Research ReportEvidence of oxidative stress-induced BNIP3 expression in amyloid beta neurotoxicity
Introduction
Alzheimer's disease (AD) is the most common neurodegenerative disorder leading to dementia. Pathologically AD is characterized by senile plaques, neurofibrillary tangles, and neuronal loss (Selkoe, 1999, Yankner, 1996). The senile plaques largely consist of amyloid β-protein (Aβ), a 40- to 42-amino-acid peptide derived from the amyloid β-protein precursor protein (APP). The formation of Aβ and its subsequent deposition in senile plaques are considered to be initial events that lead to a cascade of pathological changes resulting in neuronal loss and AD (Hardy and Selkoe, 2002).
Reactive oxygen species (ROS) are chemically unstable and highly reactive compounds that are able to cause cellular and tissue damage anytime their generation exceeds the endogenous ability to destroy them. This condition is known as oxidative stress. Substantial evidence supports that increased oxidative stress is one of the mechanisms by which Aβ induces neuronal cell death (Behl et al., 1994, Drake et al., 2003, Ho et al., 2001). Indeed, oxidative damage to proteins, lipids and DNA has been demonstrated in post-mortem tissue of AD patients (Mecocci et al., 1994, Smith et al., 2002, Smith et al., 1996). Aβ, itself being a source of free radicals (Hensley et al., 1994), induces the production of ROS (Butterfield et al., 1999, Smith et al., 1998). Meanwhile, oxidative stress has been shown to potentiate the generation of Aβ (Frederikse et al., 1996, Tamagno et al., 2005, Tong et al., 2005), and thereby causes further rises in ROS. The toxicity of Aβ is attenuated by antioxidants (Fu et al., 1998, Hirai et al., 1998, Prasad et al., 2000) and exacerbated by ROS generation (Ho et al., 2001).
In addition to oxidative damage to cells, mediators of oxidative stress have been shown to function as second messengers in signal transduction (Fratelli et al., 2005). There is strong evidence that alterations in the levels of reactive oxygen species provide a redox signal for activation of many transcriptional factors including activator protein-1 (AP-1) (Abate et al., 1990), NF-kB (Haddad et al., 2000, Toledano and Leonard, 1991), NF-E2 related factor 2 (Nrf2) (McMahon et al., 2004), p53 (Hainaut and Milner, 1993) and hypoxia-inducible factor 1 (HIF-1) (Wang and Semenza, 1993). In most cases, however, the redox signal-induced gene expression is an adaptive response to mainly reinforce the antioxidant systems.
BNIP3, a Bcl-2 19 kDa interacting protein 3, is a death-inducing mitochondrial protein that is a member of the Bcl-2 family without a functional BH3 domain. Previous studies have shown that BNIP3 expression can be induced by hypoxia (Bruick, 2000, Guo et al., 2001). In the present study, we show that BNIP3 expression is induced in Aβ neurotoxicity through oxidative stress and knockdown of BNIP3 reduced Aβ-induced neuronal death. Our results suggest a potential pathological role of BNIP3 in the etiology of AD.
Section snippets
BNIP3 expression is induced in Aβ neurotoxicity
Previous studies have demonstrated that under physiological conditions BNIP3 is only expressed in skeletal muscle cells (Vande Velde et al., 2000) and in low levels in glial cells (Burton et al., 2006). BNIP3 is not expressed constitutively in neurons. Under hypoxia, BNIP3 is induced to express in a variety of non-neural cells (Bruick, 2000, Schmidt-Kastner et al., 2004, Sowter et al., 2001). It has been shown that Aβ25–35, the biologically active fragment of Aβ, has almost the same toxic
Discussion
It is well known that Aβ treatment increases ROS production in neurons and leads to oxidative stress (Behl et al., 1994, Drake et al., 2003, Ho et al., 2001). However, the mechanisms by which Aβ-induced oxidative stress leads to neuronal apoptosis are not fully understood. The present study demonstrates for the first time that Aβ-induced oxidative stress activates the expression of the pro-death gene BNIP3 in primary cultures of cortical neurons. Aβ-treatment induces ROS accumulation in neurons
Chemicals
Aβ25–35 and Aβ35–25 peptides were purchased from Bachem (Torrance, CA, USA), dissolved in sterile double-distilled water at a concentration of 500 μM as a stock solution and stored at − 20 °C. Vitamin C was dissolved in medium and sterilized by filtration. Vitamin E (α-tocopherol) was dissolved in ethanol. 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and 2,7-dichlorofluoroescin diacetate (H2DCFDA) were purchased from Sigma-Aldrich (St. Louis, MD, USA). Anti-human and rat
Acknowledgments
This work was supported by grants from Manitoba Medical Service Foundation (to JK), the Thorlakson Foundation (to JK and JDG) and P20RR017699 from the National Center for Research (NCRR), a component of the NIH (to JDG). Dr. Surong Zhang received a postdoctoral fellowship from Manitoba Institute for Child Health. Dr. Zhengfeng Zhang received a Manitoba Health Research Council postdoctoral fellowship.
References (46)
- et al.
Hydrogen peroxide mediates amyloid beta protein toxicity
Cell
(1994) - et al.
Adenovirus E1B 19 kDa and Bcl-2 proteins interact with a common set of cellular proteins
Cell
(1994) - et al.
Amyloid beta-peptide-associated free radical oxidative stress, neurotoxicity, and Alzheimer's disease
Methods Enzymol.
(1999) - et al.
Nix and Nip3 form a subfamily of pro-apoptotic mitochondrial proteins
J. Biol. Chem.
(1999) - et al.
Oxidative stress precedes fibrillar deposition of Alzheimer's disease amyloid beta-peptide (1–42) in a transgenic Caenorhabditis elegans model
Neurobiol. Aging
(2003) - et al.
Oxidative stress increases production of beta-amyloid precursor protein and beta-amyloid (Abeta) in mammalian lenses, and Abeta has toxic effects on lens epithelial cells
J. Biol. Chem.
(1996) - et al.
Catecholamines potentiate amyloid beta-peptide neurotoxicity: involvement of oxidative stress, mitochondrial dysfunction, and perturbed calcium homeostasis
Neurobiol. Dis.
(1998) - et al.
Antioxidant/pro-oxidant equilibrium regulates HIF-1alpha and NF-kappa B redox sensitivity. Evidence for inhibition by glutathione oxidation in alveolar epithelial cells
J. Biol. Chem.
(2000) - et al.
Amyloid beta-induced changes in nitric oxide production and mitochondrial activity lead to apoptosis
J. Biol. Chem.
(2004) - et al.
Redox-regulated turnover of Nrf2 is determined by at least two separate protein domains, the redox-sensitive Neh2 degron and the redox-insensitive Neh6 degron
J. Biol. Chem.
(2004)
BNIP3 heterodimerizes with Bcl-2/Bcl-X(L) and induces cell death independent of a Bcl-2 homology 3 (BH3) domain at both mitochondrial and nonmitochondrial sites
J. Biol. Chem.
Nuclear localization of the hypoxia-regulated pro-apoptotic protein BNIP3 after global brain ischemia in the rat hippocampus
Brain Res.
Amyloid-beta, tau alterations and mitochondrial dysfunction in Alzheimer disease: the chickens or the eggs?
Neurochem. Int.
Mechanisms of neuronal degeneration in Alzheimer's disease
Neuron
Redox regulation of fos and jun DNA-binding activity in vitro
Science
Mitochondrial transport of cations: channels, exchangers, and permeability transition
Physiol. Rev.
Serum-free B27/neurobasal medium supports differentiated growth of neurons from the striatum, substantia nigra, septum, cerebral cortex, cerebellum, and dentate gyrus
J. Neurosci. Res.
Expression of the gene encoding the proapoptotic Nip3 protein is induced by hypoxia
Proc. Natl. Acad. Sci. U. S. A.
The pro-cell death Bcl-2 family member, BNIP3, is localized to the nucleus of human glial cells: implications for glioblastoma multiforme tumor cell survival under hypoxia
Int. J. Cancer
The E1B 19K/Bcl-2-binding protein Nip3 is a dimeric mitochondrial protein that activates apoptosis
J. Exp. Med.
The C. elegans orthologue ceBNIP3 interacts with CED-9 and CED-3 but kills through a BH3- and caspase-independent mechanism
Oncogene
The caspase-derived C-terminal fragment of betaAPP induces caspase-independent toxicity and triggers selective increase of Abeta42 in mammalian cells
J. Neurochem.
Gene expression profiling reveals a signaling role of glutathione in redox regulation
Proc. Natl. Acad. Sci. U. S. A.
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2019, Neurobiology of DiseaseCitation Excerpt :Other outer membrane proteins with LIR domains such as FK506 Binding Protein 8 (FKBP8) (Bhujabal et al., 2017) have also been reported to recruit LC3A for Parkin-independent mitophagy. It remains unknown the extent to which Nix and BNIP3 may participate in mitophagy in neurons, although both proteins have been reported to be upregulated in neurons in response to stress (Prabhakaran et al., 2007; Yeh et al., 2011; Zhang et al., 2007). In these contexts, however, these proteins play a pro-death role, and the potential involvement of Nix- or BNIP-mediated mitophagy were not examined.
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2017, Biochimica et Biophysica Acta - Reviews on CancerCitation Excerpt :HIF also induces the phosphorylation of Tau by modulating GSK3β, mTOR and CDK5, which would be further discussed below [186,187]. Another AD event linked to HIF is the oxidative stress-induced accumulation of Aβ [188], which is discussed in the following section. Together, it appears that aging-induced hypoxia may attenuate neuroprotective pathways and lead to increased susceptibility to AD genesis (Fig. 5).
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2016, Neuroscience LettersCitation Excerpt :BNIP3-mediated cell death is characterized by the translocation of this protein into mitochondria to open the mitochondrial permeability transition pore, reduce the MMP and produce reactive oxygen species, leading to cell death [14]. Treatment of cultured rat cortical neurons with Aβ resulted in an increase in BNIP3 expression via stabilization of HIF-1α, and knock-down of BNIP3 blocked Aβ-induced cell death [24]. This evidence suggests that BNIP3 may play a role in neuronal death in Alzheimer’s disease.
P53 and mitochondrial function in neurons
2014, Biochimica et Biophysica Acta - Molecular Basis of DiseaseCitation Excerpt :While BNIP3 and NIX are inducible transcriptional targets of HIF-1α, they are also transcriptionally regulated by p53, but in different directions in response to hypoxic conditions in non-neuronal cells such that BNIP3 is downregulated [81] while NIX is upregulated by p53 [82]. Although these regulatory pathways have not yet been established for neurons, both BNIP3 [83–85] and NIX [86,87] are upregulated in neurons in response to stress, suggesting that BNIP3 expression may be regulated differently in neurons. In studies with neurons, however, mitigating the upregulation of BNIP3 induced by oxidative and ischemic stress is neuroprotective, suggesting that BNIP3/NIX-dependent mitophagy may be excessive and detrimental or that BNIP/NIX work as pro-death proteins.
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2013, Progress in NeurobiologyCitation Excerpt :For instance, BNIP3 can dissociate the Bcl-2/Beclin 1 complex by binding and inhibiting Bcl-2 protein, which enhances the Ca2+ leakage from the ER and induces mitochondria-dependent apoptosis. Zhang et al. (2007) reported that amyloid-β-induced oxidative stress increased the expression of BNIP3 in cultured rat primary cortical neurons. They observed that the knock-down of BNIP3 reduced the neurotoxicity induced by the amyloid-β peptides.
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2012, Ageing Research ReviewsCitation Excerpt :Resveratrol is another non-flavonoid polyphenol with significant antioxidant activity, activating the HIF-1α pathway (Harikumar and Aggarwal, 2008). However, there is also evidence of definite links between hypoxia, HIF-1 activation and APP/Aβ production (Wang et al., 2006b; Zhang et al., 2007a,b). The precise role of HIF-1 alpha pathway in neurodegeneration, albeit positive or negative, is in fact a matter of debate (Ogunshola and Antoniou, 2009).