epidermal-growth-factor and Alzheimer-Disease

Vitamin B12 deficiency was recently shown to be associated with elevated levels of tumor necrosis factor-alpha and decreased levels of epidermal growth factor in both rats and humans. These findings suggest a novel pathogenetic mechanism underlying the neuropathology of vitamin B12 deficiency. They may also explain putative relationships between vitamin B12 deficiency and certain disorders, including Alzheimer's disease, rheumatoid arthritis, and AIDS.

Topics: Acquired Immunodeficiency Syndrome; Alzheimer Disease; Animals; Antineoplastic Agents; Arthritis, Rheumatoid; Epidermal Growth Factor; Humans; Rats; Tumor Necrosis Factor-alpha; Vitamin B 12 Deficiency

Topics: Aging; Alzheimer Disease; Animals; Central Nervous System; Epidermal Growth Factor; Fibroblast Growth Factors; Growth Substances; Hormones; Insulin; Lymphokines; Mammals; Nerve Growth Factors; Nerve Tissue Proteins; Neurotransmitter Agents; Platelet-Derived Growth Factor; Somatomedins; Transforming Growth Factors

Topics: Adult; Aged; Alzheimer Disease; Amyloid; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Brain; Epidermal Growth Factor; Humans; Middle Aged; Protein Precursors

This article is aimed at reviewing and analyzing studies that are related to the possible therapeutic use of a potent and ubiquitously-distributed hormone--somato-statin (SS-14), and its analogues. Administration of these substances has provided beneficial effects in treating acromegaly, gastro-intestinal hemorrhagic and hypersecretory disorders, acute pancreatitis, diabetes mellitus, and certain types of cancer. Further studies with SS-14-analogues might provide new therapies for treating certain life-threatening disorders of man.

Topics: Acromegaly; Alzheimer Disease; Epidermal Growth Factor; Gastrointestinal Diseases; Humans; Neoplasms; Pancreatic Diseases; Somatostatin

Alzheimer's disease (AD) is the most common neurodegenerative disease with high heritability. Growth factors (GFs) might contribute to the development of AD due to their broad effects on neuronal system. We herein aimed to investigate the role of rare and common variants of GFs in genetic susceptibility of AD. We screened 23 GFs in 6324 individuals using targeted sequencing. A rare-variant-based burden test and common-variant-based single-site association analyses were performed to identify AD-associated GF genes and variants. The burden test showed an enrichment of rare missense variants (p = 6.08 × 10

Topics: Alzheimer Disease; East Asian People; Epidermal Growth Factor; Genetic Predisposition to Disease; Humans; Neurodegenerative Diseases

Recent studies have proposed that microRNAs (miR) function as novel diagnostic and prognostic biomarkers and therapeutic targets in Alzheimer's disease (AD), a common disease among the elderly. In the current study, we aim to explore the effect of miR-186 on oxidative stress injury of neuron in rat models of AD with the involvement of the interleukin-2 (IL2) and the Janus kinase/signal transducers and activators of transcription (JAK-STAT) pathways. AD rat models were established, and dual-luciferase reporter assay and online software were used to confirm the targeting relationship between miR-186 and IL2. Immunohistochemistry was used evaluating the positive rate of IL2. Afterward, to define the role of miR-186 in AD, miR-186, IL2, and JAK-STAT related protein (JAK2, STAT3) expressions were quantified. Cell proliferation was measured by 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide, and cell apoptosis was detected by flow cytometry. We observed downregulated miR-186 and IL2 and upregulated JAK-STAT signaling pathway related genes in AD. The overexpression of miR-186 was shown to significantly promote cell proliferation while suppressing cell apoptosis along with the expression of the IL2 and JAK-STAT signaling pathway related protein. Collectively, the key findings obtained from the current study define the potential role of miR-186 as an inhibitor of AD development by downregulation of IL2 through suppression of the JAK-STAT signaling pathway.

Topics: Alzheimer Disease; Animals; Apoptosis; Base Sequence; bcl-2-Associated X Protein; Caspase 3; Disease Models, Animal; Down-Regulation; Epidermal Growth Factor; Glutathione Peroxidase; Growth Hormone; Hippocampus; Interferon-gamma; Interleukin-2; Janus Kinases; L-Lactate Dehydrogenase; Male; Malondialdehyde; Memory Disorders; MicroRNAs; Neurons; Oxidative Stress; Platelet-Derived Growth Factor; Rats, Sprague-Dawley; Reaction Time; Reactive Oxygen Species; STAT3 Transcription Factor; Superoxide Dismutase

Blood-brain barrier (BBB) coverage plays a central role in the homeostasis of the central nervous system (CNS). The BBB is dynamically maintained by astrocytes, pericytes and brain endothelial cells (BECs). Here, we detail methods to assess BBB coverage using single cultures of immortalized human BECs, single cultures of primary mouse BECs, and a humanized triple culture model (BECs, astrocytes and pericytes) of the BBB. To highlight the applicability of the assays to disease states, we describe the effect of oligomeric amyloid-β (oAβ), which is an important contributor to Alzheimer's disease (AD) progression, on BBB coverage. Further, we utilize the epidermal growth factor (EGF) to illuminate the drug screening potential of the techniques. Our results show that single and triple cultured BECs form meshwork-like structures under basal conditions, and that oAβ disrupts this cell meshwork formation and degenerates the preformed mesh structures, but EGF blocks this disruption. Thus, the techniques described are important for dissecting fundamental and disease-relevant processes that modulate BBB coverage.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Astrocytes; Blood-Brain Barrier; Capillaries; Cell Culture Techniques; Cells, Cultured; Coculture Techniques; Endothelial Cells; Epidermal Growth Factor; Humans; Mice; Pericytes

The Signaling and Dynamic Regulatory Events Miner (SDREM) is a powerful computational approach for identifying which signaling pathways and transcription factors control the temporal cellular response to a stimulus. SDREM builds end-to-end response models by combining condition-independent protein-protein interactions and transcription factor binding data with two types of condition-specific data: source proteins that detect the stimulus and changes in gene expression over time. Here we describe how to apply SDREM to study human diseases, using epidermal growth factor (EGF) response impacting neurogenesis and Alzheimer's disease as an example.

Topics: Alzheimer Disease; Disease Progression; Epidermal Growth Factor; Gene Regulatory Networks; Humans; Neurogenesis; Protein Interaction Maps; Signal Transduction; Software; Systems Biology

Cerebrovascular dysfunction is a critical component of Alzheimer's disease (AD) pathogenesis. Oligomeric amyloid-β42 (oAβ42) is considered a major contributor to AD progression. However, data are limited on the role of oAβ42 in brain endothelial cell vessel degeneration/angiogenesis, including the interaction with angiogenic mediators. Thus, the current study determined the effect of oAβ42 on angiogenesis in vitro, utilizing single brain endothelial cell cultures and triple cultures mimicking the microvascular unit (MVU: brain endothelial cells, astrocytes, and pericytes). oAβ42 dose-dependently reduced angiogenesis and induced vessel disruption. Critically, epidermal growth factor prevented oAβ42-induced deficits, implicating angiogenic pathways as potential therapeutics for AD.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Astrocytes; Cells, Cultured; Coculture Techniques; Dose-Response Relationship, Drug; Endothelial Cells; Endothelium, Vascular; Epidermal Growth Factor; Humans; Microvessels; Models, Biological; Neovascularization, Physiologic; Peptide Fragments; Pericytes; Protein Multimerization

Cerebrovascular (CV) dysfunction is emerging as a critical component of Alzheimer's disease (AD), including altered CV coverage. Angiogenic growth factors (AGFs) are key for controlling CV coverage, especially during disease pathology. Therefore, evaluating the effects of AGFs in vivo can provide important information on the role of CV coverage in AD. We recently demonstrated that epidermal growth factor (EGF) prevents amyloid-beta (Aβ)-induced damage to brain endothelial cells in vitro. Here, our goal was to assess the protective effects of EGF on cognition, CV coverage and Aβ levels using an AD-Tg model that incorporates CV relevant AD risk factors. APOE4 is the greatest genetic risk factor for sporadic AD especially in women and is associated with CV dysfunction. EFAD mice express human APOE3 (E3FAD) or APOE4 (E4FAD), overproduce human Aβ42 and are a well characterized model of APOE pathology. Thus, initially the role of APOE and sex in cognitive and CV dysfunction was assessed in EFAD mice in order to identify a group for EGF treatment. At 8 months E4FAD female mice were cognitively impaired, had low CV coverage, high microbleeds and low plasma EGF levels. Therefore, E4FAD female mice were selected for an EGF prevention paradigm (300 μg/kg/wk, 6 to 8.5 months). EGF prevented cognitive decline and was associated with lower microbleeds and higher CV coverage, but not changes in Aβ levels. Collectively, these data suggest that EGF can prevent Aβ-induced damage to the CV. Developing therapeutic strategies based on AGFs may be particularly efficacious for APOE4-induced AD risk.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Apolipoprotein E3; Apolipoprotein E4; Brain; Capillary Permeability; Cerebrovascular Disorders; Cognitive Dysfunction; Disease Models, Animal; Epidermal Growth Factor; Female; Humans; Male; Mice, Transgenic; Neuroprotective Agents; Nootropic Agents; Peptide Fragments; Plaque, Amyloid; Sex Characteristics

Evidence has shown that aberrant angiogenesis is an integral part of Alzheimer's disease (AD). Angiogenesis is a complex process requiring successive activation of a rather large series of factors. The aim of this study was to determine which angiogenesis molecule(s) abnormalities were changed in plasma of AD subjects and whether plasma levels of angiogenesis factors were associated with cognitive function and risk of AD. Discovery-phase antibody arrays were used to detect plasma concentrations of 55 angiogenesis-related factors. Enzyme-linked immunosorbent assays (ELISAs) in a large cohort were further performed to identify the association of plasma angiogenesis factors with AD. We found that plasma angiogenin (ANG) and tissue inhibitor of matrix metalloproteinase-4 (TIMP-4) levels were higher in patients with AD than those in normal subjects. Significantly higher ANG and TIMP-4 were observed in the severe AD group relative to the mild AD. There were different levels of plasma ANG and TIMP-4 compared with vascular dementia and other dementias. Age or gender had no major effects on levels of these proteins. Plasma ANG and TIMP-4 levels tended to be higher in ApoE ε4 carriers compared with non-carriers, but not significantly. A multiple regression analysis after adjusting for covariates revealed correlations between plasma ANG and TIMP-4 and the MMSE and CDR. Higher plasma ANG and TIMP-4 levels were associated with significant AD risk. These results demonstrate that plasma ANG and TIMP-4 may reflect the severity of cognitive function impairment, and higher levels were associated with risk of AD.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Analysis of Variance; Angiogenesis Inducing Agents; Apolipoproteins E; Enzyme-Linked Immunosorbent Assay; Epidermal Growth Factor; Female; Humans; Insulin-Like Growth Factor Binding Protein 2; Male; Matrix Metalloproteinase 8; Mental Status Schedule; Protein Array Analysis

Alzheimer's disease (AD) is a severe neurodegenerative disorder characterized mainly by accumulation of amyloid-β plaques and neurofibrillary tangles, synaptic and neuronal loss. Blood platelets contain the neurotransmitter serotonin and amyloid-precursor protein (APP), and may thus be useful as a peripheral biomarker for AD. The aim of the present study was to functionally characterize platelets by FACS, to examine alterations in APP expression and secretion, and to measure serotonin levels in hypercholesterolemia mice with AD-like pathology and in two AD mouse models, the triple transgenic AD model (3xTg) and the APP overexpressing AD model with the Swedish-Dutch-Iowa mutations (APP_SweDI). These data are supplemented with epidermal growth factor (EGF) levels and compared with changes observed in platelets of patients with AD. We observed decreased platelet APP isoforms in 3xTg mice and patients with AD when analysed by means of Western blot. In patients, a significant increase of APP levels was observed when assessed by ELISA. Secreted APPβ proved to be altered amongst all three animal models of AD at different time points and in human patients with AD. Serotonin levels were only reduced in 7 and 14 month old 3xTg mice. Moreover, we found significantly lower EGF levels in human AD patients and could thereby reproduce previous findings. Taken together, our data confirm that platelets are dysfunctional in AD, however, results from AD animal models do not coincide in all aspects, and markedly differ when compared to AD patients. We support previous data that APP, as well as EGF, could become putative biomarkers for diagnosing AD in human platelets.

Topics: Aged; Aged, 80 and over; Alzheimer Disease; Amyloid beta-Protein Precursor; Animals; Apoptosis; Biomarkers; Blood Platelets; Case-Control Studies; Cross-Sectional Studies; Disease Models, Animal; Epidermal Growth Factor; Female; Genotype; Humans; Hyperlipidemias; Male; Mice, Transgenic; Phenotype; Serotonin; Species Specificity; Time Factors

Expression of a familial Alzheimer's disease (AD)-linked mutant of amyloid β precursor protein (APP) or the binding of transforming growth factor β2 to wild-type (wt)-APP causes neuronal death by activating an intracellular death signal (a APP-mediated intracellular death signal) in the absence of the involvement of amyloid β (Aβ) toxicity in vitro. These neuronal death models may therefore be regarded as Aβ-independent neuronal death models related to AD. A recent study has shown that the A673T mutation in the APP isoform APP770 , corresponding to the A598T mutation in the most prevalent neuronal APP isoform APP695 (an AD-protective mutant of APP), is linked to a reduction in the incidence rate of AD. Consistent with this, cells expressing the AD-protective mutant of APP produce less Aβ than cells expressing wt-APP. In this study, transforming growth factor β2 caused death in cultured neuronal cells expressing wt-APP, but not in those expressing the AD-protective mutant of APP. This result suggests that the AD-protective mutation of APP reduces the incidence rate of AD by attenuating the APP-mediated intracellular death signal. In addition, a mutation that causes hereditary cerebral hemorrhage with amyloidosis-Dutch type also attenuated the APP-mediated intracellular death signal. The A598T mutation of amyloid precursor protein APP is linked to a reduction in the incidence rate of Alzheimer's disease (AD). This study shows that TGFβ2 causes death in neuronal cells expressing wild-type APP, but not in those expressing the AD-protective mutant of APP, suggesting that the AD-protective mutation of APP reduces the incidence rate of AD by attenuating the APP-mediated intracellular death signal.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Amyloidosis; Animals; Blotting, Western; Cell Death; Cell Line, Tumor; Cell Survival; Enzyme-Linked Immunosorbent Assay; Epidermal Growth Factor; ErbB Receptors; Genes, erbB-1; Humans; MAP Kinase Kinase 4; Mice; Mutation; Neurons; Neurotoxicity Syndromes; Peptide Fragments; Phosphorylation

Alzheimer's disease (AD) is the most prevalent type of dementia. Despite considerable advances in diagnostic accuracy, diagnostic procedures that are easily accessible are still sorely needed. Blood biomarkers are therefore in the focus of research. Platelets contain a high concentration of the amyloid precursor protein (APP), which has been mentioned as a potentially useful diagnostic marker. The aim of the present study was to analyze various cell adhesion molecules (CAMs), cytokines, growth factors, and matrix metalloproteinases (MMPs) in platelets of AD and mild cognitively impaired (MCI) patients as compared to healthy controls. Our data show a significant decrease in the levels of epidermal growth factor (EGF) and of MMP-2 in platelets of AD patients and decreased levels of MMP-2 in MCI. The APP ratio was slightly but not significantly decreased in AD patients, whereas CD40L and serotonin were unchanged. Our findings demonstrate specific changes in AD platelets. Whether these biomarkers can be established as potential early diagnostic biomarkers for AD remains to be established in longitudinal studies.

Topics: Aged; Alzheimer Disease; Biomarkers; Blood Platelets; Blotting, Western; Chromatography, High Pressure Liquid; Enzyme-Linked Immunosorbent Assay; Epidermal Growth Factor; Female; Humans; Immunohistochemistry; Male; Matrix Metalloproteinase 2

There is an urgent need for biomarkers in plasma to identify Alzheimer's disease (AD). It has previously been shown that a signature of 18 plasma proteins can identify AD during pre-dementia and dementia stages (Ray et al, Nature Medicine, 2007). We quantified the same 18 proteins in plasma from 174 controls, 142 patients with AD, and 88 patients with other dementias. Only three of these proteins (EGF, PDGF-BB and MIP-1δ) differed significantly in plasma between controls and AD. The 18 proteins could classify patients with AD from controls with low diagnostic precision (area under the ROC curve was 63%). Moreover, they could not distinguish AD from other dementias. In conclusion, independent validation of results is important in explorative biomarker studies.

Topics: Adult; Aged; Aged, 80 and over; Alzheimer Disease; Becaplermin; Biomarkers; Chemokines, CC; Dementia; Epidermal Growth Factor; Female; Humans; Macrophage Inflammatory Proteins; Middle Aged; Predictive Value of Tests; Proto-Oncogene Proteins c-sis; ROC Curve

Alzheimer's disease (AD) is a progressive brain disease with a huge cost to human lives. The impact of the disease is also a growing concern for the governments of developing countries, in particular due to the increasingly high number of elderly citizens at risk. Alzheimer's is the most common form of dementia, a common term for memory loss and other cognitive impairments. There is no current cure for AD, but there are drug and non-drug based approaches for its treatment. In general the drug-treatments are directed at slowing the progression of symptoms. They have proved to be effective in a large group of patients but success is directly correlated with identifying the disease carriers at its early stages. This justifies the need for timely and accurate forms of diagnosis via molecular means. We report here a 5-protein biomarker molecular signature that achieves, on average, a 96% total accuracy in predicting clinical AD. The signature is composed of the abundances of IL-1alpha, IL-3, EGF, TNF-alpha and G-CSF.. Our results are based on a recent molecular dataset that has attracted worldwide attention. Our paper illustrates that improved results can be obtained with the abundance of only five proteins. Our methodology consisted of the application of an integrative data analysis method. This four step process included: a) abundance quantization, b) feature selection, c) literature analysis, d) selection of a classifier algorithm which is independent of the feature selection process. These steps were performed without using any sample of the test datasets. For the first two steps, we used the application of Fayyad and Irani's discretization algorithm for selection and quantization, which in turn creates an instance of the (alpha-beta)-k-Feature Set problem; a numerical solution of this problem led to the selection of only 10 proteins.. the previous study has provided an extremely useful dataset for the identification of AD biomarkers. However, our subsequent analysis also revealed several important facts worth reporting: 1. A 5-protein signature (which is a subset of the 18-protein signature of Ray et al.) has the same overall performance (when using the same classifier). 2. Using more than 20 different classifiers available in the widely-used Weka software package, our 5-protein signature has, on average, a smaller prediction error indicating the independence of the classifier and the robustness of this set of biomarkers (i.e. 96% accuracy when predicting AD against non-demented control). 3. Using very simple classifiers, like Simple Logistic or Logistic Model Trees, we have achieved the following results on 92 samples: 100 percent success to predict Alzheimer's Disease and 92 percent to predict Non Demented Control on the AD dataset.

Topics: Alzheimer Disease; Biomarkers; Brain; Computational Biology; Disease Progression; Epidermal Growth Factor; Gene Expression Regulation; Granulocyte Colony-Stimulating Factor; Humans; Interleukin-1alpha; Interleukin-3; Proteins; Reproducibility of Results; Software; Tumor Necrosis Factor-alpha

Topics: Alzheimer Disease; Amyloid beta-Peptides; Amyloid Precursor Protein Secretases; Animals; Aspartic Acid Endopeptidases; Enzyme Activation; Epidermal Growth Factor; Humans; Mice; Nerve Growth Factor; Receptor Protein-Tyrosine Kinases; Signal Transduction; trans-Golgi Network

The biological function of full-length amyloid-beta protein precursor (AbetaPP), the precursor of Abeta, is not fully understood. Multiple laboratories have reported that antibody binding to cell surface AbetaPP causes neuronal cell death. Here we examined whether induced dimerization of the cytoplasmic domain of AbetaPP (AbetaPPCD) triggers neuronal cell death. In neurohybrid cells expressing fusion constructs of the epidermal growth factor (EGF) receptor with AbetaPPCD (EGFR/AbetaPP hybrids), EGF drastically enhanced neuronal cell death in a manner sensitive to acetyl-l-aspartyl-l-glutamyl-l-valyl-l-aspartyl-aldehyde (Ac-DEVD-CHO; DEVD), GSH-ethyl ester (GEE), and pertussis toxin (PTX). Dominant-negative apoptosis signal-regulating kinase 1 (ASK1) blocked this neuronal cell death, but not alpha-synuclein-induced cell death. Constitutively active ASK1 (caASK1) caused DEVD/GEE-sensitive cell death in a manner resistant to PTX and sensitive to Humanin, which also suppressed neuronal cell death by EGFR/AbetaPP hybrid. ASK1 formed a complex with AbetaPPCD via JIP-1b, the c-Jun N-terminal kinase (JNK)-interacting protein. EGFR/AbetaPP hybrid-induced and caASK1-induced neuronal cell deaths were specifically blocked by SP600125 (anthra[1,9-cd]pyrazol-6(2H)-one), a specific JNK inhibitor. Combined with our earlier study, these data indicate that dimerization of AbetaPPCD triggers ASK1/JNK-mediated neuronal cell death. We also noticed a potential role of ASK1/JNK in sustaining the activity of this mechanism after initial activation by AbetaPP, which allows for the achievement of cell death by short-term anti-AbetaPP antibody treatment. Understanding the function of AbetaPPCD and its downstream pathway should lead to effective anti-Alzheimer's disease therapeutics.

Topics: Adaptor Proteins, Signal Transducing; Alzheimer Disease; Amyloid beta-Protein Precursor; Animals; Anthracenes; Carrier Proteins; Dimerization; Epidermal Growth Factor; ErbB Receptors; Flavonoids; Humans; Hybrid Cells; Imidazoles; Intracellular Signaling Peptides and Proteins; JNK Mitogen-Activated Protein Kinases; MAP Kinase Kinase Kinase 5; MAP Kinase Kinase Kinases; Mice; Mitogen-Activated Protein Kinases; Neurons; Oligopeptides; p38 Mitogen-Activated Protein Kinases; Protein Structure, Tertiary; Proteins; Pyridines; Rats; Signal Transduction

Growth inhibitory factor (GIF) is highly expressed in the CNS under physiological conditions, but its expression is reduced in neurodegenerative diseases, such as Alzheimer's disease. The results of this study show that the levels of GIF and GIF mRNA were not influenced by neuroglial interactions. GIF was highly expressed in confluent astrocytes, but the expression was down-regulated in low-density growing astrocytes. A high level of GIF was not observed in serum-starved low-density cultures. These findings suggest that GIF is a quiescent state-specific protein and that two different mechanisms may exist for the cells to enter the quiescent state. Among interleukin-1beta (IL-1beta), fibroblast growth factor-2, epidermal growth factor (EGF), amyloid beta1-42, and 50% O2, only EGF and IL-1beta altered the level of GIF in confluent astrocytes: EGF increased both GIF mRNA and protein, and IL-1beta decreased GIF mRNA, but did not alter GIF protein. Kinetic analysis of the GIF mRNA level revealed the biphasic regulation of GIF mRNA expression by IL-1beta, i.e., a transient up-regulation followed subsequently by down-regulation, explaining in part the discrepancy between the levels of GIF mRNA and protein in astrocytes treated with IL-1beta.

Topics: Alzheimer Disease; Animals; Astrocytes; Brain Chemistry; Cattle; Cells, Cultured; Chromatography, High Pressure Liquid; Electrophoresis, Polyacrylamide Gel; Epidermal Growth Factor; Gene Expression Regulation; Growth Inhibitors; Interleukin-1; Kinetics; Metallothionein 3; Mice; Nerve Tissue Proteins; Neuroglia; Neurons; Rabbits; Rats; RNA, Messenger

Alzheimer's disease (AD) is the major cause of serious dementia and memory loss in several million elderly Americans. The most prominent lesions in the brains of these patients are the depositions of two types of abnormal filaments: the predominantly intraneuronal neurofibrillary tangles (NFT), which consist of paired helical filaments (PHF), and the extracellular amyloid fibers. These changes are characteristic of AD, and a final diagnosis of this disease is based on the presence of large numbers of these abnormal filamentous structures in the patient's brain. The amyloid fibers consist of a peptide subunit termed beta-protein or A4 peptide, which derives from a larger precursor protein. In this study we review the structural characteristics, regulation of expression, and metabolism of the Alzheimer amyloid precursor in brain tissue and cell cultures.

Topics: Aged; Alzheimer Disease; Amyloid; Amyloid beta-Protein Precursor; Brain Chemistry; Epidermal Growth Factor; Humans; Nerve Growth Factors; Neurofibrils; RNA, Messenger

The amyloid beta protein and the amyloid beta-protein precursor (APP) are major constituents of senile plaques and cerebrovascular deposits in patients with Alzheimer disease and Down syndrome. Most human tissues contain mRNA that encodes forms of APP that contain the Kunitz protease inhibitor (KPI+) domain. A major 120-kDa protein corresponding to this KPI+ mRNA is also found in these tissues. This protein is identical to the protease inhibitor protease nexin 2. Brain contains an additional mRNA species that encodes a form of APP that lacks the KPI domain (KPI-). This latter mRNA has been suggested to encode a 105-kDa KPI- form of APP protein also found in brain. Using protease inhibitory functional assays, we show that both the 105-kDa and 120-kDa APP proteins in normal and Alzheimer disease brain contain the KPI domain. Moreover, KPI domain-specific precipitation assays reveal that KPI- forms of APP protein represent less than 14% of total brain APP. Lastly, an enriched fraction from total brain homogenate contains proteolytic activity that can process the purified 120-kDa KPI+ form of APP into a 105-kDa form, resulting in a high-molecular-mass doublet identical to that seen in brain. These findings indicate that although KPI- APP mRNA is abundant in brain, little corresponding protein is present. Thus, KPI+ APP protein (equivalent to protease nexin 2) is the predominant form of APP in human brain.

Topics: Alzheimer Disease; Amyloid beta-Protein Precursor; Brain; Carrier Proteins; Chromatography, Affinity; Epidermal Growth Factor; Humans; Immunoblotting; Molecular Weight; Protease Inhibitors; Protease Nexins; Protein Binding; Receptors, Cell Surface; Reference Values; RNA, Messenger

Antisera against specific sites of the Alzheimer beta Amyloid protein precursor (beta APP) were used to study the effects of nerve and epidermal growth factors on the expression and processing of this protein in PC12 cell cultures. Two major beta APP proteins (140 and 105 kDa) both containing the Kunitz-protease inhibitor insert (KPI), were detected in cell extracts of naive PC12 cells. Treatment of these cultures with nerve growth factor (NGF) induced the release of two beta APP species 125 and 120 kDa, both of which contained the KPI domain and lacked the carboxy-terminal portion of the precursor. The released beta APP contained O-linked sugars. Only one of the released beta APP proteins bound to the lectin Concanavalin A indicating that they differ in their glycosylation. Epidermal growth factor (EGF) also induced the release of beta APP proteins into the culture medium with similar electrophoretic mobilities as those released by NGF.

Topics: Adrenal Gland Neoplasms; Alzheimer Disease; Amyloid; Amyloid beta-Protein Precursor; Animals; Cell Line; Epidermal Growth Factor; Humans; Molecular Weight; Nerve Growth Factors; Pheochromocytoma; Protein Precursors; Protein Processing, Post-Translational; Rats