Stimulation of beta-amyloid precursor protein alpha-processing by phorbol ester involves calcium and calpain activation.

Ming Chen; Hugo L Fernandez

doi:10.1016/j.bbrc.2004.02.052

Home/Archive/PubMed

PubMed · 15020222

Stimulation of beta-amyloid precursor protein alpha-processing by phorbol ester involves calcium and calpain activation.

Ming Chen·Hugo L Fernandez

View original source ↗Export metadata ↓

Abstract

Normal processing of Alzheimer's beta-amyloid precursor protein (APP) is markedly stimulated by phorbol esters, but the underlying mechanisms have yet to be fully understood. In this study, we observed that: (a) Phorbol 12,13-dibutyrate (PDBu)-stimulated APP secretion in cultured SH-SY5Y neuroblastoma and fibroblast cells was blocked by EGTA and calpain inhibitors in a concentration-dependent manner, but not by other protease inhibitors. (b) Secretion of fibronectin, another secretory protein tested for comparison, was enhanced by PDBu, but insensitive to calpain inhibitors. (c) PDBu stimulated intracellular calpain activity as measured by the hydrolysis of a fluorogenic calpain substrate. (d) PDBu also induced rapid proteolysis of two endogenous substrates of calpains, i.e., tau and microtubule-associated protein-2 (MAP-2) and the proteolysis was blocked by EGTA and calpain inhibitors. Taken together, these results suggest that stimulation of APP alpha-processing by PDBu is through a mechanism that involves the activation of Ca(2+) and, most notably, calpain. The implications of the findings are discussed in relation to the regulatory mechanism of APP alpha-processing.

Explore related subjects

Amyloid beta-Protein Precursor Calcium Calpain Cells, Cultured Chelating Agents Egtazic Acid Enzyme Activation Enzyme Inhibitors Fibronectins Humans Microtubule-Associated Proteins Peptide Fragments Phorbol 12,13-Dibutyrate tau Proteins Journal Article Research Support, U.S. Gov't, Non-P.H.S.

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Ming Chen, Hugo L Fernandez. 2004-04-02. Stimulation of beta-amyloid precursor protein alpha-processing by phorbol ester involves calcium and calpain activation.. https://doi.org/10.1016/j.bbrc.2004.02.052

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2007

The low-density lipoprotein receptor-related protein 1 (LRP1) mediates the endocytosis of the cellular prion protein.

PrP(C) (cellular prion protein) is located at the surface of neuronal cells in detergent-insoluble lipid rafts, yet is internalized by clathrin-dependent endocytosis. As PrP(C) is glycosyl-phosphatidylinositol-anchored, it requires a transmembrane adaptor protein to connect it to the clathrin endocytosis machinery. Using receptor-associated protein and small interfering RNA against particular LDL (low-density lipoprotein) family members, in combination with immunofluorescence microscopy and surface biotinylation assays, we show that the transmembrane LRP1 (LDL receptor-related protein 1) is required for the Cu(2+)-mediated endocytosis of PrP(C) in neuronal cells. We show also that another LRP1 ligand that can cause neurodegenerative disease, the Alzheimer's amyloid precursor protein, does not modulate the endocytosis of PrP(C).

Amyloid beta-Protein Precursor↗

PubMed2006

Neurobehavioral functional deficits following closed head injury in the neonatal pig.

Neurobehavioral deficits in higher cortical systems have not been described previously in a large animal model of diffuse brain injury. Anesthetized 3-5 day old piglets were subjected to either mild (142 rad/s) or moderate (188 rad/s) rapid non-impact axial rotations of the head. Multiple domains of cortical function were evaluated 5 times during the 12 day post-injury period using tests of neurobehavioral function devised for piglets. There were no observed differences in neurobehavioral outcomes between mild injury pigs (N=8) and instrumented shams (N=4). Moderately injured piglets (N=7) had significantly lower interest in exploring their environment and had higher failure rates in visual-based problem solving compared to instrumented shams (N=5) on days 1 and 4 after injury. Neurobehavioral functional deficits correlated with neuropathologic damage in the neonatal pigs after inertial head injury. Injured axons detected by immunohistochemistry (beta-APP) were absent in mild injury and sham piglets, but were observed in moderately injured piglet brains. In summary, we have developed a quantitative battery of neurobehavioral functional assessments for large animals that correlate with neuropathologic axonal damage and may have wide applications in the fields of cardiac resuscitation, stroke, and hypoxic-ischemic brain injury.

Amyloid beta-Protein Precursor↗

PubMed2006

Rat brain synaptic vesicles are devoid of Mg2+-ATPase activity and contain beta-amyloid precursor protein.

Rat brain synaptic vesicles (SVs) isolated by gel filtration on Sephacryl S-500 had little Mg2+(H+)-ATPase activity, though it was identified by Western blots with antibodies against the H+-ATPase A-subunit and other vesicle proteins. In contrast, tyrosine hydroxylase and dopa decarboxylase activities in the SVs were substantial, suggesting that the absence of Mg2+(H+)-ATPase activity was not due to inactivation during isolation but rather to the nature of the SVs. The vesicle component reactive to H+-ATPase antibody was also identified in the synaptosomal cytosol, so the antibody for the A-subunit seemed unnecessary to detect H+-ATPase. The SVs contained beta-amyloid precursor protein of approximately 100 kDa. Based on these observations, SVs without Mg2+(H+)-ATPase seemed to play a role(s) in the delivery of cytoplasmic and plasma membrane proteins to nerve terminals as well as in neurotransmission.

Amyloid beta-Protein Precursor↗