A genetic model of methionine restriction extends Drosophila health- and lifespan

2021 ◽  
Vol 118 (40) ◽  
pp. e2110387118
Author(s):  
Andrey A. Parkhitko ◽  
Lin Wang ◽  
Elizabeth Filine ◽  
Patrick Jouandin ◽  
Dmitry Leshchiner ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amino Acid ◽  
Genetic Model ◽  
Metabolic Reprogramming ◽  
Whole Body ◽  
Methionine Metabolism ◽  
Bacterial Enzyme ◽  
Methionine Restriction ◽  
Extended Lifespan

Loss of metabolic homeostasis is a hallmark of aging and is characterized by dramatic metabolic reprogramming. To analyze how the fate of labeled methionine is altered during aging, we applied 13C5-Methionine labeling to Drosophila and demonstrated significant changes in the activity of different branches of the methionine metabolism as flies age. We further tested whether targeted degradation of methionine metabolism components would “reset” methionine metabolism flux and extend the fly lifespan. Specifically, we created transgenic flies with inducible expression of Methioninase, a bacterial enzyme capable of degrading methionine and revealed methionine requirements for normal maintenance of lifespan. We also demonstrated that microbiota-derived methionine is an alternative and important source in addition to food-derived methionine. In this genetic model of methionine restriction (MetR), we also demonstrate that either whole-body or tissue-specific Methioninase expression can dramatically extend Drosophila health- and lifespan and exerts physiological effects associated with MetR. Interestingly, while previous dietary MetR extended lifespan in flies only in low amino acid conditions, MetR from Methioninase expression extends lifespan independently of amino acid levels in the food. Finally, because impairment of the methionine metabolism has been previously associated with the development of Alzheimer’s disease, we compared methionine metabolism reprogramming between aging flies and a Drosophila model relevant to Alzheimer’s disease, and found that overexpression of human Tau caused methionine metabolism flux reprogramming similar to the changes found in aged flies. Altogether, our study highlights Methioninase as a potential agent for health- and lifespan extension.

scholarly journals Disruption of a RAC1-centred network is associated with Alzheimer’s disease pathology and causes age-dependent neurodegeneration

2020 ◽  
Vol 29 (5) ◽  
pp. 817-833 ◽  
Author(s):  
Masataka Kikuchi ◽  
Michiko Sekiya ◽  
Norikazu Hara ◽  
Akinori Miyashita ◽  
Ryozo Kuwano ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Genetic Model ◽  
Neurofibrillary Tangle ◽  
Neuronal Cell ◽  
Brain Regions ◽  
Protein Domain ◽  
Expression Data ◽  
Integrated Network ◽  
Age Dependent

Abstract The molecular biological mechanisms of Alzheimer’s disease (AD) involve disease-associated crosstalk through many genes and include a loss of normal as well as a gain of abnormal interactions among genes. A protein domain network (PDN) is a collection of physical bindings that occur between protein domains, and the states of the PDNs in patients with AD are likely to be perturbed compared to those in normal healthy individuals. To identify PDN changes that cause neurodegeneration, we analysed the PDNs that occur among genes co-expressed in each of three brain regions at each stage of AD. Our analysis revealed that the PDNs collapsed with the progression of AD stage and identified five hub genes, including Rac1, as key players in PDN collapse. Using publicly available as well as our own gene expression data, we confirmed that the mRNA expression level of the RAC1 gene was downregulated in the entorhinal cortex (EC) of AD brains. To test the causality of these changes in neurodegeneration, we utilized Drosophila as a genetic model and found that modest knockdown of Rac1 in neurons was sufficient to cause age-dependent behavioural deficits and neurodegeneration. Finally, we identified a microRNA, hsa-miR-101-3p, as a potential regulator of RAC1 in AD brains. As the Braak neurofibrillary tangle (NFT) stage progressed, the expression levels of hsa-miR-101-3p were increased specifically in the EC. Furthermore, overexpression of hsa-miR-101-3p in the human neuronal cell line SH-SY5Y caused RAC1 downregulation. These results highlight the utility of our integrated network approach for identifying causal changes leading to neurodegeneration in AD.

scholarly journals Modeling the β secretase cleavage site and humanizing Amyloid-Beta Precursor Protein in rat and mouse to study Alzheimer Disease.

2020 ◽  
Author(s):  
Lutgarde Serneels ◽  
Dries T'Syen ◽  
Laura Perez-Benito ◽  
Tom Theys ◽  
Bart De Strooper
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amino Acid ◽  
Alzheimer Disease ◽  
Early Onset ◽  
Computational Modelling ◽  
Original Strain ◽  
Rodent Models ◽  
App Processing

Abstract Background Three amino acid differences between rodent and human APP affect medically important features including β-secretase cleavage of APP and aggregation of the Aβ peptide(1–3). Most rodent models for Alzheimer’s disease (AD) are therefore based on the human APP sequence expressed from artificial mini-genes randomly inserted in the rodent genome. While these models mimic rather well biochemical aspects of the disease such as Aβ-aggregation, they are also prone to overexpression artifacts and to complex phenotypical alterations due to genes affected in or close to the insertion sites of the mini-genes(4,5). Knock-in strategies introducing clinical mutants in a humanized endogenous rodent APP sequence(6) represent useful improvements, but need to be compared with appropriate humanized wild type (WT) mice.Methods Computational modelling of the human β-CTF bound to BACE1 was used to study the differential processing of rodent and human APP. We humanized the three pivotal residues G676R, F681Y and R684H (labeled according to the human APP770 isoform) in the mouse as well as in the rat by a CRISPR-Cas9 approach. These new models, termed mouse and rat App hu/hu , express APP from the endogenous promotor. We also introduced the early-onset familial Alzheimer’s disease (FAD) mutation M139T into the endogenous Rat Psen 1 gene.Results We show that the three amino acid substitutions in the rodent sequence lower the affinity of APP substrate for BACE1 cleavage. The effect on β-secretase processing was confirmed as both humanized rodent models produce three times more (human) Aβ compared to their WT rodent original strain. These models represent suitable controls or starting points for studying the effect of transgenes or knock-in mutations on APP processing(6). We introduced the early-onset familial Alzheimer disease (FAD) mutation M139T into the endogenous Rat Psen 1 gene and provide an initial characterization of Aβ processing in this novel rat AD model.Conclusion The different humanized APP models (rat and mouse) expressing human Aβ and PSEN1 M139T are valuable controls to study APP processing in vivo and allow to implement the use of human Aβ Elisa which is more sensitive than their rodent counterpart. These animals will be made available to the research community.

scholarly journals Alzheimer’s disease-relevant tau modifications selectively impact neurodegeneration and mitophagy in a novel C. elegans single-copy transgenic model

2020 ◽  
Author(s):  
Sanjib Guha ◽  
Sarah Fischer ◽  
Gail VW Johnson ◽  
Keith Nehrke
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Genetic Model ◽  
Neurodegenerative Disorder ◽  
Model Organism ◽  
Single Copy ◽  
Mitochondrial Stress ◽  
C Elegans ◽  
Touch Receptor Neurons ◽  
New Perspective

ABSTRACTBackgroundA defining pathological hallmark of the progressive neurodegenerative disorder Alzheimer’s disease (AD) is the accumulation of misfolded tau with abnormal post-translational modifications (PTMs). These include phosphorylation at Threonine 231 (T231) and acetylation at Lysine 274 (K274) and at Lysine 281 (K281). Although tau is recognized to play a central role in pathogenesis of AD, the precise mechanisms by which these abnormal PTMs contribute to the neural toxicity of tau is unclear.MethodsHuman 0N4R tau (wild type) was expressed in touch receptor neurons of the genetic model organism C. elegans through single-copy gene insertion. Defined mutations were then introduced into the single-copy tau transgene through CRISPR-Cas9 genome editing. These mutations included T231E and T231A, to mimic phosphorylation and phospho-ablation of a commonly observed pathological epitope, respectively, and K274/281Q, to mimic disease-associated lysine acetylation. Stereotypical touch response assays were used to assess behavioral defects in the transgenic strains as a function of age, and genetically-encoded fluorescent biosensors were used to measure the morphological dynamics and turnover of touch neuron mitochondria.ResultsUnlike existing tau overexpression models, C. elegans single-copy expression of tau did not elicit overt pathological phenotypes at baseline. However, strains expressing disease associated PTM-mimetics (T231E and K274/281Q) exhibited reduced touch sensation and morphological abnormalities that increased with age. In addition, the PTM-mimetic mutants lacked the ability to engage mitophagy in response to mitochondrial stress.ConclusionsLimiting the expression of tau results in a genetic model where pathological modifications and age result in evolving phenotypes, which may more closely resemble the normal progression of AD. The finding that disease-associated PTMs suppress compensatory responses to mitochondrial stress provides a new perspective into the pathogenic mechanisms underlying AD.

scholarly journals Clinical evaluation of [18F] JNJ-64326067, a novel candidate PET tracer for the detection of tau pathology in Alzheimer’s disease

2020 ◽  
Vol 47 (13) ◽  
pp. 3176-3185
Author(s):  
Mark E. Schmidt ◽  
Luc Janssens ◽  
Diederik Moechars ◽  
Frederik J. R. Rombouts ◽  
Maarten Timmers ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Healthy Subjects ◽  
Graphical Analysis ◽  
Whole Body ◽  
Healthy Controls ◽  
Pet Tracer ◽  
Cortical Regions ◽  
Pet Scans ◽  
Pet Amyloid

Abstract Purpose The accumulation of misfolded tau is a common feature of several neurodegenerative disorders, with Alzheimer’s disease (AD) being the most common. Earlier we identified JNJ-64326067, a novel isoquinoline derivative with high affinity and selectivity for tau aggregates from human AD brain. We report the dosimetry of [18F] JNJ-64326067 and results of a proof-of-concept study comparing subjects with probable Alzheimer’s disease to age-matched healthy controls. Methods [18F] JNJ-64326067 PET scans were acquired for 90 min and then from 120 to 180 min in 5 participants with [18F]-florbetapir PET amyloid positive probable AD (73 ± 9 years) and 5 [18F]-florbetapir PET amyloid negative healthy controls (71 ± 7 years). Whole-body [18F] JNJ-64326067 PET CT scans were acquired in six healthy subjects for 5.5 h in 3 scanning sessions. Brain PET scans were visually reviewed. Regional quantification included kinetic analysis of distribution volume ration (DVR) estimated by Logan graphical analysis over the entire scan and static analysis of SUVr in late frames. Both methods used ventral cerebellar cortex as a reference region. Results One of the healthy controls had focal areas of PET signal in occipital and parietal cortex underlying the site of a gunshot injury as an adolescent; the other four healthy subjects had no tau brain signal. Four of the 5 AD participants had visually apparent retention of [18F] JNJ-64326067 in relevant cortical regions. One of the AD subjects was visually negative. Cortical signal in visually positive subjects approached steady state by 120 min. Temporal and frontal cortical SUVr/DVR values in visually positive AD subjects ranged from 1.21 to 3.09/1.2 to 2.18 and from 0.92 to 1.28/0.91 to 1.16 in healthy controls. Whole-body effective dose was estimated to be 0.0257 mSv/MBq for females and 0.0254 mSv/MBq for males. Conclusions [18F] JNJ-64326067 could be useful for detection and quantitation of tau aggregates.

scholarly journals pLG72 levels increase in early phase of Alzheimer’s disease but decrease in late phase

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Chieh-Hsin Lin ◽  
Chih-Chiang Chiu ◽  
Chiung-Hsien Huang ◽  
Hui-Ting Yang ◽  
Hsien-Yuan Lane
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Amino Acid ◽  
Early Phase ◽  
Late Phase ◽  
Acid Oxidase ◽  
Matched Cohort ◽  
Amino Acid Oxidase ◽  
Gender And Age ◽  
Neurodegenerative Dementia

Abstract pLG72, named as D-amino acid oxidase activator (although it is not an activator of D-amino acid oxidase demonstrated by later studies), in mitochondria has been regarded as an important modulator of D-amino acid oxidase that can regulate the N-methyl-D-aspartate receptor (NMDAR). Both oxidative stress in mitochondria and NMDAR neurotransmission play essential roles in the process of neurodegenerative dementia. The aim of the study was to investigate whether pLG72 levels changed with the severity of neurodegenerative dementia. We enrolled 376 individuals as the overall cohort, consisting of five groups: healthy elderly, amnestic mild cognitive impairment [MCI], mild Alzheimer’s disease [AD], moderate AD, and severe AD. pLG72 levels in plasma were measured using Western blotting. The severity of cognitive deficit was principally evaluated by Clinical Dementia Rating Scale. A gender- and age- matched cohort was selected to elucidate the effects of gender and age. pLG72 levels increased in the MCI and mild AD groups when compared to the healthy group. However, pLG72 levels in the moderate and severe AD groups were lower than those in the mild AD group. D-serine level and D- to total serine ratio were significantly different among the five groups. L-serine levels were correlated with the pLG72 levels. The results in the gender- and age- matched cohort were similar to those of the overall cohort. The finding supports the hypothesis of NMDAR hypofunction in early-phase dementia and NMDAR hyperfunction in late-phase dementia. Further studies are warranted to test whether pLG72 could reflect the function of NMDAR.

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