Loss of fibrinogen rescues mice from the pleiotropic effects of plasminogen deficiency

Plasmin(ogen) is an extracellular serine protease implicated in the activation of latent growth factors and procollagenase, degradation of extracellular matrix components, and fibrin clearance. Plasminogen (Plg) deficiency in mice results in high mortality, wasting, spontaneous gastrointestinal ulceration, rectal prolapse, and severe thrombosis. Furthermore, Plg-deficient mice display delayed wound healing following skin injury, a defect partly related to impaired keratinocyte migration. We generated mice deficient in Pig and fibrinogen (Fib) and show that removal of fibrin(ogen) from the extracellular environment alleviates the diverse spontaneous pathologies previously associated with Pig deficiency and corrects healing times. Mice deficient in Pig and Fib are phenotypically indistinguishable from Fib-deficient mice. These data suggest that the fundamental and possibly only essential physiological role of Pig is fibronolysis.