Sun, 27 Jul 2008 08:22:33 BST CiteULike: lechristophe's Kinoshita http://www.citeulike.org/user/lechristophe/author/Kinoshita CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/lechristophe/article/2737420 <i>Current biology : CB, Vol. 17, No. 20. (23 October 2007), pp. 1752-1758.</i><br /><br />Septins are GTP-binding proteins that polymerize into heteromeric filaments and form microscopic bundles or ring structures in vitro and in vivo. Because of these properties and their ability to associate with membrane, F-actin, and microtubules, septins have been generally regarded as cytoskeletal components [1, 2]. Septins are known to play roles in cytokinesis, in membrane trafficking, and as structural scaffolds; however, their function in neurons is poorly understood. Many members of the septin family, including Septin 7 (Sept7), were found by mass-spectrometry analysis of postsynaptic density (PSD) fractions of the brain [3, 4], suggesting a possible postsynaptic function of septins in neurons. We report that Sept7 is localized at the base of dendritic protrusions and at dendritic branch points in cultured hippocampal neurons--a distribution reminiscent of septin localization in the bud neck of budding yeast. Overexpression of Sept7 increased dendrite branching and the density of dendritic protrusions, whereas RNA interference (RNAi)-mediated knockdown of Sept7 led to reduced dendrite arborization and a greater proportion of immature protrusions. These data suggest that Sept7 is critical for spine morphogenesis and dendrite development during neuronal maturation. Role of Septin cytoskeleton in spine morphogenesis and dendrite development in neurons. T Tada A Simonetta M Batterton M Kinoshita D Edbauer M Sheng doi:10.1016/j.cub.2007.09.039 Current biology : CB, Vol. 17, No. 20. (23 October 2007), pp. 1752-1758. 2008-04-30T09:53:48-00:00 2007 Current biology : CB 0960-9822 17 20 1752 1758 cytosqueleton dendritic_spines neurites_growth http://www.citeulike.org/user/lechristophe/article/775818 <i>J Biol Chem, Vol. 281, No. 18. (5 May 2006), pp. 12908-12918.</i><br /><br />The possible role of the peripheral cannabinoid receptor (CB2) in neutrophil migration was investigated by using human promyelocytic HL60 cells differentiated into neutrophil-like cells and human neutrophils isolated from whole blood. Cell surface expression of CB2 on HL60 cells, on neutrophil-like HL60 cells, and on human neutrophils was confirmed by flow cytometry. Upon stimulation with either of the CB2 ligands JWH015 and 2-arachidonoylglycerol (2-AG), neutrophil-like HL60 cells rapidly extended and retracted one or more pseudopods containing F-actin in different directions instead of developing front/rear polarity typically exhibited by migrating leukocytes. Activity of the Rho-GTPase RhoA decreased in response to CB2 stimulation, whereas Rac1, Rac2, and Cdc42 activity increased. Moreover, treatment of cells with RhoA-dependent protein kinase (p160-ROCK) inhibitor Y27632 yielded cytoskeletal organization similar to that of CB2-stimulated cells. In human neutrophils, neither JWH015 nor 2-AG induced motility or morphologic alterations. However, pretreatment of neutrophils with these ligands disrupted N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP)-induced front/rear polarization and migration and also substantially suppressed fMLP-induced RhoA activity. These results suggest that CB2 might play a role in regulating excessive inflammatory response by controlling RhoA activation, thereby suppressing neutrophil migration. Effects of peripheral cannabinoid receptor ligands on motility and polarization in neutrophil-like HL60 cells and human neutrophils. R Kurihara Y Tohyama S Matsusaka H Naruse E Kinoshita T Tsujioka Y Katsumata H Yamamura doi:10.1074/jbc.M510871200 J Biol Chem, Vol. 281, No. 18. (5 May 2006), pp. 12908-12918. 2006-07-27T15:24:19-00:00 2006 J Biol Chem 0021-9258 281 18 12908 12918 cb1 cytosqueleton rho signaling_pathways