The mammalian Rho family GTPases TC10 and Cdc42 share many properties. Activated forms of both proteins stimulate transcription mediated by nuclear factor kappaB, serum response factor, and the cyclin D1 promoter; activate c-Jun NH2-terminal kinase; cooperate with activated Raf to transform NIH-3T3 cells; and, by a mechanism independent of all of these effects, induce filopodia formation. In contrast, previously reported differences between TC10 and Cdc42 are not striking. We now present studies of TC10 and Cdc42 in cell culture that reveal clear functional differences: (a) wild-type TC10 localizes predominantly to the plasma membrane and less extensively to a perinuclear membranous compartment, whereas wild-type Cdc42 localizes predominantly to this compartment and less extensively to the plasma membrane; (b) expression of Rho guanine nucleotide dissociation inhibitor alpha results in a redistribution of wild-type Cdc42 to the cytosol but has no effect on the plasma membrane localization of wild-type TC10; (c) TC10 fails to rescue a Saccharomyces cerevisiae cdc42 mutation, unlike mammalian Cdc42; (d) dominant negative Cdc42, but not dominant negative TC10, inhibits neurite outgrowth in PC12 cells stimulated by nerve growth factor; and (e) activation of nuclear factor kappaB-dependent transcription by Cdc42, but not by TC10, is inhibited by sodium salicylate. These findings point to distinct pathways in which TC10 and Cdc42 may act and distinct modes of regulation of these proteins.
Currently, no pharmacological therapies treat skeletal muscle insulin resistance in pathological conditions such as type 2 diabetes, age-associated diseases, and cancer. Therefore, there is an unmet need to identify the molecular mechanisms ...The molecular events governing skeletal muscle glucose uptake have pharmacological potential for managing insulin resistance in conditions such as obesity, diabetes, and cancer. With no current pharmacological treatments to target skeletal muscle insulin ...
Although the human Ras proteins are members of a large superfamily of Ras-related proteins, to date, only the proteins encoded by the three mammalian ras genes have been found to possess oncogenic potential. Among the known Ras-related proteins, TC21/R-Ras2 exhibits the most significant amino acid identity (55%) to Ras proteins. We have generated mutant forms of TC21 that possess amino acid substitutions analogous to those that activate Ras oncogenic potential [designated TC21(22V) and TC21(71L)] and compared the biological properties of TC21 with those of Ras proteins in NIH 3T3 and Rat-1 transformation assays. Whereas wild-type TC21 did not show any transforming potential in vitro, both TC21(22V) and TC21(71L) displayed surprisingly potent transforming activities that were comparable to the strong transforming activity of oncogenic Ras proteins. Like Ras-transformed cells, NIH 3T3 cells expressing mutant TC21 proteins formed foci of morphologically transformed cells in monolayer cultures, proliferated in low serum, formed colonies in soft agar, and developed progressive tumors in nude mice. Thus, TC21 is the first Ras-related protein to exhibit potent transforming activity equivalent to that of Ras. Furthermore, mutant TC21 proteins also stimulated constitutive activation of mitogen-activated protein kinases as well as transcriptional activation from Ras-responsive promoter elements (Ets/AP-1 and NF-kappa B). We conclude that aberrant TC21 function may trigger cellular transformation via a signal transduction pathway similar to that of oncogenic Ras and suggest that deregulated TC21 activity may contribute significantly to human oncogenesis.
Abstract The alkaline pH range over which the double stranded circular DNA of the replicative form of the bacterial virus, ϕX174, is reversibly denatured has been determined in order to specify accurately the conditions for a preparative procedure for this DNA based on selective alkali denaturation. The denaturation remains entirely reversible to pH 12.6 at an ionic strength of about 0.25 over a range in which the sedimentation coefficient, after an initial drop, more than doubles. The sharp transition above pH 12.6 in which the denaturation becomes completely irreversible is accompanied by only a small further increase in sedimentation coefficient. Sedimentation-pH titration curves have been determined in detail for the replicative form of ϕX174 (molecular weight 3.4 x 106 daltons) and for the circular DNA of a penicillinase plasmid of Staphylococcus aureus (molecular weight 16.5 x 106 daltons). The latter curve is displaced to a lower pH and the two phase nature of the curve in the range of increasing sedimentation coefficient is markedly accentuated.
