A hypertrophic scar is the result of abnormal repair of the body after trauma. Histopathologically, it is mostly the result of the excessive proliferation of fibroblasts and the accumulation of extracellular matrix. Accumulating evidence has demonstrated that long non-coding RNAs (lncRNAs) have a critical role in the regulation of gene expression and in the pathogenesis of diseases. However, the roles of lncRNAs in hypertrophic scars have remained elusive. The present study investigated the profiles of differentially expressed lncRNAs between fibroblasts derived from a hypertrophic scar and normal skin, and explored the possible mechanisms underlying the development of hypertrophic scars. Microarray data indicated that 6,104 lncRNAs and 2,952 mRNAs were differentially expressed. A set of differentially expressed transcripts as confirmed by reverse transcription-quantitative polymerase chain reaction. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were performed to determine the principal functions of the significantly deregulated genes. Furthermore, associated expression networks, including subgroup analysis, competing endogenous RNAs (ceRNAs) and coding-noncoding co-expression networks were constructed using bioinformatics methods. The homology between differentially expressed lncRNAs and mRNAs was assessed and two exon lncRNA were selected to explore their regulatory mechanisms. The ceRNA network inferred that NR_125715 acted as a competing endogenous RNA, bound to microRNA (miR)-141-3p, miR-200a-3p and miR-29 to regulate the expression of the miRs' targets, including transforming growth factor β2 (TGFB2). Similarly, NR_046402 acted as a competing endogenous RNA, which bound to miR-133a-3p.1 and miR-4469 to then regulate the expression of the miRs' targets, including DNA polymerase δ1, catalytic subunit (POLD1). In addition, co-expression analysis indicated that the expression of lncRNAs NR_125715 and NR_046402 was correlated with that of TGFB2 and POLD1 mRNA. The identification of these differentially expressed lncRNAs in the hypertrophic scar-derived fibroblasts in the present study, may provide novel insight into the functional interactions of lncRNA, miRNA and mRNA, and lead to novel theories for the pathogenesis and treatment of hypertrophic scars.

Background: Hypertrophic scar is a fibroproliferative disorder caused by skin injury. The incidence of hypertrophic scar following trauma or burns is 40 to 70 percent or 70 percent, respectively. It has been shown that transforming growth factor (TGF) β1/Smad signaling plays a crucial role in hypertrophic scar, and that USP15 can regulate the activity of TGFβ1/Smad signaling to affect the progression of the disease. However, the underlying mechanism of USP15 in hypertrophic scar remains unclear. The authors hypothesized that USP15 was up-regulated and enhanced the proliferation, migration, invasion, and collagen deposition of hypertrophic scar–derived fibroblasts by deubiquitinating TGF-β receptor I (TβRI) in vitro. Methods: Fibroblasts were isolated from human hypertrophic scars in vitro. The knockdown and overexpression of USP15 in hypertrophic scar–derived fibroblasts were performed using lentivirus infection. The effect of USP15 on hypertrophic scar–derived fibroblast proliferation, migration, and invasion, and the expression of TβRI , Smad2 , Smad3 , α- SMA , COL1 , and COL3 , were detected by Cell Counting Kit-8, scratch, invasion, quantitative real-time polymerase chain reaction, and Western blot assays. The interaction between USP15 and TβRI was detected by co-immunoprecipitation and ubiquitination assays. Results: The authors demonstrated that USP15 knockdown significantly inhibited the proliferation, migration, and invasion of hypertrophic scar–derived fibroblasts in vitro and down-regulated the expression of TβRI , Smad2 , Smad3 , α- SMA , COL1 , and COL3 ; in addition, USP15 overexpression showed the opposite trends ( p < 0.05). Co-immunoprecipitation and ubiquitination assays revealed that USP15 interacted with TβRI and deubiquitinated TβRI. Conclusion: USP15 enhances the proliferation, migration, invasion, and collagen deposition of hypertrophic scar–derived fibroblasts by deubiquitinating TβRI in vitro.

tRNA-derived small RNAs (tsRNAs) have been shown to play regulatory roles in many physiological and pathological processes. However, their roles in hypertrophic scars remain unclear. The present study investigated differentially expressed tsRNAs in human hypertrophic scar fibroblasts and normal skin fibroblasts via high-throughput sequencing. Several dysregulated tsRNAs were validated by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, target prediction, coexpression networks and competing endogenous RNA (ceRNA) networks were evaluated to discover the principal functions of significantly differentially expressed tsRNAs. In total, 67 differentially expressed tsRNAs were detected, of which 27 were upregulated and 40 downregulated in hypertrophic scar fibroblasts. The GO analysis indicated that the dysregulated tsRNAs are associated with numerous biological functions, including 'nervous system development', 'cell adhesion', 'focal adhesion', 'protein binding', 'angiogenesis' and 'actin binding'. KEGG pathway analysis revealed that the most altered pathways include 'Ras signaling pathway', 'Rap1 signaling pathway' and 'cGMP-PKG signaling pathway'. The target genes of the differentially expressed tsRNAs participate in several signaling pathways important for scar formation. The results of RT-qPCR were consistent with those of sequencing. MicroRNA (miR)-29b-1-5p was identified as a target of tsRNA-23678 and was downregulated in hypertrophic scar fibroblasts, constituting a negative regulatory factor for scar formation. Furthermore, tsRNA-23761 acted as a ceRNA and bound to miR-3135b to regulate the expression of miR-3135b targets, including angiotensin-converting enzyme. collectively, these findings reveal that tsRNAs are differentially expressed in human hypertrophic scar fibroblasts, and may contribute to the molecular mechanism and treatment of hypertrophic scars.

local transplantation of epidermal stem cells (eScs) exerts a therapeutic effect on burn wounds. However, cell viability can impede their clinical application. HoX antisense intergenic rna (HoTair) is involved in regulating adult tissue stem cells, as well as in developmental patterning and pluripotency. However, little is known about its role in regulating eScs. The present study was performed to investigate the effects of HoTair in the modulation of eScs and wound repair. Firstly, reverse transcription-quantitative Pcr was used to detect the relative expression of HoTair during burn wound healing in mice to determine whether HoTair is associated with wound healing. Subsequently, eScs derived from mouse skin were transfected with a lentiviral vector to overexpress or knockdown HoTair. The effects of HoTair on cell proliferation and differentiation were measured by 5-bromodeoxyuridine and MTT assays, and by assessing nanoG mrna expression. lastly, mice with burns were administered a subcutaneous injection of HoTair-overexpressing eScs. images were captured and histological analyses were performed to evaluate wound healing. The results revealed that the expression of HoTair gradually increased and peaked at day 7 post-burn and maintained at relatively high levels until day 14 post-burn during wound healing. Furthermore, overexpression of HoTair promoted eSc proliferation and maintained the stem cell state in vitro. By contrast, suppression of HoTair inhibited cell proliferation and cell stemness. It was also identified that HoTir-overexpressing eScs accelerated re-epithelialization and facilitated burn wound repair. in conclusion, the present findings confirmed an essential role of HOTAIR in the regulation of eSc proliferation and stemness. Therefore, targeting HoTair in eScs may be a potentially promising therapy for burn wound healing.