• The MASP2 gene encodes a serine protease of the peptidase S1 family. Its preproprotein is processed proteolytically to form A and B chains that heterodimerize into the mature protease. Similar to C1s molecules in the classical complement pathway, MASP-2 cleaves C2 and C4 to generate C3 convertase in the lectin pathway of the complement system. MASP-1 and -2 activate the lectin pathway, while MASP-3 may be involved in activating the alternative complement pathway. Variant alleles related to protein expression and structure have been linked to various infectious and non-infectious diseases, often as disease modifiers. MASPs also mediate processes like coagulation, bradykinin release, and endothelial and platelet activation.
• Gene targeting strategy for B-hMASP2 mice ad. The full coding sequence of human MASP2 (human MASP2 CDS), followed by mouse 3’UTR-STOP was inserted right after mouse Masp2 ATG of mouse Masp2 gene. The chimeric CDS protein expression was driven by endogenous mouse Masp2 promoter, and the mouse Masp2 gene between exon 2 and exon 8 has been depleted, while mouse Masp2 gene transcription and translation was be disrupted. 
• Human MASP2 mRNA was exclusively detectable in homozygous B-hMASP2 mice ad but not in wild-type mice. Mouse Masp2 mRNA was exclusively detectable in wild-type mice but not homozygous B-hMASP2 mice ad. Human MASP2 protein was exclusively detectable in homozygous B-hMASP2 mice ad.

Gene targeting strategy for B-hMASP2 mice ad. The full coding sequence of human MASP2 (human MASP2 CDS), followed by mouse 3’UTR-STOP was inserted right after mouse Masp2 ATG of mouse Masp2 gene. The chimeric CDS protein expression was driven by endogenous mouse Masp2 promoter, and the mouse Masp2 gene between exon 2 and exon 8 has been depleted, while mouse Masp2 gene transcription and translation was be disrupted. 

Strain-specific analysis of MASP2 mRNA expression in wild-type C57BL/6N mice and homozygous B-hMASP2 mice ad by RT-PCR. Liver RNA were isolated from wild-type C57BL/6N mice (+/+) and homozygous B-hMASP2 mice ad (H/H), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse or human MASP2 primers. Human MASP2 mRNA was exclusively detectable in homozygous B-hMASP2 mice ad but not in wild-type mice. Mouse Masp2 mRNA was exclusively detectable in wild-type mice but not homozygous B-hMASP2 mice ad. 

Strain-specific MASP2 expression analysis in wild-type C57BL/6N mice and homozygous B-hMASP2 mice ad by ELISA. Serum was collected from wild-type C57BL/6N mice (+/+) (female, 6 weeks old, n=3; male, 6 weeks old, n=3) and homozygous B-hMASP2 mice ad (H/H) (female, 6 weeks old, n=3; male, 6 weeks old, n=3). Expression level of  human MASP2 were analyzed by ELISA (anti-human MASP2 ELISA kit: Hycult Biotech, HK326). Human MASP2 was exclusively detectable in homozygous B-hMASP2 mice ad. Values are expressed as mean ± SEM. 

Functional activity of the MBL pathway of homozygous B-hMASP2 mice ad. Serum was collected from wild-type C57BL/6 mice (+/+), homozygous B-hMASP2 mice and homozygous B-hMASP2 mice ad (H/H) (female, 5 weeks old, n=2; male, 5 weeks old, n=2) and evaluate the functional activity with the complement kit (Lectin Complement Pathway, Mouse Assay, Hycult Biotech, HIT421). (A-B) The OD value of male and female in 1:5, 1:20, and 1:40 dilution serum. (C) The OD value of positive and negative control in the kit. (D-E) Lectin Complement Pathway Activity% compared with male wild-type C57BL/6 mice.