Regulation of theNeuroligin-1Gene by Clock Transcription Factors

Abstract

NEUROLIGIN-1 (NLGN1) is a postsynaptic adhesion molecule involved in the regulation of glutamatergic transmission. It has been associated with several features of sleep and psychiatric disorders. Our previous work suggested that transcription of the Nlgn1 gene could be regulated by the transcription factors CLOCK and BMAL1 because they bind to the Nlgn1 gene promoter in vivo. However, whether CLOCK/BMAL1 can directly activate Nlgn1 transcription is not yet known. We thus aimed to verify whether CLOCK/BMAL1, as well as their homologs NPAS2 and BMAL2, can activate transcription via the Nlgn1 promoter by using luciferase assays in COS-7 cells. We also investigated how Nlgn1 expression was affected in Clock mutant mice. Our results show transcriptional activation in vitro mediated by CLOCK/BMAL1 and by combinations with their homologs NPAS2 and BMAL2. Moreover, CLOCK/BMAL1 activation via the Nlgn1 gene fragment was repressed by GSK3β. In vivo, Nlgn1 mRNA expression was significantly modified in the forebrain of Clock mutant mice in a transcript variant-dependent manner. However, no significant change in NLGN1 protein level was observed in Clock mutant mice. These findings will increase knowledge about the transcriptional regulation of Nlgn1 and the relationship between circadian rhythms, mental health, and sleep.

Neuroligin-1 is altered in the hippocampus of Alzheimer’s disease patients and mouse models, and modulates the toxicity of amyloid-beta oligomers

“…mRNA extraction and qPCR. mRNA extraction, reverse transcription and qPCR procedures were performed as previously described [48][49][50] . Briefly, hippocampal mRNA was extracted using the RNeasy Lipid Tissue mini kit according to manufacturer's instructions (Qiagen, Cat No.…”

“…4444557), and primers and probes for each gene ( Table 2). Given that NLGN1 has isoforms with different properties 51 , five different probe sets were used to quantify Nlgn1 expression as previously performed [48][49][50] . Nlgn1A corresponds to the sequence containing insert A and Nlgn1B with insert B, while Nlgn1NA is a sequence without insert A and Nlgn1NB without insert B. N1gn1C corresponds to a common sequence targeting transcripts with only insert A, only insert B, both inserts and no insert.…”

Transcriptional control of synaptic components by the clock machinery

“…In Clock delta19 mice specifically, Icam‐1 expression is altered in the SCN (Wang et al., ), and the mRNA expression of EphA4 , EfnB2, and EfnA3 is decreased in the forebrain (Freyburger et al., ). Also in Clock delta19 mice, Nlgn1 showed a modified expression in a transcript variant‐dependant manner, with Nlgn1 with or without insert A showing a decreased expression, and Nlgn1 with or without insert B showing an alteration in the phase of peak expression (Hannou et al., ). Insert A is generally linked to localization of NLGN1 at inhibitory synapses, whereas insert B localizes NLGN1 at excitatory synapses (Chih, Gollan, & Scheiffele, ).…”

“…In addition, E‐box elements have been observed in the gene of SAMs, such as E‐cadherin , EphA4 , EfnB3 , Nlgn1 , and Nlgn2 (El Helou et al., ; Freyburger et al., ; Giroldi et al., ; Hannou et al., ). Moreover, our team has shown that fragments of the promoter of both Nlgn1 and Nlgn2 are transcriptionally activated by the CLOCK/BMAL1 dimer in cell culture (Hannou et al., ), that transcriptional activation of the Nlgn1 promoter also occurs with dimers NPAS2/BMAL1 and CLOCK/BMAL2 (Hannou et al., ), and that CLOCK and BMAL1 rhythmically bind the Nlgn1 promoter region containing a canonical E‐box (CACGTG) in the mouse cerebral cortex (El Helou et al., ). Interestingly, GSK3β, a CLOCK/BMAL1 negative regulator (Sahar et al., ), decreased CLOCK/BMAL1 transcriptional activity on the Nlgn1 gene (Hannou et al., ).…”

“…Moreover, our team has shown that fragments of the promoter of both Nlgn1 and Nlgn2 are transcriptionally activated by the CLOCK/BMAL1 dimer in cell culture (Hannou et al., ), that transcriptional activation of the Nlgn1 promoter also occurs with dimers NPAS2/BMAL1 and CLOCK/BMAL2 (Hannou et al., ), and that CLOCK and BMAL1 rhythmically bind the Nlgn1 promoter region containing a canonical E‐box (CACGTG) in the mouse cerebral cortex (El Helou et al., ). Interestingly, GSK3β, a CLOCK/BMAL1 negative regulator (Sahar et al., ), decreased CLOCK/BMAL1 transcriptional activity on the Nlgn1 gene (Hannou et al., ). Besides a direct transcriptional control by the clock machinery (Figure ), adhesion molecules could be submitted to a second degree (or indirect) transcriptional regulation by clock transcription factors (Figure ).…”