The molecular cell death machinery in the simple cnidarian Hydra includes an expanded caspase family and pro- and anti-apoptotic Bcl-2 proteins.

The fresh water polyp Hydra belongs to the phylum Cnidaria, which diverged from the metazoan lineage before the appearance of bilaterians. In order to understand the evolution of apoptosis in metazoans, we have begun to elucidate the molecular cell death machinery in this model organism. Based on ESTs and the whole Hydra genome assembly, we have identified 15 caspases.

Yersinia protein kinase YopO is activated by a novel G-actin binding process.

Pathogenic bacteria of the genus Yersinia employ a type III secretion system to inject effector proteins (Yops) into host cells. The Yops down-regulate host cell functions through unique biochemical activities. YopO, a serine/threonine kinase required for Yersinia virulence, is activated by host cell actin via an unknown process.

The proteasome pathway destabilizes Yersinia outer protein E and represses its antihost cell activities.

Pathogenic Yersinia spp. neutralize host defense mechanisms by engaging a type III protein secretion system that translocates several Yersinia outer proteins (Yops) into the host cell. Although the modulation of the cellular responses by individual Yops has been intensively studied, little is known about the fate of the translocated Yops inside the cell.

Subconfluent endothelial cells form podosomes downstream of cytokine and RhoGTPase signaling.

Adhesion, migration and invasion of endothelial cells are prerequisites for the formation of blood vessels and have to be controlled on a subcellular level. We report that subconfluent human umbilical vein endothelial cells (HUVEC) are able to constitutively form podosomal adhesions that are sites of matrix metalloprotease concentration and matrix degradation. Importantly, incubation of serum-starved cells with VEGF or TNFalpha revealed the dependence of podosomes on cytokine signaling.