The
wound microenvironment comprises constituents, such as the extracellular matrix (ECM), that regulate with temporal and spatial precision, the migratory, proliferative, and contractility of
wound cells. Prompt closure of the
wound is an early and critical phase of healing and beta1
integrins are important in this process. We previously reported a marked increase in
integrin alpha9beta1 expression in epidermal keratinocytes in cutaneous and corneal
wounds. However, the functional role of keratinocyte alpha9beta1 during re-epithelialization is unknown and analysis has been precluded by the lethal phenotype of
integrin alpha9beta1 knockout mice. We now report that in conditional
integrin alpha9 knockout (K14-alpha9 null) mice, normal proliferation occurs in epidermal keratinocytes and corneal basal cells. Normal epidermal keratinocyte morphology is also retained. However, corneal basal cell morphology and epithelial thickness are altered, suggesting that loss of
integrin alpha9beta1 results in abnormal corneal differentiation. In cutaneous
wounds, the number of proliferating epidermal keratinocytes is significantly reduced in K14-alpha9 null mice compared with alpha9(fl/-) mice, but not in Cre (control) mice. The decreased keratinocyte proliferation observed in K14-alpha9 null mice negatively impacts healing, resulting in a thinner migrating epithelium, demonstrating that alpha9beta1 is crucial for efficient and proper re-epithelialization during cutaneous wound healing.