miR ‐382‐5p Drives Dermal Aging by Suppressing the Ion Exchanger SLC26A3

Skin aging is a complex process involving intrinsic and extrinsic factors that lead to progressive degradation of the extracellular matrix (ECM) and functional decline 1. MicroRNAs (miRNAs) have emerged as critical post-transcriptional regulators in this process. While several miRNAs, including miR-21, miR-29 and miR-34a, have been implicated in skin aging 2, the role of many others remains largely unexplored. To identify novel aging-associated miRNAs, we performed an integrative analysis of RNA-seq and miRNA-seq data from sun-protected skin of young and aged individuals (see Supporting Information S1 for detailed methods) (Figure 1A–C). Among the differentially expressed miRNAs identified (miR-382-5p, miR-337-3p, miR-183-5p, miR-652-3p and miR-508-3p), miR-382-5p showed the most significant upregulation in aged skin, which was validated by qRT-PCR (primer sequences are listed in Table S1) (Figure 1D). Our candidate prioritisation strategy integrated statistical significance with reproducibility and mechanistic relevance to ECM regulation. Although miR-652-3p was significantly altered, miR-382-5p was selected for its functional specificity; only its inhibition reversed MMP1 and procollagen dysregulation. Given that both arms of a miRNA duplex can be functionally active, we assessed strand specificity and subsequently focused on miR-382-5p. We then investigated the functional effects of miR-382-5p in primary human dermal fibroblasts (HDFs). Cells were transfected with either a miR-382 mimic or a specific inhibitor, and transfection efficiency was confirmed by qRT-PCR (Figure 1E,F). In HDFs, transfection with a miR-382 mimic significantly increased matrix metalloproteinase-1 (MMP1) mRNA and protein levels, while reducing type I procollagen (COL1A1) mRNA and secreted protein levels. Conversely, the inhibition of miR-382-5p reversed these effects (Figure 1G–I). These findings suggest that miR-382-5p promotes an ECM-degrading phenotype characteristic of skin aging. To elucidate the underlying mechanism, we performed a bioinformatic prediction of miRNA targets using miRDB and TargetScan. This analysis identified SLC26A3, which encodes the solute carrier family 26 member 3 ion exchanger, as a potential downstream target predicted by these algorithms. Consistent with this prediction, qRT-PCR analysis showed that SLC26A3 expression was significantly decreased following miR-382 mimic treatment and significantly increased following miR-382-5p inhibition in HDFs (Figure 1J,K). To confirm that SLC26A3 mediates the pro-aging effects of miR-382-5p, we silenced its expression using siRNA. siRNA-mediated silencing of SLC26A3 produced effects similar to those of miR-382 mimic, increasing MMP1 expression and decreasing secreted type I procollagen protein (Figure 1L,M). These results indicate that SLC26A3 downregulation is sufficient to recapitulate the key ECM changes downstream of miR-382-5p. Finally, we examined SLC26A3 expression in the context of aging. qRT-PCR analysis revealed that SLC26A3 expression was significantly reduced in aged human skin compared with young controls, and in UV-irradiated HDFs compared with non-irradiated cells (Figure 1N,O). These results indicate that downregulation of SLC26A3 is associated with intrinsic aging and is also observed under UV irradiation, suggesting potential involvement of the SLC26A3 arm of this pathway in photoaging. Our study has several limitations. Direct miR-382-5p–SLC26A3 binding was not biochemically validated, supporting a regulatory rather than definitive targeting relationship. Additionally, while SLC26A3 decreased in UV-irradiated cells, the lack of miR-382-5p data in this context leaves the photoaging link hypothetical. Finally, beyond dermal fibroblasts, miR-382-5p may influence aging-associated skin microenvironments in other cell types, underscoring the need for cell type–resolved approaches to define its spatial and cellular specificity during skin aging. Despite these limitations, our findings identify the miR-382-5p–SLC26A3 axis as a previously unrecognised regulator of dermal aging. Increased miR-382-5p expression in aged skin is associated with reduced SLC26A3 levels, accompanied by ECM degradation and collagen loss. miR-382-5p has also been implicated in age-related macular degeneration through regulation of PTEN/AKT/mTOR signaling 3, supporting a broader role in aging-associated tissue dysfunction. Given the role of ion exchangers in maintaining cellular volume and pH 4, suppression of SLC26A3 may contribute to age-associated cellular stress and ECM dysregulation 5. Previous studies indicate that MMP-1 enzymatic activity is pH-dependent 6, and that SLC26A3 loss can exacerbate inflammatory signaling 7, suggesting that miR-382-5p-mediated suppression of this exchanger creates a microenvironment permissive for matrix degradation. Further mechanistic studies will be required to clarify this relationship and to determine whether regulation of the miR-382-5p–SLC26A3 axis represents a viable strategy for modulating skin aging. M.-K.K. and D.H.L. designed and supervised the study. K.-N.Y. and M.-K.K. conducted the study. S.M.L. and Y.C. helped perform the experiments. All authors contributed to the manuscript preparation and approved the submitted version. The research was supported by the Korea Health Technology R&D Project, administered through the Korea Health Industry Development Institute (KHIDI), and funded by the Ministry of Health and Welfare, Republic of Korea (MOHW) (grant number: RS-2024-00345196). The authors declare no conflicts of interest. The datasets generated for this study can be found in the article, and further inquiries can be directed to the corresponding authors. Data S1: exd70218-sup-0001-DataS1.docx. Table S1: The primer sequences used for qRT-PCR are as follows. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.