co-cultured with beard DPC, indicating that beard DPC produce androgen-dependent diffusible growth factors. Insulin-like growth factor-I was identified as one of the androgen-dependent paracrine growth factors produced by beard DPC. We also identified the inhibitory role of androgen on the growth of KC co-cultured with DPC from androgenetic alopecia (AGA) when the DPC were transfected with an expression vector encoding the androgen receptor. This growth suppression of KC was mediated by transforming growth factor-beta1 (TGF-beta1) derived from DPC of AGA, suggesting that TGF-beta1 is a paracrine mediator for AGA.

Androgen receptor (AR) NH2- and COOH-terminal interactions result in the differential influences on the AR-mediated transactivation and cell growth

Early reports showed that androgen receptor (AR) NH2- and COOH-terminal (N-C) interaction was important for full AR function. However, the influence of these interactions on the AR in vivo effects remains unclear. Here we tested some AR-associated peptides and coregulators to determine their influences on AR N-C interaction, AR transactivation, and AR coregulator function. The results showed that AR coactivators such as ARA70N, gelsolin, ARA54, and SRC-1 can enhance AR transactivation but showed differential influences on the N-C interaction. In contrast, AR corepressors ARA67 and Rad9 can suppress AR transactivation, with ARA67 enhancing and Rad9 suppressing AR N-C interaction. Furthermore, liganded AR C terminus-associated peptides can block AR N-C interaction, but only selective peptides can block AR transactivation and coregulator function. We found all the tested peptides can suppress prostate cancer LNCaP cell growth at different levels in the presence of 5alpha-dihydrotestosterone, but only the tested FXXLF-containing peptides, not FXXMF-containing peptides, can suppress prostate cancer CWR22R cell growth. Together, these results suggest that the effects of AR N-C interactions may not always correlate with similar effects on AR-mediated transactivation and/or AR-mediated cell growth. Therefore, drugs designed by targeting AR N-C interaction as a therapeutic intervention for prostate cancer treatment may face unpredictable in vivo effects.

ARA67/PAT1 functions as a repressor to suppress androgen receptor transactivation

The androgen receptor (AR) may recruit multiple coregulators for proper or optimal transactivation. Here we report the identification and characterization of ARA67/PAT1 as an AR coregulator from a prostate cDNA library. ARA67/PAT1 was screened out as an AR N terminus interacting protein. Interaction mapping shows that the cooperation of multiple domains within ARA67/PAT1 may be required for the maximal interaction with AR. ARA67/PAT1 functions as a repressor with better suppressive effects on AR compared to glucocorticoid receptor and estrogen receptor. Further mechanism dissection reveals that the interrupted AR cytoplasmic-nuclear shuttling may play a major role in ARA67/PAT1 mediated suppression on AR. Together, these results suggest that ARA67/PAT1 may function as a novel repressor that can modulate AR function in prostate cancer.

Archvillin, a muscle-specific isoform of supervillin, is an early expressed component of the costameric membrane skeleton

The membrane skeleton protein supervillin binds tightly to both F-actin and membranes and can potentiate androgen receptor activity in non-muscle cells. We report that muscle, which constitutes the principal tissue source for supervillin sequences, contains a approximately 250 kDa isoform of supervillin that localizes within nuclei and with dystrophin at costameres, regions of F-actin membrane attachment in skeletal muscle. The gene encoding this protein, 'archvillin' (Latin, archi; Greek, árchos; 'principal' or 'chief'), contains an evolutionarily conserved, muscle-specific 5' leader sequence. Archvillin cDNAs also contain four exons that encode approximately 47 kDa of additional muscle-specific protein sequence in the form of two inserts within the function-rich N-terminus of supervillin. The first of these muscle-specific inserts contains two conserved nuclear targeting signals in addition to those found in sequences shared with supervillin. Archvillin, like supervillin, binds directly to radiolabeled F-actin and co-fractionates with plasma membranes. Colocalization of archvillin with membrane-associated actin filaments, non-muscle myosin II, and--to a lesser extent--vinculin was observed in myoblasts. Striking localizations of archvillin protein and mRNA were observed at the tips of differentiating myotubes. Transfected protein chimeras containing archvillin insert sequences inhibited myotube formation, consistent with a dominant-negative effect during early myogenesis. These data suggest that archvillin is among the first costameric proteins to assemble during myogenesis and that it contributes to myogenic membrane structure and differentiation.

Identification of androgen-inducible TGF-beta1 derived from dermal papilla cells as a key mediator in androgenetic alopecia

We attempted to establish a coculture model of human dermal papilla cells (DPCs) from androgenetic alopecia (AGA) and keratinocytes (KCs) to study the pathomechanism of AGA. Since expression of mRNA for the androgen receptor (AR) decreased during subcultivation of DPCs in vitro, we transiently transfected the AR expression vector into the DPCs and cocultured them with KCs. In this coculture, androgen inhibited the growth of KCs by 50%, indicating that the DPCs produce diffusible growth suppressive factors into the medium in an androgen-dependent manner. Since recently increasing evidence has shown the importance of transforming growth factor-beta1 (TGF-beta1) in hair growth, we further examined the concentration of TGF-beta1 in this coculture medium after androgen treatment by ELISA assays. The results showed that androgen treatment increased the secretion of TGF-beta1 into the conditioned medium. Moreover, neutralizing anti-TGF-beta1 antibody reversed the inhibition of KC proliferation. Thus, we suggest that androgen-inducible TGF-beta1 derived from DPCs mediates hair growth suppression in AGA.

Androgen-inducible TGF-beta1 from balding dermal papilla cells inhibits epithelial cell growth: a clue to understand paradoxical effects of androgen on human hair growth

We attempted establishing an in vitro coculture system by using human dermal papilla cells (DPCs) from androgenetic alopecia (AGA) and keratinocytes (KCs) to explore the role of androgens in hair growth regulation. Androgen showed no significant effect on the growth of KCs when they were cocultured with DPCs from AGA. Because the expressions of mRNA of androgen receptor (AR) decreased during subcultivation of DPCs in vitro, we transiently transfected the AR expression vector into the DPCs and cocultured them with KCs. In this modified coculture, androgen significantly suppressed the growth of KCs by approximately 50%, indicating that overexpression of AR can restore the responsiveness of the DPCs to androgen in vivo. We found that androgen stimulated the expression of TGF-beta1 mRNA in the cocultured DPCs. ELISA assays demonstrated that androgen treatment increased the secretion of both total and active TGF-beta1 in the conditioned medium. Moreover, the neutralizing anti-TGF-beta1 antibody reversed the androgen-elicited growth inhibition of KCs in a dose-dependent manner. These findings suggest that androgen-inducible TGF-beta1 derived from DPCs of AGA is involved in epithelial cell growth suppression in our coculture system, providing the clue to understand the paradoxical effects of androgens for human hair growth.

Supervillin associates with androgen receptor and modulates its transcriptional activity

Activation of androgen receptor (AR) via androgen in muscle cells has been closely linked to their growth and differentiation. Here, we report the cloning and characterization of supervillin (SV), a 205-kDa actin-binding protein, as an AR coregulator from the skeletal muscle cDNA library. Mammalian two-hybrid and glutathione S-transferase pull-down assays indicate a domain within SV (amino acids 594-1268) can interact with AR N terminus and DNA-binding domain-ligand-binding domain in a ligand-enhanced manner. Subcellular colocalization studies with fluorescence staining indicate SV can colocalize with AR in the presence of 5 alpha-dihydrotestosterone in COS-1 cells. The functional reporter assays showed full-length SV and the SV peptide (amino acids 831-1281) within the interaction domain can enhance AR transactivation. Furthermore, SV can enhance the endogenous AR target gene, p27(KIP1), expression in prostate PC-3(AR2) cells. SV preferentially enhanced AR rather than other tested nuclear receptors and could be induced by natural androgens better than other steroids. SV can also cooperate with other AR coregulators, such as ARA55 or ARA70, to enhance AR transactivation further. Unlike SRC-1 that can enhance the interaction between AR N terminus and AR C terminus, SV shows a mild suppressive effect on N-C interactions, suggesting SV may go through a different mechanism to enhance AR transactivation. Together, our data demonstrate that SV is an AR coregulator that can enhance AR transactivation in muscle and other cells.

Modulation of T-lymphocyte proliferation by exogenous natural ceramides and sphingosylphosphorylcholine

Sphingolipids such as ceramide and sphingosine are abundantly present in the stratum corneum of epidermis. In atopic stratum corneum, sphingosylphosphorylcholine (SPC) is present in association with a reduction in the amount of ceramides. We have previously shown that the cellular kinetics of T cells are affected by exogenous addition of sphingosine and synthetic ceramides, raising the possibility that sphingolipids diffusing from the stratum corneum modulate skin-infiltrating T cells. By using two natural ceramides and murine T cells, this study further clarified the conditions under which exogenous ceramides enhance the proliferation of T cells. KLH-specific T cell clones 28-4 and 24-2 proliferated in response to natural ceramides when cultured for 44-48 h in the presence of concanavalin A at 1 microg per ml. Elongation of culture periods adversely inhibited the T cell proliferation, suggesting the existence of an optimal exposure time. Augmentation of DNA synthesis by natural ceramides was more pronounced in tumor necrosis factor alpha (TNFalpha)-sensitive 28-4 cells than in less sensitive 24-2 cells, and TNFalpha-induced proliferation of 28-4 cells was suppressed by the concomitant addition of natural ceramides. Similar to ceramides, SPC augmented the proliferation of resting spleen cells. Our study suggests that ceramide modulation of T cell proliferation depends on the TNFalpha sensitivity and activation level of T cells and that SPC also has a mitogenic potential for T cells.