To establish the flox-heterozygous mouse model in which the X-box-binding protein 1 (Xbp1) gene was conditionally knocked out.

The conditional gene-targeting vector, based on the cre-loxp system and the FLP-frt system, was constructed with the ET-clone method. The vectors were linearized and electroporated into the JM8A3 embryonic stem (ES) cells. The resistant ES cell clones were obtained through G418 and Ganc screening. The positive clones with correct homologous-recombination were obtained through identification with the long-range PCR method. Positive ES cells were clonally expanded, and injected into the blastocysts of C57BL/6J mice to obtain the chimeric mice. The high-rate chimeric mice were screened, and mated with the wild-type C57BL/6J mice to obtain the positive F1 mice, which were identified by PCR and sequencing.

The targeting vectors were successfully constructed. A total of 144 resistant ES cell clones were obtained and identified by long-range PCR. Four positive homologous recombination clones were obtained. Four positive F1 mice were obtained and confirmed by sequencing. There was no obvious abnormality in the phenotypes of the Xbp1 gene flox-heterozygous mice.

The conditional knockout flox-heterozygous mouse model of Xbp1 gene was successfully established, which laid a foundation for further studies of the organ or tissue-specific biological effects of Xbp1 gene.