MMP7 accelerates lung fibrosis via ECM degradation and fibroblast activation

• Gene Information: Human MMP7 locates at chr11q22.2, encoding MMP7, a zinc-dependent protease zymogen activated via proteolysis, clustered with other MMP family genes on chromosome 11.
• Protein Expression: MMP7 is drastically overexpressed in colorectal, lung, pancreatic and fibrotic lesions, secreted extracellularly as a diagnostic and prognostic serum biomarker for epithelial injury and malignancy.
• Signaling Pathway: Wnt/β-catenin-TCF, TGF-β and MAPK/ERK-JNK-AP-1 pathways dominantly transactivate MMP7 via promoter binding sites; STAT3 also synergistically boosts its transcription, while endogenous TIMPs and nuclear receptor FXR repress MMP7 transcription and protease activity physiologically.
• Therapeutic Inhibition: Selective small-molecule MMP7 inhibitors, neutralizing antibodies and Wnt/ERK pathway blockers suppress its ECM degradation and tumor metastasis; broad-spectrum MMP inhibitors are abandoned due to side effects, natural polyphenols and gene silencing are under preclinical anti-cancer and anti-fibrosis evaluation.

Gene targeting strategy for B-hMMP7 mice.

• The exons 1-6 of mouse Mmp7 gene that encode full length protein and 3’UTR regions are replaced by human MMP7 exons 1-6 as well as 3’UTR regions in B-hMMP7 mice.
• The promoter and 5’UTR of the mouse gene are retained as mouse sequence, while 3’UTR is replaced with human sequence. Human MMP7 expression is driven by endogenous mouse Mmp7 promoter, while mouse Mmp7 gene transcription and translation will be disrupted.

• Human MMP7 was exclusively detected in homozygous B-hMMP7 mice.
• CT values of both mouse Mmp7 and human MMP7 were approximately 31 (total cycle: 40).

Strain specific analysis of MMP7 gene expression in wild-type C57BL/6 mice and B-hMMP7 mice by RT-qPCR. Lung RNA were isolated from wild-type C57BL/6 mice (+/+) (n=3, male, 9-week-old) and homozygous B-hMMP7 mice (H/H) (n=3, male, 9-week-old) , then 40 ng total RNA was used for cDNA library synthesis by reverse transcription, followed by real-time quantitative PCR with MMP7 primers. Mouse Mmp7 was only detected in wild-type C57BL/6 mice and human MMP7 was exclusively detected in homozygous B-hMMP7 mice. Values are expressed as mean ± SEM.

• Mouse MMP7 was only detectable in wild-type C57BL/6 mice, but not in homozygous B-hMMP7 mice.
• Human MMP7 was exclusively detectable in homozygous B-hMMP7 mice.

Strain specific MMP7 expression analysis in wild-type C57BL/6 mice and homozygous humanized B-hMMP7 mice by ELISA. Serum was collected from wild-type C57BL/6 mice (+/+) (female, 8-weeks-old, n=3) and homozygous B-hMMP7 mice (H/H) (female, 8-weeks-old, n=3). Protein expression level of MMP7 was analyzed by ELISA (Mouse MMP-7 ELISA Kit (Colorimetric), Novus Biologicals, NBP3-06895; Human Total MMP-7 Quantikine ELISA Kit, R&D, DMP700). Values are expressed as mean ± SEM.