Objective:To investigate the role of microRNA-25-5p (miR-25-5p) in melanogenesis, and to explore its underlying mechanisms.Methods:Target genes of miR-25-5p were predicted using the TargetScan database. The interaction between miR-25-5p and the 3' untranslated region (3' UTR) of the RAB11B gene (a member of RAS oncogene family) was validated through a dual-luciferase reporter assay. Post-inflammatory hyperpigmentation (PIH) models were established in female C57BL/6J mice (6 - 8 weeks old) and female brown guinea pigs (4 - 6 weeks old) through daily broadband ultraviolet B (UVB) irradiation on the dorsal skin of the mouse ear or shaved dorsal skin of guinea pigs, while untreated mice and untreated dorsal skin areas of guinea pigs served as control groups. During modeling, these experimental animals received intradermal injections of a miR-25-5p agomir or a miR control agomir. Changes in skin pigmentation were observed, and skin tissue samples were harvested for further analysis after modeling. Melanin content in skin tissues was evaluated using Masson-Fontana staining. Expression of RAB11B and tyrosinase (TYR) in skin tissues was determined using immunohistochemical staining and quantitative real-time PCR (qPCR). Primary human melanocytes were isolated from discarded normal foreskin tissues of healthy males after circumcision. Both primary human melanocytes and human MNT1 melanoma cells were transfected with miR-25-5p mimics or miR control mimics. Relative expression levels of miR-25-5p and RAB11B mRNA were quantified by qPCR using the 2 -ΔΔCt calculation method. In MNT1 cells, miR-25-5p and RAB11B were co-overexpressed to assess their effect on the mRNA expression of RAB11B and TYR. Statistical analysis was conducted using t test or one-way analysis of variance followed by Tukey's post hoc test for multiple comparisons. Results:The bioinformatic prediction and dual-luciferase reporter assay confirmed a binding site for miR-25-5p in the 3′ UTR of the RAB11B gene. In both animal models, the treatment with the miR-25-5p agomir significantly reduced local skin pigmentation compared to the control groups; Masson-Fontana staining showed a marked decrease in the density of melanin granules in the epidermis and dermis in the miR-25-5p agomir groups compared with the miR control agomir groups (mice: 0.050 ± 0.005 vs. 0.087 ± 0.008; guinea pigs: 0.067 ± 0.015 vs. 0.110 ± 0.013; both P < 0.05). Immunohistochemical staining revealed significantly lower expression of RAB11B in mouse skin tissues in the miR-25-5p agomir group than in those in the miR control agomir group (both P < 0.05). qPCR revealed significantly lower mRNA expression of RAB11B and TYR in skin tissues of guinea pigs in the miR-25-5p agomir group than in those in the miR control agomir group (both P < 0.05). Similarly, RAB11B mRNA expression significantly decreased in the miR-25-5p mimics group compared with the miR control mimics group in primary human melanocytes and MNT1 cells (both P < 0.05). In human MNT1 melanoma cells, miR-25-5p overexpression could suppress TYR mRNA expression, whereas co-overexpression of miR-25-5p and RAB11B could reverse this suppression. Conclusion:Overexpression of miR-25-5p could alleviate UVB-induced post-inflammatory hyperpigmentation and inhibit melanogenesis, likely by targeted suppression of RAB11B expression.

Objective:To investigate the role of microRNA-25-5p (miR-25-5p) in melanogenesis, and to explore its underlying mechanisms.Methods:Target genes of miR-25-5p were predicted using the TargetScan database. The interaction between miR-25-5p and the 3' untranslated region (3' UTR) of the RAB11B gene (a member of RAS oncogene family) was validated through a dual-luciferase reporter assay. Post-inflammatory hyperpigmentation (PIH) models were established in female C57BL/6J mice (6 - 8 weeks old) and female brown guinea pigs (4 - 6 weeks old) through daily broadband ultraviolet B (UVB) irradiation on the dorsal skin of the mouse ear or shaved dorsal skin of guinea pigs, while untreated mice and untreated dorsal skin areas of guinea pigs served as control groups. During modeling, these experimental animals received intradermal injections of a miR-25-5p agomir or a miR control agomir. Changes in skin pigmentation were observed, and skin tissue samples were harvested for further analysis after modeling. Melanin content in skin tissues was evaluated using Masson-Fontana staining. Expression of RAB11B and tyrosinase (TYR) in skin tissues was determined using immunohistochemical staining and quantitative real-time PCR (qPCR). Primary human melanocytes were isolated from discarded normal foreskin tissues of healthy males after circumcision. Both primary human melanocytes and human MNT1 melanoma cells were transfected with miR-25-5p mimics or miR control mimics. Relative expression levels of miR-25-5p and RAB11B mRNA were quantified by qPCR using the 2 -ΔΔCt calculation method. In MNT1 cells, miR-25-5p and RAB11B were co-overexpressed to assess their effect on the mRNA expression of RAB11B and TYR. Statistical analysis was conducted using t test or one-way analysis of variance followed by Tukey's post hoc test for multiple comparisons. Results:The bioinformatic prediction and dual-luciferase reporter assay confirmed a binding site for miR-25-5p in the 3′ UTR of the RAB11B gene. In both animal models, the treatment with the miR-25-5p agomir significantly reduced local skin pigmentation compared to the control groups; Masson-Fontana staining showed a marked decrease in the density of melanin granules in the epidermis and dermis in the miR-25-5p agomir groups compared with the miR control agomir groups (mice: 0.050 ± 0.005 vs. 0.087 ± 0.008; guinea pigs: 0.067 ± 0.015 vs. 0.110 ± 0.013; both P < 0.05). Immunohistochemical staining revealed significantly lower expression of RAB11B in mouse skin tissues in the miR-25-5p agomir group than in those in the miR control agomir group (both P < 0.05). qPCR revealed significantly lower mRNA expression of RAB11B and TYR in skin tissues of guinea pigs in the miR-25-5p agomir group than in those in the miR control agomir group (both P < 0.05). Similarly, RAB11B mRNA expression significantly decreased in the miR-25-5p mimics group compared with the miR control mimics group in primary human melanocytes and MNT1 cells (both P < 0.05). In human MNT1 melanoma cells, miR-25-5p overexpression could suppress TYR mRNA expression, whereas co-overexpression of miR-25-5p and RAB11B could reverse this suppression. Conclusion:Overexpression of miR-25-5p could alleviate UVB-induced post-inflammatory hyperpigmentation and inhibit melanogenesis, likely by targeted suppression of RAB11B expression.

Epilepsy is a disorder of the brain charac-terized by abnormal neuron excitability.However,the underlying molecular mechanism of neuron excitability modulation remains elusive.With the help of bioinformatic methods,we have identified receptor-type tyrosine-pro-tein phosphatase-like N(PTPRN)as a critical gene dur-ing epileptogenesis.PTPRN recruits NEDD4L ubiquitin E3 ligase to NaV1.2 sodium channels,facilitating NEDD4L-mediated ubiquitination and endocytosis.Knockout of PTPRN endows hippocampal granule cells with augmented depolarization currents and higher intrinsic excitability,which is reflected by increased seizure susceptibility of transgenic mice.On the contrary,reduced neuron excit-ability and decreased seizure susceptibility are observed after PTPRN overexpression.Meanwhile,we find that a 133 aa fragment recaptures modulation effect of PTPRN full-length,and this fragment shows therapeutic potential towards epilepsy caused by NaV1.2 gain of function vari-ants.In brief,our results demonstrate PTPRN playsa criti-calroleinregulatingneuronexcitability,providing a poten-tial therapeutic approach for epilepsy.

Objective:To investigate the effect of miRNA (miR) -193b-5p on melanogenesis and its possible mechanisms.Methods:Human primary melanocytes were isolated from discarded normal foreskin tissues of healthy males after circumcision, and cultured in vitro. miR-NC mimics (miR-NC mimic group) and miR-193b-5p mimics (miR-193b-5p mimic group) were transfected into human primary melanocytes and human MNT1 melanoma cells, separately. After transfection, real-time quantitative PCR (RT-qPCR) was performed to determine the overexpression efficiency of miR-193b-5p at 48 hours, Western blot analysis to determine the expression of melanogenesis-related proteins tyrosinase (TYR) and microphthalmia-associated transcription factor (MITF) in human primary melanocytes and human MNT1 melanoma cells at 72 hours, and the melanin content in the above cells was determined by a sodium hydroxide solubilization method at 1 week. The target gene of miR-193b-5p was predicted by using Targetscan algorithms and verified by dual-luciferase reporter assay, and RT-qPCR and Western blot analysis were performed to analyze changes in mRNA and protein expression of the target gene respectively after the overexpression of miR-193b-5p. Two-independent-samples t test was used for comparisons between two groups. Results:In human primary melanocytes and human MNT1 melanoma cells, the miR-193b-5p expression levels were significantly higher in the miR-193b-5p mimic groups than in the miR-NC mimic groups ( t = 65.57, 22.49, respectively, both P < 0.001) , and the melanin content was significantly lower in the miR-193b-5p mimic groups (0.091 ± 0.007, 0.130 ± 0.004, respectively) than in the miR-NC mimic groups (0.117 ± 0.002, 0.188 ± 0.032, t = 5.98, 3.24, P < 0.01, < 0.05, respectively) . Western blot analysis showed that the expression of melanogenesis-related proteins TYR and MITF in both human primary melanocytes and human MNT1 melanoma cells was significantly lower in the miR-193b-5p mimic groups than in the miR-NC mimic groups (all P < 0.01) . TargetScan analysis and dual-luciferase reporter assay revealed a binding site for miR-193b-5p in the 3′ untranslated region of the transcriptional regulator CITED2. After up-regulation of miR-193b-5p expression in human primary melanocytes and human MNT1 melanoma cells, the CITED2 mRNA and protein expression levels significantly decreased compared with the miR-NC mimic groups (all P < 0.05) . Conclusion:miR-193b-5p overexpression can down-regulate the expression of melanogenesis-related proteins TYR and MITF, and then inhibit melanogenesis, which may be related to the targeted inhibition of CITED2 expression.