A defining feature of mitochondria is their maternal mode of inheritance. However, little is understood about the cellular mechanism through which paternal mitochondria, delivered from sperm, are eliminated from early mammalian embryos. Autophagy has been implicated in nematodes, but whether this mechanism is conserved in mammals has been disputed. Here, we show that cultured mouse fibroblasts and pre-implantation embryos use a common pathway for elimination of mitochondria. Both situations utilize mitophagy, in which mitochondria are sequestered by autophagosomes and delivered to lysosomes for degradation. The E3 ubiquitin ligases PARKIN and MUL1 play redundant roles in elimination of paternal mitochondria. The process is associated with depolarization of paternal mitochondria and additionally requires the mitochondrial outer membrane protein FIS1, the autophagy adaptor P62, and PINK1 kinase. Our results indicate that strict maternal transmission of mitochondria relies on mitophagy and uncover a collaboration between MUL1 and PARKIN in this process.DOI:
http://dx.doi.org/10.7554/eLife.17896.001
All authors retract this paper due to misconduct carried out by the first author. The first author acknowledges that the experiments presented in Figure 4b were fabricated. Figure 4b describes the effects of β-amyloid-seeded α-synuclein oligomers delivered into PC12 cells on exocytosis. The authors apologize to the scientific community and colleagues for the potential misleading information caused by this paper.
Background Adult hippocampal neurogenesis (AHN) is a process of continuously generating functional mature neurons from neural stem cells in the dentate gyrus. In Alzheimer’s disease (AD) brains, amyloid pathology has deleterious effects on AHN, but molecular mechanisms for dysregulated AHN are unclear. Mitochondria of neural stem/progenitor cells play crucial roles in determining cell fate. Since mitochondrial dysfunction by amyloid pathology is the typical symptom of AD pathogenesis, we aim to study whether mitochondrial dysfunction of neural stem/progenitor cells by amyloid pathology causes the impairment of AHN, and elucidate the molecular mechanism of the phenomenon. Methods To investigate the effect of mitochondrial dysfunction of neural stem/progenitor cells on neuronal differentiation, we expressed mitochondria-targeted amyloid beta (mitoAβ) in neural stem/progenitor cells in vitro and in vivo. Proteomic analysis of the hippocampal tissue implicated mitochondrial dysfunction by mitoAβ as a cause of AHN deficits. We identified epigenetic regulators of neural progenitor cells that are regulated by mitoAβ expression or drug-induced mitochondrial toxicity and proposed a link between mitochondria and AHN. Results Amyloid pathology characteristically inhibited the neuronal differentiation stage, not the proliferation of neural stem/progenitor cells during AHN in early AD model mice. Mitochondrial dysfunction in neural stem/progenitor cells by expressing mitoAβ inhibited the neuronal differentiation and AHN with cognitive impairment. Mechanistic studies revealed that lysine demethylase 5A (KDM5A) was involved in the neuronal differentiation and could be degraded by mitochondrial dysfunction in neural progenitor cells, thereby inhibiting the differentiation and cognitive functions. Conclusions These results reveal the new role of KDM5A as a mediator of retrograde signaling, reflecting mitochondrial status, and that the decrease of KDM5A in neural progenitor cells by mitochondrial dysfunction impairs the neuronal differentiation and AHN, finally leading to memory deficits. These findings and its relationship to mitochondrial dysfunction suggest that mitochondrial failure in neural progenitor cells by amyloid pathology closely associates with reduced AHN in AD.
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