Cytoplasmic Lncrna MSTRG.18075.2 Associated with Embryonic Hair Follicle Development in Cashmere Goats: Dermal Fibroblast Phenotypes and a Candidate Chi-Mir-145-5p/wnt16 Regulatory Axis

Long non-coding RNAs (lncRNAs) are important regulators of developmental gene expression, but their roles during key windows of embryonic hair follicle morphogenesis in cashmere goats remain unclear. This study aimed to identify temporally specific lncRNAs associated with early hair follicle development and to evaluate a candidate cytoplasmic lncRNA and its potential regulatory relationship in an in vitro dermal fibroblast model. Temporal screening identified 32 candidate lncRNAs with transient, stage-specific expression changes at embryonic day 55, suggesting that this stage may represent an important window of transcriptional regulation associated with embryonic hair follicle morphogenesis. Enrichment analysis showed positive enrichment of Wnt-related gene sets in the day 55 vs. day 45 and day 65 vs. day 55 comparisons; however, this finding does not constitute a direct measurement of Wnt pathway activity. Among the prioritized candidates, MSTRG.18075.2 showed relatively high expression at day 55 and was predominantly localized to the cytoplasm. In a heterologous 293T-cell reporter system, chi-miR-145-5p reduced the activity of wild-type reporters containing the predicted MSTRG.18075.2 or WNT16 3’ UTR site, whereas the corresponding mutant reporters did not show the same changes, supporting sequence-specific reporter responses mediated by these predicted sites. In cashmere goat dermal fibroblasts, MSTRG.18075.2 knockdown was associated with reduced apoptosis, slower cell-cycle progression, impaired proliferation and migration, and increased intracellular reactive oxygen species (ROS). Combined knockdown of chi-miR-145-5p partially reversed some phenotypes induced by MSTRG.18075.2 or WNT16 knockdown. These results are consistent with a candidate MSTRG.18075.2/chi-miR-145-5p/WNT16 regulatory model. This study provides supporting evidence for a relationship between MSTRG.18075.2 and the candidate chi-miR-145-5p/WNT16 regulatory axis at the levels of temporal expression, cytoplasmic localization, sequence-specific reporter responses, and in vitro cellular phenotypes. Because endogenous RNA complexes, downstream Wnt activity, and effects on hair follicle morphogenesis in vivo were not examined, the current findings do not directly establish an endogenous ceRNA mechanism or a causal relationship in vivo.