Leukocyte extravasation is an important step of inflammation, in which integrins have been demonstrated to play an essential role by mediating the interaction of leukocytes with the vascular endothelium and the subendothelial extracellular matrix. Previously, we identified an integrin-linked kinase (ILK)-binding protein affixin (β-parvin), which links initial integrin signals to rapid actin reorganization, and thus plays critical roles in fibroblast migration. In this study, we demonstrate that γ-parvin, one of three mammalian parvin family members, is specifically expressed in several lymphoid and monocytic cell lines in a complementary manner to affixin. Like affixin, γ-parvin directly associates with ILK through its CH2 domain and colocalizes with ILK at focal adhesions as well as the leading edge of PMA-stimulated U937 cells plated on fibronectin. The overexpression of the C-terminal fragment containing CH2 domain or the depletion of γ-parvin by RNA interference inhibits the substrate adhesion of MCP-1-stimulated U937 cells and the spreading of PMA-stimulated U937 cells on fibronectin. Interestingly, the overexpression of the CH2 fragment or the γ-parvin RNA interference also disrupts the asymmetric distribution of PTEN and F-actin observed at the very early stage of cell spreading, suggesting that the ILK-γ-parvin complex is essential for the establishment of cell polarity required for leukocyte migration. Taken together with the results that γ-parvin could form a complex with some important cytoskeletal proteins, such as αPIX, α-actinin, and paxillin as demonstrated for affixin and actopaxin (α-parvin), the results in this study suggest that the ILK-γ-parvin complex is critically involved in the initial integrin signaling for leukocyte migration.
A 62-year-old man was admitted to hospital with general malaise, arthralgia, edema, and high-grade fever. He was diagnosed as dermatomyositis because of typical skin rashes and muscle weakness. His symptoms were improved by high-doses of prednisolone and cyclosporin A, with the exception of the skin rash over the back. High-grade fever developed again when tapering prednisolone. His condition deteriorated gradually. Paresthesia, hypothyroidism, metabolic acidosis, and disseminated intravascular coagulopathy occurred, and he died eight months after the first admission. Postmortem examination revealed intravascular proliferation of atypical mononuclear cells in the lumens of small vessels in all organs. Intravascular lymphomatosis (B cell type) was diagnosed. (Internal Medicine 41 : 241-244, 2002)
A flow injection system was designed for the spectrophotometric measurement of enzymatic hydrolysis of pyrophosphate by inorganic pyrophosphatase (EC 3.6.1.1). Rapid hydrolysis with a very short half-life (2 min) could be easily monitored by the selective detection of orthophosphate using a Mo(VI) reagent.
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