• KREMEN2 acts as a high-affinity transmembrane receptor for the WNT signaling pathway inhibitory protein DKK1. Kremen2 inhibits WNT /beta-catenin signaling by forming a terpolymer complex with DKK1 and Wnt receptor lipoprotein recepter-associated protein 6 (LRR6) and inducing Wnt receptor LRP6 to rapidly endocytosis and clearance from the plasma membrane. KREMEN2, as an important regulatory factor in the classical Wnt signaling pathway, is mainly involved in embryonic development, bone formation and tumorigenesis. It is highly expressed in skin, bone marrow and lymphoid tissue, but low in other tissues, and upregulated in multiple myeloma. Studies have shown that enhancing Wnt/β-catenin signal in bone marrow microenvironment or multiple myeloma cells can significantly inhibit osteoblast generation. It is speculated that inhibiting Kremen2 gene expression will block the occurrence and progression of multiple myeloma. In addition, knocking out Kremen2 in gastric cancer cells can inhibit the growth and migration of tumor cells, so Kremen2 is a potential target for the treatment of multiple myeloma and gastric cancer. The drug under study is an ADC for multiple myeloma, which targets Kremen2 to inhibit the Wnt signaling pathway and thus inhibit the growth and migration of tumor cells.
• mRNA expression analysis: Mouse Kremen2 mRNA was detectable in thymus, brain and stomach of wild-type C57BL/6N mice. Human KREMEN2 mRNA was detectable in thymus, brain and stomach of homozygous B-hKREMEN2 mice. 
• Protein expression analysis: Human and mouse KREMEN2 was both detectable in brain, colon, stomach, skin, thymus and liver of wild-type C57BL/6N mice and homozygous B-hKREMEN2 mice, as the antibody is cross-reactive between human and mouse KREMEN2.

Gene targeting strategy for B-hKREMEN2 mice. The exons 2-7 of mouse Kremen2 gene that encode the signal peptide, extracellular domain and part of transmembrane region domain is replaced by human counterparts in B-hKREMEN2 mice. The genomic region of mouse Kremen2 gene that encodes cytoplasmic portion is retained. The promoter, 5’UTR and 3’UTR region of the mouse gene are also retained. The chimeric KREMEN2 expression is driven by endogenous mouse Kremen2 promoter, while mouse Kremen2 gene transcription and translation will be disrupted. 

Strain specific analysis of KREMEN2 mRNA expression in wild-type C57BL/6N mice and B-hKREMEN2 mice by RT-PCR. Thymus, brain and stomach RNA was isolated from wild-type C57BL/6N mice (+/+) and homozygous B-hKREMEN2 mice (H/H), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse or human KREMEN2 primers. Mouse Kremen2 mRNA was detectable in wild-type C57BL/6N mice only. Human KREMEN2 mRNA was detectable only in homozygous B-hKREMEN2 mice but not in wild-type mice.