scholarly journals Elevated Levels of miR-144-3p Induce Cholinergic Degeneration by Impairing the Maturation of NGF in Alzheimer’s Disease

2021 ◽  
Vol 9 ◽  
Author(s):  
Lan-Ting Zhou ◽  
Juan Zhang ◽  
Lu Tan ◽  
He-Zhou Huang ◽  
Yang Zhou ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cholinergic Neurons ◽  
Memory Deficits ◽  
Brain Regions ◽  
Potential Therapeutic Target ◽  
Memory Impairments ◽  
Tissue Plasminogen ◽  
Elevated Expression ◽  
Cholinergic Degeneration

Cholinergic degeneration is one of the key pathological hallmarks of Alzheimer’s disease (AD), a condition that is characterized by synaptic disorders and memory impairments. Nerve growth factor (NGF) is secreted in brain regions that receive projections from the basal forebrain cholinergic neurons. The trophic effects of NGF rely on the appropriate maturation of NGF from its precursor, proNGF. The ratio of proNGF/NGF is known to be increased in patients with AD; however, the mechanisms that underlie this observation have yet to be elucidated. Here, we demonstrated that levels of miR-144-3p are increased in the hippocampi and the medial prefrontal cortex of an APP/PS1 mouse model of AD. These mice also exhibited cholinergic degeneration (including the loss of cholinergic fibers, the repression of choline acetyltransferase (ChAT) activity, the reduction of cholinergic neurons, and an increased number of dystrophic neurites) and synaptic/memory deficits. The elevated expression of miR-144-3p specifically targets the mRNA of tissue plasminogen activator (tPA) and reduces the expression of tPA, thus resulting in the abnormal maturation of NGF. The administration of miR-144-3p fully replicated the cholinergic degeneration and synaptic/memory deficits observed in the APP/PS1 mice. The injection of an antagomir of miR-144-3p into the hippocampi partially rescued cholinergic degeneration and synaptic/memory impairments by restoring the levels of tPA protein and by correcting the ratio of proNGF/NGF. Collectively, our research revealed potential mechanisms for the disturbance of NGF maturation and cholinergic degeneration in AD and identified a potential therapeutic target for AD.

scholarly journals KL-VS heterozygosity is associated with lower amyloid-dependent tau accumulation and memory impairment in Alzheimer’s disease

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Julia Neitzel ◽  
Nicolai Franzmeier ◽  
Anna Rubinski ◽  
Martin Dichgans ◽  
Matthias Brendel ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Brain Regions ◽  
Protective Role ◽  
Amyloid Pet ◽  
Tau Pathology ◽  
Cross Sectional ◽  
Memory Impairments ◽  
Amyloid A ◽  
Tau Pet

AbstractKlotho-VS heterozygosity (KL-VShet) is associated with reduced risk of Alzheimer’s disease (AD). However, whether KL-VShet is associated with lower levels of pathologic tau, i.e., the key AD pathology driving neurodegeneration and cognitive decline, is unknown. Here, we assessed the interaction between KL-VShet and levels of beta-amyloid, a key driver of tau pathology, on the levels of PET-assessed neurofibrillary tau in 551 controls and patients across the AD continuum. KL-VShet showed lower cross-sectional and longitudinal increase in tau-PET per unit increase in amyloid-PET when compared to that of non-carriers. This association of KL-VShet on tau-PET was stronger in Klotho mRNA-expressing brain regions mapped onto a gene expression atlas. KL-VShet was related to better memory functions in amyloid-positive participants and this association was mediated by lower tau-PET. Amyloid-PET levels did not differ between KL-VShet carriers versus non-carriers. Together, our findings provide evidence to suggest a protective role of KL-VShet against amyloid-related tau pathology and tau-related memory impairments in elderly humans at risk of AD dementia.

scholarly journals miR-135a-5p mediates memory and synaptic impairments via the Rock2/Adducin1 signaling pathway in a mouse model of Alzheimer’s disease

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kai Zheng ◽  
Fan Hu ◽  
Yang Zhou ◽  
Juan Zhang ◽  
Jie Zheng ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
Signaling Pathway ◽  
Hippocampal Neurons ◽  
Therapeutic Strategy ◽  
Memory Deficits ◽  
Synaptic Activity ◽  
Memory Impairments ◽  
Model Of Alzheimer’S Disease

AbstractAberrant regulation of microRNAs (miRNAs) has been implicated in the pathogenesis of Alzheimer’s disease (AD), but most abnormally expressed miRNAs found in AD are not regulated by synaptic activity. Here we report that dysfunction of miR-135a-5p/Rock2/Add1 results in memory/synaptic disorder in a mouse model of AD. miR-135a-5p levels are significantly reduced in excitatory hippocampal neurons of AD model mice. This decrease is tau dependent and mediated by Foxd3. Inhibition of miR-135a-5p leads to synaptic disorder and memory impairments. Furthermore, excess Rock2 levels caused by loss of miR-135a-5p plays an important role in the synaptic disorder of AD via phosphorylation of Ser726 on adducin 1 (Add1). Blocking the phosphorylation of Ser726 on Add1 with a membrane-permeable peptide effectively rescues the memory impairments in AD mice. Taken together, these findings demonstrate that synaptic-related miR-135a-5p mediates synaptic/memory deficits in AD via the Rock2/Add1 signaling pathway, illuminating a potential therapeutic strategy for AD.

scholarly journals Chemogenetic activation of midline thalamic nuclei fails to ameliorate memory deficits in two mouse models of Alzheimer's disease

2021 ◽  
Author(s):  
Shivali Kohli ◽  
Lilya Andrianova ◽  
Gabriella Margetts-Smith ◽  
Erica Brady ◽  
Michael Thomas Craig
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
Mouse Models ◽  
Viral Vectors ◽  
Spatial Working Memory ◽  
Memory Deficits ◽  
Brain Regions ◽  
Pathological Changes ◽  
Thalamic Nuclei

One of the main features of Alzheimer's disease is the progressive loss of memory, likely due to pathological changes within brain regions such as the hippocampus and entorhinal cortex. These structures are embedded within the Papez circuit, an interconnected set of brain regions that are essential for episodic memory. The anterior thalamic nuclei (ATN) and thalamic nucleus reuniens (NRe) are both extensively and reciprocally connected with these important memory regions, so we sought to test the hypothesis that chemogenetically-enhancing neurotransmission through NRe and ATN would ameliorate memory deficits in two mechanistically-distinct mouse models of Alzheimer's disease. Using the hAPP-J20 mouse model of amyloidopathy and the Tg4510 mouse model of tauopathy, we carried out stereotaxic injections of viral vectors to transduce hM3Dq (Gq)_mCherry into NRe or the anterio-dorsal/anterio-ventral nuclei of ATN, using mCherry as a control. At nine months (hAPP-J20) or six months (Tg4510) of age, mice underwent a behaviour battery of open field (OF), novel object recognition (NOR) and radial arm maze (RAM), with DREADD agonist 21 administered 30min prior to each behaviour test. Tissue was collected post-behaviour to confirm injection site and virus expression. Both Tg4510 and hAPP-J20 mice show marked hyperactivity in the OF, significant deficits in recognition memory, and a significant impairment in spatial reference and spatial working memory. Unexpectedly, chemogenetic activation of ATN or NRe did not significantly improve these memory impairments or reduce the observed hyperactivity. This may be due to compensation elsewhere within the memory circuit, or that the pathological changes are too far advanced for behaviour reversal.

scholarly journals Early Hippocampal Sharp-Wave Ripple Deficits Predict Later Learning and Memory Impairments in an Alzheimer’s Disease Mouse Model

2019 ◽  
Author(s):  
Emily A. Jones ◽  
Anna K. Gillespie ◽  
Seo Yeon Yoon ◽  
Loren M. Frank ◽  
Yadong Huang
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Spatial Memory ◽  
Genetic Risk ◽  
Memory Impairment ◽  
Memory Loss ◽  
Memory Deficits ◽  
Power Reduction ◽  
Memory Impairments ◽  
Sharp Wave

SUMMARYAlzheimer’s disease (AD) is characterized by progressive memory loss, and there is a pressing need to identify early pathophysiological alterations that predict subsequent memory impairment. Hippocampal sharp-wave ripples (SWRs) – electrophysiological signatures of memory reactivation in the hippocampus – are a compelling candidate for doing so. Mouse models of AD show reductions in both SWR abundance and associated slow gamma (SG) power during aging, but these alterations have yet to be directly linked to memory impairments. In aged apolipoprotein E4 knock in (apoE4-KI) mice – a model of the major genetic risk factor for AD – we found that reduced SWR abundance and associated CA3 SG power predicted spatial memory impairments measured 1–2 months later. Importantly, SWR-associated CA3 SG power reduction in young apoE4-KI mice also predicted spatial memory deficits measured 10 months later. These results establish features of SWRs as potential functional biomarkers of memory impairment in AD.

scholarly journals The Cholinergic System, the Adrenergic System and the Neuropathology of Alzheimer’s Disease

2021 ◽  
Vol 22 (3) ◽  
pp. 1273
Author(s):  
Rola A. Bekdash
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cholinergic System ◽  
Wide Spectrum ◽  
Cholinergic Neurons ◽  
Public Health Problem ◽  
Brain Regions ◽  
Nucleus Basalis ◽  
Adrenergic System ◽  
Major Public Health Problem

Neurodegenerative diseases are a major public health problem worldwide with a wide spectrum of symptoms and physiological effects. It has been long reported that the dysregulation of the cholinergic system and the adrenergic system are linked to the etiology of Alzheimer’s disease. Cholinergic neurons are widely distributed in brain regions that play a role in cognitive functions and normal cholinergic signaling related to learning and memory is dependent on acetylcholine. The Locus Coeruleus norepinephrine (LC-NE) is the main noradrenergic nucleus that projects and supplies norepinephrine to different brain regions. Norepinephrine has been shown to be neuroprotective against neurodegeneration and plays a role in behavior and cognition. Cholinergic and adrenergic signaling are dysregulated in Alzheimer’s disease. The degeneration of cholinergic neurons in nucleus basalis of Meynert in the basal forebrain and the degeneration of LC-NE neurons were reported in Alzheimer’s disease. The aim of this review is to describe current literature on the role of the cholinergic system and the adrenergic system (LC-NE) in the pathology of Alzheimer’s disease and potential therapeutic implications.

scholarly journals KL-VS heterozygosity is associated with reduced tau accumulation and lower memory impairment in Alzheimer's disease

2020 ◽  
Author(s):  
Julia Neitzel ◽  
Nicolai Franzmeier ◽  
Anna Rubinski ◽  
Martin Dichgans ◽  
Matthias Brendel ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Brain Regions ◽  
Protective Role ◽  
Amyloid Pet ◽  
Tau Pathology ◽  
Cross Sectional ◽  
Memory Impairments ◽  
Amyloid A ◽  
Tau Pet

Klotho-VS heterozygosity (KL-VShet) is associated with reduced risk of Alzheimer's disease (AD). However, whether KL-VShet is associated with lower levels of pathologic tau, i.e. the key AD pathology driving neurodegeneration and cognitive decline, is unknown. Here, we assessed the interaction between KL-VShet and levels of beta-amyloid, a key driver of tau pathology, on the levels of PET-assessed neurofibrillary tau in 354 controls and patients within the AD continuum. KL-VShet showed lower cross-sectional increase in tau-PET per unit increase in amyloid-PET when compared to that of non-carriers. This effect of KL-VShet on tau-PET showed a tendency to be stronger in Klotho mRNA-expressing brain regions mapped onto a gene expression atlas. KL-VShet was related to better memory functions and this association was mediated by lower tau-PET. Amyloid-PET levels did not differ between KL-VShet carriers versus non-carriers. Together, our findings provide evidence for a protective role of KL-VShet against tau pathology and tau-related memory impairments in elderly humans at risk of AD dementia.

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