• ROR2 is a receptor protein tyrosine kinase that belongs to the ROR subfamily of cell surface receptors. Both canonical and non-canonical Wnt proteins bind to the ROR2 receptor. ROR2 may play a role during embryonic development in the formation of chondrocytes and cartilage and growth plate development and mediates WNT5A-induced noncanonical Wnt signaling, which induces filopodia formation and cell migration.
• The exons 2~8 of mouse Ror2 gene that encode the extracellular domain were replaced by human ROR2 exons 2~8 in B-hROR2 mice. The genomic region of mouse Ror2 gene that encodes transmembrane domain and cytoplasmic portion was retained. The promoter, 5’UTR and 3’UTR region of the mouse gene were also retained. The chimeric ROR2 expression was driven by endogenous mouse Ror2 promoter, while mouse Ror2 gene transcription and translation will be disrupted.
• Mouse Ror2 mRNA was only detectable in wild-type mice. Human ROR2 mRNA was exclusively detectable in homozygous B-hROR2 mice.
• ROR2 was detectable in spleen, lung, brain, stomach, colon, fetal body-mid, fetal body-down in wild-type mice and homozygous B-hROR2 mice. The antibody was cross-reactive between human and mouse.
• B-hROR2 mice can be used to study the in vivo efficacy and safety evaluation of ROR2 antibody drugs and ADC drugs.

Gene targeting strategy for B-hROR2 mice. The exons 2~8 of mouse Ror2 gene that encode the extracellular domain were replaced by human ROR2 exons 2~8 in B-hROR2 mice. The genomic region of mouse Ror2 gene that encodes transmembrane domain and cytoplasmic portion was retained. The promoter, 5’UTR and 3’UTR region of the mouse gene were also retained. The chimeric ROR2 expression was driven by endogenous mouse Ror2 promoter, while mouse Ror2 gene transcription and translation will be disrupted.

Strain specific analysis of ROR2 mRNA expression in wild-type C57BL/6JNifdc mice and B-hROR2 mice by RT-PCR. Colon RNA were isolated from wild-type C57BL/6JNifdc mice (+/+) and homozygous B-hROR2 mice (H/H), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse or human ROR2 primers. Mouse Ror2 mRNA was only detectable in wild-type mice. Human ROR2 mRNA was exclusively detectable in homozygous B-hROR2 mice.

Western blot analysis of ROR2 protein expression in homozygous B-hROR2 mice. Various tissues were collected from wild-type C57BL/6JNifdc mice (+/+) and homozygous B-hROR2 mice (H/H), and then analyzed by western blot with anti-ROR2 antibody (Abcam, ab309483). 40 μg total proteins were loaded for western blotting analysis. ROR2 were detectable in spleen, lung, brain, stomach, colon, fetal body-mid, fetal body-down in wild-type mice and homozygous B-hROR2 mice. The antibody was cross-reactive between human and mouse.

Human ROR2 expression in different tissues of B-hROR2 mice by IHC. Tissues were stained with the antibody was cross-reactive between human and mouse ROR2 (Anti-ROR2[EPR19980] (ab218105)). Heart, liver, lung, kidney, brain, stomach, muscle and intestines of homozygous B-hROR2 mice (H/H) show positive (A-H), Human ROR2 high expression in the brain and low expression in other tissues. Original magnification ×200. Abbreviations: IHC, immunohistochemistry. "+": positive; " - ": negative.The arrow indicates positive cells.

Mouse Ror2 expression in different tissues of C57BL/6JNifdc mice by IHC. Tissues were stained with the antibody was cross-reactive between human and mouse ROR2 (Anti-ROR2[EPR19980] (ab218105)). Heart, liver, lung, kidney, brain, stomach, muscle and intestines of C57BL/6JNifdc mice (+/+) show positive (A-H). Mouse Ror2 high expression in the brain and low expression in other tissues. Original magnification ×200. Abbreviations: IHC, immunohistochemistry. "+": positive; " - ": negative.The arrow indicates positive cells.