Cutaneous transcriptome analysis in NIH hairless mice

Whole-genome resequencing of Hu sheep identifies candidate genes associated with agronomic traits

The phenotypic diversity resulting from artificial or natural selection of sheep has made a significant contribution to human civilization. Hu sheep are a local sheep breed unique to China with high reproductive rates and rapid growth. Genomic selection signatures have been widely used to investigate the genetic mechanisms underlying phenotypic variation in livestock. Here, we conduct whole-genome sequencing of 207 Hu sheep and compare them with the wild ancestors of domestic sheep (Asiatic mouflon) to investigate the genetic characteristics and selection signatures of Hu sheep. Based on six signatures of selection approaches, we detect genomic regions containing genes related to reproduction (BMPR1B, BMP2, PGFS, CYP19, CAMK4, GGT5, and GNAQ), vision (ALDH1A2, SAG, and PDE6B), nervous system (NAV1), and immune response (GPR35, SH2B2, PIK3R3, and HRAS). Association analysis with a population of 1299 Hu sheep reveal those missense mutations in the GPR35 (GPR35 g.952651 A>G; GPR35 g.952496 C>T) and NAV1 (NAV1 g.84216190 C>T; NAV1 g.84227412 G>A) genes are significantly associated (P < 0.05) with immune and growth traits in Hu sheep, respectively. This research offers unique insights into the selection characteristics of Hu sheep and facilitates further genetic improvement and molecular investigations.

Screening of hair follicle telogen-associated circRNAs in sheep and construction of their ceRNA network

Sheep breeds with hair-shedding traits have many advantages over non-shedding sheep breeds, not only because of reduced shearing labor and feeding management costs but also because it reduces in vitro parasites and improves adaptability to summer heat stress. The wool of Dorper sheep naturally sheds in spring due to the periodic growth of hair follicles. CircRNAs primarily regulate the morphogenesis of hair follicles through the ceRNA mechanism. In this study, five 2-year-old Dorper ewes with extreme hair-shedding phenotype (S) and three Dorper ewes with non-shedding (N) phenotype were selected for subsequent analyses. For RNA extraction, skin tissues were collected on 27th September 2019 (S1, N1), 3rd January 2020 (S2, N2), and 17th March 2020 (S3, N3), which were then subjected to RNA-seq. RNA-seq technology revealed 20,185 novel circRNAs in the hair follicles of Dorper sheep. Among them, 1450 circRNAs were differentially expressed (DE). Clustering heatmap and expression pattern analyses were performed on DE circRNAs, which indicated 78 circRNAs with T pattern (Telogen, highly expressed in telogen), and the source genes for candidate circRNAs were further screened by functional enrichment analysis, which identified 13 crucial genes enriched in pathways associated with hair follicle development. Additionally, a ceRNA regulatory network comprising 4 circRNAs, 11 miRNAs, and 13 target genes was constructed. Overall, this study screened circRNAs that may be associated with the telogen phase of hair follicles in sheep, providing a relevant theoretical basis for wool shedding in sheep and for breeding Dorper sheep with automatic wool shedding.

A missense mutation in Lama3 causes androgen alopecia

Hair loss disorders such as androgenetic alopecia have caused serious disturbances to normal human life. Animal models play an important role in exploring pathogenesis of disease and evaluating new therapies. NIH hairless mice are a spontaneous hairless mouse discovered and bred in our laboratory. In this study, we resequenced the genomes of NIH normal mice and NIH hairless mice and obtained 3,575,560 high-quality, plausible SNP loci and 995,475 InDels. The Euclidean distance algorithm was used to assess the association of SNP loci with the hairless phenotype, at a threshold of 0.62. Two regions of chromosome 18 having the highest association with the phenotype contained 345 genes with a total length of 13.98 Mb. The same algorithm was used to assess the association of InDels with the hairless phenotype at a threshold of 0.54 and revealed a region of 25.45 Mb in length, containing 518 genes. The mutation candidate gene Lama3 (NM_010680.2: c.652C>T; NP_034810.1: p. Arg217Cys) was selected based on the results of functional gene analysis and mutation prediction screening. Lama3 (R217C) mutant mice were further constructed using CRISPR/Cas9 technology, and the relationship between Lama3 point mutations and the hairless phenotype were clarified by phenotypic observation. The results showed that male Lama3 point mutation mice started to lose hair on the 80th day after birth, and the hair loss area gradually expanded over time. H&E staining of skin sections showed that the point mutation mice had increased sebaceous glands in the dermis and missing hair follicle structure (i.e., typical symptoms of androgenetic alopecia). This study is a good extension of the current body of knowledge about the function of Lama3, and the constructed Lama3 (R217C) mutant mice may be a good animal model for studying androgenetic alopecia.

miR-27a Targeting PIK3R3 Regulates the Proliferation and Apoptosis of Sheep Hair Follicle Stem Cells

Micro RNAs are regulatory factors in tissue development, organ formation, cell growth, apoptosis and other biological processes. In particular, several miRNAs are related to the development of hair follicles. Here, we investigated the effect of the targeting of PIK3R3 by miR-27a on the AKT/MTOR pathway and on the proliferation and apoptosis of hair follicle stem cells (HFSCs) in sheep. Knockdown of the expression of PIK3R3 was found to significantly inhibit the proliferation and promote the apoptosis of HFSCs. Similarly, a miR-27a mimic significantly inhibited the proliferation and promoted the apoptosis of HFSCs. The miR-27a mimic was also shown to significantly inhibit the expression of PIK3R3, AKT, and MTOR and the phosphorylation of AKT and MTOR, while a miR-27a inhibitor increased the expression of these genes. The presence of an miR-27a binding site in the 3' UTR of PIK3R3 was identified by a bioinformatics analysis, and the interaction was verified with a dual-luciferase reporter assay. The expression of PIK3R3 mRNA and protein was negatively correlated with the presence of miR-27a, which suggests that this interaction may be involved in the biological impacts on proliferation and apoptosis. Thus, this study demonstrates that miR-27a plays a potential role in the proliferation and apoptosis of sheep hair follicle stem cells by targeting PIK3R3, which can be used to design new methods to improve sheep wool.

Recombinant Oil-Body-Expressed Oleosin-hFGF5 in Arabidopsis thaliana Regulates Hair Growth

FGF5 (Fibroblast Growth Factor) is a member of the fibroblast growth factor family, which not only regulates growth and development but also inhibits hair regeneration. The oil-body expression vector pOTB-hFGF5 was constructed by the genetic engineering method and it was transformed into Arabidopsis by flora dip. T3 homozygous transgenic Arabidopsis was obtained after screening and propagation by the PCR and Western blot methods. The recombinant oil-body-expressed oleosin-hFGF5 can inhibit the proliferation of hair follicle epithelial cells and it exhibits the pharmacological activity of inhibiting hair regeneration in vivo by protein hybridization and imunohistochemistry. At the same time, the potential mechanism of recombinant oil-body-expressed oleosin-hFGF5 inhibiting hair growth was also revealed by RNA-Seq. This implies that the recombinant oil-body-expressed oleosin-hFGF5 has a good effect on inhibiting hair growth.

Transcriptomic Analysis Reveals the Involvement of lncRNA-miRNA-mRNA Networks in Hair Follicle Induction in Aohan Fine Wool Sheep Skin

Long non-coding RNAs (lncRNA) and microRNAs (miRNA) are new found classes of non-coding RNAs (ncRNAs) that are not translated into proteins but regulate various cellular and biological processes. In this study, we conducted a transcriptomic analysis of ncRNA and mRNA expression in Aohan fine wool sheep (AFWS) at different growth stages (embryonic day 90, embryonic day 120, and the day of birth), and explored their relationship with wool follicle growth. In total, 461 lncRNAs, 106 miRNAs, and 1,009 mRNAs were found to be differentially expressed during the three stages of wool follicle development. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed to clarify the roles of the differentially expressed lncRNA, miRNA, and mRNA in the different stages of wool follicle development. Quantitative real-time PCR (qRT-PCR) was used to validate the results of RNA-seq analysis. lncRNA (MSTRG.223165) was found to act as a competing endogenous RNA (ceRNA) and may participate in wool follicle development by acting as an miR-21 sponge. Network prediction implicated the MSTRG.223165-miR-21-SOX6 axis in the wool follicle development. The targeting relationships of miR-21 with SOX6 and MSTRG.223165 were validated in dual-luciferase assays. This is the first report indicating the association of the lncRNA-miRNA-mRNA network with wool follicle development in AFWS. This study provides new insights into the regulation of the wool follicle growth and represents a solid foundation for wool sheep breeding programs.

Characterization of TCF4-mediated oncogenic role in cutaneous squamous cell carcinoma

The aberrant highly expressed T-cell factor 4 (TCF4) has been determined to be closely connected with carcinogenesis of cutaneous squamous cell carcinoma (cSCC) in previous studies. However, the underlying regulatory network and the potential therapeutic targets of TCF4 in SCC are still not fully understood. In this study, the highly expressed TCF4 was observed in human cSCC cancer compared to the paired adjacent tissues. A431 cell lines with TCF4 RNA silencing were found to be the repressive cell proliferation and invasion as well as the enhanced apoptosis. Furthermore, RNA-Seq was conducted and observed that 147 genes were up-regulated (including 113 coding genes and 34 lncRNA) while 172 genes were down-regulated (including 64 coding genes and 108 lncRNA) in TCF4 silencing compared to blank RNAi and untreated control A431 cells. 18 pathways including steroid, porphyrin, arachidonic acid, and retinol metabolism, as well as the functions associated with angiogenesis, inflammatory response, and cell adhesion were involved in the differentially expressed genes of A431 cells with TCF4 silencing. Finally, ChIP-qPCR of TCF4 and β-catenin were performed and we found that the enrichments of β-catenin were lost on the promoters on top ten down-regulated genes in A431 cells with TCF4 silencing compared to the untreated A431. Additionally, in untreated A431 cells, some genes such as ALDH8A1, DRICH1, and UGT1A5 were observed with high enrichment of TCF4, but without β-catenin, which indicated a Wnt/β-catenin independent way of TCF4 for gene transcriptional regulation. In conclusion, we declared that TCF4 played an important role in tumorigenesis of skin cancer via the aberrant activation of variety of signaling pathways, and could be considered as a potential therapeutic target for cSCC treatment.

Analyzing the innate immunity of NIH hairless mice and the impact of gut microbial polymorphisms on Listeria monocytogenes infection

Spontaneous mutant hairless (HL) mice are often used to study hair growth and hair follicle development, and they often exhibit immune dysfunctions. Listeria monocytogenes, an important food-borne bacterium, has been used in animal models to study immune responses to infection. Herein, we analyzed the innate immunity of HL mice and the impact of gut microbial polymorphisms on L. monocytogenes infection. Compared to NIH mice, NIH HL mice were more susceptible to L. monocytogenes, as weight losses, mortality, bacterial load, and histopathological lesions were more severe; the decrease in monocytes may be an important underlying reason. The degree of spleen damage was reduced after co-housing, indicating that the host guides the gut microbiota to alleviate infection. High-throughput pyrosequencing of 16S rRNA demonstrated that gut microbiota composition differed between NIH HL and NIH mice. Infection with L. monocytogenes induced an increase in the number of bacteria belonging to the Rikenellaceae family and Gammaproteobacteria class, and decreased bacteria belonging to the Clostridiales class and Lachnospiraceae family. A substantial reduction in Clostridiales bacteria in infected HL mice may cause a serious infection. The Mycoplasma genus was present only in NIH HL mice and was, thus, considered a biomarker. The results of this study improve our understanding of the use of NIH HL mice as a good animal model of innate immune dysfunction.