| Popis: |
The α2β1 integrin is a collagen/laminin receptor expressed on platelets, endothelial cells, fibroblasts, and epithelial cells. To define the role of the α2β1 integrin in vivo, we created a genetically engineered mouse in which expression of the α2β1 integrin was completely eliminated. Mice deficient in the α2β1 integrin are viable, fertile, and develop normally with no excess lethality of homozygotes. Both α2β1-integrin protein and α2 mRNA were undetectable in the α2-null mice. Gross and histological evaluation of the heart, lungs, kidneys, gastrointestinal tract, pancreas, skin, and reproductive tracts revealed no abnormalities. However, quantitative analysis of mammary gland branching morphogenesis demonstrated that branching complexity is markedly diminished in the α2-deficient animals. Studies in the α2-deficient animals do not support the proposed roles for the α2β1 integrin on fibroblasts and keratinocytes in wound healing. When compared to platelets from wild-type littermates, platelets from α2-null mice failed to adhere to type I collagen under either static or shear-stress conditions. Although platelets from α2-deficient animals aggregated in response to collagen, they did so with prolonged lag time and lessened intensity. The α2β1 integrin-null mouse thus exhibits diverse, sometimes subtle, phenotypes consistent with the widespread pattern of α2β1 integrin expression. |
