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.

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.