• Three RAMPs have been defined in humans: RAMP1, RAMP2, and RAMP3. RAMPs are most extensively studied for their interactions with two class B GPCRs: the calcitonin receptor (CTR) and calcitonin receptor-like receptor (CLR). In humans, CTR, CLR and their RAMP-bound complexes constitute no fewer than seven pharmacologically distinct receptor subtypes (excluding splice variants). These receptors differ markedly in ligand selectivity toward six closely related peptides of the calcitonin family, namely calcitonin (CT), amylin (Amy), α- and β-calcitonin gene-related peptide (αCGRP, βCGRP), adrenomedullin (AM) and adrenomedullin 2/intermedin (AM2).
• Gene editing strategy: The exons 1-4 of the mouse Ramp2 gene that encode the whole molecule, including promoter, 5’UTR, and 3’UTR, were replaced by the exons 1-4 of the human counterparts, including human promoter, 5’UTR, and human 3’UTR in B-hRAMP2 mice. The human RAMP2 expression is driven by the human RAMP2 promoter, while the mouse Ramp2 gene transcription and translation will be disrupted.
• mRNA Expression Analysis: Mouse Ramp2 mRNA was detectable in wild-type C57BL/6JNifdc mice but not in homozygous B-hRAMP2 mice. Human RAMP2 mRNA was detectable only in homozygous B-hRAMP2 mice but not in wild-type mice. RAMP2 protein was detectable in homozygous B-hRAMP2 mice and wild-type C57BL/6JNifdc mice, as the antibody cross-recognizes both human and mouse RAMP2.
• Application: This product is used for pharmacodynamics and safety evaluation of Amylin-related drugs

Gene editing strategy for B-hRAMP2 mice. The exons 1-4 of the mouse Ramp2 gene that encode the whole molecule, including promoter, 5’UTR, and 3’UTR, were replaced by the exons 1-4 of the human counterparts, including human promoter, 5’UTR, and human 3’UTR in B-hRAMP2 mice. The human RAMP2 expression is driven by the human RAMP2 promoter, while the mouse Ramp2 gene transcription and translation will be disrupted.

Species specific analysis of RAMP2 mRNA expression in wild-type C57BL/6JNifdc mice and homozygous humanized B-hRAMP2 mice by RT-PCR. Kidney RNA was isolated from wild-type C57BL/6JNifdc mice (+/+) and homozygous B-hRAMP2 mice (H/H), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse or human RAMP2 primers. Human RAMP2 mRNA was detectable only in homozygous B-hRAMP2 mice but not in wild-type mice. Mouse Ramp2 mRNA was detectable in wild-type mice but not B-hRAMP2 mice.

Western blot analysis of RAMP2 protein expression in homozygous B-hRAMP2 mice. Various tissue lysates were collected from wild-type C57BL/6JNifdc mice (+/+) and homozygous B-hRAMP2 mice (H/H) (male, 8-week-old), and then analyzed by western blot with anti-RAMP2 antibody (Abcam, ab96546). 40 μg total protein was loaded for western blot analysis. RAMP2 protein was detectable in homozygous B-hRAMP2 mice and wild-type C57BL/6JNifdc mice, as the antibody cross-recognizes both human and mouse RAMP2.