The basement membrane functions as a barrier against the invasion of cancer cells. It is therefore important to investigate the mechanism of basement membrane degradation by matrix metalloproteinases (MMPs). Previously, cancer cells were long considered to be the major source of MMPs; however, current evidence indicates that most MMPs in cancer tissue are produced by stromal rather than cancer cells. A glycoprotein highly expressed on the cancer-cell membrane, EMMPRIN (extra-cellular matrix metalloproteinase inducer), exhibits the potential role of the MMP inductor in stromal cells. Depending on the cell type, EMMPRIN can stimulate the production of MMP-1, MMP-2, and MMP-3.
We here report that soluble full-length EMMPRIN is liberated from HEp-2 human laryngeal epidermoid carcinoma cells, probably via microvesicle shedding. Soluble EMMPRIN stimulates human fibroblasts to produce MMP-2, after which the augmented migration of HEp-2 cells occurs, as observed in an invasion chamber assay with separately cultured fibroblasts. An anti-EMMPRIN function-blocking antibody reduced MMP-2 activity in the conditioned medium and inhibited the migration of HEp-2; obviously, EMMPRIN activity contributes to cancer-cell migration. We postulate that soluble EMMPRIN probably triggers the promotion of cancer invasion in vivo.

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The receptor for advanced glycation endproducts (RAGE) is a cell-surface multiligand receptor, which interacts with amyloid β (Aβ), a key protein in Alzheimer's disease (AD). RAGE-Aβ interaction is thought to be associated with pathological progression in AD. A splice variant of RAGE, endogenous secretory RAGE (esRAGE) can act as a decoy receptor for RAGE ligands that would prevent the progression of some pathologic conditions. In this study, the expression of esRAGE in the hippocampal tissues from AD brains compared with control (non-AD) was examined by immunohistochemistry and Western blot analysis. Semiquantitative immunohistochemical analysis of hippocampal tissues using esRAGE-specific antibody revealed significantly decreased immunoreactivities in pyramidal cells in CA1 and CA3 regions of AD compared with non-AD. On the other hand, immunoreactivities of astrocytes for esRAGE significantly increased in those regions. Dentate granule cells and astrocytes showed essentially invariant immunoreactivities between AD and non-AD. Changes in esRAGE immunoreactivity in CA3 neurons and astrocytes were observed from the early pathological stages. Moreover, the esRAGE-immunoreactive bands of AD samples were weaker than those of non-AD samples in Western blot analysis. The results indicate that low expression of esRAGE in the hippocampus would be associated with the development of AD.

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Vallate taste buds in the guinea-pig tongue were immunohistochemically investigated with regard to the colocalization of gustducin with calbindin-D28K (=spot 35 protein) and type III inositol triphosphate receptor (IP₃R-3) in order to characterize gustducin-immunoreactive cells. Individual taste bud cells ranged from totally immunopositive to totally immunonegative for these three molecules. Among the immunoreactive cells, gustducin-immunoreactive cells were divided into two cell populations: one immunopositive and the other immunonegative for calbindin-D28K. Applying our previous data to the present results, the former cells should belong to Type III cells designated by electron microscopy. This finding provides new evidence regarding the taste bud types of cells expressing gustducin in the guinea pig.

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Carbocyanine fluorescent dye, DiI, is an excellent anterograde/retrograde neural tracer, but its efficacy for the anterograde labeling of neural circuits in the adult brain tends to decrease with ages. The present study shows that an injection of DiI into the motor cortex of the young adult jimpy mutant mice (Plp1^jp/+) resulted in successful anterograde labeling of corticospinal tract fibers. Furthermore, an injection of Fast Blue into the lumbar spinal cord of the mutant mice resulted in retrograde labeling of layer 5 corticospinal tract neurons within the motor cortex. Since no abnormality except for myelin deficiency is known in the long descending and ascending tracts of jimpy mutant mouse, this mutant is suitable for neural tracing studies of long axonal trajectories with the use of carbocyanine dye, DiI, although these males die between 20 and 40 days of age

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Three mammalian GGAs (Golgi-localized, γ-ear-containing, ARF-binding proteins), GGA1, 2, and 3 have been implicated in the sorting of mannose 6-phosphate receptor (MPR). To investigate the distinct roles of GGA2 in lysosomal enzyme transport, we established two stable cell lines that had a reduced expression of GGA2 by RNA interference. The expression levels of GGA2 were approximately 5% of the control levels, whereas those of non-targeted GGA1 and GGA3 were not apparently reduced. The depletion of GGA2 did not cause changes in the overall distribution of GGA1, GGA3, cation-dependent MPR, or cation-independent MPR. However, the cell lines showed increased secretion of a lysosomal enzyme, cathepsin D. In addition, a moderate expression of the dominant negative VHS-GAT domain of GGA2 had no effect on the trans-Golgi network (TGN) signal of three GGAs, nor was the GGA2 signal affected by the expression of VHS-GAT domain of GGA1 or 3. These results suggest that GGA2 is recruited to the TGN independently of the other GGAs and is required for the efficient sorting of lysosomal enzymes.

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We studied distribution patterns of type IV collagen α chains in the subepithelial basement membrane (SBM) of the human gastrointestinal tract - the esophagus through the anal canal - by immunofluorescent microscopy using α(IV) chain-specific monoclonal antibodies. The α1(IV), α2(IV), α5(IV), and α6(IV) chains were found in the SBM throughout the tract, indicating the localization of [α1(IV)]₂α2(IV) and [α5(IV)]₂α6(IV) heterotrimeric molecules. The [α1(IV)]₂α2(IV) molecule was continuously stained, while the [α5(IV)]₂α6(IV) molecule was weakly stained in gastric glands and small intestinal crypts. In addition, the SBM at the luminal surface epithelium of the stomach and large intestine contained small amounts of α3(IV) and α4(IV) chains which combined to form the α3(IV)α4(IV)α5(IV) heterotrimeric molecule with α5(IV) chain. The SBM beneath the villous epithelium of the small intestine was also demonstrated to have an α3(IV) chain and α4(IV) chain. Considering the specific locations of the type IV collagen trimers throughout the gastrointestinal SBM, the supramolecular network containing the α3(IV)α4(IV)α5(IV) molecule appears to function as a selective permeability barrier and /or as a protection against chemical stress from the luminal digestive enzymes.

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