Generation of c-Fos knockout rats, and observation of their phenotype

c-Fos is a useful marker gene of neuron activation for neuroscience and physiology research. The mechanism and function of neural networks have been elucidated using c-Fos reporter knock-in (KI) mice, but the small size of the mice makes it difficult to perform surgical procedures on specific brain regions. On the other hand, there is a large amount of accumulated data on behavioral studies using rats. Thus, the generation of c-Fos reporter rat is expected, but it is difficult to generate gene-modified rats. Furthermore, c-Fos gene abnormality is expected to be severe in rats, as shown in homozygous of c-Fos knockout (KO) mouse, but such analysis has rarely been performed and is not certain. This study generated c-Fos-deficient rats using CRISPR/Cas, with 1067 bp deletion including exon 1 of the c-Fos gene. Homozygous c-Fos KO rats had growth latency and the same tooth and bone abnormality as homozygous c-Fos KO mice but not heterozygous c-Fos KO rats. Therefore, the c-Fos gene in rats is expected to have the same function as that in mice, and the generation of c-Fos reporter KI rats is further anticipated.