Description

• Background: PTGER2 (prostaglandin E receptor 2) is a G protein-coupled receptor that is mainly involved in a variety of physiological and pathological processes, including inflammatory responses, pain perception, and vascular regulation.
• Targeting strategy: In the B-hPTGER2 mice, exons 1-2 of the mouse Ptger2 gene are replaced by the corresponding human PTGER2 exons.
• Validation: Human PTGER2 is only detected in homozygous B-hPTGER2 mice, but not in wild-type C57BL/6 mice.
• Application: The overexpression of PTGER2 in colorectal cancer is associated with microsatellite instability (MSI) and is independent of the CpG island methylator phenotype (CIMP). This suggests that PTGER2 may play a significant role in the development and progression of colorectal cancer and could serve as a potential biomarker and therapeutic target.

Targeting strategy

Gene targeting strategy for B-hPTGER2 mice.The exons 1-2 of mouse Ptger2 gene that encode signal peptide, extracellular domain and transmembrane domain is replaced by human counterparts in B-hPTGER2 mice. The genomic region of mouse Ptger2 gene that encodes cytoplasmic portion is retained. The promoter, 5’UTR and 3’UTR region of the mouse gene are also retained. The chimeric PTGER2 expression is driven by endogenous mouse Ptger2 promoter, while mouse Ptger2 gene transcription and translation will be disrupted.

Protein expression analysis

Western blot analysis of PTGER2 protein expression in homozygous B-hPTGER2 mice. Various tissue lysates were collected from wild-type C57BL/6N mice (+/+) and homozygous B-hPTGER2 mice (H/H), and then analyzed by western blot with cross reactive anti-PTGER2 antibody (abcam; ab167171). 40 μg total proteins were loaded for western blotting analysis. PTGER2 was detected in liver, spleen, lung, kidneys, ovaries, uterus and eyes except heart in both wild-type and homozygous mice, as the antibody was cross-reactive between human and mouse.

mRNA expression analysis

Strain specific analysis of PTGER2 mRNA expression in wild-type C57BL/6N mice and homozygous B-hPTGER2 mice by RT-PCR. Stomach RNA were isolated from wild-type C57BL/6N mice (+/+) and homozygous B-hPTGER2 mice (H/H), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse or human PTGER2 primers. Human PTGER2 mRNA was detectable only in homozygous B-hPTGER2 mice but not in wild-type mice.