ABSTRACT
Fibrillar amyloid-beta (fAß) peptide causes neuronal cell death, which is known as Alzheimer's disease. One of the mechanisms for neuronal cell death is the activation of microglia which releases toxic compounds like reactive oxygen species (ROS) in response to fAß. We observed that fAß rather than soluble form blocked BV2 cell proliferation of microglial cell line BV2, while N-acetyl-l-cysteine (NAC), a scavenger of superoxide, prevented the cells from death, suggesting that cell death is induced by ROS. Indeed, both fAß1-42 and fAß25-35 induced superoxide production in BV2 cells. fAß25-35 produced superoxide, although fAß25-35 is not phagocytosed into BV2 cells. Thus, superoxide production by fAß does not seem to be dependent on phagocytosis of fAß. Herein we studied how fAß produces superoxide in BV2. Transfection of dominant negative (DN) RhoA (N19) cDNA plasmid, small hairpin (sh)-RhoA forming plasmid, and Y27632, an inhibitor of Rho-kinase, abrogated the superoxide formation in BV2 cells stimulated by fAß. Furthermore, fAß elevated GTP-RhoA level as well as Rac1 and Cdc42. Tat-C3 toxin, sh-RhoA, and Y27632 inhibited the phosphorylation of p47(PHOX). Moreover, peritoneal macrophages from p47(PHOX) (-/-) knockout mouse could not produce superoxide in response to fAß. These results suggest that RhoA closely engages in the regulation of superoxide production induced by fAß through phosphorylation of p47(PHOX) in microglial BV2 cells.
Subject(s)
Amyloid beta-Peptides/metabolism , Microglia/cytology , Superoxides/metabolism , rhoA GTP-Binding Protein/metabolism , Amino Acid Sequence , Amyloid beta-Peptides/chemistry , Animals , Cell Line , Mice , Microglia/metabolism , Molecular Sequence Data , NADPH Oxidases/metabolism , PhosphorylationABSTRACT
Autoimmune hemolytic anemia associated with an ovarian teratoma is a very rare disease. However, treating teratoma is the only method to cure the hemolytic anemia, so it is necessary to include ovarian teratoma in the differential diagnosis of autoimmune hemolytic anemia. We report herein on a case of a young adult patient who had severe autoimmune hemolytic anemia that was induced by an ovarian teratoma. A 25-yr-old woman complained of general weakness and dizziness for 1 week. The hemoglobin level was 4.2 g/dL, and the direct and indirect antiglobulin tests were all positive. The abdominal computed tomography scan revealed a huge left ovarian mass, and this indicated a teratoma. She was refractory to corticosteroid therapy; however, after surgical resection of the ovarian mass, the hemoglobin level and the reticulocyte count were gradually normalized. The mass was well encapsulated and contained hair and teeth. She was diagnosed as having autoimmune hemolytic anemia associated with an ovarian teratoma. To the best of our knowledge, this is the first such a case to be reported in Korea.
