Establishment and functional characterization of immortalized rabbit dermal papilla cell lines.

Hair follicle (HF) undergo periodic growth and development in mammals, which regulated by dermal papilla cells (DPCs) are reported to play an important role in HF morphogenesis and development. However, primary DPCs have low proliferative activity, age quickly, and fresh cell isolation is both time-consuming and laborious. In this study, we introduced the SV40 large T antigen (SV40T) into dissociated early passage rabbit vibrissae DPCs with lentiviral vectors and established seven immortalized DPC lines (R-1, R-2, R-3, R-4, R-5, R-6 and R-7). These cell lines displayed early passage morphology and high alkaline phosphatase activity. RT-PCR and immunofluorescence staining showed that all the immortalized cell lines expressed the DPC markers (α-SMA, IGF1, ALPL, FGF2, BMP2 and TGFß2), but α-SMA was only expressed well in R-3, R-4, and R-7. Furthermore, it was found that R-7 was the only line to survive beyond 50 passages. Compared to melanoma cells, R-7 did not undergo malignant transformation. Karyotyping and cell growth viability analysis illustrated that the R-7 cell line preserved the basic characteristics of primary DPCs. The R-7 DPCs established have potential application for future hair research. The study provides the theoretical basis in the cell research of HF growth and development.

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.

Characterization and functional analysis of SMAD2 regulation in hair follicle cycle in Angora rabbits.

Hair follicle (HF) development is characterized by periodic growth cycles regulated by numerous factors. We previously showed that SMAD2 might be involved in the HF growth cycle in Angora rabbits. However, its extra role in the HF growth and development remains obscure. In this study, we cloned the complete coding sequence (CDS) of the Angora rabbit SMAD2 gene. Within SMAD2 CDS, we identified the open reading frame (ORF) had a length of 1314 bp and encoding 437 amino acids. Bioinformatics analyses revealed that the SMAD2 protein is unstable and hydrophilic, and predominatelylocalizesin the cell nucleus. We identified that SMAD2 expression was elevated in the telogen phase of the during HF cycle. The knockdown and overexpression of SMAD2 could regulate HF growth and development related genes, such as WNT2, FGF2, and LEF1.Furthermore, SMAD2 may upregulate TGF-ß signaling pathway-related genes, including TFDP1, E2F4, and RBL1. In conclusion, our results indicate that SMAD2 plays a vital role in HF development by regulating the TGF-ß signaling pathway.

A Treatment Combination of IGF and EGF Promotes Hair Growth in the Angora Rabbit.

The hair follicle (HF) growth cycle is a complex, multistep biological process, for which dysfunction affects hair-related diseases in humans and wool production in animals. In this study, a treatment combination of 10 ng/mL insulin-like growth factor-1 (IGF-1) and 20 ng/mL epidermal growth factor (EGF) significantly increased the elongation length of hair shafts for cultured HFs. The combined treatment of IGF-1 and EGF enhanced the proliferation of HFs and promoted HF growth and development in vitro. In vivo, the combined treatment of IGF-1 and EGF was subcutaneously injected into the dorsal skin in HF synchronized rabbits. The IGF-1 and EGF combination promoted the transition of the hair cycle from telogen to anagen and stimulated the growth of hair shafts. This IGF-1 and EGF combination maintained the structure of the HF and enhanced the cell proliferation of outer root sheaths and the dermal papilla within rabbit skin. The combined treatment of IGF-1 and EGF regulated HF-related genes, including LEF1, CCND1 and WNT2, suggesting that IGF-1 and EGF play a positive role in HF growth and development. Utilization of the combined IGF-1 and EGF treatment may assist with hair and wool production and HF related diseases in mammals.

Characterization and Establishment of an Immortalized Rabbit Melanocyte Cell Line Using the SV40 Large T Antigen.

Melanocytes (MCs) are specialized cells that synthesize melanin within the melanosome. Cultured MCs are useful in order to study their role in relation to pigmentation. However, MC isolation is laborious and the obtained cells have a limited culture time. In this study, we transformed lentivirus-mediated simian virus 40 Large T (SV40-LT) into primary rabbit melanocytes (Pri RMCs) to establish an immortalized cell line. Morphologically, the immortalized RMCs (Im RMC) were indistinguishable from the Pri RMCs, and dendrites were visible following Dopa staining. No significant differences in cell proliferation or growth between immortalized and primary RMCs were observed. Based on melanocyte-specific markers, the expression of MITF, TYR, and TYRP1 were detected by PCR, immunofluorescence staining, and western blot analysis. Through karyotype, soft agar, and tumorigenesis assays, the immortalized RMCs did not undergo malignant transformation. Our results show that Im RMCs can be used as a tool cell for future MC studies on the pigmentation mechanisms of fur animals.

Slc7a11 Modulated by POU2F1 is Involved in Pigmentation in Rabbit.

Solute carrier family 7 member 11 (Slc7a11) is a cystine/glutamate xCT transporter that controls the production of pheomelanin pigment to change fur and skin color in animals. Previous studies have found that skin expression levels of Slc7a11 varied significantly with fur color in Rex rabbits. However, the molecular regulation mechanism of Slc7a11 in pigmentation is unknown. Here, rabbit melanocytes were first isolated and identified. The distribution and expression pattern of Slc7a11 was confirmed in skin from rabbits with different fur colors. Slc7a11 affected the expression of pigmentation related genes and thus affected melanogenesis. Meanwhile, Slc7a11 decreased melanocyte apoptosis, but inhibition of Slc7a11 enhanced apoptosis. Furthermore, the POU2F1 protein was found to bind to the -713 to -703 bp region of Slc7a11 promoter to inhibit its activity in a dual-luciferase reporter and site-directed mutagenesis assay. This study reveals the function of the Slc7a11 in melanogenesis and provides in-depth analysis of the mechanism of fur pigmentation.

miR-218-5p regulates skin and hair follicle development through Wnt/ß-catenin signaling pathway by targeting SFRP2.

The hair follicle is a complex biological system involved in a dynamic process governed by gene regulation. MicroRNAs play a critical role in the regulation of gene expression. We demonstrated that the expression of miR-218-5p and SFRP2 showed the opposite relationship in catagen and telogen phases and that miR-218-5p promoted the growth of hair shafts. The luciferase reporter assays confirmed that SFRP2 is the direct target of miR-218-5p. The expression of miR-218-5p may decrease the expression of SFRP2, which activates the Wnt signaling pathway, including the regulation of downstream genes and ß-catenin/T-cell-specific factor transcriptional activity. Moreover, miR-218-5p enhanced apoptosis, but inhibition of miR-218-5p decreased apoptosis and inhibited RAB-9 cell proliferation. In this study, we show that miR-218-5p positively regulates the Wnt signaling pathway by targeting SFRP2 and acts as a dynamic governor during skin and hair follicle development.

RNAi-mediated SLC7A11 knockdown inhibits melanogenesis-related genes expression in rabbit skin fibroblasts.

Solute carrier family 7 member 11 (SLC7A11) is a cystine/glutamate exchanger, also known as xCT, has been found to play an important role in pheomelanin synthesis. Adjusting the cystine content of cells to influence pheomelanin synthesis affects the proportion of total melanin, changing mammalian coat colour. In our previous study, we used RNA-seq to show that SLC7A11 was involved in coat colour regulation in Rex rabbits. However, the precise role of SLC7A11 in rabbit coat colour formation has not been investigated. To better understand the functions of SLC7A11 in rabbits, we used RNA interference (RNAi) to explore the effects of small interfering RNA (siRNA)-mediated downregulation of SLC7A11 gene expression on the expression of melanogenesis-related genes in rabbit skin fibroblasts (RAB-9). The effects of siRNA treatment were measured by quantitative real-time polymerase chain reaction and the efficiency of RNAi was calculated. The expression levels of melanogenesis-related genes, including MITF, MC1R, Agouti, CREB1 and SLC24A5 were detected at 24 h after RNAi transfection. The results showed that MITF, MC1R, SLC24A5, Agouti and CREB1 expression was significantly downregulated after SLC7A11 inhibition. This suggested that changes in SLC7A11 gene expression could directly affect the transcription of genes related to melanin production. This provides a scientific basis for further study of the role of SLC7A11 in the formation of coat colour.