Aberrant Membranes and Double-Membrane Structures Accumulate in the Axons of<i>Atg5</i>-Null Purkinje Cells before Neuronal Death

Nishiyama, Jun; Miura, Eriko; Mizushima, Noboru; Watanabe, Masahiko; Yuzaki, Michisuke

doi:10.4161/auto.4964

Cited by 150 publications

(154 citation statements)

References 23 publications

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“…The stained slices were viewed using a confocal laser-scanning microscope (Fluoview; Olympus). For quantification of Purkinje cell death in cerebellar slices, the number of Purkinje cells was quantified from four lobules (lobules III, IV, VIII, and IX) using NIH Image software (Scion) as described previously (Nishiyama et al, 2007). For the quantification of axon terminal swelling of Purkinje cells, fluorescent images immunostained by anti-calbindin (a Purkinje cell marker) and anti-synaptophysin (a presynaptic marker) antibodies in the deep cerebellar nucleus (DCN) region were acquired.…”

Section: Methodsmentioning

confidence: 99%

“…GluD2 wt and GluD2 wt -⌬CT7 transgenic mice on a GluD2-null background were generated as described previously (Kakegawa et al, 2008). Genotypes were determined by PCR analysis of genomic DNA from mouse tail (Nishiyama et al, 2007). For genotyping the Lc/ϩ allele, exon 12 of the GluD2 gene was amplified by PCR using a forward primer (5Ј-GTT GTC TGT CTT GGC ACT GA-3Ј) and a reverse primer (5Ј-ATG TGC AGA GGG CTT TCC TT-3Ј) and subjected to digestion by a restriction endonuclease Fnu4HI (Bio-Rad).…”

Section: Methodsmentioning

confidence: 99%

“…Purkinje-cell-specific Atg5-deficient mice (Atg5 flox/flox ; pcp2-Cre) were generated as described previously (Nishiyama et al, 2007) and crossed with Lc/ϩ mice (B6CBACa A w-J /A-Grid2 Lc /J; The Jackson Laboratory). GluD2 wt and GluD2 wt -⌬CT7 transgenic mice on a GluD2-null background were generated as described previously (Kakegawa et al, 2008).…”

Section: Methodsmentioning

confidence: 99%

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Reevaluation of Neurodegeneration inlurcherMice: Constitutive Ion Fluxes Cause Cell Death with, Not by, Autophagy

Nishiyama¹,

Matsuda²,

Kakegawa³

et al. 2010

J. Neurosci.

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The lurcher (Lc) mice have served as a valuable model for neurodegeneration for decades. Although the responsible mutation was identified in genes encoding ␦2 glutamate receptors (GluD2s), which are predominantly expressed in cerebellar Purkinje cells, how the mutant receptor (GluD2 Lc ) triggers cell death has remained elusive. Here, taking advantage of recent knowledge about the domain structure of GluD2, we reinvestigated Lc-mediated cell death, focusing on the "autophagic cell death" hypothesis. Although autophagy and cell death were induced by the expression of GluD2Lc in heterologous cells and cultured neurons, they were blocked by the introduction of mutations in the channel pore domain of GluD2Lc or by removal of extracellular Na ϩ . In addition, although GluD2 Lc is reported to directly activate autophagy, mutant channels that are not associated with n-PIST (neuronal isoform of protein-interacting specifically with TC10)-Beclin1 still caused autophagy and cell death. Furthermore, cells expressing GluD2Lc showed decreased ATP levels and increased AMP-activated protein kinase (AMPK) activities in a manner dependent on extracellular Na ϩ . Thus, constitutive currents were likely necessary and sufficient to induce autophagy via AMPK activation, regardless of the n-PIST-Beclin1 pathway in vitro. Interestingly, the expression of dominant-negative AMPK suppressed GluD2 Lc -induced autophagy but did not prevent cell death in heterologous cells. Similarly, the disruption of Atg5, a gene crucial for autophagy, did not prevent but rather aggravated Purkinje-cell death in Lc mice. Furthermore, calpains were specifically activated in Lc Purkinje cells. Together, these results suggest that Lc-mediated cell death was not caused by autophagy but necrosis with autophagic features both in vivo and in vitro.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Reevaluation of Neurodegeneration inlurcherMice: Constitutive Ion Fluxes Cause Cell Death with, Not by, Autophagy

Nishiyama¹,

Matsuda²,

Kakegawa³

et al. 2010

J. Neurosci.

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“…6 Induced autophagy maintains the amino acid pool inside cells to adapt to starvation while constitutive autophagy has been shown to function as a cell-repair mechanism that is important for long-lived postmitotic cells. [7][8][9][10][11] Defects in autophagy have been associated with neurodegenerative diseases, [12][13][14][15] diabetes, 16,17 lysosomal storage disease 18 and the loss of vision. 19 In addition to macroautophagy, microautophagy and chaperone-mediated autophagy (CMA) have been described.…”

mentioning

confidence: 99%

Autophagy supports survival and phototransduction protein levels in rod photoreceptors

et al. 2015

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Damage and loss of the postmitotic photoreceptors is a leading cause of blindness in many diseases of the eye. Although the mechanisms of photoreceptor death have been extensively studied, few studies have addressed mechanisms that help sustain these non-replicating neurons for the life of an organism. Autophagy is an intracellular pathway where cytoplasmic constituents are delivered to the lysosomal pathway for degradation. It is not only a major pathway activated in response to cellular stress, but is also important for cytoplasmic turnover and to supply the structural and energy needs of cells. We examined the importance of autophagy in photoreceptors by deleting the essential autophagy gene Atg5 specifically in rods. Loss of autophagy led to progressive degeneration of rod photoreceptors beginning at 8 weeks of age such that by 44 weeks few rods remained. Cone photoreceptor numbers were only slightly diminished following rod degeneration but their function was significantly decreased. Rod cell death was apoptotic but was not dependent on daily light exposure or accelerated by intense light. Although the light-regulated translocation of the phototransduction proteins arrestin and transducin were unaffected in rods lacking autophagy, Atg5-deficient rods accumulated transducin-α as they degenerated suggesting autophagy might regulate the level of this protein.This was confirmed when the light-induced decrease in transducin was abolished in Atg5-deficient rods and the inhibition of autophagy in retinal explants cultures prevented its degradation. These results demonstrate that basal autophagy is essential to the long-term health of rod photoreceptors and a critical process for maintaining optimal levels of the phototransduction protein transducin-α. As the lack of autophagy is associated with retinal degeneration and altered phototransduction protein degradation in the absence of harmful gene products, this process may be a viable therapeutic target where rod cell loss is the primary pathologic event. Autophagy is an intracellular pathway where cytoplasmic constituents are delivered to the lysosomes for degradation. Defective autophagy can contribute to the age-dependent accumulation of damaged proteins and organelles leading to altered cellular homeostasis and loss of function. [1][2][3][4][5] The metabolic roles of autophagy can be classified into two types, basal and induced. In nutrient-rich conditions, autophagy is suppressed but still occurs at low levels (basal autophagy); however, when cells are subjected to stress (starvation, injury, hypoxia), autophagy is activated immediately (induced autophagy). 6 Induced autophagy maintains the amino acid pool inside cells to adapt to starvation while constitutive autophagy has been shown to function as a cell-repair mechanism that is important for long-lived postmitotic cells. 7-11 Defects in autophagy have been associated with neurodegenerative diseases, 12-15 diabetes, 16,17 lysosomal storage disease 18 and the loss of vision. 19 In addition to macroautophagy, m...

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“…In brief, haplo‐insufficiency of Beclin1 and Ambra1, both proteins contributing to the assembly of autophagosomes, leads to neuronal apoptosis, accumulation of Aβ, and impaired neurogenesis (Pickford, Masliah, Britschgi, Lucin, & Narasimhan, 2008; Yazdankhah, Farioli‐Vecchioli, Tonchev, Stoykova, & Cecconi, 2014). Depletion of ATG5 , a constitutive component of Atg12‐Atg5‐Atg16 hetero‐trimer that facilitates the elongation of phagopores, also corresponds to neurodegenerative phenotypes including neuronal death and accumulation of inclusion bodies (Hara, Nakamura, Matsui, Yamamoto, & Nakahara, 2006; Nishiyama, Miura, Mizushima, Watanabe, & Yuzaki, 2007). On the other hand, transgenic overexpression of Atg5 displays anti‐aging consequences, ameliorating insulin sensitivity, and motor function in the central nervous system (Pyo, Yoo, Ahn, Nah, & Hong, 2013).…”

Section: Pathological Association Between Autophagic Pathways and Alzmentioning

confidence: 99%

The emerging roles of protein homeostasis‐governing pathways in Alzheimer's disease

et al. 2018

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Pathways governing protein homeostasis are involved in maintaining the structural, quantitative, and functional stability of intracellular proteins and involve the ubiquitin–proteasome system, autophagy, endoplasmic reticulum, and mTOR pathway. Due to the broad physiological implications of protein homeostasis pathways, dysregulation of proteostasis is often involved in the development of multiple pathological conditions, including Alzheimer's disease (AD). Similar to other neurodegenerative diseases that feature pathogenic accumulation of misfolded proteins, Alzheimer's disease is characterized by two pathological hallmarks, amyloid‐β (Aβ) plaques and tau aggregates. Knockout or transgenic overexpression of various proteostatic components in mice results in AD‐like phenotypes. While both Aβ plaques and tau aggregates could in turn enhance the dysfunction of these proteostatic pathways, eventually leading to apoptotic or necrotic neuronal death and pathogenesis of Alzheimer's disease. Therefore, targeting the components of proteostasis pathways may be a promising therapeutic strategy against Alzheimer's disease.

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Aberrant Membranes and Double-Membrane Structures Accumulate in the Axons ofAtg5-Null Purkinje Cells before Neuronal Death

Cited by 150 publications

References 23 publications

Reevaluation of Neurodegeneration inlurcherMice: Constitutive Ion Fluxes Cause Cell Death with, Not by, Autophagy

Reevaluation of Neurodegeneration inlurcherMice: Constitutive Ion Fluxes Cause Cell Death with, Not by, Autophagy

Autophagy supports survival and phototransduction protein levels in rod photoreceptors

The emerging roles of protein homeostasis‐governing pathways in Alzheimer's disease

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