Ceramide Ehux-C22 Targets the miR-199a-3p/mTOR Signaling Pathway to Regulate Melanosomal Autophagy in Mouse B16 Cells

• Published in: International journal of molecular sciences Vol. 25; no. 15; p. 8061
• Main Authors: Wan, Jiyue, Zhang, Shumiao, Li, Guiling, Huang, Shiying, Li, Jian, Zhang, Zhengxiao, Liu, Jingwen
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 01.08.2024
• Subjects: alpha-MSH - metabolism; Analysis; Animals; Autophagy; Cell growth; Cell Line, Tumor; Ceramides - metabolism; Ehux-C22; Free radicals (Chemistry); Gene expression; Genes; Intermedin; Kinases; Lymphomas; Melanins - biosynthesis; Melanins - metabolism; Melanocytes - drug effects; Melanocytes - metabolism; Melanoma; Melanoma, Experimental - genetics; Melanoma, Experimental - metabolism; Melanoma, Experimental - pathology; melanosomal autophagy; Melanosomes - metabolism; Metabolism; Mice; MicroRNA; MicroRNAs; MicroRNAs - genetics; MicroRNAs - metabolism; miR-199a-3p; mouse B16 melanoma cells; mTOR-ULK1 signaling pathway; Physiological aspects; Physiology; Scientific equipment and supplies industry; Signal Transduction; TOR Serine-Threonine Kinases - metabolism; Vemurafenib; United States; China; mouse B16 melanoma cells; Ehux-C22; mTOR-ULK1 signaling pathway; melanosomal autophagy; miR-199a-3p
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms25158061

Melanosomes are specialized membrane-bound organelles where melanin is synthesized and stored. The levels of melanin can be effectively reduced by inhibiting melanin synthesis or promoting melanosome degradation via autophagy. Ceramide, a key component in the metabolism of sphingolipids, is crucial for preserving the skin barrier, keeping it hydrated, and warding off the signs of aging. Our preliminary study indicated that a long-chain C22-ceramide compound (Ehux-C22) isolated from the marine microalga , reduced melanin levels via melanosomal autophagy in B16 cells. Recently, microRNAs (miRNAs) were shown to act as melanogenesis-regulating molecules in melanocytes. However, whether the ceramide Ehux-C22 can induce melanosome autophagy at the post-transcriptional level, and which potential autophagy-dependent mechanisms are involved, remains unknown. Here, miR-199a-3p was screened and identified as a novel upregulated miRNA in Ehux-C22-treated B16 cells. An in vitro high melanin expression model in cultured mouse melanoma cells (B16 cells) was established by using 0.2 μM alpha-melanocyte-stimulating hormone(α-MSH) and used for subsequent analyses. miR-199a-3p overexpression significantly enhanced melanin degradation, as indicated by a reduction in the melanin level and an increase in melanosome autophagy. Further investigation demonstrated that in B16 cells, Ehux-C22 activated miR-199a-3p and inhibited mammalian target of rapamycin(mTOR) level, thus activating the mTOR-ULK1 signaling pathway by promoting the expression of unc-51-like autophagy activating kinase 1 (ULK1), B-cell lymphoma-2 (Bcl-2), Beclin-1, autophagy-related gene 5 (ATG5), and microtubule-associated protein light chain 3 (LC3-II) and degrading p62. Therefore, the roles of Ehux-C22-regulated miR-199a-3p and the mTOR pathway in melanosomal autophagy were elucidated. This research may provide novel perspectives on the post-translational regulation of melanin metabolism, which involves the coordinated control of melanosomes.