• CPM is a membrane-bound, zinc-dependent protease that can cleave the C-terminal basic residues (such as arginine or lysine) from peptides/proteins. It’s widespread distribution in human tissues suggests that CPM plays a significant role in regulating the activity of cell surface peptide hormones and growth factors, as well as in the intracellular degradation of extracellular proteins. In recent years, CPM has been recognized as a potential biomarker for cancer and has been associated with stromal cells and tumor-associated macrophages.
• Human CPM mRNA was exclusively detectable in homozygous B-hCPM mice but not in wild-type mice.
• Human CPM was detected in liver, kidney, spleen, uterus and lung of B-hCPM mice but not wild-type C57BL/6JNifdc mice.
• The exons 2-9 of mouse Cpm gene that encode the whole molecule (ATG to STOP codon) were replaced by human counterparts in B-hCPM mice. The promoter, 5’UTR and 3’UTR region of the mouse gene were retained. The human CPM expression was driven by endogenous mouse Cpm promoter, while mouse Cpm gene transcription and translation will be disrupted.

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

Western blot analysis of CPM protein expression in homozygous B-hCPM mice. Various tissue lysates were collected from wild-type C57BL/6JNifdc mice (+/+) (Female, 6-week-old, n=1) and homozygous B-hCPM mice (H/H) (Female, 6-week-old, n=1), and then analyzed by western blot with anti-human CPM antibody (abcam, ab150405). 40 μg total proteins were loaded for western blotting analysis. Human CPM was detected in liver, kidney, spleen, uterus and lung of B-hCPM mice but not wild-type C57BL/6JNifdc mice. Note: The small intestine samples were suspected to be degraded.