Background-Endothelial damage and dysfunction are crucial mediators that link diabetes mellitus with atherosclerotic cardiovascular disease. AMP-activated kinase (AMPK) has been implicated in regulation of both energy metabolism and vascular homeostasis. The present study investigated whether endothelium-selective activation of AMPK prevents diabetes mellitus-induced endothelial damage and vascular dysfunction by improving reendothelialization in mice. Methods and Results-Transgenic mice with endothelium-selective expression of a constitutively active (CA) AMPK were generated and rendered diabetic by the injection of streptozotocin. Relaxation and reendothelialization of carotid arteries and circulating numbers of endothelial progenitor cells (EPCs) were examined after wire-induced denudation. Bone marrow-derived EPCs were isolated to monitor their in vivo and in vitro function. Compared with wild-type littermates, the CA-AMPK transgenic mice were resistant to diabetes mellitus-induced impairment in endotheliumdependent relaxation and reendothelialization of their injured carotid arteries. These changes in the transgenic mice were accompanied by increased mobilization of EPCs and enhanced incorporation of EPCs into injured blood vessels. Furthermore, EPCs from the transgenic mice exhibited augmented adhesion, migration, and tube formation capacities. At the molecular level, the expression of heme oxygenase (HO)-1 and the secretion of stromal cell-derived factor (SDF)-1␣ were upregulated in EPCs derived from the transgenic mice, whereas AMPK-mediated elevation of serum SDF-1␣ levels and improvements of EPC function and reendothelialization were all abrogated by pharmacological inhibition of heme oxygenase-1. Conclusions-Endothelium-specific AMPK activation is sufficient to protect against diabetes mellitus-induced aggravation of vascular injury by promoting EPC function and reendothelialization via upregulation of heme oxygenase-1 and

Recent studies have implicated heat shock proteins (HSP) and heat shock transcription factor 1 (HSF1) in tumor progression. We have examined the role of HSF1 in the malignant phenotype of PC-3 prostate carcinoma cells. We have developed a dominant negative construct of HSF1 that antagonizes transcription from HSP promoters and results in the depletion of intracellular HSP 70. Our studies indicate that expression of DN-HSF1 dramatically alters the DNA content of PC-3 cells (derived from p53 null prostatic carcinoma) and inhibits aneuploidy in these cells. This effect is due to prolonged expression of DN-HSF1, and transient expression of the dominant negative factor from an inducible promoter failed to cause the effect. Inhibition of aneuploidy in p53 null PC-3 cells by DN-HSF1 expression was recapitulated by expression within the cells of wild type p53. Furthermore, cells expressing DN-HSF1 showed a profound inhibition in the development of aneuploidy when exposed to chemical agents that disrupt the mitotic spindle and prevent progression through metaphase. Inhibition of aneuploidy in PC-3 cells expressing DN-HSF1 was associated with delayed breakdown of cyclin B1 compared with controls, consistent with a role for wild type HSF1 in the regulation of cyclin B1 degradation, a key step in the control of mitosis. Our experiments therefore demonstrate that HSF1 plays a functional role in cancer cells under nonstress conditions and influences cell cycle behavior and progression through mitosis and promotes the development of the aneuploid state.Exposure of cells to elevated temperatures leads to expression of the heat shock response, which involves the induction of a cohort of heat shock proteins (HSPs) 1 by stress and is accompanied by the expression of heat resistance (1, 2). HSPs accumulate to high levels in stressed cells and remain elevated for a prolonged period (1, 2). Accumulation of HSPs is due to activation of HSP gene expression at the levels of transcription, mRNA stability, translation, and protein stability (1-3). In mammalian cells, heat shock genes are transcriptionally regulated by heat shock factor-1 (HSF1), a sequence-specific transcription factor that binds to the heat shock elements (HSE) in their promoters (3-5). The mechanisms involved in HSF1 activation are post-translational and involve the conversion of HSF1 from a latent cytoplasmic form to an active nuclear protein (6 -8). HSF family members are unique among transcription factors in binding to DNA as homotrimers (6 -11). Trimerization is governed by arrays of amphipathic ␣-helical residues in the amino-terminal domain of HSF family proteins that interact to form coiled coils, and trimerization is negatively regulated under nonstress conditions by a fourth region of amphipathic ␣-helix in the carboxyl-terminal domain (6 -10). Most evidence indicates a model for HSF1 regulation in which the protein exists as a monomer in the cytoplasm associated with molecular chaperones that act as repressors of activation (3, 10, 12, 13).Recent studies sug...

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