Clusterin is an enigmatic glycoprotein that is overexpressed in several human cancers such as prostate and breast cancers, and squamous cell carcinoma. Because the suppression of clusterin expression renders human cancer cells sensitive to chemotherapeutic drug-mediated apoptosis, it is currently an antisense target in clinical trials for prostate cancer. However, the molecular mechanisms by which clusterin inhibits apoptosis in human cancer cells are unknown. Here we report that intracellular clusterin inhibits apoptosis by interfering with Bax activation in mitochondria. Intriguingly, in contrast to other inhibitors of Bax, clusterin specifically interacts with conformation-altered Bax in response to chemotherapeutic drugs. This interaction impedes Bax oligomerization, which leads to the release of cytochrome c from mitochondria and caspase activation. Moreover, we also find that clusterin inhibits oncogenic c-Myc-mediated apoptosis by interacting with conformation-altered Bax. Clusterin promotes c-Myc-mediated transformation in vitro and tumour progression in vivo. Taken together, our results suggest that the elevated level of clusterin in human cancers may promote oncogenic transformation and tumour progression by interfering with Bax pro-apoptotic activities.

This study details the profile of 13 cell surface cluster differentiation markers on human reserve stem cells derived from connective tissues. Stem cells were isolated from the connective tissues of dermis and skeletal muscle derived from fetal, mature, and geriatric humans. An insulin/dexamethasone phenotypic bioassay was used to determine the identity of the stem cells from each population. All populations contained lineage-committed myogenic, adipogenic, chondrogenic, and osteogenic progenitor stem cells as well as lineageuncommitted pluripotent stem cells capable of forming muscle, adipocytes, cartilage, bone, fibroblasts, and endothelial cells. Flow cytometric analysis of adult stem cell populations revealed positive staining for CD34 and CD90 and negative staining for CD3, CD4, CD8, CD11c, CD33, CD36, CD38, CD45, CD117, Glycophorin-A, and HLA DR-II. Anat Rec 264: [51][52][53][54][55][56][57][58][59][60][61][62] 2001.

Sodium channel ␤1 subunits modulate ␣ subunit gating and cell surface expression and participate in cell adhesive interactions in vitro. ␤1 (Ϫ/Ϫ) mice appear ataxic and display spontaneous generalized seizures. In the optic nerve, the fastest components of the compound action potential are slowed and the number of mature nodes of Ranvier is reduced, but Na v 1.6, contactin, caspr 1, and K v 1 channels are all localized normally at nodes. At the ultrastructural level, the paranodal septate-like junctions immediately adjacent to the node are missing in a subset of axons, suggesting that ␤1 may participate in axo-glial communication at the periphery of the nodal gap. Sodium currents in dissociated hippocampal neurons are normal, but Na v 1.1 expression is reduced and Na v 1.3 expression is increased in a subset of pyramidal neurons in the CA2/CA3 region, suggesting a basis for the epileptic phenotype. Our results show that ␤1 subunits play important roles in the regulation of sodium channel density and localization, are involved in axo-glial communication at nodes of Ranvier, and are required for normal action potential conduction and control of excitability in vivo.

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Single-crystalline silicon nanomembranes (Si NMs) represent a critically important class of material for high-performance forms of electronics that are capable of complete, controlled dissolution when immersed in water and/or biofluids, sometimes referred to as a type of "transient" electronics. The results reported here include the kinetics of hydrolysis of Si NMs in biofluids and various aqueous solutions through a range of relevant pH values, ionic concentrations and temperatures, and dependence on dopant types and concentrations. In vitro and in vivo investigations of Si NMs and other transient electronic materials demonstrate biocompatibility and bioresorption, thereby suggesting potential for envisioned applications in active, biodegradable electronic implants.

BiP/GRP78 is a lumenal stress protein of the endoplasmic reticulum (ER) that interacts with polypeptide folding intermediates transiting the secretory compartment. We have studied the secretion and the stress response in Chinese hamster ovary (CHO) cells that overexpress either wild-type immunoglobulin binding protein (BiP) or a BiP deletion molecule (residues 175-201) that can bind peptides and ATP but is defective in ATP hydrolysis and concomitant peptide release. Overexpressed wild-type BiP was localized to the ER and unique vesicles within the nucleus, whereas overexpressed ATPase-defective BiP was localized to the ER and cytoplasmic vesicles but was absent from the nucleus. Compared with wild-type CHO cells, overexpression of ATPase-defective BiP prevented secretion of factor VIII, a coagulation factor that extensively binds BiP in the lumen of the ER. Under these conditions factor VIII was stably associated with the ATPase-defective BiP. In contrast, the secretion of monocyte/macrophage colony stimulating factor, a protein that is not detected in association with BiP, was not affected by overexpression of ATPase-defective BiP. These results show that BiP function is not required for secretion of some proteins and suggest that some proteins do not interact with BiP upon transport through the ER.The The endoplasmic reticulum is the site where folding occurs for newly synthesized proteins that are destined for the cell surface. In addition, it is the principal cellular storage site for calcium. Calcium homeostasis is required for proper polypeptide folding and secretion of selective proteins (1) as well as for intracellular signaling events that occur within the cell. Within the ER 1 are resident cellular proteins, such as the glucoseregulated protein of 78 kDa (2), that are also known as the immunoglobulin-binding protein (BiP) (3, 4), the glucose-regulated protein of 94 kDa (GRP94), calnexin, calreticulin, and ERp72 that associate with folding intermediates. It is proposed that these cellular ER proteins act as chaperones to prevent aggregation of polypeptide folding intermediates (5). In addition, several of these proteins are documented to be the major calcium-binding proteins in the cell (1, 6, 7). Thus, the processes that maintain calcium homeostasis and proper polypeptide folding are likely to be intimately intertwined.Like all hsp70 family members, BiP binds ATP tightly (8) and has a weak ATPase activity (9) that is stimulated in vitro by small hydrophobic peptides (10) and that induces the release of BiP from bound polypeptides (4). Depletion of cellular ATP inhibits protein folding (11) and results in prolonged association of some proteins with BiP (12), whereas lowering ER calcium levels causes the release of T cell receptor subunits from BiP in vivo, presumably by inappropriately activating ATP hydrolysis (13). These results, together with the recent demonstration of ATP in the ER (14) and an ER ATP transport system (15), have provided evidence that the ATPase activity of BiP is important for its ...

In this study the bacterial invasion in root cementum and radicular dentin of periodontally diseased, caries-free human teeth was examined. In addition, structural changes in these tissues, which could be related to the bacterial invasion, were reported. Twenty-one caries-free human teeth with extensive periodontal attachment loss were studied by light and scanning electron microscopy. At the base of the gingival pocket, bacteria were found in the spaces between remnants of Sharpey's fibers and their point of insertion in the cementum. In teeth that had been scaled and root planed, most of the root cementum had been removed. Bacterial invasion was found in the remaining root cementum. The invasion seemed to start as a localized process, often involving only one bacterium. In other areas bacteria were present in lacunar defects in the cementum. These lacunae extended into the radicular dentin. In 11 teeth bacteria had invaded the dentinal tubules. Most bacteria were located in the outer 300 microns of the dentinal tubules, although occasionally they were found in deeper parts. In two of the nontreated teeth, bacteria were detected on the pulpal wall. No correlation was found between the presence of bacterial invasion and the absence of radicular cementum. No bacteria were found in the portion of the root located apically to the epithelial attachment. These data are in agreement with our results from cultural studies of the bacterial flora in these structures. It was also demonstrated that in spite of meticulous scaling and root planning and personal oral hygiene, bacterial plaque remained present on radicular surfaces. Both the invaded dentinal tubules and the lacunae could act as bacterial reservoirs from which recolonization of treated root surfaces occurs. From these reservoirs bacteria could also induce pulpal pathoses. Since these bacterial reservoirs are not eliminated by conventional mechanical periodontal treatment, it seems appropriate to combine mechanical periodontal therapy with the use of chemotherapeutic agents.