• CD49c is a 150 kD α integrin chain known as α3 integrin or VLA-3 α chain. It is a type I transmembrane glycoprotein which is proteolytically cleaved into two disulfide linked fragments of 125 kD and 30 kD. CD49c forms a heterodimer with integrin β1 (α3β1, CD49c/CD29, VLA-3) and is expressed by many types of adhesion cells, such as endothelial cells, epithelial cells, and dermal fibroblasts. Weak expression has been reported on leukocytes. VLA-3 plays a role in cell-cell and cell-matrix adhesion through binding Kalinin, collagen, laminin-1, laminin-5, entactin, and fibronectin.
• The exons 1~23 of mouse Itga3 gene that encode the full-length protein were replaced by human ITGA3 exons 1~26 in B-hITGA3 mice.
• Human ITGA3 protein was detectable in endothelial cells and epithelial cells of homozygous B-hITGA3 mice, but not in wild-type mice. Mouse Itga3 mRNA was only detectable in wild-type mice. Human ITGA3 mRNA was exclusively detectable in homozygous B-hITGA3 mice but not in wild-type mice.

Gene targeting strategy for B-hITGA3 mice. The exons 1-23 of mouse Itga3 gene that encode signal peptide, extracellular domain, transmembrane domain, cytoplasmic region and 3’UTR are replaced by human counterparts in B-hITGA3 mice. The promoter and 5’UTR region of the mouse gene are also retained. The human ITGA3 expression is driven by endogenous mouse Itga3 promoter, while mouse Itga3 gene transcription and translation will be disrupted.

Strain specific analysis of ITGA3 mRNA expression in wild-type C57BL/6JNifdc mice and homozygous B-hITGA3 mice by RT-PCR. Lung RNA were isolated from wild-type C57BL/6JNifdc mice (+/+) and homozygous B-hITGA3 mice (H/H), then cDNA libraries were synthesized by reverse transcription, followed by PCR with mouse or human ITGA3 primers. Mouse Itga3 mRNA was only detectable in wild-type mice. Human ITGA3 mRNA was exclusively detectable in homozygous B-hITGA3 mice but not in wild-type mice.

Strain specific ITGA3 expression analysis in wild-type C57BL/6JNifdc and homozygous B-hITGA3 mice by flow cytometry. Lung cells were collected from wild-type C57BL/6JNifdc (+/+) and homozygous B-hITGA3 mice (H/H) and analyzed by flow cytometry with strain specific anti-hITGA3 antibody（Biolegend, 343808). Human ITGA3 was detectable in endothelial cells and epithelial cells of homozygous B-hITGA3 mice but not in wild-type mice.