5 results found
Vaillant-Beuchot L, Mary A, Pardossi-Piquard R, et al., 2021, Accumulation of amyloid precursor protein C-terminal fragments triggers mitochondrial structure, function, and mitophagy defects in Alzheimer's disease models and human brains, Acta Neuropathologica, Vol: 141, Pages: 39-65, ISSN: 0001-6322
Several lines of recent evidence indicate that the amyloid precursor protein-derived C-terminal fragments (APP-CTFs) could correspond to an etiological trigger of Alzheimer's disease (AD) pathology. Altered mitochondrial homeostasis is considered an early event in AD development. However, the specific contribution of APP-CTFs to mitochondrial structure, function, and mitophagy defects remains to be established. Here, we demonstrate in neuroblastoma SH-SY5Y cells expressing either APP Swedish mutations, or the β-secretase-derived APP-CTF fragment (C99) combined with β- and γ-secretase inhibition, that APP-CTFs accumulation independently of Aβ triggers excessive mitochondrial morphology alteration (i.e., size alteration and cristae disorganization) associated with enhanced mitochondrial reactive oxygen species production. APP-CTFs accumulation also elicit basal mitophagy failure illustrated by enhanced conversion of LC3, accumulation of LC3-I and/or LC3-II, non-degradation of SQSTM1/p62, inconsistent Parkin and PINK1 recruitment to mitochondria, enhanced levels of membrane and matrix mitochondrial proteins, and deficient fusion of mitochondria with lysosomes. We confirm the contribution of APP-CTFs accumulation to morphological mitochondria alteration and impaired basal mitophagy in vivo in young 3xTgAD transgenic mice treated with γ-secretase inhibitor as well as in adeno-associated-virus-C99 injected mice. Comparison of aged 2xTgAD and 3xTgAD mice indicates that, besides APP-CTFs, an additional contribution of Aβ to late-stage mitophagy activation occurs. Importantly, we report on mitochondrial accumulation of APP-CTFs in human post-mortem sporadic AD brains correlating with mitophagy failure molecular signature. Since defective mitochondria homeostasis plays a pivotal role in AD pathogenesis, targeting mitochondrial dysfunctions and/or mitophagy by counteracting early APP-CTFs accumulation may represent relevant therapeutic intervent
Bussiere, Oulès, Mary, et al., 2019, Upregulation of the sarco-Endoplasmic Reticulum calcium ATPase 1 truncated isoform plays a pathogenic role in Alzheimer’s disease, Cells, Vol: 8, Pages: 1539-1539, ISSN: 2073-4409
Dysregulation of the Endoplasmic Reticulum (ER) Ca2+ homeostasis and subsequent ER stress activation occur in Alzheimer Disease (AD). We studied the contribution of the human truncated isoform of the sarco-endoplasmic reticulum Ca2+ ATPase 1 (S1T) to AD. We examined S1T expression in human AD-affected brains and its functional consequences in cellular and transgenic mice AD models. S1T expression is increased in sporadic AD brains and correlates with amyloid β (Aβ) and ER stress chaperone protein levels. Increased S1T expression was also observed in human neuroblastoma cells expressing Swedish-mutated β-amyloid precursor protein (βAPP) or treated with Aβ oligomers. Lentiviral overexpression of S1T enhances in return the production of APP C-terminal fragments and Aβ through specific increases of β-secretase expression and activity, and triggers neuroinflammation. We describe a molecular interplay between S1T-dependent ER Ca2+ leak, ER stress and βAPP-derived fragments that could contribute to AD setting and/or progression.
Lacampagne A, Liu X, Reiken S, et al., 2017, Post-translational remodeling of ryanodine receptor induces calcium leak leading to Alzheimer’s disease-like pathologies and cognitive deficits, Acta Neuropathologica, Vol: 134, Pages: 749-767, ISSN: 0001-6322
Bussiere R, Lacampagne A, Reiken S, et al., 2017, Amyloid β production is regulated by β2-adrenergic signaling-mediated post-translational modifications of the ryanodine receptor, Journal of Biological Chemistry, Vol: 292, Pages: 10153-10168, ISSN: 0021-9258
Alteration of ryanodine receptor (RyR)-mediated calcium (Ca2+) signaling has been reported in Alzheimer disease (AD) models. However, the molecular mechanisms underlying altered RyR-mediated intracellular Ca2+ release in AD remain to be fully elucidated. We report here that RyR2 undergoes post-translational modifications (phosphorylation, oxidation, and nitrosylation) in SH-SY5Y neuroblastoma cells expressing the β-amyloid precursor protein (βAPP) harboring the familial double Swedish mutations (APPswe). RyR2 macromolecular complex remodeling, characterized by depletion of the regulatory protein calstabin2, resulted in increased cytosolic Ca2+ levels and mitochondrial oxidative stress. We also report a functional interplay between amyloid β (Aβ), β-adrenergic signaling, and altered Ca2+ signaling via leaky RyR2 channels. Thus, post-translational modifications of RyR occur downstream of Aβ through a β2-adrenergic signaling cascade that activates PKA. RyR2 remodeling in turn enhances βAPP processing. Importantly, pharmacological stabilization of the binding of calstabin2 to RyR2 channels, which prevents Ca2+ leakage, or blocking the β2-adrenergic signaling cascade reduced βAPP processing and the production of Aβ in APPswe-expressing SH-SY5Y cells. We conclude that targeting RyR-mediated Ca2+ leakage may be a therapeutic approach to treat AD.
Del Prete D, Suski JM, Oulès B, et al., 2016, Localization and processing of the amyloid-β protein precursor in mitochondria-associated membranes, Journal of Alzheimer's Disease, Vol: 55, Pages: 1549-1570, ISSN: 1387-2877
Alteration of mitochondria-associated membranes (MAMs) has been proposed to contribute to the pathogenesis of Alzheimer’s disease (AD). We studied herein the subcellular distribution, the processing, and the protein interactome of the amyloid- protein precursor (AβPP) and its proteolytic products in MAMs. We reveal that A PP and its catabolites are present in MAMs in cellular models overexpressing wild type A PP or A PP harboring the double Swedish or Londonfamilial AD mutations, and in brains of transgenic mice model of AD. Furthermore, we evidenced that both - and -secretases are present and harbor A PP processing activities in MAMs. Interestingly, cells overexpressing APPsweshowincreased ER-mitochondria contact sites. We also document increased neutral lipid accumulation linked to A production and reversed by inhibiting -or -secretases. Using a proteomic approach, we show that A PP and its catabolites interact with key proteins of MAMs controlling mitochondria and ER functions. These data highlight the role of A PP processing and proteomic interactome in MAMs deregulation taking place in AD.
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