• Background: PROKR1 gene (GPR73), a member of the G protein-coupled receptor family, is primarily expressed in peripheral tissues including the circulatory system, lungs, reproductive system, endocrine system, and gastrointestinal tract. The protein encoded by this gene binds to either PROK1 or PROK2, leading to activation of the MAPK and STAT signaling pathways. It is associated with several critical physiological functions such as gastrointestinal smooth muscle contraction, circadian rhythm regulation, neurogenesis, angiogenesis, pain perception, mood regulation, and reproduction. Diseases linked to PROKR1 include Hirschsprung Disease 1 and Kallmann syndrome.
• Targeting strategy: The exons 2-3 of mouse Prokr1 gene that encode the whole, including 3’UTR are replaced by human counterparts in B-hPROKR1 mice. The promoter and 5’UTR region of the mouse gene are retained. The PROKR1 expression is driven by the endogenous mouse Prokr1 promoter, while mouse Prokr1 gene transcription and translation will be disrupted.
• Validation: Human PROKR1 mRNA were detected in the B-hPROKR1 mice but not in C57BL/6JNifdc mice.
• Application: evaluating the efficacy and safety of drugs acting on this target.

Gene targeting strategy for B-hPROKR1 mice. The exons 2-3 of mouse Prokr1 gene that encode the whole, including 3’UTR were replaced by human counterparts in B-hPROKR1 mice. The promoter and 5’UTR region of the mouse gene are retained. The PROKR1 expression is driven by the endogenous mouse Prokr1 promoter, while mouse Prokr1 gene transcription and translation will be disrupted.

Strain specific analysis of PROKR1 mRNA expression in wild-type C57BL/6JNifdc mice and B-hPROK1 mice by RT-PCR. Lung RNA was isolated from wildtype C57BL/6JNifdc mice (+/+) and homozygous B-hPROKR1 mice (H/H). Mouse Prokr1 mRNA was detectable only in wild-type C57BL/6JNifdc mice. Human PROKR1 mRNA was detectable only in homozygous B-hPROKR1 mice, but not in wild-type C57BL/6JNifdc mice.