Table 1. Association of Tfap2b and Tfap2a-controlled genes with sleep and behavioral phenotypes.

Assay		Tfap2a+/−	Tfap2b+/−
	Phenotype	DE genes	Phenotype	DE genes
EEG/EMG recording	Normal sleep amount but increased sleep power	Slc5a5a	Shortened sleep amount and impaired sleep quality	Fosa, Fosba, Slc5a5a Slc18a2b
EPM	Normal anxiety-associated behavior	—	Normal anxiety-associated behavior	—
Rotarod	Normal motor function	—	Normal motor function	—
MWM	Normal spatial learning and memory	—	Impaired spatial learning and memory	Arca, Fosa, Fosba, Vgfa
SPT, FST, TST	Hyperactive in TST, but normal in SPT or TST	—	Depression-like behavior only in FST, but normal in SPT or TST	Fosba, Dusp1a
				Slc6a4b
Contextual fear conditioning	Shortened freezing behavior	—	Shortened freezing behavior	Arca, Vgfa
				Slc6a4b
Wheel-running	Normal circadian activity	—	Shortened circadian period and accelerated re-entrainment	Vgfa

Literature analysis of genes that are differentially expressed in Tfap2a^+/− and TFAP2b^+/−. All interpretations are purely speculative. Fos and Fosb from the Fos family of transcription factors as well as Slc5a5 and Slc18a2 from the solute carrier (SLC) group of membrane transport proteins were found to be differentially regulated in Tfap2b^+/− mice, which might contribute to the shortened sleep (Figure 3). Slc5a5, which encodes a sodium/iodide symporter (NIS), was down regulated in both Tfap2a^+/− and Tfap2b^+/− mice. The NIS plays a fundamental role in the first step in thyroid hormone biosynthesis (Dohán et al. 2003). Multiple phenotypes relating to neurological features, skeleton, vision, and metabolism have been discovered in Slc5a5 knockouts. Among those phenotypes, abnormal sleep behavior, such as shorter sleep bout duration during the dark phase, has been found in male Slc5a5^−/− mice (Dickinson et al. 2016). Fos (c-fos) is a nuclear proto-oncogene, whose expression is used as an indirect marker of neuronal activity. Fosb expression is induced often in the same cells as Fos, but at a later time (Gass et al. 1992; Peters et al. 1994). In Tfap2b^+/− mice, Fos and Fosb were downregulated. Abnormal sleep has been found in Fos or Fosb-deficient mice such that Fos-null mice have less NREMS and normal REM sleep, but Fosb-deficient mice have less REMS but unchanged NREMS (Shiromani et al. 2000). Dopamine is transported into synaptic vesicles by the vesicular monoamine transporter (VMAT2), which is encoded by Slc18a2. VMAT2-deficient mice are used as a model of Parkinson’s Disease (PD) that exhibits shorter latency to sleep and lower circadian activity except for a major phenotype of the motor dysfunction (Taylor et al. 2009). In Tfap2b^+/− animals, Slc18a2 was upregulated, and overexpression of this gene was reported to have neuroprotective effects, such as antidepressive and anxiolytic activity and increased ambulation during the dark phase (Lohr et al. 2014). The downregulation of Arc, Fos, Fosb, and Vgf might be associated with the impaired spatial learning and memory that we found in Tfap2b^+/− animals (Figure 8, C–E). The deletion of either Arc, Fos, Fosb, or Vgf in mice result in impaired spatial learning (Paylor et al. 1994; Plath et al. 2006; Bozdagi et al. 2008; Ohnishi et al. 2011). Increased immobility was observed in Tfap2b^+/− mice (Figure 8H), which is consistent with downregulation of Fosb and Duspt1 as well as upregulation of Slc6a4. Fosb null mice have increased immobility in FST compared with their controls (Ohnishi et al. 2011). On the contrary, overexpression of Dusp1 causes depressive behaviors and mice lacking Dusp-1 are resilient to stress (Duric et al. 2010). Slc6a4 encodes the serotonin transporter (SERT) in mice. It is reported that mice that are more susceptible to stress have increased expression of SERT and exhibit longer immobility in FST (Couch et al. 2013). In addition, SERT overexpression (5-HTTOE) mice have reduced freezing time in the cued fear conditioning test (McHugh et al. 2015). In Tfap2b^+/− mice, we found a shortened freezing time in the contextual fear conditioning test (Figure 8L). The downregulation of Arc and Vgf might also contribute to this fear-related phenotype, as Arc and Vgf null mice exhibit shortened freezing time in the contextual fear conditioning test (Plath et al. 2006; Bozdagi et al. 2008). Moreover, Vgf^−/− mice have a slightly shortened circadian period length (Hahm et al. 1999), which might help explain the similar phenotype we observed in Tfap2b^+/− mice (Figure 10).

^aUpregulated genes.

^bDownregulated genes. “—” indicates that no information was found.