P2-288: Pyroglutamate and Full-Length Amyloid-B Concentrations in the Superior Frontal Cortex Across Clinical Stages of Alzheimer's Disease

Abstract Background. Members of the low-density lipoprotein (LDL) receptor family are involved in endocytosis and in transducing signals, but also in APP (amyloid precursor protein) processing and β-amyloid secretion. ApoER2/LRP8 is a member of this family with key roles in synaptic plasticity in the adult brain. ApoER2 is cleaved after the binding of its ligand, the reelin protein, generating an intracellular domain (ApoER2-ICD) that modulates reelin gene transcription itself. In this work, we have analysed whether ApoER2-ICD is able to regulate the expression of other members of the LDL receptor family. We focused on LRP3, the most unknown member of the LDL receptor family, whose precise physiological role and potential participation in pathological processes such as Alzheimer’s disease (AD) are still unknown.Methods. The effects of full-length ApoER2 and ApoER2-ICD overexpression on protein levels, in presence of recombinant reelin or Ab42 peptide, were evaluated by a microarray, qRT-PCRs and western blots. The expression of LRP3 was analysed in human frontal cortex extracts from AD and non-demented subjects by qRT-PCRs and western blot; and LRP3 interaction with other proteins was assessed by immunoprecipitation. In CHO cells overexpressing LRP3, protein levels of full-length APP and fragments were evaluated by western blots. Results. We have identified that ApoER2 overexpression increases LRP3 expression. Stimulation of ApoER2 signaling by reelin increased LRP3 levels, and the same occurred following ApoER2-ICD overexpression. In human frontal cortex extracts we demonstrate that LRP3 interacts with apolipoprotein E and APP. In extracts from AD subjects, the levels of LRP3 mRNA and protein were lower than those in control subjects. Interestingly, LRP3 transfection in CHO-PS70 cells induced a decrease of full-length APP levels and APP-CTF, and in the supernatant, levels of soluble APP fragments from the amyloidogenic (sAPPa) or non-amyloidogenic (sAPPβ) pathway, as well as Aβ peptides, were drastically reduced respect to mock-transfected cells.Limitations. There is a scarce knowledge of LRP3 physiological function as a neuronal receptor.Conclusion. We describe that LRP3 expression is regulated via ApoER2/reelin signaling, and its levels are affected in AD; similarly to other LDL receptors, LRP3 is involved in APP expression.

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P1-171: BOTH FULL-LENGTH AND PYROGLUTAMATE AMYLOID-BETA ARE ASSOCIATED WITH PITTSBURGH COMPOUND-B BINDING IN THE PRECUNEUS ACROSS CLINICAL STAGES OF ALZHEIMER'S DISEASE

Alzheimer s & Dementia ◽

10.1016/j.jalz.2019.06.726 ◽

2019 ◽

Vol 15 ◽

pp. P302-P302

Author(s):

Violetta Pivtoraiko ◽

Eric E. Abrahamson ◽

William R. Paljug ◽

Manik L. Debnath ◽

Chester Mathis ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Amyloid Beta ◽

Full Length ◽

Pittsburgh Compound B ◽

Clinical Stages

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Reduced N-Methyl-D-Aspartate (NMDA) Receptor-Ion Channel Complex in Alzheimer’s Disease Frontal Cortex

Basic, Clinical, and Therapeutic Aspects of Alzheimer’s and Parkinson’s Diseases - Advances in Behavioral Biology ◽

10.1007/978-1-4684-5844-2_115 ◽

1990 ◽

pp. 575-578

Author(s):

Shun Shimohama ◽

Haruaki Ninomiya ◽

Masakuni Kameyama

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Nmda Receptor ◽

Ion Channel ◽

Frontal Cortex

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Apolipoprotein E and β-amyloid levels in the hippocampus and frontal cortex of Alzheimer's disease subjects are disease-related and apolipoprotein E genotype dependent

Brain Research ◽

10.1016/s0006-8993(99)01894-6 ◽

1999 ◽

Vol 843 (1-2) ◽

pp. 87-94 ◽

Cited By ~ 85

Author(s):

Uwe Beffert ◽

Jeffrey S Cohn ◽

Caroline Petit-Turcotte ◽

Michel Tremblay ◽

Nicole Aumont ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Apolipoprotein E ◽

Frontal Cortex ◽

Β Amyloid ◽

Apolipoprotein E Genotype

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Regulation of interleukin 6 by a polymorphic CpG within the frontal cortex in Alzheimer’s disease

Neurobiology of Aging ◽

10.1016/j.neurobiolaging.2020.04.008 ◽

2020 ◽

Vol 92 ◽

pp. 75-81

Author(s):

Xenia Sawkulycz ◽

Steven Bradburn ◽

Andrew Robinson ◽

Antony Payton ◽

Neil Pendleton ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Frontal Cortex ◽

Interleukin 6

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SRSF1 and PTBP1 Aretrans-Acting Factors That Suppress the Formation of a CD33 Splicing Isoform Linked to Alzheimer’s Disease Risk

Molecular and Cellular Biology ◽

10.1128/mcb.00568-18 ◽

2019 ◽

Vol 39 (18) ◽

Cited By ~ 3

Author(s):

Petra van Bergeijk ◽

Uthpala Seneviratne ◽

Estel Aparicio-Prat ◽

Robert Stanton ◽

Samuel A. Hasson

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Disease Risk ◽

Late Onset ◽

Splice Junction ◽

Full Length ◽

Receptor Expression ◽

Genetic Associations ◽

Rna Sequences ◽

Exon 2

ABSTRACTA single nucleotide polymorphism (SNP) in exon 2 of the CD33 gene is associated with reduced susceptibility to late-onset Alzheimer’s disease (AD) and causal for elevated mRNA lacking exon 2. In contrast to full-length CD33, transcripts lacking exon 2 result in CD33 protein unable to suppress activation responses in myeloid cells, including microglia. Currently, little is known about the regulation of CD33 exon 2 splicing. Using functional genomics and proteomic approaches, we found that SRSF1 and PTBP1 act as splicing enhancers to increase CD33 exon 2 inclusion in mRNA. Binding of PTBP1 to RNA sequences proximal to the intron 1-exon 2 splice junction is altered by the SNP and represents a potential mechanism behind the SNP-genotype dependent alternative splicing. Our studies also reveal that binding of SRSF1 to the CD33 RNA is not altered by the SNP genotype. Instead, a putative SRSF1 binding sequence at the 3′ end of exon 2 directs CD33 exon 2 inclusion into the mRNA, indicating that PTBP1 and SRSF1 promote full-length isoform expression through different mechanisms. Our findings shed light on molecular interactions that regulate CD33 exon 2 splicing, ultimately impacting receptor expression on the cell surface. These data aid in the understanding of CD33’s regulation of microglial signaling underpinning the AD genetic associations.

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Full-length and C-terminal neurogranin in Alzheimer’s disease cerebrospinal fluid analyzed by novel ultrasensitive immunoassays

Alzheimer s Research & Therapy ◽

10.1186/s13195-020-00748-6 ◽

2020 ◽

Vol 12 (1) ◽

Author(s):

Annika Öhrfelt ◽

Julien Dumurgier ◽

Henrik Zetterberg ◽

Agathe Vrillon ◽

Nicholas J. Ashton ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Single Molecule ◽

Full Length ◽

The Novel ◽

Drug Candidates ◽

Postsynaptic Protein ◽

Coefficients Of Variation ◽

Assay Precision ◽

Novel Drug

Abstract Background Neurogranin (Ng) is a neuron-specific and postsynaptic protein that is abundantly expressed in the brain, particularly in the dendritic spine of the hippocampus and cerebral cortex. The enzymatic cleavage of Ng produces fragments that are released into cerebrospinal (CSF), which have been shown to be elevated in Alzheimer’s disease (AD) patients and predict cognitive decline. Thus, quantification of distinctive cleavage products of Ng could elucidate different features of the disease. Methods In this study, we developed novel ultrasensitive single molecule array (Simoa) assays for measurement of full-length neurogranin (FL-Ng) and C-terminal neurogranin (CT-Ng) fragments in CSF. The Ng Simoa assays were evaluated in CSF samples from AD patients (N = 23), mild cognitive impairment due to AD (MCI-AD) (N = 18), and from neurological controls (N = 26). Results The intra-assay repeatability and inter-assay precision of the novel methods had coefficients of variation below 7% and 14%, respectively. CSF FL-Ng and CSF CT-Ng median concentrations were increased in AD patients (6.02 ng/L, P < 0.00001 and 452 ng/L, P = 0.00001, respectively) and in patients with MCI-AD (5.69 ng/L, P < 0.00001 and 566 ng/L, P < 0.00001) compared to neurological controls (0.644 ng/L and 145 ng/L). The median CSF ratio of CT-Ng/FL-Ng were decreased in AD patients (ratio = 101, P = 0.008) and in patients with MCI-AD (ratio = 115, P = 0.016) compared to neurological controls (ratio = 180). CSF of FL-Ng, CT-Ng, and ratio of CT-Ng/FL-Ng could each significantly differentiate AD patients from controls (FL-Ng, AUC = 0.907; CT-Ng, AUC = 0.913; CT-Ng/FL-Ng, AUC = 0.775) and patients with MCI-AD from controls (FL-Ng, AUC = 0.937; CT-Ng, AUC = 0.963; CT-Ng/FL-Ng, AUC = 0.785). Conclusions Assessments of the FL-Ng and CT-Ng levels in CSF with the novel sensitive immunoassays provide a high separation of AD from controls, even in early phase of the disease. The novel Ng assays are robust and highly sensitive and may be valuable tools to study synaptic alteration in AD, as well as to monitor the effect on synaptic integrity of novel drug candidates in clinical trials.

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