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In dealing with systems as complex as the cytoskeleton, we need organizing principles or, short of that, an empirical framework into which these systems fit. We report here unexpected invariants of cytoskeletal behavior that comprise such an empirical framework. We measured elastic and frictional moduli of a variety of cell types over a wide range of time(More)
Tuberous sclerosis (TSC) is a autosomal dominant genetic disorder caused by mutations in either TSC1 or TSC2, and characterized by benign hamartoma growth. We developed a murine model of Tsc1 disease by gene targeting. Tsc1 null embryos die at mid-gestation from a failure of liver development. Tsc1 heterozygotes develop kidney cystadenomas and liver(More)
Mammalian epidermis is maintained by self-renewal of stem cells, but the underlying mechanisms are unknown. Deletion of Rac1, a Rho guanosine triphosphatase, in adult mouse epidermis stimulated stem cells to divide and undergo terminal differentiation, leading to failure to maintain the interfollicular epidermis, hair follicles, and sebaceous glands. Rac1(More)
Defects in myeloid cell function in Rac2 knockout mice underline the importance of this isoform in activation of NADPH oxidase and cell motility. However, the specific role of Rac1 in neutrophil function has been difficult to assess since deletion of Rac1 results in embryonic lethality in mice. To elucidate the specific role of Rac1 in neutrophils, we(More)
Although both of the small Rho guanosine triphosphatases (GTPases) Rac1 and Rac2 have been demonstrated to play a role in chemotaxis, the precise and possible unique roles performed by each of these 2 Rac isoforms in neutrophil chemotaxis have not been defined. To elucidate the specific roles of Rac1 and Rac2 in neutrophils during the process of chemotaxis,(More)
We developed a permeabilization method that retains coupling between N-formyl-methionyl-leucyl-phenylalanine tripeptide (FMLP) receptor stimulation, shape changes, and barbed-end actin nucleation in human neutrophils. Using GTP analogues, phosphoinositides, a phosphoinositide-binding peptide, constitutively active or inactive Rho GTPase mutants, and(More)
The role of gelsolin, a calcium-dependent actin-severing protein, in mediating collagen phagocytosis, is not defined. We examined alpha 2 beta 1 integrin-mediated phagocytosis in fibroblasts from wild-type (WT) and gelsolin knockout (Gsn(-)) mice. After initial contact with collagen beads, collagen binding and internalization were 60% lower in Gsn(-) than(More)
Tooth loss is common, and exploring the neuroplastic capacity of the face primary motor cortex (face-M1) and adjacent primary somatosensory cortex (face-S1) is crucial for understanding how subjects adapt to tooth loss and their prosthetic replacement. The aim was to test if functional reorganization of jaw and tongue motor representations in the rat(More)
An overwhelming neutrophil-driven response causes both acute symptoms and the lasting sequelae that result from infection with Neisseria gonorrhoeae. Neutrophils undergo an aggressive opsonin-independent response to N. gonorrhoeae, driven by the innate decoy receptor CEACAM3. CEACAM3 is exclusively expressed by human neutrophils, and drives a potent(More)
Actin assembly at the leading edge of migrating cells depends on the availability of high-affinity free barbed ends (FBE) that drive actin filament elongation and subsequent membrane protrusion. We investigated the specific mechanisms through which the Rac1 and Rac2 small guanosine triphosphatases (GTPases) generate free barbed ends in neutrophils. Using(More)