Proteomic analysis of microvesicles from plasma of healthy donors reveals high individual variability

Healthy blood plasma is required for several therapeutic procedures. To maximize successful therapeutic outcomes it is critical to control the quality of blood plasma. Clearly initiatives to improve the safety of blood transfusions will have a high economical and social impact. A detailed knowledge of the composition of healthy blood plasma is essential to facilitate such improvements. Apart from free proteins, lipids and metabolites, blood plasma also contains cell-derived microvesicles, including exosomes and microparticles from several different cellular origins. In this study, we have purified microvesicles smaller than 220nm from plasma of healthy donors and performed proteomic, ultra-structural, biochemical and functional analyses. We have detected 161 microvesicle-associated proteins, including many associated with the complement and coagulation signal-transduction cascades. Several proteases and protease inhibitors associated with acute phase responses were present, indicating that these microvesicles may be involved in these processes. There was a remarkably high variability in the protein content of plasma from different donors. In addition, we report that this variability could be relevant for their interaction with cellular systems. This work provides valuable information on plasma microvesicles and a foundation to understand microvesicle biology and clinical implications.     

PRKX critically regulates endothelial cell proliferation, migration, and vascular-like structure formation

Angiogenesis is a fundamental step in several important physiological events and pathological conditions including embryonic development, wound repair, tumor growth and metastasis. PRKX was identified as a novel type-I cAMP-dependent protein kinase gene expressed in multiple developing tissues. PRKX has also been shown to be phylogenetically and functionally distinct from PKA. This study presents the first evidence that PRKX stimulates endothelial cell proliferation, migration, and vascular-like structure formation, which are the three essential processes for angiogenesis. In contrast, classic PKA demonstrated an inhibitory effect on endothelia vascular-like structure formation. Our findings suggest that PRKX is an important protein kinase engaged in the regulation of angiogenesis and could play critical roles in various physiological and pathological conditions involving angiogenesis. PRKX binds to Pin-1, Magi-1 and Bag-3, which regulate cell proliferation, apoptosis, differentiation and tumorigenesis. The interaction of PRKX with Pin-1, Magi-1 and Bag-3 could contribute to the stimulating role of PRKX in angiogenesis.     

Late stage antibacterial drugs in the clinical pipeline

Bacterial resistance to antimicrobial agents is a growing problem worldwide. Not only is issue compounded by the fact that there are fewer pharmaceutical companies conducting research to discover novel antimicrobials than in the past but development time lines have stretched so that a dozen years from discovery to the market is now the standard. Eleven antibacterial drugs in late stage clinical development are discussed. Whereas many of these may successfully deal with resistant strains of Gram-positive pathogens, there is very little in development to address the gorwing unmet medical need of multi-drug resistant Gram-negative infections.     

Therapeutic angiogenesis for cardiovascular disease

The identification of angiogenic growth factors, such as vascular endothelial growth factor and fibroblast growth factor, has fueled interest in using such factors to induce therapeutic angiogenesis. The results of numerous animal studies and clinical trials have offered promise for new treatment strategies for various ischemic diseases. Increased understanding of the cellular and molecular biology of vessel growth has, however, prompted investigators and clinicians alike to reconsider the complexity of therapeutic angiogenesis. The realization that formation of a stable vessel is a complex, multistep process may provide useful insights into the design of the next generation of angiogenesis therapy.     

HLA-DR alpha 2 mediates negative signalling via binding to Tirc7 leading to anti-inflammatory and apoptotic effects in lymphocytes in vitro and in vivo

Classically, HLA-DR expressed on antigen presenting cells (APC) initiates lymphocyte activation via presentation of peptides to TCR bearing CD4+ T-Cells. Here we demonstrate that HLA-DR alpha 2 domain (sHLA-DRalpha2) also induces negative signals by engaging TIRC7 on lymphocytes. This interaction inhibits proliferation and induces apoptosis in CD4+ and CD8+ T-cells via activation of the intrinsic pathway. Proliferation inhibition is associated with SHP-1 recruitment by TIRC7, decreased phosphorylation of STAT4, TCR-zeta chain & ZAP70, and inhibition of IFN-gamma and FasL expression. HLA-DRalpha2 and TIRC7 co-localize at the APC-T cell interaction site. Triggering HLA-DR - TIRC7 pathway demonstrates that sHLA-DRalpha2 treatment inhibits proinflammatory-inflammatory cytokine expression in APC & T cells after lipopolysaccaride (LPS) stimulation in vitro and induces apoptosis in vivo. These results suggest a novel antiproliferative role for HLA-DR mediated via TIRC7, revise the notion of an exclusive stimulatory interaction of HLA-DR with CD4+ T cells and highlights a novel physiologically relevant regulatory pathway.     

Focal adhesion regulation of cell behavior

Focal adhesions lie at the convergence of integrin adhesion, signaling and the actin cytoskeleton. Cells modify focal adhesions in response to changes in the molecular composition, two-dimensional (2D) vs. three-dimensional (3D) structure, and physical forces present in their extracellular matrix environment. We consider here how cells use focal adhesions to regulate signaling complexes and integrin function. Furthermore, we examine how this regulation controls complex cellular behaviors in response to matrices of diverse physical and biochemical properties. One event regulated by the physical structure of the ECM is phosphorylation of focal adhesion kinase (FAK) at Y397, which couples FAK to several signaling pathways that regulate cell proliferation, survival, migration, and invasion.