Browsing by Author "Beck, Simon J."
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Item Deregulation of Mitochondrial F1FO-ATP Synthase via OSCP in Alzheimer's Disease(Nature Publishing Group) Beck, Simon J.; Guo, Lan; Phensy, Aarron; Tian, Jing; Wang, Lu; Tandon, Neha; Gauba, Esha; Lu, Lin; Pascual, J. M.; Kroener, Sven; Du, Heng; 0000-0003-1728-8111 (Kroener, S); Beck, Simon J.; Guo, Lan; Phensy, Aarron; Tian, Jing; Wang, Lu; Tandon, Neha; Gauba, Esha; Lu, Lin; Kroener, Sven; Du, HengF1FO-ATP synthase is critical for mitochondrial functions. The deregulation of this enzyme results in dampened mitochondrial oxidative phosphorylation (OXPHOS) and activated mitochondrial permeability transition (mPT), defects which accompany Alzheimerâ (tm) s disease (AD). However, the molecular mechanisms that connect F1FO-ATP synthase dysfunction and AD remain unclear. Here, we observe selective loss of the oligomycin sensitivity conferring protein (OSCP) subunit of the F1FO-ATP synthase and the physical interaction of OSCP with amyloid beta (Aβ) in the brains of AD individuals and in an AD mouse model. Changes in OSCP levels are more pronounced in neuronal mitochondria. OSCP loss and its interplay with Aβ disrupt F1FO-ATP synthase, leading to reduced ATP production, elevated oxidative stress and activated mPT. The restoration of OSCP ameliorates Aβ-mediated mouse and human neuronal mitochondrial impairments and the resultant synaptic injury. Therefore, mitochondrial F1FO-ATP synthase dysfunction associated with AD progression could potentially be prevented by OSCP stabilization.Item Synaptosomal Mitochondrial Dysfunction In 5xFAD Mouse Model of Alzheimer's Disease(2018-06-01) Wang, Lu; Guo, Lan; Lu, Lin; Sun, Huili; Shao, Muming; Beck, Simon J.; Li, Lin; Ramachandran, Janani; Du, Yifeng; Du, Heng; 24824108100 (Du. H); Wang, Lu; Guo, Lan; Lu, Lin; Sun, Huili; Beck, Simon J.; Li, Lin; Ramachandran, Janani; Du, HengBrain mitochondrial dysfunction is hallmark pathology of Alzheimer’s disease (AD). Recently, the role of synaptosomal mitochondrial dysfunction in the development of synaptic injury in AD has received increasing attention. Synaptosomal mitochondria are a subgroup of neuronal mitochondria specifically locating at synapses. They play an essential role in fueling synaptic functions by providing energy on the site; and their defects may lead to synaptic failure, which is an early and pronounced pathology in AD. In our previous studies we have determined early synaptosomal mitochondrial dysfunction in an AD animal model (J20 line) overexpressing human Amyloid beta (Aβ), the key mediator of AD. In view of the limitations of J20 line mice in representing the full aspects of amyloidopathy in AD cases, we employed 5xFAD mice which are thought to be a desirable paradigm of amyloidopathy as seen in AD subjects. In addition, we have also examined the status of synaptosomal mitochondrial dynamics as well as Parkin-mediated mitophagy which have not been previously investigated in this mouse model. In comparison to nontransgenic (nonTg mice), 5xFAD mice demonstrated prominent synaptosomal mitochondrial dysfunction. Moreover, synaptosomal mitochondria from the AD mouse model displayed imbalanced mitochondrial dynamics towards fission along with activated Parkin and LC3BII recruitment correlating to spatial learning and memory impairments in 5xFAD mice in an age-dependent manner. These results suggest that synaptosomal mitochondrial deficits are primary pathology in Aβ-rich environments and further confirm the relevance of synaptosomal mitochondrial deficits to the development of AD.Item Transient Cerebral Ischemia Promotes Brain Mitochondrial Dysfunction and Exacerbates Cognitive Impairments in Young 5xFAD Mice(Public Library of Science, 2015-12-03) Lu, Lin; Guo, Lan; Gauba, Esha; Tian, Jing; Wang, Lu; Tandon, Neha; Shankar, Malini; Beck, Simon J.; Du, Yifeng; Du, Heng; Lu, Lin; Guo, Lan; Gauba, Esha; Tian, Jing; Wang, Lu; Tandon, Neha; Shankar, Malini; Beck, Simon J.; Du, HengAlzheimer's disease (AD) is heterogeneous and multifactorial neurological disorder; and the risk factors of AD still remain elusive. Recent studies have highlighted the role of vascular factors in promoting the progression of AD and have suggested that ischemic events increase the incidence of AD. However, the detailed mechanisms linking ischemic insult to the progression of AD is still largely undetermined. In this study, we have established a transient cerebral ischemia model on young 5xFAD mice and their non-transgenic (nonTg) littermates by the transient occlusion of bilateral common carotid arteries. We have found that transient cerebral ischemia significantly exacerbates brain mitochondrial dysfunction including mitochondrial respiration deficits, oxidative stress as well as suppressed levels of mitochondrial fusion proteins including optic atrophy 1 (OPA1) and mitofusin 2 (MFN2) in young 5xFAD mice resulting in aggravated spatial learning and memory. Intriguingly, transient cerebral ischemia did not induce elevation in the levels of cortical or mitochondrial Amyloid beta (Aß)1-40 or 1-42 levels in 5xFAD mice. In addition, the glucose- and oxygen-deprivation-induced apoptotic neuronal death in Aß-treated neurons was significantly mitigated by mitochondria-targeted antioxidant mitotempo which suppresses mitochondrial superoxide levels. Therefore, the simplest interpretation of our results is that young 5xFAD mice with pre-existing AD-like mitochondrial dysfunction are more susceptible to the effects of transient cerebral ischemia; and ischemic events may exacerbate dementia and worsen the outcome of AD patients by exacerbating mitochondrial dysfunction.;