Analysis of the Fam181 gene family during mouse development reveals distinct strain-specific expression patterns, suggesting a role in nervous system development and function

• FAM181 proteins are conserved in vertebrates with two paralogs per species.
• Fam181a/b expression is mainly associated with, and overlapping, in neural tissues.
• Fam181b strain-dependently cycles in the psm under the control of Notch signaling.
• Single knock-out of Fam181b has in no obvious morphological phenotype.
• Loss of Fam181b reduces expression levels of Fam181a in neural tissues.

During somitogenesis differential gene expression can be observed for so-called cyclic genes, which display expression changes with a periodicity of 120 min in the mouse. In screens to identify novel cyclic genes in murine embryos, Fam181b was predicted to be an oscillating gene in the presomitic mesoderm (psm). This gene, and its closely related paralog Fam181a, belong to the thus far uncharacterized Fam181 gene family.Here we describe the expression of Fam181b and Fam181a during murine embryonic development. In addition, we confirm oscillation of Fam181b in the psm in-phase with targets of, and regulated by, Notch signaling. Fam181b expression in the psm, as well as in the lateral plate mesoderm, was found to be affected by genetic background. We show that Fam181a and b exhibit partially overlapping mRNA expression patterns, and encode for proteins containing highly-conserved motifs, which predominantly localize to the nucleus. A Fam181b loss-of-function model was generated and found to result in no obvious phenotype.