Regulation of nuclear retention of glucocorticoid receptor by nuclear Hsp90

Heat shock protein 90 (Hsp90) has been demonstrated in both cytoplasm and nucleus, and regulates cytoplasmic retention of glucocorticoid receptor (GR). However, the role of nuclear Hsp90 in GR trafficking is less characterized. The present study examined the role of Hsp90 in nuclear retention of GR after ligand withdrawal. Hsp90 inhibitors; geldanamycin (GA) and radicicol (Rad), significantly accelerated nuclear export of GR after withdrawal of ligands including dexamethasone, corticosterone and RU486. GA accelerated relocalization of GR in the cytoplasm even when reimport of GR into the nucleus was inhibited by okadaic acid or when novel GR synthesis was inhibited by cycloheximide. Overexpression of wild type or nuclear-targeted Hsp90 attenuated Hsp90 inhibitor-induced acceleration of GR nuclear export, although nuclear Hsp90 showed higher activity than the wild type. Only nuclear-targeted Hsp90 prolonged basal nuclear retention of GR after withdrawal of dexamethasone and corticosterone. These results suggest that nuclear Hsp90 regulates the nuclear retention of GR.     

A father and son with Turcot's syndrome: Evidence for autosomal dominant inheritance

Typical Turcot's syndrome is characterized by the association of a brain glioma together with multiple colonic polyposis, in which the number of polypoid lesions is small and the association of colonic cancer occurs at a younger age than in familial adenomatous polyposis. We describe a family in which both the father and his son presented with typical Turcot's syndrome without parental consanguinity. This is the first report of a family that is considered to follow an autosomal dominant inheritance. After reviewing 25 documented cases in which the average age of death was 20.3 years old, it was learned that the major cause of death was brain tumor (76 percent) and the minor cause was colon cancer (16 percent). Patients were very young and, therefore, unlikely to have produced a child before their death. These facts seem to support the theory that Turcot's syndrome is an autosomal dominant disorder.     

Pathogenesis of Focal Cytoplasmic Necrosis of the Smooth Muscle Cells in Hypertensive Rat Arterial Media

Hypertensive rat arteries exhibited severe medial smooth muscle cell injury and necrosis. Electron microscopic observations showed the smooth muscle cells of these arteries exhibited characteristics of focal cytoplasmic necrosis forming new cytodemarcating membrane between the healthy cytoplasm and necrotic cytoplasm. When the focal necrotic cytoplasm disappeared from the injured smooth muscle cells, it left it with a moth-eaten leaf-like appearance (moth-eaten necrosis). At an advanced stage of injury, smooth muscle cells changed to islet-like cell bodies with newly formed basement membranes around them, and further islet-like cell bodies and cell debris disappeared leaving lamellar and reticular basement membranes.In hypertensive rats injected with nitroblue tetrazolium (NBT), formazan deposits were observed in the medial cells and nitrotyrosine, a biomarker of peroxynitrite, were immunohistochemically observed in the arterial media. Nick-end positive extranuclear small granular bodies, which might have derived from focal necrotic cytoplasm and nucleus, were detected in the arterial media using DNA nick-end labeling method. Based on electron microscopical and histochemical findings, we conjectured that the focal cytoplasmic necrosis of the smooth muscle cells in the arterial media depended on injury arising from mitochondria-derived oxidants.     

Microsatellite Instability,EMAST, and Morphology Associations with T Cell Infiltration in Colorectal Neoplasia

Background and Objectives  

Colorectal tumors are often observed with tumor infiltrating lymphocytes, presumably as a host-immune response, and patterns may segregate by types of genomic instability. Microsatellite unstable (MSI) colorectal cancers contain a pronounced lymphocyte reaction that can pathologically identify these tumors. Colorectal tumors with elevated microsatellite alterations at selected tetranucleotide repeats (EMAST) have not been examined for lymphocyte patterns.