Neurogranin͞RC3 is a neural-specific Ca 2؉ -sensitive calmodulin (CaM)-binding protein whose CaM-binding affinity is modulated by phosphorylation and oxidation. Here we show that deletion of the Ng gene in mice did not result in obvious developmental or neuroanatomical abnormalities but caused an impairment of spatial learning and changes in hippocampal short-and long-term plasticity (paired-pulse depression, synaptic fatigue, long-term potentiation induction). These deficits were accompanied by a decreased basal level of the activated Ca 2؉ ͞CaM-dependent kinase II (CaMKII) (Ϸ60% of wild type). Furthermore, hippocampal slices of the mutant mice displayed a reduced ability to generate activated CaMKII after stimulation of protein phosphorylation and oxidation by treatments with okadaic acid and sodium nitroprusside, respectively. These results indicate a central role of Ng in the regulation of CaMKII activity with decisive influences on synaptic plasticity and spatial learning.

1-Cys peroxiredoxin (1-cysPrx) is a novel antioxidant enzyme able to reduce phospholipid hydroperoxides in vitro by using glutathione as a reductant. This enzyme is widely expressed and is enriched in lungs. A fusion protein of green fluorescent protein with 1-cysPrx was stably expressed in a lung-derived cell line (NCI-H441) lacking endogenous enzyme. Overexpressing cells (C17 or C48) degraded H 2O2 and t-butylhydroperoxide more rapidly and showed decreased sensitivity to oxidant stress as measured by 51

Neurogranin/RC3 is a protein that binds calmodulin and serves as a substrate for protein kinase C. Neuronally distributed in the hippocampus and forebrain, neurogranin is highly expressed in dendritic spines of hippocampal pyramidal cells, implicating this protein in long-term potentiation and in learning and memory processes. Null mutation of the neurogranin gene Ng generated viable knockout mice for analysis of the behavioral phenotype resulting from the absence of neurogranin protein. Ng -/- mice were normal on measures of general health, neurological reflexes, sensory abilities, and motor functions, as compared to wild type littermate controls. On the Morris water task, Ng -/- mice failed to reach acquisition criterion on the hidden platform test and did not show selective search on the probe trial. In the Barnes circular maze, another test for spatial navigation learning, Ng -/- mice showed impairments on some components of transfer, but normal performance on time spent around the target hole. Abnormal and idiosyncratic behaviors were detected, that appeared to represent an anxiogenic phenotype in Ng -/- mice, as measured in the light<-->dark exploration test and the open field center time parameter. These findings of apparent deficits in spatial learning and anxiety-like tendencies in Ng -/- support a role for neurogranin in the hippocampally-mediated interaction between stress and performance.

Prdx6 (peroxiredoxin 6), a bifunctional protein with both GSH peroxidase and PLA2 (phospholipase A2) [aiPLA2 (acidic calcium-independent PLA2)] activities, is responsible for the metabolism of lung surfactant phospholipids. We propose that the aiPLA2 activity of the enzyme is regulated through phosphorylation. Incubation of isolated rat alveolar type II cells (AECII) with PMA, a PKC (protein kinase C) agonist, had no effect on Prdx6 expression but led to ~75 % increase in aiPLA2 activity that was abolished by pretreatment of cells with the MAPK (mitogen-activated protein kinase) inhibitors, SB202190 or PD98059. Prdx6 phosphorylation after incubation of AECII with PMA was demonstrated by autoradiography after immunoprecipitation with either anti-phosphothreonine or -phosphoserine antibodies. In vitro, several active isoforms of ERK (extracellular-signal-regulated kinase) and p38 phosphorylated Prdx6, resulting in an 11-fold increase in aiPLA2 activity. The increased activity was calcium-independent and was abolished by the aiPLA2 inhibitors, surfactant protein A and hexadecyl-3-trifluorethylglycero-sn-2-phospho-methanol (MJ33). The peroxidase activity of Prdx6 was unaffected by phosphorylation. Mass spectroscopic analysis of in vitro phosphorylated Prdx6 showed a unique phosphorylation site at Thr-177 and mutation of this residue abolished protein phosphorylation and the increase in MAPK-mediated activity. These results show that the MAPKs can mediate phosphorylation of Prdx6 at Thr-177 with a consequent marked increase in its aiPLA2 activity.

f Histone lysine methylation and demethylation are considered critical steps in transcriptional regulation. In this report, we performed chromatin immunoprecipitation with microarray technology (ChIP-chip) analysis to examine the genome-wide occupancy of H3K9-me2 during all-trans-retinoic acid (ATRA)-induced differentiation of HL-60 promyelocytic leukemia cells. Using this approach, we found that KDM3B, which contains a JmjC domain, was downregulated during differentiation through the recruitment of a corepressor complex. Furthermore, KDM3B displayed histone H3K9-me1/2 demethylase activity and induced leukemogenic oncogene lmo2 expression via a synergistic interaction with CBP. Here, we found that KDM3B repressed leukemia cell differentiation and was upregulated in blood cells from acute lymphoblastic leukemia (ALL)-type leukemia patients. The combined results of this study provide evidence that the H3K9-me1/2 demethylase KDM3B might play a role in leukemogenesis via activation of lmo2 through interdependent actions with the histone acetyltransferase (HAT) complex containing CBP.

No abstract

Parasitic diseases remain an unarguable public health problem worldwide. Liver fluke Clonorchis sinensis is a high risk pathogenic parasitic helminth which is endemic predominantly in Asian countries, including Korea, China, Taiwan, Vietnam, and the far eastern parts of Russia, and is still actively transmitted. According to the earlier 8th National Survey on the Prevalence of Intestinal Parasitic Infections in 2012, C. sinensis was revealed as the parasite with highest prevalence of 1.86% in general population among all parasite species surveyed in Korea. This fluke is now classified under one of the definite Group 1 human biological agents (carcinogens) by International Agency of Research on Cancer (IARC) along with two other parasites, Opisthorchis viverrini and Schistosoma haematobium. C. sinensis infestation is mainly linked to liver and biliary disorders, especially cholangiocarcinoma (CCA). For the purposes of this mini-review, we will only focus on C. sinensis and review pathogenesis and carcinogenesis of clonorchiasis, disease condition by C. sinensis infestation, and association between C. sinensis infestation and CCA. In this presentation, we briefly consider the current scientific status for progression of CCA by heavy C. sinensis infestation from the food-borne trematode and development of CCA.

No abstract