Dataset Information

Par3 regulates polarized convergence between APP and BACE1 in hippocampal neurons.

ABSTRACT: The convergence between amyloid precursor protein (APP) and its ?-secretase ?-site APP cleaving enzyme 1 (BACE1) is a prerequisite for the generation of ?-amyloid peptide, a key pathogenic agent for Alzheimer's disease. Yet the underlying molecular mechanisms regulating their convergence remain unclear. Here, we show that the polarity protein partitioning-defective 3 (Par3) regulates the polarized convergence between APP and BACE1 in hippocampal neurons. Par3 forms a complex with BACE1 through its first PDZ domain, which is important for regulating BACE1 endosome-to-TGN trafficking. In the absence of Par3, there is an increase in the convergence between internalized APP and BACE1. In hippocampal neurons, loss of Par3 leads to increased APP and BACE1 convergence in axons but not in dendrites. This polarized convergence mainly occurs in retrograde or stalled axonal late endocytic organelles and is likely due to compartment-specific regulation of APP trafficking by Par3. Together, our data show a novel function for Par3 in regulating polarized convergence between APP and BACE1 in hippocampal neurons.

SUBMITTER: Sun M

PROVIDER: S-EPMC6528466 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Par3 regulates polarized convergence between APP and BACE1 in hippocampal neurons.

Sun Miao M Huang Chengyu C Wang Hui H Zhang Huaye H

Neurobiology of aging 20190130

The convergence between amyloid precursor protein (APP) and its β-secretase β-site APP cleaving enzyme 1 (BACE1) is a prerequisite for the generation of β-amyloid peptide, a key pathogenic agent for Alzheimer's disease. Yet the underlying molecular mechanisms regulating their convergence remain unclear. Here, we show that the polarity protein partitioning-defective 3 (Par3) regulates the polarized convergence between APP and BACE1 in hippocampal neurons. Par3 forms a complex with BACE1 through i ...[more]

PMID: 30784815

Similar Datasets

Project description:Alzheimer's disease (AD) is characterized pathologically by amyloid β (Aβ)-containing plaques. Generation of Aβ from amyloid precursor protein (APP) by two enzymes, β- and γ-secretase, has therefore been in the AD research spotlight for decades. Despite this, how the physical interaction of APP with the secretases influences APP processing is not fully understood. Herein, we compared two genetically identical human iPSC-derived neuronal cell types: low Aβ-secreting neuroprogenitor cells (NPCs) and high Aβ-secreting mature neurons, as models of low versus high Aβ production. We investigated levels of substrate, enzymes and products of APP amyloidogenic processing and correlated them with the proximity of APP to β- and γ-secretase in endo-lysosomal organelles. In mature neurons, increased colocalization of full-length APP with the β-secretase BACE1 correlated with increased β-cleavage product sAPPβ. Increased flAPP/BACE1 colocalization was mainly found in early endosomes. In the same way, increased colocalization of APP-derived C-terminal fragment (CTF) with presenilin-1 (PSEN1), the catalytic subunit of γ-secretase, was seen in neurons as compared to NPCs. Furthermore, most of the interaction of APP with BACE1 in low Aβ-secreting NPCs seemed to derive from CTF, the remaining APP part after BACE1 cleavage, indicating a possible novel product-enzyme inhibition. In conclusion, our results suggest that interaction of APP and APP cleavage products with their secretases can regulate Aβ production both positively and negatively. β- and γ-Secretases are difficult targets for AD treatment due to their ubiquitous nature and wide range of substrates. Therefore, targeting APP-secretase interactions could be a novel treatment strategy for AD. Colocalization of APP species with BACE1 in a novel model of low- versus high-Aβ secretion-Two genetically identical human iPSC-derived neuronal cell types: low Aβ-secreting neuroprogenitor cells (NPCs) and high Aβ secreting mature neurons, were compared. Increased full-length APP (flAPP)/BACE1 colocalization in early endosomes was seen in neurons, while APP-CTF/BACE1 colocalization was much higher than flAPP/BACE1 colocalization in NPCs, although the cellular location was not determined.

Project description:Tubulin is a major substrate of the cytoplasmic class II histone deacetylase HDAC6. Inhibition of HDAC6 results in higher levels of acetylated tubulin and enhanced binding of the motor protein kinesin-1 to tubulin, which promotes transport of cargoes along microtubules. Microtubule-dependent intracellular trafficking may therefore be regulated by modulating the activity of HDAC6. We have shown previously that the neuromodulator serotonin increases mitochondrial movement in hippocampal neurons via the Akt-GSK3beta signaling pathway. Here, we demonstrate a role for HDAC6 in this signaling pathway.We found that the presence of tubacin, a specific HDAC6 inhibitor, dramatically enhanced mitochondrial movement in hippocampal neurons, whereas niltubacin, an inactive tubacin analog, had no effect. Compared to control cultures, higher levels of acetylated tubulin were found in neurons treated with tubacin, and more kinesin-1 was associated with mitochondria isolated from these neurons. Inhibition of GSK3beta decreased cytoplasmic deacetylase activity and increased tubulin acetylation, whereas blockade of Akt, which phosphorylates and down-regulates GSK3beta, increased cytoplasmic deacetylase activity and decreased tubulin acetylation. Concordantly, the administration of 5-HT, 8-OH-DPAT (a specific 5-HT1A receptor agonist), or fluoxetine (a 5-HT reuptake inhibitor) increased tubulin acetylation. GSK3beta was found to co-localize with HDAC6 in hippocampal neurons, and inhibition of GSK3beta resulted in decreased binding of antibody to phosphoserine-22, a potential GSK3beta phosphorylation site in HDAC6. GSK3beta may therefore regulate HDAC6 activity by phosphorylation.This study demonstrates that HDAC6 plays an important role in the modulation of mitochondrial transport. The link between HDAC6 and GSK3beta, established here, has important implications for our understanding of neurodegenerative disorders. In particular, abnormal mitochondrial transport, which has been observed in such disorders as Alzheimer's disease and Parkinson's disease, could result from the misregulation of HDAC6 by GSK3beta. HDAC6 may therefore constitute an attractive target in the treatment of these disorders.

Dataset Information

Par3 regulates polarized convergence between APP and BACE1 in hippocampal neurons.

Publications

Par3 regulates polarized convergence between APP and BACE1 in hippocampal neurons.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets