The Regulatory Factor ZFHX3 Modifies Circadian Function in SCN via an AT Motif-Driven Axis.
Bottom Line: Using RNA sequencing, we found minimal effects on core clock genes in Zfhx3(Sci/+) SCN, whereas the expression of neuropeptides critical for SCN intercellular signaling was significantly disturbed.Moreover, mutant ZFHX3 had a decreased ability to activate AT motifs in the promoters of these neuropeptide genes.Lentiviral transduction of SCN slices showed that the ZFHX3-mediated activation of AT motifs is circadian, with decreased amplitude and robustness of these oscillations in Zfhx3(Sci/+) SCN slices.
Affiliation: MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire OX11 0RD, UK.Show MeSH
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Mentions: We conducted an ENU screen to uncover genetic factors affecting mammalian circadian behavior (Bacon et al., 2004). Among G1 animals in a dominant screen, we identified a mouse with a circadian period (τDD; behavioral circadian period of the animals in constant darkness) shorter than the population mean (23.6 ± 0.08 hr; mean ± SEM). This phenotype was inherited in a dominant fashion, with a τDD (23.0 ± 0.05 hr) ranging from 21.4 to 23 hr (Figures 1A and 1B). We named the mutation short circuit (Sci) and mapped the dominant phenotype to mouse chromosome 8 between D8Mit138 (107.67 Mb) and D8Mit213 (110.57 Mb), containing 25 annotated genes. Among the candidates, zinc-finger homeobox 3 (Zhfx3) was highly and almost exclusively expressed in adult SCN (Lein et al., 2007). We identified a point mutation in exon 9, resulting in a G → T transversion at position 6620 (Zfhx3 transcript, ENSMUST00000043896) (Figure 1C). The Sci mutation substitutes a phenylalanine for a valine at residue 1963 (V1963F) in a highly conserved region just upstream of the 17th zinc-finger motif (Figures 1D and 1E). Following the identification of the causative mutation, genotype and phenotype correlation demonstrated that the mutation causes homozygous lethality during embryonic development; therefore, only Zfhx3Sci/+ adult animals could be assessed phenotypically.
Affiliation: MRC Harwell, Harwell Science and Innovation Campus, Oxfordshire OX11 0RD, UK.