Establishment and characterization of liver-specific Apoa4-Cre and Cyp2c11-Cre rat models in juvenile and adult stages.

Abstract

Background: Liver diseases are a major contributor to both morbidity and mortality. Conditional knockout animals are always produced through crossing floxed animals with a tissue-specific Cre animal. The use of floxed rat resource has rapidly increased, but the liver-specific Cre rat lines for studying liver diseases and interested genes are limited, especially in a spatially and temporally restricted manner.

Methods: RNA sequencing and real-time polymerase chain reaction (PCR) were used to screen and confirm the presence of liver-specific genes. Apoa4-Cre rats and Cyp2c11-Cre rats were produced by CRISPR/Cas9 knockin. Rosa26-imCherry rats were employed to hybridize with the Cre rats to obtain the Apoa4-Cre/Rosa26-imCherry and Cyp2c11-Cre/Rosa26-imCherry rats. The temporal and spatial patterns of Cre expression were determined by the observation of red fluorescence on tissue sections. Hematoxylin-eosin stain was used to evaluate the liver histopathologic changes. The blood biochemical analysis of several liver enzymes and liver lipid profile was performed to evaluate the liver function of Cre rats.

Results: Apoa4 and Cyp2c11 were identified as two liver-specific genes. Apoa4-Cre and Cyp2c11-Cre rats were produced and hybridized with Rosa26-imCherry rats. The red fluorescence indicated that the Cre recombinases were specially expressed in the juvenile and adult liver and not in other organs of two hybridized rats. All the blood biochemical parameters except low-density lipoprotein (LDL) did not change significantly in the Cre rats. No histological alterations were detected in the livers of the Cre rats.

Conclusions: Liver-specific Apoa4-Cre and Cyp2c11-Cre rats have been established successfully and could be used to study gene knockout, specifically in juvenile and adult liver.