Numerous genes govern male reproduction, modulating testicular development and spermatogenesis. Our study leveraged RNA-Seq to explore candidate genes and pivotal pathways influencing fecundity in an F1 hybrid of Southdown × Hu sheep testes across four developmental milestones: M0 (0 months old, newborn), M3 (3 months old, sexually immature), M6 (6 months old, sexually mature), and Y1 (1 years old, adult). Histological examination using hematoxylins and eosin staining revealed that the cross-sectional area of the spermatid tubules and the number of supportive cells increased in the other groups, as compared to the M0 group. The cross-sectional area of the vasculature and the number of supporting cells were found to be significantly increased in all other groups in comparison to the M0 group. We conducted GO and KEGG analyses of the differentially expressed genes (DEGs) in the three comparison groups and identified key pathways, including cAMP, MAPK, ECM–receptor interactions, PI3K-Akt, and FOXO signaling, which are closely related to testicular development and spermatogenesis. Notably, alternative splicing (AS) events were markedly elevated in M6 and Y1 stages. Key genes like GATA4, GATA6, SMAD4, SOX9, YAP1, ITGB1 and MAPK1 emerged as significantly enriched in these pathways, potentially orchestrating the transition from immature to mature testes in sheep. These findings offer valuable insights into male reproductive potential and can inform strategies for optimizing animal breeding.

Hair follicle stem cells (HFSCs) are resident stem cells within hair follicles (HFs) that possess self-renewal and differentiation capacities, serving as a critical model for regenerative medicine research. Their dynamic interaction with dermal papilla cells (DPCs) plays a decisive role in HF development and cycling. FGF22 is a paracrine fibroblast growth factor that can regulate the proliferation, differentiation and migration of epithelial cells. This study established a DPC-HFSC co-culture system, revealing that FGF22 overexpression in DPCs significantly upregulated FGFR1/FGFR2 mRNA expression levels in HFSCs (p < 0.05), with a 1.67-fold increase in EdU-positive cell proportion (p < 0.01). CCK-8 assays demonstrated markedly enhanced HFSC viability (p < 0.01), with a 17% reduction in HFSC apoptosis (p < 0.05). Conversely, FGF22 knockout downregulated FGFR1/FGFR2 expression (p < 0.05), reduced HFSC proliferation capacity by 25% (p < 0.01), and increased HFSC apoptosis levels by 1.81-fold (p < 0.05). In addition, FGF22 overexpression promotes the proliferation and differentiation of HFSCs by activating Wnt/β-Catenin, Sonic Hedgehog (Shh) and Notch signaling pathways, or inhibiting BMP signaling pathways. Knockout of FGF22 weakens these processes and inhibits the activation and differentiation of HFSCs. This study, through the DPCs-HFSCs co-culture system, revealed the regulatory mechanism of FGF22 secreted by DPCs on the proliferation and differentiation of HFSCs, thereby providing theoretical references for fields such as fine-wool sheep breeding, human regenerative medicine, and hair loss treatment.

Junken meat sheep exhibit a characteristic postnatal coat-color transition, in which the initially black fleece gradually fades and develops into a white-trunk phenotype; however, the transcriptional basis of this developmental change in follicular pigment output remains unclear. In this study, three Junken meat sheep lambs showing a natural postnatal black-to-white coat-color transition were sampled longitudinally at the newborn black-fleece stage and the 179-day white-trunk stage, generating three matched biological pairs for RNA-seq analysis. Representative candidate genes were further validated by RT-qPCR. Differential expression analysis identified 1657, 400, and 1086 differentially expressed genes in the C11 vs. C1, C22 vs. C2, and C33 vs. C3 comparisons, respectively. Functional enrichment analysis indicated that these genes were mainly associated with tyrosine metabolism, ECM–receptor interaction, focal adhesion, Phosphoinositide 3-kinase-Akt signaling pathway (PI3K-Akt), arachidonic acid metabolism, estrogen signaling, and immune-related pathways. Integrated analysis of shared downregulated genes and expression patterns highlighted candidate genes related to pigmentation, the ECM/follicular microenvironment, and regulatory or metabolic processes. Pigmentation-related genes, including SOX10, TYR, TYRP1, PMEL, OCA2 and SLC45A2, were generally downregulated in 179-day white-trunk-stage skin, while changes in ECM- and metabolism-related genes suggested altered follicular microenvironmental regulation. These findings identify candidate transcriptional features associated with developmental coat-color fading in Junken meat sheep and support a follicular microenvironment–melanogenesis expression axis as a transcriptome-based framework for further investigation.

Various signalling molecules and pathways critical for wool production and quality regulate wool secondary follicle (SF) development. Circular RNAs (circRNAs) regulate SF morphogenesis through a competing endogenous RNA (ceRNA) mechanism; these novel cyclic non-coding RNAs are not known to regulate the development of SFs in the foetal period of fine-wool sheep. Here, we analysed circRNA expression profiles in the foetal skin of Gansu Alpine fine-wool sheep at 10 developmental stages (E87, E90, E93, E96, E99, E102, E105, E108, E111, and E138) using RNA sequencing. Among the differentially expressed circRNAs (DE circRNAs), 173 were significantly enriched in signalling pathways related to hair follicle (HF) development, such as Wnt/β-catenin, transforming growth factor-β/Smad, Notch, and mitogen-activated protein kinase. Six HF-development-related circRNAs were expressed at different stages and potentially regulated SF development through the ceRNA network. In total, 16 DE circRNAs and their targets, 44 miRNAs, and 65 mRNAs were screened, and 88 ceRNA regulatory network pathways related to SF development were constructed. These key DE circRNAs could be candidate genes for further exploration of the molecular HF development mechanism, providing an important theoretical basis for unravelling the regulatory network of SF development in fine-wool sheep and genetic wool trait improvement.

Sertoli cells are essential for testicular development and spermatogenesis, but the post-transcriptional mechanisms regulating their function in sheep remain incompletely understood. This study investigated the regulatory relationship between miR-132-y and Yes-associated protein 1 (YAP1), a core effector of the Hippo pathway, in primary Sertoli cells isolated from Southdown × Hu F1 sheep. Target prediction and dual-luciferase reporter assays supported a direct interaction between miR-132-y and the YAP1 3′ untranslated region. YAP1 overexpression was associated with increased CCK-8-based cell viability and altered mRNA expression of selected viability-associated, YAP1-related, and Sertoli cell function-associated genes, whereas YAP1 silencing showed opposite trends. Conversely, miR-132-y overexpression reduced YAP1 mRNA abundance and was associated with decreased CCK-8-based cell viability and corresponding transcriptional changes, while miR-132-y inhibition produced the opposite pattern. Rescue experiments showed that ectopic YAP1 expression partially attenuated miR-132-y-associated changes. Overall, these findings provide in vitro, cell-based evidence that miR-132-y targets YAP1 at the transcript level and is associated with viability-related transcriptional responses in sheep Sertoli cells.

Wool fibre diameter is a key economic trait in wool-producing animals, and its formation is regulated by the synergistic interaction between the proliferation and differentiation of hair follicle stem cells (HFSCs) and signals from the microenvironment. Dermal papilla cells (DPCs), as a key signal source, regulate the fate of HFSCs via paracrine pathways; however, the key molecular mechanisms remain unclear. Single-cell RNA sequencing (scRNA-seq) and genome-wide association studies (GWAS) revealed that ZNF280B is specifically expressed in both DPCs and HFSCs, and its g.677G>A variant is significantly associated with wool fibre diameter. Functional studies indicate that overexpression of ZNF280B promotes the proliferation of DPCs and HFSCs and inhibits apoptosis, whilst knockdown has the opposite effect; mechanistically, ZNF280B alters mRNA levels of key marker genes of the Wnt/β-catenin signalling pathway while selectively changing transcripts of the TGF-β pathway components in DPCs, and differentially modulates key marker transcripts in both the Wnt/β-catenin and Notch pathways in HFSCs. In summary, ZNF280B mediates the paracrine signalling of DPCs to influence HFSC proliferation and differentiation. It achieves this by integrating the Wnt/β-catenin/TGF-β/Notch signalling axes. This reveals that ZNF280B acts as an important regulatory node mediating DPC-HFSC paracrine communication, and provides new insights into the developmental mechanisms of fine-wool hair follicles and molecular breeding for fibre diameter.