Dynamic behavior of FCHO1 revealed by live-cell imaging microscopy: its possible involvement in clathrin-coated vesicle formation.

The intracellular behavior of human FCHO1 protein was investigated by live-cell imaging microscopy. The fluorescence intensity of green fluorescent protein (GFP)-FCHO1 fluctuated periodically in a perinuclear region approximately every 100 s, reminding us of the periodic fluctuations of clathrin reported in our recent work. The periodicity of FCHO1 was temporally correlated with that of clathrin, suggesting that FCHO1 is involved in clathrin-coated vesicle formation.

Non-receptor protein-tyrosine kinases as molecular targets for antiangiogenic therapy (Review).

Antiangiogenic therapy, including blockade of vascular endothelial growth factor (VEGF) signaling, was highly anticipated to improve the prognosis for patients with advanced cancers following the success of preclinical animal models. However, antiangiogenic monotherapy with VEGF antagonists has produced disappointing results in clinical trials to date. One of the reasons for this poor outcome is that angiogenesis is not solely regulated by VEGF. Inhibition of VEGF signaling, therefore, may select for tumor cell populations that stimulate angiogenesis through VEGF-independent pathways. Successful antiangiogenic therapy, therefore, may require simultaneous blockade of signaling downstream from multiple proangiogenic factor receptors. Recently, we found that non-receptor protein-tyrosine kinases, including members of the Src and Fes families, play vital roles in the responses of cultured endothelial cells to several proangiogenic factors. In this review, we summarize the contributions of these kinase families to angiogenic pathways in endothelial cells, and discuss the potential of these kinases as new targets for antiangiogenic drug discovery.

Schistosoma mansoni: expression of Fes-like tyrosine kinase SmFes in the tegument and terebratorium suggests its involvement in host penetration.

Protein Tyrosine Kinases (PTKs) are important molecules in intra- and inter-cellular communication, playing a major role in signal transduction processes. We have previously identified and characterized the molecular structure of a new PTK in Schistosoma mansoni, SmFes. SmFes exhibits the characteristic features of Fes/Fps protein tyrosine kinase subfamily of which it is the first member described in helminths. Herein, we show that genes orthologous to SmFes are also present in other Schistosoma species and the transcript is detected in Schistosoma japonicum. The SmFes protein was detected at all the main life-cycle stages and was most abundant in cercariae and newly-transformed schistosomula. However, no protein was detected in schistosomula maintained in vitro for 7 days. By immunolocalization assays we showed that SmFes is particularly concentrated at the terebratorium of miracidia and tegument of cercaria and schistosomula skin-stage. These findings suggest that SmFes may play a role in signal transduction pathways involved in larval transformation after penetration into intermediate and definitive hosts.

Fer and Fps/Fes participate in a Lyn-dependent pathway from FcepsilonRI to platelet-endothelial cell adhesion molecule 1 to limit mast cell activation.

Mast cells express the high affinity IgE receptor FcepsilonRI, which upon aggregation by multivalent antigens elicits signals that cause rapid changes within the mast cell and in the surrounding tissue. We previously showed that FcepsilonRI aggregation caused a rapid increase in phosphorylation of both Fer and Fps/Fes kinases in bone marrow-derived mast cells. In this study, we report that FcepsilonRI aggregation leads to increased Fer/Fps kinase activities and that Fer phosphorylation downstream of FcepsilonRI is independent of Syk, Fyn, and Gab2 but requires Lyn. Activated Fer/Fps readily phosphorylate the C terminus of platelet-endothelial cell adhesion molecule 1 (Pecam-1) on immunoreceptor tyrosine-based inhibitory motifs (ITIMs) and a non-ITIM residue (Tyr(700)) in vitro and in transfected cells. Mast cells devoid of Fer/Fps kinase activities display a reduction in FcepsilonRI aggregation-induced tyrosine phosphorylation of Pecam-1, with no defects in recruitment of Shp1/Shp2 phosphatases observed. Lyn-deficient mast cells display a dramatic reduction in Pecam-1 phosphorylation at Tyr(685) and a complete loss of Shp2 recruitment, suggesting a role as an initiator kinase for Pecam-1. Consistent with previous studies of Pecam-1-deficient mast cells, we observe an exaggerated degranulation response in mast cells lacking Fer/Fps kinases at low antigen dosages. Thus, Lyn and Fer/Fps kinases cooperate to phosphorylate Pecam-1 and activate Shp1/Shp2 phosphatases that function in part to limit mast cell activation.