Neuronal PAS Domain Protein 1 Is a Transcriptional Repressor and Requires Arylhydrocarbon Nuclear Translocator for Its Nuclear Localization

Christina H.L Teh,Kevin K.Y Lam,Chin C Loh,Jia M Loo,Tie Yan,Tit Meng Lim

doi:10.1074/jbc.m604409200

Christina H.L Teh, Kevin K.Y Lam + Show 4 more

Open Access

https://doi.org/10.1074/jbc.m604409200

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Abstract

Neuronal PAS domain protein 1 (NPAS1), a basic helix-loop-helix-PAS transcription factor expressed in the central nervous system, has been suggested to be involved in neuronal differentiation. However, relatively little is known about the molecular mechanism underlying the role of NPAS1 during development. In this study we set out to characterize the different domains within NPAS1. We showed that the nuclear localization of NPAS1 is dependent on the presence of ARNT. In addition, the transcriptional potential of ARNT is not required for this localization. In the absence of ARNT, NPAS1 is excluded from the nucleus, and this exclusion is due to the presence of a nuclear export signal within the N terminus of NPAS1. The interaction between NPAS1 and ARNT is via their N termini. We found no transactivation domain within NPAS1; instead, we mapped out at least three repression domains within NPAS1, suggesting that NPAS1 acts as a repressor. Furthermore, our experiments showed that NPAS1 is able to repress the transactivation functions of ARNT and ARNT2. We suggest that NPAS1 is guided into the nucleus by ARNT via the ARNT nuclear localization signal, and NPAS1 can override the activation function of adjacent transcription factors, providing a mechanism by which NPAS1 may inhibit transcription.

Highlights

Ber of this family consists of an N-terminal basic region that binds DNA, the HLH and PAS domains for dimerization and specificity of interacting partner, and a highly divergent C-terminal region [9, 10]
Neuronal PAS domain protein 1 (NPAS1) knock-out mice showed behavioral abnormalities that may be related to schizophrenia, relatively little is known about the mechanism of action by NPAS1, except that it forms a heterodimer with AhR nuclear translocator (ARNT) and negatively regulates the expression of erythropoietin [22], a factor that promotes production of neuronal progenitors in the central nervous system [23, 24]
In this study we report that NPAS1 requires the presence of either ARNT or ARNT2 for translocation into the nucleus, and the N terminus prevents nuclear localization in the absence of ARNT or ARNT2

Summary

Introduction

Ber of this family consists of an N-terminal basic region that binds DNA, the HLH and PAS domains for dimerization and specificity of interacting partner, and a highly divergent C-terminal region [9, 10]. FLAG_ARNT or FLAG_ARNT2 in both cell lines (results not leucine residues within the NES of NPAS1 were mutated to shown), indicating that the nuclear translocation is specific to alanine (Fig. 4A), and the subcellular localization of the mutated

Results

Conclusion