scholarly journals Enhanced Activity of Alzheimer Disease-associated Variant of Protein Kinase Cα Drives Cognitive Decline

2021 ◽  
Author(s):  
Gema Lorden ◽  
Jacob Wozniak ◽  
Kim Doré ◽  
Lara Dozier ◽  
Chelsea Cates-Gatto ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Protein Kinase ◽  
Mouse Model ◽  
Cognitive Decline ◽  
Hippocampal Neurons ◽  
Amyloid Β ◽  
Spine Density ◽  
Loss Of Function ◽  
Enhanced Activity ◽  
Behavioral Studies

Abstract Exquisitely tuned activity of protein kinase C (PKC) isozymes is essential to maintaining cellular homeostasis. Whereas loss-of-function mutations are generally associated with cancer, gain-of-function variants in one isozyme, PKCα, are associated with Alzheimer’s disease (AD). Here we show that the enhanced activity of one variant, PKCα M489V, is sufficient to rewire the brain phosphoproteome, drive synaptic degeneration, and impair cognition in a mouse model. This variant causes a modest 30% increase in catalytic activity without altering on/off activation dynamics or stability, underscoring that enhanced catalytic activity is sufficient to drive the biochemical, cellular, and ultimately cognitive effects observed. Analysis of hippocampal neurons from the PKCα M489V mice reveals enhanced amyloid-β-induced synaptic depression and reduced spine density compared to wild-type mice. Behavioral studies reveal that this mutation alone is sufficient to impair cognition, and, when coupled to a mouse model of AD, further accelerates cognitive decline. The druggability of protein kinases positions PKCα as a new and promising therapeutic target in AD.

scholarly journals 24(S)-Saringosterol Prevents Cognitive Decline in a Mouse Model for Alzheimer’s Disease

Marine Drugs ◽  
2021 ◽  
Vol 19 (4) ◽  
pp. 190
Author(s):  
Nikita Martens ◽  
Melissa Schepers ◽  
Na Zhan ◽  
Frank Leijten ◽  
Gardi Voortman ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Model ◽  
Cognitive Decline ◽  
Inflammatory Marker ◽  
Amyloid Β ◽  
Liver Fat ◽  
Gas Chromatography Mass Spectrometry ◽  
Memory Decline ◽  
Plaque Load

We recently found that dietary supplementation with the seaweed Sargassum fusiforme, containing the preferential LXRβ-agonist 24(S)-saringosterol, prevented memory decline and reduced amyloid-β (Aβ) deposition in an Alzheimer’s disease (AD) mouse model without inducing hepatic steatosis. Here, we examined the effects of 24(S)-saringosterol as a food additive on cognition and neuropathology in AD mice. Six-month-old male APPswePS1ΔE9 mice and wildtype C57BL/6J littermates received 24(S)-saringosterol (0.5 mg/25 g body weight/day) (APPswePS1ΔE9 n = 20; C57BL/6J n = 19) or vehicle (APPswePS1ΔE9 n = 17; C57BL/6J n = 19) for 10 weeks. Cognition was assessed using object recognition and object location tasks. Sterols were analyzed by gas chromatography/mass spectrometry, Aβ and inflammatory markers by immunohistochemistry, and gene expression by quantitative real-time PCR. Hepatic lipids were quantified after Oil-Red-O staining. Administration of 24(S)-saringosterol prevented cognitive decline in APPswePS1ΔE9 mice without affecting the Aβ plaque load. Moreover, 24(S)-saringosterol prevented the increase in the inflammatory marker Iba1 in the cortex of APPswePS1ΔE9 mice (p < 0.001). Furthermore, 24(S)-saringosterol did not affect the expression of lipid metabolism-related LXR-response genes in the hippocampus nor the hepatic neutral lipid content. Thus, administration of 24(S)-saringosterol prevented cognitive decline in APPswePS1ΔE9 mice independent of effects on Aβ load and without adverse effects on liver fat content. The anti-inflammatory effects of 24(S)-saringosterol may contribute to the prevention of cognitive decline.

scholarly journals TheGαoActivator Mastoparan-7 Promotes Dendritic Spine Formation in Hippocampal Neurons

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Valerie T. Ramírez ◽  
Eva Ramos-Fernández ◽  
Nibaldo C. Inestrosa
Keyword(s):  
Protein Kinase ◽  
Dendritic Spine ◽  
Hippocampal Neurons ◽  
Biological Effects ◽  
Critical Role ◽  
Head Width ◽  
Dependent Manner ◽  
Spine Density ◽  
Dendritic Spine Density

Mastoparan-7 (Mas-7), an analogue of the peptide mastoparan, which is derived from wasp venom, is a direct activator ofPertussis toxin-(PTX-) sensitive G proteins. Mas-7 produces several biological effects in different cell types; however, little is known about how Mas-7 influences mature hippocampal neurons. We examined the specific role of Mas-7 in the development of dendritic spines, the sites of excitatory synaptic contact that are crucial for synaptic plasticity. We report here that exposure of hippocampal neurons to a low dose of Mas-7 increases dendritic spine density and spine head width in a time-dependent manner. Additionally, Mas-7 enhances postsynaptic density protein-95 (PSD-95) clustering in neurites and activatesGαosignaling, increasing the intracellular Ca2+concentration. To define the role of signaling intermediates, we measured the levels of phosphorylated protein kinase C (PKC), c-Jun N-terminal kinase (JNK), and calcium-calmodulin dependent protein kinase IIα(CaMKIIα) after Mas-7 treatment and determined that CaMKII activation is necessary for the Mas-7-dependent increase in dendritic spine density. Our results demonstrate a critical role forGαosubunit signaling in the regulation of synapse formation.

scholarly journals Acute MPTP Treatment Impairs Dendritic Spine Density in the Mouse Hippocampus

2021 ◽  
Vol 11 (7) ◽  
pp. 833
Author(s):  
Poornima D. E. Weerasinghe-Mudiyanselage ◽  
Mary Jasmin Ang ◽  
Mai Wada ◽  
Sung-Ho Kim ◽  
Taekyun Shin ◽  
...  
Keyword(s):  
Mouse Model ◽  
Hippocampal Neurons ◽  
Late Phase ◽  
Spine Density ◽  
Branch Points ◽  
Synaptic Structure ◽  
Mouse Hippocampus ◽  
Cornu Ammonis ◽  
Mptp Treatment ◽  
Dendritic Complexity

Among the animal models of Parkinson’s disease (PD), the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned mouse model has shown both dopaminergic (DA) damage and related motor control defects, as observed in patients with PD. Recent studies have suggested that the DA system interacts with the synaptic plasticity of the hippocampus in PD. However, little is known about how alterations in the hippocampal structural plasticity are affected by the DA damage in MPTP-lesioned models. In the present study, we investigated alterations in dendritic complexity and spine density in the mouse hippocampus following acute MPTP treatment (22 mg/kg, intraperitoneally, four times/day, 2-h intervals). We confirmed that acute MPTP treatment significantly decreased initial motor function and persistently reduced the number of tyrosine hydroxylase-positive DA neurons in the substantia nigra. Golgi staining showed that acute MPTP treatment significantly reduced the spine density of neuronal dendrites in the cornu ammonis 1 (CA1) apical/basal and dentate gyrus (DG) subregions of the mouse hippocampus at 8 and 16 days after treatment, although it did not affect dendritic complexity (e.g., number of crossing dendrites, total dendritic length, and branch points per neuron) in both CA1 and DG subregions at all time points after treatment. Therefore, the present study provides anatomical evidence that acute MPTP treatment affects synaptic structure in the hippocampus during the late phase after acute MPTP treatment in mice, independent of any changes in the dendritic arborization of hippocampal neurons. These findings offer data for the ability of the acute MPTP-lesioned mouse model to replicate the non-nigrostriatal lesions of clinical PD.

l-Serine dietary supplementation is associated with clinical improvement of loss-of-function GRIN2B-related pediatric encephalopathy

2019 ◽  
Vol 12 (586) ◽  
pp. eaaw0936 ◽  
Author(s):  
David Soto ◽  
Mireia Olivella ◽  
Cristina Grau ◽  
Judith Armstrong ◽  
Clara Alcon ◽  
...  
Keyword(s):  
Hippocampal Neurons ◽  
De Novo ◽  
Dietary Supplementation ◽  
293T Cell ◽  
Therapeutic Interventions ◽  
Spine Density ◽  
Loss Of Function ◽  
De Novo Mutations ◽  
Electrophysiological Recordings ◽  
Neurological Conditions

Autosomal dominant mutations in GRIN2B are associated with severe encephalopathy, but little is known about the pathophysiological outcomes and any potential therapeutic interventions. Genetic studies have described the association between de novo mutations of genes encoding the subunits of the N-methyl-d-aspartate receptor (NMDAR) and severe neurological conditions. Here, we evaluated a missense mutation in GRIN2B, causing a proline-to-threonine switch (P553T) in the GluN2B subunit of NMDAR, which was found in a 5-year-old patient with Rett-like syndrome with severe encephalopathy. Structural molecular modeling predicted a reduced pore size of the mutant GluN2B-containing NMDARs. Electrophysiological recordings in a HEK-293T cell line expressing the mutated subunit confirmed this prediction and showed an associated reduced glutamate affinity. Moreover, GluN2B(P553T)-expressing primary murine hippocampal neurons showed decreased spine density, concomitant with reduced NMDA-evoked currents and impaired NMDAR-dependent insertion of the AMPA receptor subunit GluA1 at stimulated synapses. Furthermore, the naturally occurring coagonist d-serine restored function to GluN2B(P553T)-containing NMDARs. l-Serine dietary supplementation of the patient was hence initiated, resulting in the increased abundance of d-serine in the plasma and brain. The patient has shown notable improvements in motor and cognitive performance and communication after 11 and 17 months of l-serine dietary supplementation. Our data suggest that l-serine supplementation might ameliorate GRIN2B-related severe encephalopathy and other neurological conditions caused by glutamatergic signaling deficiency.

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