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

Abstract

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 (DCNP1) and truncated form (DCNP1), 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 DCNP1 or DCNP1 significantly decreased the levels of melatonin. Furthermore, overexpression of full-length DCNP1, but not DCNP1 or DCNP1, 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 DCNP1 or DCNP1 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.

Poly-PR in C9ORF72-Related Amyotrophic Lateral Sclerosis/Frontotemporal Dementia Causes Neurotoxicity by Clathrin-Dependent Endocytosis

“…Small Interfering RNA (siRNA) RNA oligonucleotides were transfected into cells as described previously [41]. Briefly, the cells were incubated in a mixture of Opti-MEM, RNAiMAX (Invitrogen, Carlsbad, CA, USA) and RNA oligonucleotides for 20 min at room temperature before transfection.…”

E3 ubiquitin ligase HRD1 modulates the circadian clock through regulation of BMAL1 stability

“…Primarily, two core circadian clock transcriptional factors [brain and muscle ARNT-like1 (BMAL1) and clock circadian regulator (CLOCK)] form heterodimers and rhythmically bind to enhancer boxes in the promoters of target genes, such as the negative regulators periods 1-3 (PER 1-3) and cryptochromes 1 and 2 (CRY 1 and 2). Subsequently, PERs and CRYs suppress the transcriptional activity of BMAL1 and CLOCK (5)(6)(7)(8). The precision of the circadian clock is further influenced by clock protein posttranslational modifications, including ubiquitination, phosphorylation, acetylation and SUMOylation, that are critical for the maintenance of normal physiological function (9)(10)(11).…”

Melatonin in food allergy: Mechanism and potential therapy

“…Dendritic cell nuclear protein-1(DCNP1), one of the DCspecific genes associated with serum IgE level in allergy, 23 could inhibit melatonin biosynthesis by binding to brain and muscle ARNT-like protein-1 (BMAL1) and inhibiting the transcription of AANAT. 24 Furthermore, local tryptophan depletion caused by high expression of IDO is a metabolic characteristic of tolerogenic dendritic cells, 19 and the expression of IDO in DCs is significantly downregulated under allergic conditions. 25 Although the alteration in melatonin metabolism during T cell differentiation is rarely reported, T cells express four enzymes involved in melatonin synthesis.…”

“…On the other hand, alteration in melatonin metabolism is associated with the differentiation and activation of immune cells that participate in food allergies (Table 1). Dendritic cell nuclear protein‐1(DCNP1), one of the DC‐specific genes associated with serum IgE level in allergy, 23 could inhibit melatonin biosynthesis by binding to brain and muscle ARNT‐like protein‐1 (BMAL1) and inhibiting the transcription of AANAT 24 . Furthermore, local tryptophan depletion caused by high expression of IDO is a metabolic characteristic of tolerogenic dendritic cells, 19 and the expression of IDO in DCs is significantly downregulated under allergic conditions 25 .…”