Differential targeting of protein kinase C and CaM kinase II signalings to vimentin.

Abstract

Abstract. Hydrolysis of inositol phospholipids by receptor stimulation activates two separate signaling pathways, one leading to the activation of protein kinase C (C kinase) via formation of diacylglycerol. The other is the inositol trisphosphate (IP3)/Ca 2÷ pathway and a major downstream kinase which is activated is Ca2÷/calmodulin-dependent protein kinase II (CaM kinase II). To examine signaling pathways of C kinase and CaM kinase II to the cytoskeletal protein vimentin, we prepared monoclonal antibodies YT33 and MO82 which recognize the phosphorylation state of vimentin by C kinase and by CaM kinase II, respectively. Ectopic expression of constitutively active C kinase or CaM kinase II in primary cultured astrocytes by microinjection of the corresponding expression vectors induced phosphorylation of vimentin at each specific phosphorylation site, followed by reorganization of vimentin filament networks. In contrast, simultaneous activation of C kinase and CaM kinase II by inositol phospholipid hydrolysis with receptor stimulation led to an exclusive phosphorylation of vimentin at the CaM kinase II site, not at the site of C kinase. These results indicate that the intracellular targeting of C kinase and CaM kinase II signalings to vimentin is regulated separately, under physiological conditions. "r~ECEPTOR-mediated hydrolysis of phosphatidylinosi-1 ~" tol 4,5-bisphosphate (PIP2) relays extracellular l ~. signals into the cell and two kinases, protein kinase C (C kinase) and Ca2÷/calmodulin-dependent protein kinase II (CaM kinase II) play a central role in this signaling. Hydrolysis of PIP2 leads to formation of diacylglycerol and activation of inositol trisphosphate (IP3)-induced Ca 2+ signaling (for reviews see Michell, 1992;Berridge, 1993). C kinase and CaM kinase II, activated by diacylglycerol and Ca 2+, respectively, transmit these two signalings to downstream molecules (for reviews see Nishizuka, 1984Nishizuka, , 1986Colbran et al., 1989; Hanson and Schtflman, 1992). From the viewpoint of signaling cascade, one of the most distinctive features of kinases represented by C kinase and CaM ki-

Specific accumulation of Rho-associated kinase at the cleavage furrow during cytokinesis: cleavage furrow-specific phosphorylation of intermediate filaments

“…Immunocytochemical studies using TM38 and TM71 revealed that these two sites were phosphorylated at the cleavage furrow during cytokinesis in U251 human glioma cells (Figure 1c and d). Together with previous immunocytochemical studies (Matsuoka et al, 1992;Tsujimura et al, 1994;Ogawara et al, 1995;Takai et al, 1996;Sekimata et al, 1996;Inagaki et al, 1997b) (Table 1).…”

Cytoplasmic retention of mutant tsp53 is dependent on an intermediate filament protein (Vimentin) scaffold

“…These data argue that either a properly organized vimentin ®lament network or the vimentin tail domain itself is necessary to retain tsp53 on the cytoskeleton. While the function of the head domain of vimentin has well been described, that of the tail domain is still not completely understood (Ciesielski-Treska et al, 1991;Inagaki et al, 1990;Ogawara et al, 1995;Traub and Vorgias, 1983). Probably, the tail controls the lateral association of IF-protein tetramers and thereby stabilizes the ®lament structure, which may be essential to establish a proper ®lament network (Heins and Aebi, 1994).…”

Leukocyte transmigration is modulated by chemokine‐mediated PI3Kγ‐dependent phosphorylation of vimentin

“…These phosphorylation events are triggered by a wide range of protein kinases, such as PKA and PKC [15,19], PKG [20], Rho-kinase and Aurora B [21], PAK [22,23], MAPKAP K-2 [10], Cdc2 kinase [24] and CaMKII [25] and involve a large number of serine residues (e.g. Ser 4,[6][7][8][9]25,33,38,41,50,55,65,71,72,82) with a complex pattern of overlapping specificities [15,26,27].…”

“…Consistently, treatment with protein phosphatase inhibitors, such as calyculin-A [15] or okadaic acid [16], results in a dose-and time-dependent increase in vimentin phosphorylation, causing rapid disassembly of pre-existing filaments, delay of fiber assembly and increased levels of soluble vimentin tetramers [15,17,18]. These phosphorylation events are triggered by a wide range of protein kinases, such as PKA and PKC [15,19] [25] and involve a large number of serine residues (e.g. Ser 4,[6][7][8][9]25,33,38,41, 50, 55, 65, 71, 72, 82) with a complex pattern of overlapping specificities [15,26,27].…”

“…These phosphorylation events are triggered by a wide range of protein kinases, such as PKA and PKC [15,19] [25] and involve a large number of serine residues (e.g. Ser 4,[6][7][8][9]25,33,38,41, 50, 55, 65, 71, 72, 82) with a complex pattern of overlapping specificities [15,26,27].Although vimentin appears involved in multiple cellular processes, mice lacking this protein are viable and do not show overt phenotypes [28]. Nonetheless, fibroblasts from vimentindeficient mice show mechanical instability and impaired ability to migrate and to contract a 3-D collagen network [29], thus providing a genetic evidence for the involvement of vimentin in cell plasticity and motility [30,31].…”