Poly(ADP-ribose) polymerase 1 (PARP-1) and p53 are two key proteins in the DNA-damage response. Although PARP-1 is known to poly(ADP-ribosyl)ate p53, the role of this modification remains elusive. Here, we identify the major poly(ADP-ribosyl)ated sites of p53 by PARP-1 and find that PARP-1-mediated poly(ADP-ribosyl)ation blocks the interaction between p53 and the nuclear export receptor Crm1, resulting in nuclear accumulation of p53. These findings molecularly link PARP-1 and p53 in the DNA-damage response, providing the mechanism for how p53 accumulates in the nucleus in response to DNA damage. PARP-1 becomes super-activated by binding to damaged DNA, which in turn poly(ADP-ribosyl)ates p53. The nuclear export machinery is unable to target poly(ADP-ribosyl)ated p53, promoting accumulation of p53 in the nucleus where p53 exerts its transactivational function.

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Myo-inositol-1,2,3,4,5,6-hexakisphosphate (InsP6), also known as phytic acid, accumulates in large quantities in plant seeds, serving as a phosphorus reservoir, but is an animal antinutrient and an important source of water pollution. Here, we report that Gle1 (GLFG lethal 1) in conjunction with InsP6 functions as an activator of the ATPase/RNA helicase LOS4 (low expression of osmotically responsive genes 4), which is involved in mRNA export in plants, supporting the Gle1-InsP6-Dbp5 (LOS4 homolog) paradigm proposed in yeast. Interestingly, plant Gle1 proteins have modifications in several key residues of the InsP6 binding pocket, which reduce the basicity of the surface charge. Arabidopsis thaliana Gle1 variants containing mutations that increase the basic charge of the InsP6 binding surface show increased sensitivity to InsP6 concentrations for the stimulation of LOS4 ATPase activity in vitro. Expression of the Gle1 variants with enhanced InsP6 sensitivity rescues the mRNA export defect of the ipk1 (inositol 1,3,4,5,6-pentakisphosphate 2-kinase) InsP6-deficient mutant and, furthermore, significantly improves vegetative growth, seed yield, and seed performance of the mutant. These results suggest that Gle1 is an important factor responsible for mediating InsP6 functions in plant growth and reproduction and that Gle1 variants with increased InsP6 sensitivity may be useful for engineering high-yielding low-phytate crops.

Mortalin is a member of Hsp70 chaperoning protein family involved in various cellular functions. Through the search of the kinases that mortalin physically interact with, we identified Mps1 as such a kinase. Mps1 kinase has been implicated in the regulation of centrosome duplication and mitotic checkpoint response. Mortalin binds to Mps1, and is phosphorylated by Mps1 on Thr62 and Ser65. The phosphorylated mortalin then super-activates Mps1 in a feedback manner. Mortalin has been previously shown to localize to centrosomes, and to be involved in the regulation of centrosome duplication. We found that centrosomal localization of mortalin depends on the presence of Mps1. Moreover, Mps1-associated acceleration of centrosome duplication depends on the presence of mortalin and super-activation by the Thr62/Ser65 phosphorylated mortalin.

This study was carried out to investigate the effects of different types of β-cyclodextrin (β-CD) treatments on chemical and sensory characteristics of cholesterol-reduced cream cheese. The cholesterol removal rates were 92.0% in cream cheese treated by powder β-CD, and 82.6% in cream cheese treated by crosslinked β-CD. Amounts of short-chain fatty acid and free amino acids were significantly lower in cream cheese made by crosslinked β-CD-treated milk, especially after 2 weeks storage, compared with those of no β-CD-treated control and cream cheese made by powder β-CD treated milk. Among rheological properties, cohesiveness was significantly higher, and gumminess in cream cheese made by crosslinked β-CD-treated milk was slightly lower than others. In sensory analysis, no difference was found in texture among treatments, while bitterness was lower in the early stage of storage, and overall quality was higher score, in cream cheese made by crosslinked β-CD-treated cream at 3 and 4 week storage, compared with those in control and powder β-CD-treated group. The present study indicated that crosslinked β-CD treatment resulted in an efficient cholesterol removal rate over 80% and a deceleration of ripening, which may provide a longer shelf life without significant adverse effects in chemical and sensory properties.