CR6-interacting factor 1 is a key regulator in Aß-induced mitochondrial disruption and pathogenesis of Alzheimer's disease.

Mitochondrial dysfunction, often characterized by massive fission and other morphological abnormalities, is a well-known risk factor for Alzheimer's disease (AD). One causative mechanism underlying AD-associated mitochondrial dysfunction is thought to be amyloid-ß (Aß), yet the pathways between Aß and mitochondrial dysfunction remain elusive. In this study, we report that CR6-interacting factor 1 (Crif1), a mitochondrial inner membrane protein, is a key player in Aß-induced mitochondrial dysfunction. Specifically, we found that Crif1 levels were downregulated in the pathological regions of Tg6799 mice brains, wherein overexpressed Aß undergoes self-aggregation. Downregulation of Crif1 was similarly observed in human AD brains as well as in SH-SY5Y cells treated with Aß. In addition, knockdown of Crif1, using RNA interference, induced mitochondrial dysfunction with phenotypes similar to those observed in Aß-treated cells. Conversely, Crif1 overexpression prevented Aß-induced mitochondrial dysfunction and cell death. Finally, we show that Aß-induced downregulation of Crif1 is mediated by enhanced reactive oxygen species (ROS) and ROS-dependent sumoylation of the transcription factor specificity protein 1 (Sp1). These results identify the ROS-Sp1-Crif1 pathway to be a new mechanism underlying Aß-induced mitochondrial dysfunction and suggest that ROS-mediated downregulation of Crif1 is a crucial event in AD pathology. We propose that Crif1 may serve as a novel therapeutic target in the treatment of AD.

High-dose of vitamin C supplementation reduces amyloid plaque burden and ameliorates pathological changes in the brain of 5XFAD mice.

Blood-brain barrier (BBB) breakdown and mitochondrial dysfunction have been implicated in the pathogenesis of Alzheimer's disease (AD), a neurodegenerative disease characterized by cognitive deficits and neuronal loss. Besides vitamin C being as one of the important antioxidants, recently, it has also been reported as a modulator of BBB integrity and mitochondria morphology. Plasma levels of vitamin C are decreased in AD patients, which can affect disease progression. However, investigation using animal models on the role of vitamin C in the AD pathogenesis has been hampered because rodents produce with no dependence on external supply. Therefore, to identify the pathogenic importance of vitamin C in an AD mouse model, we cross-bred 5 familial Alzheimer's disease mutation (5XFAD) mice (AD mouse model) with ι-gulono-γ-lactone oxidase (Gulo) knockout (KO) mice, which are unable to synthesize their own vitamin C, and produced Gulo KO mice with 5XFAD mice background (KO-Tg). These mice were maintained on either low (0.66 g/l) or high (3.3 g/l) supplementation of vitamin C. We found that the higher supplementation of vitamin C had reduced amyloid plaque burden in the cortex and hippocampus in KO-Tg mice, resulting in amelioration of BBB disruption and mitochondrial alteration. These results suggest that intake of a larger amount of vitamin C could be protective against AD-like pathologies.

Meigs' syndrome with elevated serum CA 125 level in a case of ovarian fibrothecoma.

Meigs' syndrome is the association of benign ovarian tumor, pleural effusion, and ascites. Meigs' syndrome with marked elevated CA 125 is a rare clinical entity and only 42 cases have been reported. Although there is difficulty in discerning the diagnosis of Meigs' syndrome from that of an ovarian malignancy, it should be considered in the differential diagnosis in postmenopausal patients with an ovarian mass, hydrothorax, ascites, and elevated CA 125. In this report, the authors present the case of a 52-year-old postmenopausal woman with ovarian fibrothecoma, pleural effusion, ascites, and elevated CA 125 (319.2 IU/ml). Exploratory laparotomy with total hysterectomy and bilateral salpingo-oophorectomy was performed, and the pathologic diagnosis was ovarian fibrothecoma. After the surgery, the pleural effusion disappeared spontaneously and the CA 125 became normal. The authors also summarized other cases of Meigs' syndrome with elevated CA 125, and reviewed the mechanism of elevation of CA 125, ascites, and pleural effusion.

Vitamin D-binding protein interacts with Aß and suppresses Aß-mediated pathology.

The level of vitamin D-binding protein (DBP) is increased in the cerebrospinal fluid of patients with Alzheimer's disease (AD), suggesting a relationship with its pathogenesis. In this study, we investigated whether and how DBP is related to AD using several different approaches. A pull-down assay and a surface plasmon resonance binding assay indicated direct interactions between purified DBP and amyloid beta (Aß), which was confirmed in the brain of AD patients and transgenic AD model mice by immunoprecipitation assay and immunohistochemical double-staining method. Moreover, atomic force microscopic examination revealed that DBP reduced Aß aggregation in vitro. DBP also prevented Aß-mediated death in cultured mouse hippocampal HT22 cell line. Finally, DBP decreased Aß-induced synaptic loss in the hippocampus and rescued memory deficits in mice after injection of Aß into the lateral ventricle. These results provide converging evidence that DBP attenuates the harmful effects of Aß by a direct interaction, and suggest that DBP is a promising therapeutic agent for the treatment of AD.

Mutational spectrum of X-ray induced TK- human cell mutants.

Mutations induced by ionizing radiation have historically elicited significant public concern. However, only a limited database of ionizing radiation-induced point mutations is available, particularly at endogenous human cell loci. Here, we report the mutational spectrum for 184 X-ray induced TK- mutants derived from TK6 human lymphoblasts. This report represents the first large scale utilization of the tk locus for investigation of mutational specificity at the DNA sequence level. Rapid, single nucleotide sequencing assays at frameshift polymorphism sites in tk exons 4 and 7 were used to partition TK- mutants into two groups: 126 were attributed to either partial gene deletion or to loss of heterozygosity, and DNA sequence alterations were identified for 51. X-ray-induced point mutations included all classes of transitions and transversions, tandem base substitutions, frameshifts, small deletions and a small duplication. The distribution within tk was characterized by clustering at some sites. Twelve TK- point mutations, including five entirely within the coding sequence in exons 3 and 4, resulted in aberrant splicing of the tk transcript. The spectrum of X-ray-induced point mutations was found to be highly reproducible when TK- mutations were compared with HPRT- mutations in TK6. A statistically significant decrease in transitions (P = 0.04) was observed in the combined data set as compared to the spontaneous background. These findings suggest a reproducible pattern which may be utilized in recognizing radiation-induced mutations at other loci of interest.