Dendritic cell nuclear protein-1 regulates melatonin biosynthesis by binding to BMAL1 and inhibiting the transcription of N-acetyltransferase in C6 cells  

作　　者：Dong CHEN Yi-pei LI Yan-xia YU Tian ZHOU Chao LIU Er-kang FEI Feng GAO Chen-chen MU Hai-gang REN Guang-hui WANG 

机构地区：[1]Laboratory of Molecular Neuropathology, Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases and College of Pharmaceutical Sciences, Soochow University, Suzhou 215123, China [2]Department of Pharmacy, Suzhou Hospital Affiliated with Nanjing Medical University, Suzhou 215002, China [3]Medical School of Nanchang University, Nanchang 330031, China [4]Department of Histology and Embryology, School of Basic Medical Science, Anhui Medical University, Hefei 230032, China [5]Laboratory of Synapse Development and Plasticity, Institute of Life Science, Nanchang University, Nanchang 330031, China

出　　处：《Acta Pharmacologica Sinica》2018年第4期597-606,共10页中国药理学报（英文版）

摘　　要：Dendritic cell nuclear protein-1 （DCNP1） is a protein associated with major depression. In the brains of depression patients, DCNP1 is up-regulated. However, how DCNP1 participates in the pathogenesis of major depression remains unknown. In this study, we first transfected HEK293 cells with EGFP-DCNP1 and demonstrated that the full-length DCNP1 protein was localized in the nucleus, and RRK （the residues 117-119） composed its nuclear localization signal （NLS）. An RRK-deletion form of DCNP1 （DCNP1ΔRRK） and truncated form （DCNP11-116）, each lacking the RRK residues, did not show the specific nuclear localization like full-length DCNP1 in the cells. A rat glioma cell line C6 can synthesize melatonin, a hormone that plays important roles in both sleep and depression. We then revealed that transfection of C6 cells with full-length DCNP1 but not DCNP1ΔRRK or DCNP11-116 significantly decreased the levels of melatonin. Furthermore, overexpression of full-length DCNP1, but not DCNP1ΔRRK or DCNP11-116, in C6 cells significantly decreased both the mRNA and protein levels of N-acetyltransferase （NAT）, a key enzyme in melatonin synthesis. Full-length DCNP1 but not DCNP1ΔRRK or DCNP11-116 was detected to interact with the Nat promoter and inhibited its activity through its E-box motif. Furthermore, full-length DCNP1 but not the mutants interacted with and repressed the transcriptional activity of BMAL1, a transcription factor that transactivates Nat through the E-box motif. In conclusion, we have shown that RRK （the residues 117-119） are the NLS responsible for DCNP1 nuclear localization. Nuclear DCNP1 represses NAT expression and melatonin biosynthesis by interacting with BMAL1 and repressing its transcriptional activity. Our study reveals a connection between the major depression candidate protein DCNP1, circadian system and melatonin biosynthesis, which may contribute to the pathogenesis of depression.Dendritic cell nuclear protein-1 （DCNP1） is a protein associated with major depression. In the brains of depression patients, DCNP1 is up-regulated. However, how DCNP1 participates in the pathogenesis of major depression remains unknown. In this study, we first transfected HEK293 cells with EGFP-DCNP1 and demonstrated that the full-length DCNP1 protein was localized in the nucleus, and RRK （the residues 117-119） composed its nuclear localization signal （NLS）. An RRK-deletion form of DCNP1 （DCNP1ΔRRK） and truncated form （DCNP11-116）, each lacking the RRK residues, did not show the specific nuclear localization like full-length DCNP1 in the cells. A rat glioma cell line C6 can synthesize melatonin, a hormone that plays important roles in both sleep and depression. We then revealed that transfection of C6 cells with full-length DCNP1 but not DCNP1ΔRRK or DCNP11-116 significantly decreased the levels of melatonin. Furthermore, overexpression of full-length DCNP1, but not DCNP1ΔRRK or DCNP11-116, in C6 cells significantly decreased both the mRNA and protein levels of N-acetyltransferase （NAT）, a key enzyme in melatonin synthesis. Full-length DCNP1 but not DCNP1ΔRRK or DCNP11-116 was detected to interact with the Nat promoter and inhibited its activity through its E-box motif. Furthermore, full-length DCNP1 but not the mutants interacted with and repressed the transcriptional activity of BMAL1, a transcription factor that transactivates Nat through the E-box motif. In conclusion, we have shown that RRK （the residues 117-119） are the NLS responsible for DCNP1 nuclear localization. Nuclear DCNP1 represses NAT expression and melatonin biosynthesis by interacting with BMAL1 and repressing its transcriptional activity. Our study reveals a connection between the major depression candidate protein DCNP1, circadian system and melatonin biosynthesis, which may contribute to the pathogenesis of depression.

关 键 词：major depression DCNP1 N-ACETYLTRANSFERASE MELATONIN circadian system BMAL1 rat glioma cell line C6 

分 类 号：TP393.4[自动化与计算机技术—计算机应用技术] O571.2[自动化与计算机技术—计算机科学与技术]