α4β1 Integrin Regulates Lamellipodia Protrusion via a Focal Complex/Focal Adhesion-independent Mechanism

α4β1 integrin plays an important role in cell migration. We show that when ectopically expressed in Chinese hamster ovary cells, α4β1 is sufficient and required for promoting protrusion of broad lamellipodia in response to scratch-wounding, whereas α5β1 does not have this effect. By time-lapse microscopy of cells expressing an α4/green fluorescent protein fusion protein, we show that α4β1 forms transient puncta at the leading edge of cells that begin to protrude lamellipodia in response to scratch-wounding. The cells expressing a mutant α4/green fluorescent protein that binds paxillin at a reduced level had a faster response to scratch-wounding, forming α4-positive puncta and protruding lamellipodia much earlier. While enhancing lamellipodia protrusion, this mutation reduces random motility of the cells in Transwell assays, indicating that lamellipodia protrusion and random motility are distinct types of motile activities that are differentially regulated by interactions between α4β1 and paxillin. Finally, we show that, at the leading edge, α4-positive puncta and paxillin-positive focal complexes/adhesions do not colocalize, but α4β1 and paxillin colocalize partially in ruffles. These findings provide evidence for a specific role of α4β1 in lamellipodia protrusion that is distinct from the motility-promoting functions of α5β1 and other integrins that mediate cell adhesion and signaling events through focal complexes and focal adhesions

The E-economy and the Rise of Technocapitalism: Networks, Firms, and Transportation

The e-economy is part of a larger phenomenon, technocapitalism, that is transforming business organizations and the ways in which they transact, produce, and ship their goods. Technocapitalism is an evolution of market capitalism that is rooted in technological innovation and supported by such intangibles as creativity and knowledge. This paper considers first the main characteristics of networks that support the e-economy and its source phenomenon, the emergence of technocapitalism. Networks are thought to be the main vehicle through which the e-economy spreads, and they have major effects on the organization of business firms. The culture of technocapitalism, with its emphasis on continuous innovation and rapid adjustment, is largely behind the rising importance of networks. A second section then considers the deconstruction of business firms and its relation to networks, the e-economy, and the rise of technocapitalism. A historical perspective is provided to show the contrast with previous eras. The deconstruction of business organizations involves a major transformation of the norms and ways in which firms are run and structured. Finally, the likely implications for transportation and shipping of the rise of the e-economy, its networks, and the deconstruction of firms are discussed. The logistics, pricing, and infrastructure of shipping are likely to be substantially affected by the spread of the e-economy, its networks, and the deconstruction of firms. Copyright 2003 Gatton College of Business and Economics, University of Kentucky..