scholarly journals Fe65 is the sole member of its family that mediates transcription regulated by the amyloid precursor protein

2020 ◽  
Vol 133 (17) ◽  
pp. jcs242917
Author(s):  
Sabine Probst ◽  
Maik Krüger ◽  
Larissa Kägi ◽  
Sarina Thöni ◽  
Daniel Schuppli ◽  
...  
Keyword(s):  
Amyloid Precursor Protein ◽  
Transcriptional Activity ◽  
Nuclear Translocation ◽  
Precursor Protein ◽  
Adapter Proteins ◽  
Nuclear Signaling ◽  
Regulated Intramembrane Proteolysis ◽  
Amyloidogenic Processing ◽  
Signaling Function ◽  
The Impact

ABSTRACTThe amyloid precursor protein (APP), a central molecule in Alzheimer's disease (AD), has physiological roles in cell adhesion and signaling, migration, neurite outgrowth and synaptogenesis. Intracellular adapter proteins mediate the function of transmembrane proteins. Fe65 (also known as APBB1) is a major APP-binding protein. Regulated intramembrane proteolysis (RIP) by γ-secretase releases the APP intracellular domain (AICD), together with the interacting proteins, from the membrane. We studied the impact of the Fe65 family (Fe65, and its homologs Fe65L1 and Fe65L2, also known as APBB2 and APBB3, respectively) on the nuclear signaling function of the AICD. All Fe65 family members increased amyloidogenic processing of APP, generating higher levels of β-cleaved APP stubs and AICD. However, Fe65 was the only family member supporting AICD translocation to nuclear spots and its transcriptional activity. Using a recently established transcription assay, we dissected the transcriptional activity of Fe65 and provide strong evidence that Fe65 represents a transcription factor. We show that Fe65 relies on the lysine acetyltransferase Tip60 (also known as KAT5) for nuclear translocation. Furthermore, inhibition of APP cleavage reduces nuclear Tip60 levels, but this does not occur in Fe65-knockout cells. The rate of APP cleavage therefore regulates the nuclear translocation of AICD–Fe65–Tip60 (AFT) complexes, to promote transcription by Fe65.

scholarly journals The orphan drug dichloroacetate reduces amyloid beta-peptide production whilst promoting non-amyloidogenic proteolysis of the amyloid precursor protein

PLoS ONE ◽  
2022 ◽  
Vol 17 (1) ◽  
pp. e0255715
Author(s):  
Edward T. Parkin ◽  
Jessica E. Hammond ◽  
Lauren Owens ◽  
Matthew D. Hodges
Keyword(s):  
Amyloid Precursor Protein ◽  
Orphan Drug ◽  
Amyloid Beta ◽  
Precursor Protein ◽  
Amyloid Beta Peptide ◽  
Amyloid Beta Peptides ◽  
Over Expression ◽  
Beta Peptides ◽  
Amyloidogenic Processing ◽  
Beta Peptide

The amyloid cascade hypothesis proposes that excessive accumulation of amyloid beta-peptides is the initiating event in Alzheimer’s disease. These neurotoxic peptides are generated from the amyloid precursor protein via sequential cleavage by β- and γ-secretases in the ’amyloidogenic’ proteolytic pathway. Alternatively, the amyloid precursor protein can be processed via the ’non-amyloidogenic’ pathway which, through the action of the α-secretase a disintegrin and metalloproteinase (ADAM) 10, both precludes amyloid beta-peptide formation and has the additional benefit of generating a neuroprotective soluble amyloid precursor protein fragment, sAPPα. In the current study, we investigated whether the orphan drug, dichloroacetate, could alter amyloid precursor protein proteolysis. In SH-SY5Y neuroblastoma cells, dichloroacetate enhanced sAPPα generation whilst inhibiting β–secretase processing of endogenous amyloid precursor protein and the subsequent generation of amyloid beta-peptides. Over-expression of the amyloid precursor protein partly ablated the effect of dichloroacetate on amyloidogenic and non-amyloidogenic processing whilst over-expression of the β-secretase only ablated the effect on amyloidogenic processing. Similar enhancement of ADAM-mediated amyloid precursor protein processing by dichloroacetate was observed in unrelated cell lines and the effect was not exclusive to the amyloid precursor protein as an ADAM substrate, as indicated by dichloroacetate-enhanced proteolysis of the Notch ligand, Jagged1. Despite altering proteolysis of the amyloid precursor protein, dichloroacetate did not significantly affect the expression/activity of α-, β- or γ-secretases. In conclusion, dichloroacetate can inhibit amyloidogenic and promote non-amyloidogenic proteolysis of the amyloid precursor protein. Given the small size and blood-brain-barrier permeability of the drug, further research into its mechanism of action with respect to APP proteolysis may lead to the development of therapies for slowing the progression of Alzheimer’s disease.

Phosphatidylinositol‐4‐phosphate 5‐kinase type 1α attenuates Aβ production by promoting non‐amyloidogenic processing of amyloid precursor protein

2020 ◽  
Vol 34 (9) ◽  
pp. 12127-12146
Author(s):  
Po‐Fan Wu ◽  
Noopur Bhore ◽  
Yen‐Lurk Lee ◽  
Ju‐Yun Chou ◽  
Yun‐Wen Chen ◽  
...  
Keyword(s):  
Amyloid Precursor Protein ◽  
Precursor Protein ◽  
Amyloidogenic Processing ◽  
Phosphatidylinositol 4 ◽  
Aβ Production

scholarly journals Pyk2 overexpression in postsynaptic neurons blocks amyloid β1–42-induced synaptotoxicity in microfluidic co-cultures

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Devrim Kilinc ◽  
Anaïs-Camille Vreulx ◽  
Tiago Mendes ◽  
Amandine Flaig ◽  
Diego Marques-Coelho ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amyloid Precursor Protein ◽  
Genetic Risk ◽  
Association Studies ◽  
Amyloid Β ◽  
Precursor Protein ◽  
Genome Wide Association Studies ◽  
Risk Genes ◽  
The Impact

Abstract Recent meta-analyses of genome-wide association studies identified a number of genetic risk factors of Alzheimer’s disease; however, little is known about the mechanisms by which they contribute to the pathological process. As synapse loss is observed at the earliest stage of Alzheimer’s disease, deciphering the impact of Alzheimer’s risk genes on synapse formation and maintenance is of great interest. In this article, we report a microfluidic co-culture device that physically isolates synapses from pre- and postsynaptic neurons and chronically exposes them to toxic amyloid β peptides secreted by model cell lines overexpressing wild-type or mutated (V717I) amyloid precursor protein. Co-culture with cells overexpressing mutated amyloid precursor protein exposed the synapses of primary hippocampal neurons to amyloid β1–42 molecules at nanomolar concentrations and induced a significant decrease in synaptic connectivity, as evidenced by distance-based assignment of postsynaptic puncta to presynaptic puncta. Treating the cells with antibodies that target different forms of amyloid β suggested that low molecular weight oligomers are the likely culprit. As proof of concept, we demonstrate that overexpression of protein tyrosine kinase 2 beta—an Alzheimer’s disease genetic risk factor involved in synaptic plasticity and shown to decrease in Alzheimer’s disease brains at gene expression and protein levels—selectively in postsynaptic neurons is protective against amyloid β1–42-induced synaptotoxicity. In summary, our lab-on-a-chip device provides a physiologically relevant model of Alzheimer’s disease-related synaptotoxicity, optimal for assessing the impact of risk genes in pre- and postsynaptic compartments.

scholarly journals Impairment of amyloid precursor protein alpha-processing in cerebral microvessels of type 1 diabetic mice

2017 ◽  
Vol 39 (6) ◽  
pp. 1085-1098
Author(s):  
Tongrong He ◽  
Ruohan Sun ◽  
Anantha VR Santhanam ◽  
Livius V d'Uscio ◽  
Tong Lu ◽  
...  
Keyword(s):  
Amyloid Precursor Protein ◽  
Precursor Protein ◽  
Local Concentration ◽  
Microvascular Endothelium ◽  
Cerebral Microvessels ◽  
Protein Levels ◽  
Enhanced Production ◽  
Amyloidogenic Processing

The mechanisms underlying dysfunction of cerebral microvasculature induced by type 1 diabetes (T1D) are not fully understood. We hypothesized that in cerebral microvascular endothelium, α-processing of amyloid precursor protein (APP) is impaired by T1D. In cerebral microvessels derived from streptozotocin (STZ)-induced T1D mice protein levels of APP and its α-processing enzyme, a disintegrin and metalloprotease 10 (ADAM10) were significantly decreased, along with down-regulation of adenylate cyclase 3 (AC3) and enhanced production of thromboxane A2 (TXA2). In vitro studies in human brain microvascular endothelial cells (BMECs) revealed that knockdown of AC3 significantly suppressed ADAM10 protein levels, and that activation of TXA2 receptor decreased APP expression. Furthermore, levels of soluble APPα (sAPPα, a product of α-processing of APP) were significantly reduced in hippocampus of T1D mice. In contrast, amyloidogenic processing of APP was not affected by T1D in both cerebral microvessels and hippocampus. Most notably, studies in endothelial specific APP knockout mice established that genetic inactivation of APP in endothelium was sufficient to significantly reduce sAPPα levels in the hippocampus. In aggregate, our findings suggest that T1D impairs non-amyloidogenic processing of APP in cerebral microvessels. This may exert detrimental effect on local concentration of neuroprotective molecule, sAPPα, in the hippocampus.

Fe65 Ser228 is phosphorylated by ATM/ATR and inhibits Fe65–APP-mediated gene transcription

2015 ◽  
Vol 465 (3) ◽  
pp. 413-421 ◽  
Author(s):  
Paul A. Jowsey ◽  
Peter G. Blain
Keyword(s):  
Amyloid Precursor Protein ◽  
Gene Transcription ◽  
Transcriptional Activity ◽  
Phosphorylation Site ◽  
Amyloid Β ◽  
Protein Processing ◽  
Precursor Protein ◽  
Amyloid Precursor Protein Processing ◽  
Protein Fragment ◽  
Active Protein

APP (amyloid precursor protein) processing generates cytotoxic amyloid β-peptides (Aβ) and a transcriptionally active protein fragment (AICD). In the present study, we identify a novel ATM/ATR phosphorylation site in the APP-binding protein Fe65. Phosphorylation of this site decreases the transcriptional activity of the Fe65–APP complex.

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