Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.23.5 (cathepsin D)
 4,130 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The vasopressin-induced trafficking of aquaporin-2 (AQP2) water channels in kidney collecting duct is likely mediated by vesicle-targeting proteins (N-ethylmaleimide-sensitive factor attachment protein receptors). Hrs-2 is an ATPase believed to have a modulatory role in regulated exocytosis. To examine whether Hrs-2 is expressed in rat kidney, we carried out RT-PCR combined with DNA sequence analysis and Northern blotting using a digoxigenin-labeled Hrs-2 RNA probe. RT-PCR and Northern blotting revealed that Hrs-2 mRNA is localized in all zones of rat kidney. The presence of Hrs-2 protein in rat kidney was confirmed by immunoblotting, revealing a 115-kDa protein in kidney and brain membrane fractions corresponding to the expected molecular size of Hrs-2. Immunostaining and confocal laser scanning microscopy of LLC-PK(1) cells (a porcine proximal tubule cell line) transfected with Hrs-2 DNA confirmed the specificity of the antibody and revealed that Hrs-2 is mainly localized in intracellular compartments, including cathepsin D-containing lysosomal/endosomal compartments. The cellular and subcellular localization of Hrs-2 in rat kidney was examined by immunocytochemistry and confocal laser scanning microscopy. Hrs-2 immunoreactivity was observed in collecting duct principal cells, and weaker labeling was detected in other nephron segments. The labeling was predominantly present in intracellular vesicles, but labeling was also observed in the apical plasma membrane domains of some cells. Colabeling with AQP2 revealed colocalization in vesicles and apical plasma membrane domains, suggesting a role for Hrs-2 in regulated AQP2 trafficking.
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PMID:SNAP-25-associated Hrs-2 protein colocalizes with AQP2 in rat kidney collecting duct principal cells. 1150 3

The cellular endomembrane system requires the proper kinetic balance of synthesis and degradation of its individual components, which is maintained in part by a specific membrane fusion apparatus. In this study, we describe the molecular properties of D12, which was identified from a mouse expression library. This C-terminal anchored membrane protein has sequence similarity to both a yeast soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptor (SNARE), Use1p/Slt1p, and a recently identified human syntaxin 18-binding protein, p31. D12 formed a tight complex with syntaxin 18 as well as Sec22b and bound to alpha-SNAP, indicating that D12 is a SNARE protein. Although the majority of D12 is located in the endoplasmic reticulum and endoplasmic reticulum-Golgi intermediate compartments at steady state, overexpression or knockdown of D12 had no obvious effects on membrane trafficking in the early secretory pathway. However, suppression of D12 expression caused rapid appearance of lipofuscin granules, accompanied by apoptotic cell death without the apparent activation of the unfolded protein response. The typical cause of lipofuscin formation is the impaired degradation of mitochondria by lysosomal degradative enzymes, and, consistent with this, we found that proper post-Golgi maturation of cathepsin D was impaired in D12-deficient cells. This unexpected observation was supported by evidence that D12 associates with VAMP7, a SNARE in the endosomal-lysosomal pathway. Hence, we suggest that D12 participates in the degradative function of lysosomes.
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PMID:Involvement of a novel Q-SNARE, D12, in quality control of the endomembrane system. 1635 70

Based on the observation that 3 months alpha-tocopherol supplementation caused an up-regulation of the mRNA of vesicular transport proteins in livers of mice, the functional relevance was investigated in RBL-2H3 cells, a model for mast cell degranulation. In total, 24 h incubation with 100 muM alpha-tocopherol enhanced the basal and phorbol-12-myristyl-13-acetate/ionomycin-stimulated release of beta-hexosaminidase and cathepsin D as measured by enzymatic analysis as well as Western blotting and immunocytochemistry, respectively. beta-Tocopherol exerted the same effect, whereas alpha-tocopheryl phosphate and trolox were inactive, indicating that both the side chain and the 6-OH group at the chroman ring are essential for activation of degranulation. alpha-Tocopherol did not induce mRNA expression of soluble NSF-attachment protein receptor (soluble N-ethylmaleimide-sensitive factor-attachment protein receptor) proteins, such as N-ethylmaleimide sensitive fusion protein, complexin-2, SNAP23 or syntaxin-3, in the RBL-2H3 cell model. In view of the well known alpha-tocopherol-mediated activation of protein phosphatases, which regulate soluble NSF-attachment protein receptor activities by dephosphorylation, underlying mechanisms are discussed in terms of preventing oxidative inactivation of protein phosphatases and so far unknown functions in certain membrane domains.
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PMID:alpha-Tocopherol enhances degranulation in RBL-2H3 mast cells. 2016 86