Gene targeting strategy for B-hCGRP mice.
The exon 4 of mouse Calca gene that encodes the calcitonin gene-related peptide was replaced by human CALCR exon 4 in B-hCGRP mice.

Strain specific analysis of CGRP gene expression in wild-type C57BL/6 mice and B-hCGRP mice by RT-PCR and western blot. (A) mRNA expression. Due to the high homology, sequencing were performed to verify whether humanization is successful (right). Combining the results of RT-PCR and sequencing, mouse Cgrp mRNA was detectable only in brain of wild-type C57BL/6 mice (+/+). Human CGRP mRNA was detectable only in homozygous B-hCGRP mice (H/H), but not in wild-type C57BL/6 mice. (B) Protein expression. Heart was collected from wild-type C57BL/6 mice (+/+) and homozygous B-hCGRP mice (H/H), and analyzed by western blot with a known cross-reactive anti-CGRP antibody. The CGRP protein can be detected in wild-type C57BL/6 mice and homozygous B-hCGRP mice.