The vascular endothelium is a multifunctional organ and is critically involved in modulating vascular tone and structure. Endothelial cells produce a wide range of factors that also regulate cellular adhesion, thromboresistance, smooth muscle cell proliferation, and vessel wall inflammation. Thus, endothelial function is important for the homeostasis of the body and its dysfunction is associated with several pathophysiological conditions, including atherosclerosis, hypertension and diabetes. Patients with diabetes invariably show an impairment of endothelium-dependent vasodilation. Therefore, understanding and treating endothelial dysfunction is a major focus in the prevention of vascular complications associated with all forms of diabetes mellitus. The mechanisms of endothelial dysfunction in diabetes may point to new management strategies for the prevention of cardiovascular disease in diabetes. This review will focus on the mechanisms and therapeutics that specifically target endothelial dysfunction in the context of a diabetic setting. Mechanisms including altered glucose metabolism, impaired insulin signaling, low-grade inflammatory state, and increased reactive oxygen species generation will be discussed. The importance of developing new pharmacological approaches that upregulate endothelium-derived nitric oxide synthesis and target key vascular ROS-producing enzymes will be highlighted and new strategies that might prove clinically relevant in preventing the development and/or retarding the progression of diabetes associated vascular complications.

Abstract. We report here that disruption of a recently discovered kinesin-like protein in Drosophila melanogaster, KLP61F, results in a mitotic mutation lethal to the organism. We show that in the absence of KLP61F function, spindle poles fail to separate, resulting in the formation of monopolar mitotic spindles. The resulting phenotype of metaphase arrest with polyploid cells is reminiscent of that seen in the fungal bimC and cut7 mutations, where it has also been shown that spindle pole bodies are not segregated. KLP61F is specifically expressed in proliferating tissues during embryonic and larval development, consistent with a primary role in cell division. The structural and functional homology of the KLP61F, bimC, cut7, and Eg5 kinesin-like proteins demonstrates the existence of a conserved family of kinesin-like molecules important for spindle pole separation and mitotic spindle dynamics.T HE existence of microtubule-dependent force generating molecules has been known for nearly thirty years (reviewed in Vallee and Shpetner, 1990). The intrinsic polarity of the microtubule suggests there should be two classes of molecules capable of transducing force in either direction along the fiber. In general, dyneins move organelles along microtubules in the minus-end direction, whereas kinesins have been implicated in plus end-directed movement (reviewed in Endow, 1991;Goldstein, 1991; Mclntosh and Pfarr, 1991;Sawin and Scholey, 1991;Vallee, 1991). The matriarch of the kinesin superfamily (kinesin) was discovered in squid axoplasm and as such, is likely to function in axonal transport (Allen et al., 1985;Brady, 1985;Vale et al., 1985). As expected for this role, mutation of the kinesin heavy chain in Drosophila melanogaster results in lethality with associated disruption of neuromuscular function (Gho et al., 1992;Saxton et al., 1991).Since the initial identification of the kinesin heavy chain, a number of studies have led to the conclusion that a superfamily of kinesin-like proteins (KLPs) ~ plays diverse roles in cellular functions in all single-and multi-cellular eukaryotes examined to date (reviewed in Endow, 1991;Goldstein, 1991). These KLPs all share homology within the motor domain of the protein which is involved in ATP hydrolysis, microtubule binding, and force generation. Two PCR-based screens (using primers to conserved sequences within the mechanochemical region) in Drosophila melanogaster have identified six, and probably more, genes encoding potential KLPs (Endow and Hatsumi, 1991;Stewart et al., 1991). Functional analysis is incomplete at best, and awaits the discovery of mutations in these putative KLP genes.In addition to axonal transport, what other cellular processes may require microtubule-based motility? In the cell, the minus-ends of microtubules are embedded in the centrosome or microtubule organizing center, while the plus ends extend into the cytoplasm. The most dramatic cellular rearrangements occur during cell division. A mitotic spindle is first constructed from the duplicated centrosome...

The Gram-negative bacteria Yersinia pestis , causative agent of plague, is extremely virulent. One mechanism contributing to Y. pestis virulence is the presence of a type-three secretion system, which injects effector proteins, Yops, directly into immune cells of the infected host. One of these Yop proteins, YopJ, is proapoptotic and inhibits mammalian NF-κB and MAP-kinase signal transduction pathways. Although the molecular mechanism remained elusive for some time, recent work has shown that YopJ acts as a serine/threonine acetyl-transferase targeting MAP2 kinases. Using Drosophila as a model system, we find that YopJ inhibits one innate immune NF-κB signaling pathway (IMD) but not the other (Toll). In fact, we show YopJ mediated serine/threonine acetylation and inhibition of dTAK1, the critical MAP3 kinase in the IMD pathway. Acetylation of critical serine/threonine residues in the activation loop of Drosophila TAK1 blocks phosphorylation of the protein and subsequent kinase activation. In addition, studies in mammalian cells show similar modification and inhibition of hTAK1. These data present evidence that TAK1 is a target for YopJ-mediated inhibition.

We have performed a mutational analysis together with RNA interference to determine the role of the kinesin-like protein KLP67A in Drosophila cell division. During both mitosis and male meiosis, Klp67A mutations cause an increase in MT length and disrupt discrete aspects of spindle assembly, as well as cytokinesis. Mutant cells exhibit greatly enlarged metaphase spindle as a result of excessive MT polymerization. The analysis of both living and fixed cells also shows perturbations in centrosome separation, chromosome segregation, and central spindle assembly. These data demonstrate that the MT plus end-directed motor KLP67A is essential for spindle assembly during mitosis and male meiosis and suggest that the regulation of MT plus-end polymerization is a key determinant of spindle architecture throughout cell division.