Angiopoietin-1 (Ang1) has potential therapeutic applications in inducing angiogenesis, enhancing endothelial cell survival, and preventing vascular leakage. However, production of Ang1 is hindered by aggregation and insolubility resulting from disulfidelinked higher-order structures. Here, by replacing the N-terminal portion of Ang1 with the short coiled-coil domain of cartilage oligomeric matrix protein (COMP), we have generated a soluble, stable, and potent Ang1 variant, COMP-Ang1. This variant is more potent than native Ang1 in phosphorylating the tyrosine kinase with Ig and epidermal growth factor homology domain 2 (Tie2) receptor and Akt in primary cultured endothelial cells, enhancing angiogenesis in vitro and increasing adult angiogenesis in vivo. Thus, COMP-Ang1 is an effective alternative to native Ang1 for therapeutic angiogenesis in vivo.

Using degenerate PCR we isolated a cDNA encoding a novel 406- and 410-amino acid protein from human and mouse embryonic cDNAs and have designated it 'hepatic fibrinogen/angiopoietin-related protein' (HFARP). The N-terminal and C-terminal portions of HFARP contain the characteristic coiled-coil domains and fibrinogen-like domains that are conserved in angiopoietins. In human and mouse tissues, HFARP mRNA is specifically expressed in the liver. HFARP mRNA and protein are mainly present in the hepatocytes. HFARP has a highly hydrophobic region at the N-terminus that is typical of a secretory signal sequence and one consensus glycosylation site. Recombinant HFARP expressed in COS-7 cells is secreted and glycosylated. HFARP protein is present not only in the hepatocytes, but also in the circulating blood. Recombinant HFARP acts as an apoptosis survival factor for vascular endothelial cells, but does not bind to Tie1 or Tie2 (endothelial-cell tyrosine kinase receptors). These results suggest that HFARP may exert a protective function on endothelial cells through an endocrine action.

Sung MJ, Kim W. SIRT1 activation by resveratrol ameliorates cisplatin-induced renal injury through deacetylation of p53. Am J Physiol Renal Physiol 301: F427-F435, 2011. First published May 18, 2011 doi:10.1152/ajprenal.00258.2010.-Nephrotoxicity is one of the important dose-limiting factors during cisplatin treatment. There is a growing body of evidence that activation of p53 has a critical role in cisplatin-induced renal apoptotic injury. The nicotinamide adenine dinucleotide-dependent protein deacetylase SIRT1 decreases apoptosis through deacetylating of p53, and resveratrol is known as an activator of SIRT1. To study the role of SIRT1 in cisplatin-induced renal injury through interaction with p53, mouse proximal tubular cells (MPT) were treated with cisplatin and examined the expression level of SIRT1, acetylation of p53, PUMA-␣, Bax, the cytosolic/ mitochondrial cytochrome c ratio, and active caspase-3. The expression of SIRT1 was decreased by cisplatin. Resveratrol, a SIRT1 activator, ameliorated cisplatin-induced acetylation of p53, apoptosis, and cytotoxicity in MPT cells. In addition, resveratrol remarkably blocked cisplatin-induced decrease of Bcl-xL in MPT cells. Further specific SIRT1 inhibition with EX 527 or small interference RNA specific to SIRT1 reversed the effect of resveratrol on cisplatininduced toxicity. Inhibition of p53 by pifithrin-␣ reversed the effect of EX527 in protein expression of PUMA-␣, Bcl-xL, and caspase-3 and cytotoxicity in MPT cells. SIRT1 protein expression after cisplatin treatment was significantly decreased in the kidney. SIRT1 activation by resveratrol decreased cisplatin-induced apoptosis while improving the glomerular filtration rate. Taken together, our findings suggest that the modulation of p53 by SIRT1 could be a possible target to attenuate cisplatin-induced kidney injury. apoptosis; cisplatin nephrotoxicity CISPLATIN IS A CHEMOTHERAPEUTIC agent widely used for the treatment of malignant tumors in solid organs. One of the important dose-limiting factors of cisplatin treatment is nephrotoxicity. Direct DNA damage, inflammatory injury, and oxidative stress have been recognized as the mechanism of cisplatin-induced renal injury. Especially, cisplatin-induced apoptotic cell death after DNA damage is the major mechanism in cytotoxicity in renal tubule cells.In response to DNA damage, p53 can induce cell cycle arrest and apoptosis. p53-induced apoptosis affects its transcriptional activity and Bcl2 family members in mitochondria (24). In kidney disease, p53 is involved in the apoptotic injury in ischemic injury and aristolochic acid-induced nephrotoxicity (11,30,33). There is also a growing body of evidence that p53 plays a critical role in cisplatin-induced renal injury (2, 9, 30). Furthermore, it has been demonstrated that downregulation of p53 by small interference (si) RNA is an effective way of preventing or treating cisplatin-induced nephrotoxicity (25). Activation of p53 is regulated by posttranslational modification of p53 such as ubiquitination, phosphorylati...

Inflammation is a key mediator of renal ischemia-reperfusion (IR) injury. Gender disparities have been reported in acute and chronic kidney disease. In particular, males are considered to be more susceptible to renal ischemic injury compared with females according to animal studies. The purpose of the present study was to investigate the effect of gender on the renal inflammatory response following acute renal IR injury in mice. Experiments were performed in male and female C57BL/6 mice. Two weeks prior to the study, castration or ovariectomy were performed and testosterone propionate (100 μg/kg) or 17β-estradiol (100 μg/kg) was injected. Acute kidney injury (AKI) was induced by bilateral clamping of the renal pedicle for 23 min. Histological examination, western blot analysis and quantitative polymerase chain reaction were performed. In the acute renal IR injury model, the female mice were more resistant to kidney injury compared with the male mice. However, castration of the male mice reduced the levels of IR-induced tubular injury and macrophage infiltration compared with those in the injured male mice. Supplementation of testosterone reversed this protective effect in the male AKI model. Depletion of estrogen in the female mice increased the levels of IR-induced tubular injury and macrophage infiltration compared with those in the injured female mice. However, supplementation of estrogen in the ovariectomized female mice attenuated the IR-induced tubular injury and reduced the levels of macrophage infiltration. The expression levels of inflammatory cytokines, including tumor necrosis factor-α, monocyte chemotactic protein-1, interferon-γ and chemokine (C-C motif) ligand 17, were elevated in the male AKI mice compared with those in the control male mice, and were attenuated by castration. Estrogen depletion in the female mice significantly increased the expression levels of the renal inflammatory cytokines compared with those in the injured female mice, and were attenuated by estrogen supplementation in the ovariectomized female mice. These results suggested that the male gender confers greater susceptibility to IR renal injury due to an enhanced inflammatory response.

Oxidative stress and inflammation contribute to the pathogenesis of cisplatin-induced nephrotoxicity. We found that genistein, a tyrosine kinase inhibitor with broad specificities, and which also has estrogen-like activity, had protective effects on cisplatin-induced renal injury in mice. Genistein significantly decreased reactive oxygen species production, the expression of intercellular adhesion molecule-1 and monocyte chemoattractant protein-1 proteins, as well as the translocation of the p65 subunit of nuclear factor-kappaB into the nucleus and the infiltration of macrophages, all of which were increased in the kidney by cisplatin treatment. Genistein also decreased cisplatin-induced apoptosis by regulating p53 induction in kidney. Genistein significantly reduced reactive oxygen species production in cisplatin-treated normal human kidney HK-2 cells. These studies show that genistein or similar compounds might be useful in prevention of cisplatin-induced renal injury.

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Adrenomedullin (AM) is a multifunctional peptide in human pheochromocytoma. To evaluate whether AM could be an angiogenic factor, we examined its effect on kinases and angiogenic processes. AM induced tyrosine phosphorylation of Akt and mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase1/2 (ERK1/2) by using distinct signaling pathways in human umbilical vein endothelial cells (HUVECs). AM also phosphorylated focal adhesion kinase, and phosphatidylinositol 3'-kinase inhibitor inhibited AM-induced focal adhesion kinase phosphorylation. Pretreatment with high concentrations of AM22-52, a putative AM receptor antagonist, partially suppressed AM-induced phosphorylation of Akt, ERK1/2, and focal adhesion kinase. AM and vascular endothelial growth factor produced increases in DNA synthesis and migration in HUVECs. AM induced tube formation in HUVECs, and its effect was inhibited by pretreatment with phosphatidylinositol 3'-kinase inhibitor or ERK1/2 inhibitor. AM induced sprouting in porcine pulmonary arterial endothelial cells and promoted neovessel formation in a mouse Matrigel plug assay. Inhibitors of phosphatidylinositol 3'-kinase and ERK1/2 inhibited AM-induced endothelial sprouting in vitro and angiogenesis in vivo. AM exerts angiogenic activity through activation of Akt, MAPK, and focal adhesion kinase in endothelial cells.

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