The C-terminal domain of PLD2 participates in degradation of protein kinase CKII β subunit in human colorectal carcinoma cells

Elevated phospholipase D (PLD) expression prevents cell cycle arrest and apoptosis. However, the roles of PLD isoforms in cell proliferation and apoptosis are incompletely understood. Here, we investigated the physiological significance of the interaction between PLD2 and protein kinase CKII (CKII) in HCT116 human colorectal carcinoma cells. PLD2 interacted with the CKIIβ subunit in HCT116 cells. The C-terminal domain (residues 578-933) of PLD2 and the N-terminal domain of CKIIβ were necessary for interaction between the two proteins. PLD2 relocalized CKIIβ to the plasma membrane area. Overexpression of PLD2 reduced CKIIβ protein level, whereas knockdown of PLD2 led to an increase in CKIIβ expression. PLD2-induced CKIIβ reduction was mediated by ubiquitin-dependent degradation. The C-terminal domain of PLD2 was sufficient for CKIIβ degradation as the catalytic activity of PLD2 was not required. Taken together, the results indicate that the C-terminal domain of PLD2 can regulate CKII by accelerating CKIIβ degradation in HCT116 cells.     

Factors affecting the characteristics of melamine resin microcapsules containing fragrant oils

Microcapsules containing fragrant oils as a core material were prepared byin situ polymerization, using melamine-formaldehyde prepolymer as the wall material. The several parameters, such as stirring times, stirring rates, emulsifier types, emulsifier concentrations, and the viscosity of the core materials, affect the characteristics of the microcapsules. These parameters were investigated by the analyses of microcapsule size, particle size distribution, and morphology. The average microcapsule size decreased with an increase in stirring time, stirring rate, emulsifier concentration, and viscosity of the core material. It was also found that poly(vinyl alcohol) as a protective colloid could enhance the stability of the melamine-formaldehyde microcapsules.     

Expression of the INU2 gene for an endoinulinase of Aspergillus ficuum in Saccharomyces cerevisiae

The INU2 gene encoding an endoinulinase of Aspergillus ficuum was expressed by the Kluyveromyces marxianus INU1 promoter in a SUC2-deleted Saccharomyces cerevisiae to produce the endoinulinase preparation free of an exoinulinase and an extracellular invertase in the culture medium. A recombinant yeast strain produced the sufficient amount of the enzyme to make a halo around its colony, when inulin was included in the medium.     

Involvement of caspase-2 activation in aurora kinase inhibitor-induced cell death in axin-expressing L929 cells

Axin is a multifunctional protein that participates in many cellular events including Wnt signaling and cell fate determination. Aurora kinase inhibitor (AKI)-induced cell death and cell membrane rupture is facilitated in L929 cells expressing axin (L-axin cells) through the activation of poly ADP-ribose polymerase (PARP). We observed that caspase-2 activity is required for AKI-induced cell death. Inhibition of caspase-2 activity suppressed AKI-induced PARP activation and mitochondrial dysfunction, resulting in a decrease in AKI-induced cell death. When an axin mutant deleted for the glycogen synthase kinase 3β (GSK3β)-binding domain was expressed in L929 cells (L-ΔGSK cells), AKI-induced caspase-2 activation and cell death decreased. AKI treatment reduced the expression of a 32-kDa caspase-2 splicing variant (caspase-2S) in most L-axin cells, but not in L-ΔGSK cells. These results suggest that AKI-induced caspase-2 activation in L-axin cells might be due to a decrease in the expression of caspase-2S, which inhibits caspase-2 activity. In addition, AKI treatment failed to activate caspase-8 and treatment with necrostatin inhibited AKI-induced cell death in L-axin cells, suggesting that the absence of caspase-8 activation might favor necrotic cell death. Axin expression may facilitate AKI-induced caspase-2 activation followed by activation of PARP and initiation of the necrotic cell death pathway.