Various factors are thought to be responsible for Candida albicans virulence, such as lipases, proteases and adhesins. Many of these factors are GPI-anchored cell surface proteins responsible for pathogenicity. Hwp2 is a putative GPI-anchored protein. The purpose of this study is to characterize the role of Hwp2 regarding filamentation on various filamentation-inducing and non-inducing solid and liquid media, virulence in a mouse model of disseminated candidiasis, and drug resistance to six widely used antifungal agents, by creating a homozygous null hwp2 strain and comparing it with the parental and a revertant HWP2(+)strain. It was observed that an hwp2Delta strain was highly filamentation-deficient on solid agar media as opposed to most liquid media tested. Furthermore, the mutant strain was slightly reduced in virulence compared to the wild strain since all mice infected with the control strain died after 6 days of injection compared with 11 days for the mutant. These results indicate a possible role for Hwp2 in adhesion and invasiveness. Finally a previously unidentified 37-amino-acid-long, stretch of Hwp2, possibly involved in protein aggregation, was found to align with high sequence identity and exclusively to C. albicans cell wall proteins.

Yasuda K, Vasko R, Hayek P, Ratliff B, Bicer H, Mares J, Maruyama S, Bertuglia S, Mascagni P, Goligorsky MS. Functional consequences of inhibiting exocytosis of Weibel-Palade bodies in acute renal ischemia. Am J Physiol Renal Physiol 302: F713-F721, 2012. First published December 7, 2011 doi:10.1152/ajprenal.00541.2011.-Exocytosis of Weibel-Palade bodies (WPB) represents a distinct response of endothelial cells to stressors, and local release of WPB contents leads to systemic escalation of this response. We synthesized a glycine-(N␣-Et)lysine-proline-arginine (ITF 1697) peptide that has a potential to inhibit exocytosis of WPB and protect microcirculation. Here, we confirmed an inhibitory effect of ITF 1697 using intravital videoimaging and point-tracking of individual organelles. In an in vivo study, mice were implanted with Alzet osmotic pumps (10 g ITF 1697·kg Ϫ1 ·min Ϫ1 at volume of 1 l/h) and subjected to renal ischemia (IRI). IRI resulted in marked renal injury and elevation of serum creatinine in mice treated with a vehicle. In contrast, renal injury and elevation of creatinine were significantly ameliorated in mice subjected to IRI and receiving ITF 1697. ITF 1697 prevented a systemic response to IRI: a significant surge in the levels of eotaxin and IL-8 (KC; both components of WPB), IL-1␣, IL-1␤, and RANTES was all prevented or blunted by the administration of ITF 1697, whereas the levels of an anti-inflammatory, IL-10, and macrophage inflammatory protein-1␣ were upregulated in ITF 1697-treated animals. En face staining of aortic endothelial cells showed that WPB were depleted after 40 -180 min post-IRI, and this was significantly blunted in aortic preparations obtained from mice treated with ITF 1697. WPB exocytosis contributed to IRI-associated mobilization of endothelial progenitor cells and hematopoietic stem cells, and ITF 1697 blunted their mobilization. Unexpectedly, 1 mo after IRI, mice treated with ITF 1697 showed a significantly more pronounced degree of scarring than nontreated animals. In conclusion, 1) application of ITF 1697 inhibits exocytosis of WPB and IRI; 2) the systemic inflammatory response of IRI is in part due to the exocytosis of WPB and its blockade blunts it; and 3) ITF 1697 improves short-term renal function after IRI, but not the long-term fibrotic complications.cytokines; chemokines; mobilization of stem cells; fibrosis WEIBEL-PALADE BODIES (WPB) are rod-shaped organelles (0.2 ϫ 2-3 m) characteristic of endothelial cells and containing an array of proteins, peptides, and cytokines, which can be released emergently on demand. Among these biologically active compounds are von Willebrand factor, P-selectin, IL-8, endothelin-1, angiopoietin-2 (Ang-2), and many others, which contribute to the induction of a proinflammatory milieu on the one hand but also induce mobilization of stem cells on the other. A list of compounds known to induce exocytosis of WPB is long and includes thrombin, histamine, peptido-leukotrienes, complement components, superoxide anion, VEGF, sphingosine-1-p...

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