Phosphorylation cytoskeleton

Cohen-Hillel E, Yron I, Meshel T, Soria G, Attal H, Ben-Baruch A. CXCL8-induced FAK phosphorylation via CXCR1 and CXCR2 Cytoskeleton- and integrin-related mechanisms converge with FAK regulatory pathways in a receptor-specific manner. Cytokine 2006 33 1-16. 

Chrzanowska-Wodnicka M, Burridge K. Tyrosine phosphorylation is involved in reorganization of the actin cytoskeleton in response to serum or LPA stimulation. J Cell Sci 1994 107(Pt 12) 3643-3654. 

Chia We have looked at the potential phosphorylation sites of Insc, and this is the only apical complex component for which the functional domain has been defined. All the putative Cdc2 phosphorylation sites lie outside the region required for function (at least using an over-expression paradigm). For the other two known components, Baz and Pins, we don t know which the functional parts of the molecule are. It seems more appealing to think in terms of effects on the cytoskeleton, and in particular actin. 

Phosphorylation also plays an evident part in cell division. Specifically, cytoskeleton-associated protein 2 (CKAP2) has a phosphorylation site at threonine 596. This threonine has been tracked and gets phosphorylated between prophase and metaphase, and dephosphorylated a short time later before anaphase, suggesting that the protein is phosphorylated during the formation of mitotic spindles. ... 

In addition to its influence on protein—protein interactions, phosphorylation also affects protein structure and activity. One case involves a protein termed dematin headpiece (DHP), an actin-binding protein found in a variety of tissues including heart, brain, skeletal muscle, kidney, and lung." DHP is known to interact with Ras-guanine nucleotide exchange factor (Ras-GRF2) and this interaction can modulate MARK pathways, which can link the cytoskeleton and signaling pathways." ... 

Intracellular protein phosphorylation is enhanced by chronic antidepressant treatment. This leads to the increased synthesis of microtubules that form an important feature of the cellular cytoskeleton. Thus antidepressants might change signal transduction with the neurone. 

The progression of the cell cycle is regulated by interconversion processes, in each phase, special Ser/Thr-specific protein kinases are formed, which are known as cyclin-depen-dent kinases (CDKs). This term is used because they have to bind an activator protein (cyclin) in order to become active. At each control point in the cycle, specific CDKs associate with equally phase-specific cyclins. if there are no problems (e.g., DNA damage), the CDK-cyclin complex is activated by phosphorylation and/or dephosphorylation. The activated complex in turn phosphorylates transcription factors, which finally lead to the formation of the proteins that are required in the cell cycle phase concerned (enzymes, cytoskeleton components, other CDKs, and cyclins). The activity of the CDK-cyclin complex is then terminated again by proteolytic cyclin degradation. 

Entry of animal cells into mitosis is based on the mitosis-promoting factor (MPF). MPF consists of CDK1 (cdc2) and cyclin B. The intracellular concentration of cyclin B increases constantly until mitosis starts, and then declines again rapidly (top left). MPF is initially inactive, because CDKl is phosphorylated and cyclin B is dephosphorylated (top center). The M phase is triggered when a protein phosphatase [1] dephosphorylates the CDK while cyclin B is phosphorylated by a kinase [2]. in its active form, MPF phosphorylates various proteins that have functions in mitosis—e.g., histone HI (see p. 238), components of the cytoskeleton such as the laminins in the nuclear membrane, transcription factors, mitotic spindle proteins, and various enzymes. 

Overexpression of one PKC isoenzyme may lead to altered expression and activity of one or more of the other PKC isoenzymes. For certain effects several PKC isoenzymes maybe involved. For example, the combined effects of PKCX, E and are essential for the transcriptional activation of c-fos by oncogenic H-ras (Kampfer et aL, 1998). PKCX. and participate in the ras-mediated reorganization of the F-actin cytoskeleton (Oberall et al., 1999). PKC can control the phosphorylation and activation of PKC5 (Ziegler et al., 1999). It may be that not the levels of PKCs, but the levels of the dephospho-rylated forms of PKCs are important for apoptosis (Whelan and Parker, 1998). 

---