Generation of Mice Harboring Bicc1 Conditional Null Alleles.

Bicaudal C1 (Bicc1) encodes an RNA-binding protein critical for many organ development and epithelial tissue homeostasis. Bicc1 null mutations have been shown to lead to the development of polycystic kidney disease (PKD) and death at an early prenatal stage. To elucidate the tissue-specific functions of Bicc1, we engineered two independent conditional knockout (cKO) mouse lines targeting distinct exonic regions of the gene. The first line was generated using a traditional embryonic stem (ES) cell-based approach, wherein loxP sites were inserted flanking exon 4 (E4), enabling Cre-mediated excision of a functionally essential coding region. The second line was created using CRISPR/Cas9 genome editing, introducing loxP sites around both exon 4 and exon 5 (E4-5) in a double-step zygote injection strategy. Both alleles were validated by PCR genotyping, sequencing, and functional recombination was confirmed via a tissue-specific Cre driver. These independent cKO models provide a robust platform for dissecting the role of Bicc1 in specific tissues and developmental stages, and offer new avenues for studying the mechanistic basis of PKD and other Bicc1-related pathologies.