Bersten David C, Bruning John B, Peet Daniel J, Whitelaw Murray L
School of Molecular and Biomedical Science (Biochemistry), and Australian Research Council Special Research Centre for the Molecular Genetics of Development, The University of Adelaide, Adelaide, South Australia, Australia.
PLoS One. 2014 Jan 17;9(1):e85768. doi: 10.1371/journal.pone.0085768. eCollection 2014.
Neuronal Per-Arnt-Sim homology (PAS) Factor 4 (NPAS4) is a neuronal activity-dependent transcription factor which heterodimerises with ARNT2 to regulate genes involved in inhibitory synapse formation. NPAS4 functions to maintain excitatory/inhibitory balance in neurons, while mouse models have shown it to play roles in memory formation, social interaction and neurodegeneration. NPAS4 has therefore been implicated in a number of neuropsychiatric or neurodegenerative diseases which are underpinned by defects in excitatory/inhibitory balance. Here we have explored a broad set of non-synonymous human variants in NPAS4 and ARNT2 for disruption of NPAS4 function. We found two variants in NPAS4 (F147S and E257K) and two variants in ARNT2 (R46W and R107H) which significantly reduced transcriptional activity of the heterodimer on a luciferase reporter gene. Furthermore, we found that NPAS4.F147S was unable to activate expression of the NPAS4 target gene BDNF due to reduced dimerisation with ARNT2. Homology modelling predicts F147 in NPAS4 to lie at the dimer interface, where it appears to directly contribute to protein/protein interaction. We also found that reduced transcriptional activation by ARNT2 R46W was due to disruption of nuclear localisation. These results provide insight into the mechanisms of NPAS4/ARNT dimerisation and transcriptional activation and have potential implications for cognitive phenotypic variation and diseases such as autism, schizophrenia and dementia.
神经元Per-Arnt-Sim同源性（PAS）因子4（NPAS4）是一种依赖神经元活动的转录因子，它与ARNT2形成异二聚体，以调节参与抑制性突触形成的基因。NPAS4的功能是维持神经元中的兴奋性/抑制性平衡，而小鼠模型显示它在记忆形成、社交互动和神经退行性变中发挥作用。因此，NPAS4与许多神经精神疾病或神经退行性疾病有关，这些疾病的基础是兴奋性/抑制性平衡缺陷。在这里，我们研究了NPAS4和ARNT2中一系列广泛的非同义人类变体对NPAS4功能的破坏。我们在NPAS4中发现了两个变体（F147S和E257K），在ARNT2中发现了两个变体（R46W和R107H），它们显著降低了异二聚体对荧光素酶报告基因的转录活性。此外，我们发现NPAS4.F147S由于与ARNT2的二聚化减少而无法激活NPAS4靶基因BDNF的表达。同源建模预测NPAS4中的F147位于二聚体界面，在那里它似乎直接参与蛋白质/蛋白质相互作用。我们还发现ARNT2 R46W导致的转录激活减少是由于核定位的破坏。这些结果为NPAS4/ARNT二聚化和转录激活的机制提供了见解，并对认知表型变异以及自闭症、精神分裂症和痴呆等疾病具有潜在影响。
