Lessons from Volunteering and Free/Libre Open Source Software Development for the Future of Work

Part 6: Section 5: The Future of Industrial-Institutional Practices and Outcomes through Information TechnologyInternational audienceIn this paper, we review research on voluntary organizations to identify key features of and problems in volunteer work and organizations. We then use the example of free/libre open source software (FLOSS) development teams to examine how those features and problems apply in this situation and how they might be affected by the use of information and communications technologies (ICT). We suggest that understanding volunteer organizations can illuminate the changing nature of all knowledge work, paid as well as unpaid

Function of the Tetraspanin CD151–α6β1 Integrin Complex during Cellular Morphogenesis

Upon plating on basement membrane Matrigel, NIH3T3 cells formed an anastomosing network of cord-like structures, inhibitable by anti-α6β1 integrin antibodies. For NIH3T3 cells transfected with human CD151 protein, the formation of a cord-like network was also inhibitable by anti-CD151 antibodies. Furthermore, CD151 and α6β1 were physically associated within NIH3T3 cells. On removal of the short 8-amino acid C-terminal CD151 tail (by deletion or exchange), exogenous CD151 exerted a dominant negative effect, as it almost completely suppressed α6β1-dependent cell network formation and NIH3T3 cell spreading on laminin-1 (an α6β1 ligand). Importantly, mutant CD151 retained α6β1 association and did not alter α6β1-mediated cell adhesion to Matrigel. In conclusion, the CD151–α6β1 integrin complex acts as a functional unit that markedly influences cellular morphogenesis, with the CD151 tail being of particular importance in determining the “outside-in” functions of α6β1-integrin that follow ligand engagement. Also, antibodies to α6β1 and CD151 inhibited formation of endothelial cell cord-like networks, thus pointing to possible relevance of CD151–α6β1 complexes during angiogenesis

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