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PubMed2006

Taking down the unindicted co-conspirators of amyloid beta-peptide-mediated neuronal death: shared gene regulation of BACE1 and APP genes interacting with CREB, Fe65 and YY1 transcription factors.

Major hallmarks of Alzheimer's disease (AD) include brain deposition of the amyloid-beta peptide (Abeta), which is proteolytically cleaved from a large Abeta precursor protein (APP) by beta and gamma- secretases. A transmembrane aspartyl protease, beta-APP cleaving enzyme (BACE1), has been recognized as the beta-secretase. We review the structure and function of the BACE1 protein, and of 4129 bp of the 5'-flanking region sequence of the BACE1 gene and its interaction with various transcription factors involved in cell signaling. The promoter region and 5'-untranslated region (UTR) contain multiple transcription factor binding sites, such as AP-1, CREB and MEF2. A 91 bp fragment is the shortest region with significant reporter gene activity and constitutes the minimal promoter element for BACE1. The BACE1 promoter contains six unique functional domains and three structural domains of increasing sequence complexity as the "ATG" start codon is approached. Notably, the BACE1 gene promoter contains basal regulatory elements, inducible features and sites for regulation by various important transcription factors. Herein, we also discuss and speculate how the interaction of these transcription factors with the BACE1 promoter can modulate synaptic plasticity, neuronal apoptosis and oxidative stress, which are pertinent to the pathogenesis and progression of AD.

Amyloid Precursor Protein Secretases↗

PubMed1999

[Molecular genetic analysis of Alzheimer's dementia in the Czech population. The APP-717 mutation in the gene for amyloid protein precursor].

BACKGROUND: Although locus mutations in the gene for the amyloid precursor protein were already described in patients with Alzheimer's disease, there still are some patients where this mutation was not found and no link was found with other possible genetic loci on chromosomes 14 and 19. Therefore a group of subjects with Alzheimer's disease was subjected to tests for the presence of a mutation in the APP gene (in position 717). METHODS AND RESULTS: In a selected group of subjects with Alzheimer's disease (AD) in the gene for amyloid precursor protein in position 717 mutations of its transmembraneous region are found. The authors analyzed the genome DNA of cerebral tissue of Czech subjects for the presence of this mutation by means of the polymerase chain reaction with subsequent verification by sequencing analysis. In every subject genetic analyses from cerebral areas of the frontal lobe, temporal lobe, parietal lobe and hippocampus were performed. The methods used were the polymerase chain reaction (PCR) and sequencing. From the total number of 18 subjects with confirmed Alzheimer's disease and six non-related subjects without histopathological signs of Alzheimer's disease after the age of 90 years, three sequencing changes were found in position 717 of exon 17 of the transmembranous region of the precursor of beta-4 amyloid glycoprotein. In the first case it was substitution of thymin for adenine in codon 717, in the second case substitution of cytosine for thymine, in the third case a sporadic mutation of guanine for thymine in codon 717 was found. CONCLUSIONS: It was revealed that codon 717 could be a so-called hot spot site preferred for the preferential development of mutations in codon 717 in the gene for the amyloid precursor protein (APP).

Aged↗

PubMed2002

Alterations in vascular reactivity in single- and double-transgenic mice coexpressing human APP-C100 and mutant SOD(1) genes.

OBJECTIVE: To explore the mechanism underlying changes in microvascular reactivity in single- and double-transgenic mice. METHODS: Peripheral vascular reactivity to the vasodilators, acetylcholine and sodium nitroprusside, on perfused microvasculature of the hind footpad was investigated using nontransgenic mice, single-transgenic mice expressing the human APP-C100 (TgC100. WT or TgC100. V717F) and double-transgenic mice coexpressing human APP-C100 and human SOD(1) (G93A) genes. RESULTS: Single TgC100 and double Tg mice C100/SOD(1) (G93A) at 2 - 3 months old showed a statistical decrease of 28% in blood flux compared to nontransgenic control mice. In addition, vasodilative responsiveness was markedly reduced to 34% in 8 - 9 months old TgC100 mice compared to control mice. There was no significant difference in the profile of vasodilative reaction between TgC100. WT and TgC100. V717F mice. TgC100 and double Tg mice also had higher levels of A beta peptide in plasma than nontransgenic mice (P < 0.01). CONCLUSIONS: The present study suggests that the altered reactivity of the microvasculature may be mediated by circulating soluble A beta peptides. The mechanisms underlying the vasoactivity of circulating A beta in TgC100 and double Tg mice may involve both the endothelium and nonendothelium.

Acetylcholine↗

PubMed2004

APP, NGF & the 'Sunday-driver' in a Trolley on the Road.

Alzheimer's disease (AD) is one of the most common and challenging neurodegenerative diseases in humans and is characterized by: progressive impairment in cognitive function, degeneration of cholinergic neurons of the basal forebrain (CBF), neurofibrillary tangles and amyloid beta-peptide (Abeta) depositions. The amyloid precursor protein (APP) is a transmembrane protein of which abnormal processing produces Abeta that is associated with the pathogenesis of AD. Neurotrophic factors have attracted much attention for their potential as a remedy for neurological disorders. In this regard, nerve growth factor (NGF) has generated a great interest as a potential target for the treatment of AD. This interest is based on the observation that CBF neurons, which provide the major source of cholinergic innervation to the cerebral cortex and hippocampus, undergo selective and severe degeneration in advanced AD and that the survival of CBF neurons depends upon NGF and its receptors, namely, trkA and p75NTR. This review focuses on recent findings about APP, NGF and their potential signaling-connections to the protein encoded by the 'Sunday-driver' (SYD) gene.

Alzheimer Disease↗

PubMed2005

beta-Secretase, APP and Abeta in Alzheimer's disease.

Amyloid plaques, hallmark neuropathological lesions in Alzheimer's disease (AD) brain, are composed of the beta-amyloid peptide (Abeta). A large body of evidence suggests Abeta is central to the pathophysiology of AD and is likely to start this intractable neurodegenerative disorder. Mutations in three genes (amyloid precursor protein/APP, presenilin1, presenilin2) cause early on-set familial AD by increasing synthesis of the toxic 42 amino acid species of Abeta (Abeta42). Fibrillar Abeta in amyloid plaques appears to cause neurodegeneration, although recent studies suggest soluble Abeta oligomers may also be neurotoxic. Regardless, given the strong correlation between Abeta and AD, therapeutic strategies to lower cerebral Abeta levels should prove beneficial for the treatment of AD. Abeta is derived from APP via cleavage by two proteases, beta- and gamma-secretase. beta-secretase, recently identified as the novel aspartic protease BACEI, initiates the formation of Abeta. Consequently, BACE1 in principle is an excellent therapeutic target for strategies to reduce the production of Abeta in AD. However, the discovery of the homologue BACE2 raised the question of whether it too may be a beta-secretase. To settle this issue, our group and others have used gene targeting to generate BACE1 deficient (knockout) mice. These BACEI knockout mice have been instrumental in validating BACEI as the authentic beta-secretase in vivo. Here, I review the roles of BACE1, APP, and Abeta in AD and discuss the implications of therapeutic approaches that target BACE1 for the treatment of AD.

Alzheimer Disease↗

PubMed2006

Does shifting a physician payment system shift physician priorities? A multi-site evaluation of an alternative payment plan (APP) for gynecologic oncologists in Ontario.

OBJECTIVE: The objective of this study was to attempt to understand how changing the mode of reimbursement alters physician behavior from the physician's perspective. METHOD: Individual interviews were conducted with 14 Ontario gynecologic oncologists. Each interview was analyzed using grounded theory. RESULTS: The move to an alternative payment plan (APP) significantly shifted physician clinical and personal priorities. This resulted in improvements in recruitment and retention. A model was developed to explain the link between the shift in the payment system and physician perceptions of their behavior. The model is comprised of two themes: (a) need for change: site similarities and differences, (b) effects of change: shifting priorities and time management. Even when the same compensation package was offered to four sites, the interpretations and motivations differed from site to site. We identified two types of situations: sites that were operating in 'survival mode' and those that were 'meeting core clinical and academic requirements'. They experienced the APP very differently. CONCLUSION: This study presents a model that depicts how and why a funding shift has variable effects on physician behaviors, depending on the individual physician, site, and multi-site perspectives. It offers one of the few qualitative evaluations of a funding change.

Attitude of Health Personnel↗

PubMed1985

Ultrastructural studies in 4-aminopyrazolopyrimidine (4-APP)-induced fatty liver.

Ultrastructural alterations of 4-aminopyrazolopyrimidine (4-APP)-induced fatty liver were studied. Light microscopically, liver sections after 3 to 5 days of 4-APP administration demonstrated more extensive fatty changes and highly osmiophilic lipid droplets were mainly observed in the portal zones of the lobules. The most striking ultrastructural alterations were seen in the Golgi complexes and rough endoplasmic reticulum. Golgi complexes were markedly dilated and osmiophilic vesicles were noted near the Golgi complexes. In the rough endoplasmic reticulum, dilatation of cisternae, loss of the parallel arrangement and dilated vesicles, most of which contained diminished numbers of ribosomes, were also seen. In addition, degranulation of rough endoplasmic reticulum was observed. However, no remarkable changes were noted in the mitochondria. Based on these findings, the functional state of the organellae concerned was discussed.

Adenine↗

PubMed1995

Distribution of an APP homolog, APLP2, in the mouse olfactory system: a potential role for APLP2 in axogenesis.

Deposition of beta-amyloid (A beta) in senile plaques is a major pathological characteristic of Alzheimer's disease. A beta is generated by proteolytic processing of amyloid precursor proteins (APP). APP is a member of a family of related polypeptides that includes amyloid precursor-like proteins APLP1 and APLP2. To examine the distribution of APLP2 in the nervous system, we generated antibodies specific for APLP2 and used these reagents in immunocytochemical and biochemical studies of the rodent nervous system. In this report, we document that in cortex and hippocampus, APLP2 is enriched in postsynaptic compartments. In the olfactory system, however, APLP2 is abundant in olfactory sensory axons, and axon terminals in glomeruli. Confocal microscopy revealed that APLP2 is present in both pre- and postsynaptic compartments in the olfactory bulb. Notably, mRNA encoding chondroitin sulfate glycosaminoglycan (CS GAG)-modified forms of APLP2 are enriched in the olfactory epithelium, relative to alternatively-spliced mRNA, encoding CS GAG-free forms of APLP2. In addition, we demonstrate that CS-modified APLP2 forms accumulate in the olfactory bulb. CS proteoglycans are known to play an important role in regulating cell migration and neuronal outgrowth. Since sensory neurons in the olfactory epithelium are in a state of continual turnover, axons of newly generated cells must establish synaptic connections with neurons in the olfactory bulb in adult life. The presence of APLP2 in olfactory sensory axons and glomeruli is consistent with the view that this protein may play an important role in axonal pathfinding and/or synaptogenesis.

Amyloid beta-Protein Precursor↗

PubMed1994

In vivo phosphorylation in the rat basal nucleus induces PHF-like and APP immunoreactivity.

In vivo phosphorylation was stimulated in the rat basal nucleus by stereotaxic injection of the phosphatase inhibitor okadaic acid (OA). Hyperphosphorylation of neurofilaments and of the microtubule-associated proteins tau and MAP2 was associated with their redistribution from the axonal compartment into the cell bodies of large projection neurones where they appeared as paired helical filament (PHF)-like immunoreactivity. Astrocytes showed a dramatic increase in APP immunoreactivity and changed their appearance to a stellate shape with long processes. The results demonstrate that abnormal tau phosphorylation and changes in the expression and/or metabolism of APP can be induced in vivo by altering protein phosphorylation. The present experimental paradigm might, therefore, provide a useful tool to model early steps of the pathomechanism of Alzheimer's disease.

Alzheimer Disease↗

PubMed1996

APPL, the Drosophila member of the APP-family, exhibits differential trafficking and processing in CNS neurons.

The Drosophila Appl gene encodes a transmembrane protein that is expressed exclusively in neurons. Amino acid comparisons show that APPL protein is a member of the amyloid precursor protein (APP)-like family of proteins. Similar to mammalian APP-family proteins, APPL is synthesized as a transmembrane holoprotein and cleaved to release a large secreted amino-terminal domain. Using immunocytochemical methods, we have analyzed the distribution of APPL in the Drosophila CNS. Surprisingly, although APPL is present in all neuronal cell bodies, the neurophil shows sterotypic differential distribution. Double-labeling experiments with different neuronal markers were used to distinguish between APPL associated with neuronal processes or extracellular matrix. The distribution of APPL protein produced from transgenes encoding wild-type (APPL), secretion-defective (APPLsd), and constitutively secreted (APPLs) forms was analyzed in an Appl-deficient background to determine which APPL form is associated with different neuropil regions. We found that APPLsd protein is enriched where APPL immunoreactivity coincides with neuronal processes. In contrast, APPLs preferentially localizes to those parts of the neuropil that show a diffuse APPL signal that rarely colocalizes with processes, and thus seems to be a component of the extracellular matrix. These data indicate that proteolytic cleavage and trafficking of APPL is differentially regulated in different neuronal populations. Through metamorphosis, APPL is especially abundant in growing axons and in areas where synapses are forming. Interestingly, in adult brains, APPL protein is enriched in the mushroom bodies and to a lesser extent in the central complex, structures involved in learning and memory.

Amyloid beta-Protein Precursor↗

PubMed2026

BMT4me En Español: Multisite Feasibility and Usability Testing of a Spanish-Language mHealth Adherence Support App for Spanish-Speaking Caregivers of Children After Hematopoietic Stem Cell Transplantation and Cancer Treatment.

BACKGROUND: Medication nonadherence during the first 100 days after pediatric hematopoietic stem cell transplantation (HSCT) and during oncology treatment increases risk for complications. BMT4me is a caregiver-facing mobile health (mHealth) application providing medication reminders, symptom tracking, and note-taking features to support medication management. Spanish-speaking caregivers are frequently excluded from digital adherence interventions due to the lack of language-accessible tools. PROCEDURE: We conducted a multisite, mixed-methods usability testing of a Spanish-language version of BMT4me ("BMT4me en Español") with Spanish-speaking caregivers of children (ages 2-17 years) post-HSCT or with an oncology diagnosis on active treatment. Caregivers completed a facilitated, three-step usability session (unobtrusive observation, interactive observation, and debriefing), followed by a semi-structured interview, and then completed the system usability scale (SUS). Quantitative outcomes were summarized descriptively; qualitative data were analyzed using content analysis with constant comparison. RESULTS: Fifteen participants enrolled at each site for a total of 30 participants. Across both sites, the recruitment rate was 91%. All participants completed all parts of the study. The SUS score (M = 80.09; SD = 17.35) was above average (>68). Two key qualitative themes emerged: (1) the perceived positive impact of BMT4me on managing a serious illness and (2) the acceptance and sociocultural relevance of BMT4me for Spanish-speaking families. Caregivers also shared suggestions to add educational content and multiuser functionalities to BMT4me. CONCLUSIONS: The acceptance and perceived positive impact of the Spanish BMT4me app indicates that socioculturally relevant, Spanish mHealth interventions have strong potential to support Spanish-speaking caregivers in pediatric oncology and HSCT settings. CLINICAL TRIALS NCT: NCT06361173.

Adolescent↗

PubMed1983

Striatal neurons containing both somatostatin- and avian pancreatic polypeptide (APP)-like immunoreactivities and NADPH-diaphorase activity: a light and electron microscopic study.

Striatal neurons containing both somatostatin- and avian pancreatic polypeptide (APP)-like immunoreactivities have been shown to be selectively stained by the histochemical method for nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase activity. In the present study, we have utilized this histochemical technique to examine the morphology of these striatal neurons at the light and electron microscopic levels. Our results indicate that the striatal somatostatin/APP/NADPH-diaphorase neurons occur throughout the striatum and have long, aspiny dendrites, oval, invaginated nuclei with prominent nucleoli, and receive few axosomatic contacts. These cells appear to correspond to a population of medium-sized aspiny interneurons reported previously in Golgi and electron microscopic studies of the striatum.

Animals↗

PubMed2001

Early formation of mature amyloid-beta protein deposits in a mutant APP transgenic model depends on levels of Abeta(1-42).

The main objective of the present study was to develop an alternative singly-transgenic (tg) hAPP model where amyloid deposition will occur at an earlier age. For this purpose, we generated lines of tg mice expressing hAPP751 cDNA containing the London (V717I) and Swedish (K670M/N671L) mutations under the regulatory control of the murine (m)Thy-1 gene (mThy1-hAPP751). In the brains of the highest (line 41) and intermediate (lines 16 and 11) expressers, high levels of hAPP expression were found in neurons in layers 4-5 of the neocortex, hippocampal CA1 and olfactory bulb. As early as 3-4 months of age, line 41 mice developed mature plaques in the frontal cortex, whereas at 5-7 months plaque formation extended to the hippocampus, thalamus and olfactory region. Ultrastructural and double-immunolabeling analysis confirmed that most plaques were mature and contained dystrophic neurites immunoreactive with antibodies against APP, synaptophysin, neurofilament and tau. In addition, a decrease in the number of synaptophysin-immunoreactive terminals was most prominent in the frontal cortex of mice from line 41. Mice from line 11 developed diffuse amyloid deposits at 11 months of age, whereas mice from line 16 did not show evidence of amyloid deposition. Analysis of Abeta by ELISA showed that levels of Abeta(1-40) were higher in mice that did not show any amyloid deposits (line 16), whereas Abeta(1-42) was the predominant species in tg animals from the lines showing plaque formation (lines 41 and 11). Taken together this study indicates that early onset plaque formation depends on levels of Abeta(1-42).

Aging↗

PubMed1995

Cloning and functional expression of a metalloendopeptidase from human brain with the ability to cleave a beta-APP substrate peptide.

Using a combination of PCR and hybridization screening, we have isolated a cDNA clone for a metalloendopeptidase (h-MP78) from a human temporal cortex library. This 2.5-kb cDNA encodes a 689-amino acid protein with a predicted molecular mass of approximately 78.5 kDa. The primary structure of h-MP78 exhibits high similarity to those of porcine (94%) and rat (92%) thimet oligopeptidase. Expression of the cDNA in HEK-293 resulted in the production of an active enzyme able to cleave a chromogenic beta-APP derived substrate peptide KTEEISEVKM-P-nitro-anilide. RNA blot analysis of various human tissues revealed one major species of h-MP78 mRNA of approximately 2.55 kb. The highest level of mRNA was found in the brain.

Amino Acid Sequence↗

PubMed2002

Selective nicotinic receptor consequences in APP(SWE) transgenic mice.

The nicotinic (nAChRs) and muscarinic (mAChRs) acetylcholine receptors and acetylcholinesterase (AChE) activity were studied in the brains of APP(SWE) transgenic mice (Tg+) and age-matched nontransgenic controls (Tg-) that were between 4 and 19 months of age. A significant increase in the binding of 125I-labeled alpha-bungarotoxin (alpha7 nAChRs) was observed in most brain regions analyzed in 4-month-old Tg+ mice, preceding learning and memory impairments and amyloid-beta (Abeta) pathology. The enhanced alpha7 receptor binding was still detectable at 17-19 months of age. Increase in [3H]cytisine binding (alpha4beta2 nAChRs) was measured at 17-19 months of age in Tg+ mice, at the same age when the animals showed heavy Abeta pathology. No significant changes in [3H]pirenzepine (M1 mAChRs) or [3H]AFDX 384 (M2 mAChRs) binding sites were found at any age studied. The upregulation of the nAChRs probably reflects compensatory mechanisms in response to Abeta burden in the brains of Tg+ mice.

Acetylcholinesterase↗

PubMed2006

Involvement of multiple survival signal transduction pathways in the neuroprotective, neurorescue and APP processing activity of rasagiline and its propargyl moiety.

Our recent studies aimed to elucidate the molecular and biochemical mechanism of actions of the novel anti-Parkinson's drug, rasagiline, an irreversible and selective monoamine oxidase (MAO)-B inhibitor and its propargyl moiety, propargylamine. In cell death models induced by serum withdrawal in rat PC12 cells and human SH-SY5Y neuroblastoma cells, both rasagiline and propargylamine exerted neuroprotective and neurorescue activities via multiple survival pathways, including: stimulation of protein kinase C (PKC) phosphorylation; up-regulation of protein and gene levels of PKCalpha, PKCepsilon and the anti-apoptotic Bcl-2, Bcl-xL, and Bcl-w; and up-regulation of the neurotrophic factors, BDNF and GDNF mRNAs. Rasagiline and propargylamine inhibited the cleavage and subsequent activation of pro-caspase-3 and poly ADP-ribose polymerase. Additionally, these compounds significantly down-regulated PKCgamma mRNA and decreased the level of the pro-apoptotic proteins, Bax, Bad, Bim and H2A.X. Rasagiline and propargylamine both regulated amyloid precursor protein (APP) processing towards the non-amyloidogenic pathway. These structure-activity studies have provided evidence that propargylamine promoted neuronal survival via neuroprotective/neurorescue pathways similar to that of rasagiline. In addition, recent study demonstrated that chronic low doses of rasagiline administered to mice subsequently to 1 methyl-4 phenyl 1,2,3,6 tetrahydropyridine (MPTP), rescued dopaminergic neurons in the substantia nigra pars compacta via activation of the Ras-PI3K-Akt survival pathway, suggesting that rasagiline may possess a disease modifying activity.

Amyloid beta-Protein Precursor↗

PubMed1996

Altered beta-APP metabolism after head injury and its relationship to the aetiology of Alzheimer's disease.

There is increasing evidence of a link between head injury and the subsequent onset of Alzheimer's disease. Deposits of amyloid beta-protein (A beta) are found not only in cases of dementia pugilistica but in some 30% of patients dying after a single episode of severe head injury. Detailed clinicopathological studies have shown that A beta deposition is most likely, but not exclusively, to occur, the older the patient at the time of injury, and if the injury is the result of a fall. Distribution studies have shown that the A beta is widely deposited in the neocortex and there is no apparent association with any of the multiple primary or secondary pathologies of traumatic brain injury. There is an increased expression of beta-APP particularly in the pre-alpha cells of the entorhinal cortex and in areas of axonal damage. Recent molecular genetic studies have shown that there is a strong association between deposits of A beta and the apolipoprotein E genotype of the individual.

Alzheimer Disease↗

PubMedDate not supplied

Heart failure and Ca++ activation of the cardiac contractile system: hereditary cardiomyopathy in hamsters (BIO 14.6), isoprenaline overload and the effect of APP 201-533.

In the present paper, two experimental models of heart failure, namely hereditary cardiomyopathy in hamsters (BIO 14.6) and cardiac insufficiency due to mild (0.06 microM) isoprenaline overload of rabbit isolated perfused hearts, were compared in terms of resulting alterations at the level of the functionally isolated contractile system of detergent/glycerol treated skinned cardiac fibres. As the main features of Ca activation of tension in these models, the following were found: 1. Within the same species (RB hamsters, BIO 14.6 hamsters or rabbits), the Ca sensitivity, measured as pCa for half maximal Ca activation, was invariably higher in left than in right ventricular skinned fibres. 2. During the development of hereditary cardiomyopathy (BIO 14.6), maximum Ca-activated tension, measured per unit cross-sectional area, was reduced in an age-dependent manner, without any significant reduction in Ca sensitivity. This effect appeared to be more pronounced in left than in right ventricles. 3. In skinned fibres from right or left ventricular papillary muscles from in vitro isoprenaline pretreated rabbit hearts, no significant alteration in the maximum Ca-activated tension (per unit area) was observed in comparison to non-pretreated control hearts, whereas the Ca sensitivity was reduced. Treatment of control or failing heart skinned fibres with cAMP showed no additivity to the Ca desensitization induced by isoprenaline pretreatment. 4. Skinned fibres from isoprenaline pretreated left ventricular rabbit hearts showed a higher susceptibility to the Ca sensitizing effect of APP 201-533 than fibres from unpretreated control hearts. Mild isoprenaline overload and hereditary cardiomyopathy both are forms of heart failure which are presumably not associated with a lack of activator Ca. It is concluded that cardiotonic agents increasing the cardiac myofibrillar sensitivity to Ca ions would be beneficial in both cases, representing a phenomenologically causative treatment in hearts failing due to isoprenaline pretreatment. A main advantage over "classical" cardiotonic agents like cardiac glycosides, beta adrenergic stimulants or phosphodiesterase inhibitors would be the absence of the risk of drug-induced Ca overload.

Animals↗