APP Gene Research Articles

The landscape of autosomal-dominant Alzheimer’s disease: global distribution and age of onset

Abstract We present a comprehensive global analysis of genetic variants associated with autosomal-dominant Alzheimer's disease (ADAD). A total of 550 variants in the APP, PSEN1, and PSEN2 genes were identified, of which 279 were classified as pathogenic or likely pathogenic based on ACMG-AMP criteria, utilizing data from the Dominantly Inherited Alzheimer Network (DIAN), literature, and public databases. Symptomatic age at onset (AAO) data was estimated for 227 of these variants, allowing detailed characterization of their frequency, pathogenicity, and AAO. Importantly, 226 variants meet eligibility criteria for inclusion in disease-modifying clinical trials. Furthermore, we demonstrate the predictive value of mean variant AAO and parental AAO in predicting symptomatic AAO, validated against converters who became symptomatic during follow-up in the DIAN Observational Study (DIAN-OBS). This dataset provides critical insights into the global landscape of ADAD and reveals the genetic and AAO heterogeneity of ADAD variants while refining variant trial eligibility criteria.

ParSite is a multicolor DNA labeling system that allows for simultaneous imaging of triple genomic loci in living cells.

The organization of the human genome in space and time is critical for transcriptional regulation and cell fate determination. However, robust methods for tracking genome organization or genomic interactions over time in living cells are lacking. Here, we developed a multicolor DNA labeling system, ParSite, to simultaneously track triple genomic loci in the U2OS cells. The tricolor ParSite system is derived from the T. thermophilus ParB/ParSc (TtParB/ParSc) system by rational design. We mutated the interface between TtParB and ParSc and generated a new pair of TtParBm and ParSm for genomic DNA labeling. The insertions of 16 base-pair palindromic ParSc and ParSm into genomic loci allow dual-color DNA imaging in living cells. A pair of genomic loci labeled by ParSite could be colocalized with p53-binding protein 1 (53BP1) in response to CRISPR/Cas9-mediated double-strand breaks (DSBs). The ParSite permits tracking promoter and terminator dynamics of the APP gene, which spans 290 kilobases in length. Intriguingly, the hybrid ParS (ParSh) of half-ParSc and half-ParSm enables for the visualization of a third locus independent of ParSc or ParSm. We simultaneously labeled 3 loci with a genomic distance of 36, 89, and 352 kilobases downstream the C3 repeat locus, respectively. In sum, the ParSite is a robust DNA labeling system for tracking multiple genomic loci in space and time in living cells.

Changes in RNA Splicing: A New Paradigm of Transcriptional Responses to Probiotic Action in the Mammalian Brain.

Elucidating the gene regulatory mechanisms underlying the gut-brain axis is critical for uncovering novel gut-brain interaction pathways and developing therapeutic strategies for gut bacteria-associated neurological disorders. Most studies have primarily investigated how gut bacteria modulate host epigenetics and gene expression; their impact on host alternative splicing, particularly in the brain, remains largely unexplored. Here, we investigated the effects of the gut-associated probiotic Lacidofil® on alternative splicing across 10 regions of the rat brain using published RNA-sequencing data. The Lacidofil® altogether altered 2941 differential splicing events, predominantly, skipped exon (SE) and mutually exclusive exon (MXE) events. Protein-protein interactions and a KEGG analysis of differentially spliced genes (DSGs) revealed consistent enrichment in the spliceosome and vesicle transport complexes, as well as in pathways related to neurodegenerative diseases, synaptic function and plasticity, and substance addiction across brain regions. Using the PsyGeNET platform, we found that DSGs from the locus coeruleus (LConly), medial preoptic area (mPOA), and ventral dentate gyrus (venDG) were enriched in depression-associated or schizophrenia-associated genes. Notably, we highlight the App gene, where Lacidofil® precisely regulated the splicing of two exons causally involved in amyloid β protein-based neurodegenerative diseases. Although the splicing factors exhibited both splicing plasticity and expression plasticity in response to Lacidofil®, the overlap between DSGs and differentially expressed genes (DEGs) in most brain regions was rather low. Our study provides novel mechanistic insight into how gut probiotics might influence brain function through the modulation of RNA splicing.

Dietary supplements for prevention of Alzheimer's disease: In vivo and in silico molecular docking studies.

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases in people over 65. The present research aimed to investigate the potential of different dietary supplements (DS) in preventing AD in an experimental animal model and in silico study. Three DS containing a mixture of wheat-germ oil and black pepper extract/or turmeric extract were prepared. Total phenolic content, HPLC-phenolic profile, phytosterols content, fatty-acids profile, and anti-oxidant activity were evaluated in all DS. The protective effect of the prepared DS was assessed through their impact on cholinergic neurotransmission and the gene expression of GSK3β, APP, and Akt. Oxidative stress and inflammatory markers were evaluated. The inhibition activities against acetylcholinesterase (AChE) and reduction of amyloid-β aggregation of the major phytochemicals present in the studied DS were evaluated using in silico molecular docking study. Molecular docking revealed that rosmarinic acid and β-Sitosterol exhibited the strongest binding affinities for AChE and Amyloid-β, respectively. The results showed that all DS reduced cholinergic neurotransmission, decreased TNF-α as an inflammatory marker, and improved oxidative stress status. All DS down-regulated the expression of GSK3β and APP while significantly up-regulating the expression of the Akt gene. The present study concluded that all DS enhanced cholinergic neurotransmission, reduced inflammation, and improved oxidative stress status by impacting the expression of GSK3β, Akt, and APP genes. Rosmarinic acid and β-sitosterol showed promising effects for treating AD, according to an in silico molecular docking study. The studied dietary supplements were considered promising candidates for the prevention of AD.

MeRIP-seq data analysis and validation reveal the regulatory role of m6A modified circRNAs in the apoptosis of secondary hair follicle cells in Inner Mongolia cashmere goats.

As a widely epigenetic modification, m6A (N6-methyladenosine, m6A) can regulate the degradation, translation, and other biological functions of circRNAs through dynamic reversible processes. It plays an important role in regulating the life activities of biological organisms, particularly in cell differentiation, apoptosis, embryonic development, stress response, and innate immunity. In this study, bioinformatics analysis, qRT-PCR identification, FISH subcellular localization, and ceRNA network construction were performed on m6A modified circRNAs regulating the apoptosis of secondary hair follicle cells of Inner Mongolia Albas white cashmere goats based on the skin m6A sequencing data of secondary hair follicles in anagen and catagen. The results showed that 8 m6A modified circRNAs regulating the cell apoptosis of secondary hair follicles, namely circRNA_2130, circRNA_0013, circRNA_1203, circRNA_1462, circRNA_1242, circRNA_2308, circRNA_2654 and circRNA_1442 were identified, and they are respectively derived from ANGEL2, APP, GKAP1, HNRNPC, PTBP3, NUCB1, SNRK and ZNF609 genes. Among them, circRNA_0013, circRNA_1442 and circRNA_1462 were located in the cytoplasm of the secondary hair follicle papilla, while circRNA_1203, circRNA_1242, circRNA_2130, circRNA_2308 and circRNA_2654 were located in the nucleus. There are complex and diverse regulatory relationships among 8 circRNAs, with each circRNA targeting one or more miRNAs, revealing that each m6A circRNA can exert regulatory effects through multiple potential miRNA-mRNA axes, to regulate the apoptosis of secondary hair follicle cells of cashmere goats during the growth cycles. This result provides a direction for further elucidating the regulatory mechanism of m6A modified circRNAs in cashmere growth and exploring biomarkers.

Unravelling excitation/inhibition imbalance in early and familial Alzheimer's Disease

AbstractBackgroundAn early disruption in excitation‐inhibition (E‐I) balance is believed to underlie abnormal local and global network dynamics in Alzheimer’s disease (AD). While prior studies proposed that changes in E‐I balance may underlie the established slowing of oscillatory activity and changes in functional connectivity in symptomatic AD, the specific alterations occurring in the presymptomatic stage of AD remain poorly understood. This study aims to identify local and global spectral power and functional connectivity changes in individuals with familial AD before the onset of clinical symptoms.MethodResting‐state magnetoencephalography (MEG) recordings were conducted in a unique cohort of cognitively unimpaired individuals carrying autosomal dominant mutations in the APP and PSEN1 genes (n = 11), leading to early‐onset AD. Each mutation carrier was demographically matched with three cognitively healthy subjects (HCs) without mutations and with available MEG. We compared source‐level whole‐brain average and regional spectral power and volume‐conduction corrected functional connectivity measures across different frequency bands. Hub vulnerability was assessed using the hub disruption index. Significant MEG measures were correlated with age, estimated years before symptom onset (EYBSO), and cognitive performance.ResultCognitively normal mutation carriers exhibited signatures of oscillatory slowing, characterized by a widespread higher relative power in the theta band (4‐8 Hz) and a lower parieto‐temporal‐occipital peak frequency compared to HCs. Additionally, they presented frequency‐ and degree‐dependent functional connectivity changes: higher phase‐based functional connectivity in the theta band in initial low‐degree regions (as determined by weighted degree in HCs), but lower global amplitude‐based functional connectivity in the alpha (8‐13 Hz) and beta (13‐30 Hz) bands compared to HCs, most strongly in initial high‐degree regions. No correlations between MEG measures and age, EYBSO, or cognitive indices were found after correction for multiple comparisons.ConclusionNeurophysiological changes occur before the onset of cognitive symptoms in individuals carrying mutations in the APP or PSEN1 genes. These changes include oscillatory slowing and frequency‐ and degree‐dependent functional connectivity alterations, mirroring alterations observed in clinical stages of AD and suggesting an early E‐I imbalance. These findings contribute to a comprehensive understanding of presymptomatic pathophysiological alterations in AD.

The genetic landscape of early and late-onset Alzheimer’s disease: A review

Abstract Alzheimer’s disease(AD) is a multifactorial neurodegenerative disorder characterized by the progressive loss of neurons and synaptic dysfunction, primarily affecting the cortex and hippocampus. The etiology of AD is complex, involving the continuous and intricate interaction between genetic and non-genetic environmental factors. Genetic predisposition plays a significant role, with approximately 60-80% of AD risk attributed to hereditary factors. Familial early-onset AD(EOAD), with autosomal-dominant mutations in APP, PSEN1, and PSEN2, represents about 1-5% of cases and typically manifests before age 65. Rare autosomal-recessive mutations, like A673V(APP gene), are also implicated. Late-onset AD(LOAD), more common, is influenced by a combination of genetic and environmental factors, with the APOE ε4 allele being a major risk factor. Protective factors, such as the APOE ε2 allele and rare mutations like Ala673Thr, can reduce AD risk. The interplay between genetic variants, environmental influences, and pathological processes underpins the disease’s progression. This study highlights the importance of understanding the genetic and non-genetic determinants of AD to advance personalized treatment and early detection strategies. Future research and personalized medicine approaches are essential for mitigating AD risks and improving management outcomes.

Sex dependent pleiotropic effects of Apolipoprotein (ApoE) 4 on executive function in mice and humans

AbstractBackgroundApoE4 is the strongest genetic risk factor for late onset Alzheimer’s Disease (AD). However, ApoE4 has also been suggested to exhibit antagonistic pleiotropy, a phenomenon by which some allelic variations of a gene promote fitness during certain periods of life but may be detrimental in others. Previous work suggests that ApoE4 carriers exhibit superior performance on executive function tasks in early and middle age, while later in life (>70 years) ApoE4 carriers experience greater cognitive decline across multiple domains. We examined this ApoE4 antagonistic pleiotropy hypothesis using a cross‐species translational approach, focusing on cognitively unimpaired human adult ApoeE4 carriers and non‐carriers who were within a relatively younger age range (<70 years). We complement this using knock‐in mouse models that express humanized wild‐type App, MAPT, and ApoE3 or ApoE4 genes. To quantify executive function in both human and mouse, we used cross‐species touchscreen based Continuous Performance Task (CPT) to assess selective attention.MethodHuman participants were recruited from the PREVENT‐AD program at the Douglas Research Centre. Human touchscreen CPT testing was conducted using an MS SurfacePro. Mice were tested with the same task as humans using an operant chamber platform.ResultOur initial behavioural results suggest that ApoE4 facilitates attentional processes in both older adults and mouse ApoE4 carriers, as indexed by discrimination performance on the CPT. Further strengthening this translational pattern, we found that the facilitative effect of ApoE4 on CPT was more pronounced in female ApoE4 carriers of both species. In mice, we were able to examine this ApoE‐dependent effect on attention longitudinally. Consistent with antagonistic pleiotropy hypothesis, ApoE4 female mice present a higher CPT performance early in life (6‐9 months of age) when compared to ApoE3 mice, but this difference was reduced by 12 months of age.ConclusionTaken together, these results support the ApoE4 antagonistic pleiotropy hypothesis, whereby ApoE4 carriership confers greater attentional performance early in life in both female humans and mice. These new mouse models, in combination with fully translatable touchscreen tests of cognition, can be used to explore potential mechanisms by which ApoE4 can affect different aspects of brain function across the life span

Late onset Alzheimer’s Disease mouse model with altered synaptic and behavior phenotypes

AbstractBackgroundGenetically modified mouse models have provided a vital understanding of the Alzheimer’s disease (AD) mechanisms, but these models were generally focused on familial AD and do not recapitulate the late‐onset human AD pathophysiology. To circumvent the complications of existing AD mice models, we are investigating a novel non‐mutant humanized amyloid beta (Aβ) expressing mouse line that expresses the humanized mouse App gene within the Aβ peptide sequenceMethodThis study aims to investigate the learning and memory function in this novel human Aβ knock‐in (h‐Aβ KI) mice of different age and sex groups using behavioral tests, neuronal circuitry, and long‐term potentiation experiments.ResultBehavioral studies revealed age and sex specific phenotype: 12 and 18 months old female h‐Aβ KI mice demonstrated reduced locomotor and exploration activities along with pronounced deficits in the preference for social novelty. h‐Aβ KI mice also showed impaired spatial learning and memory in behavior tests as well as reduced synaptic plasticity in hippocampal CA1 and DG regions. Cultured h‐Aβ KI hippocampal neurons had significantly slower rate of synaptic vesicle release but no difference in average recycling pool sizes compared to wild‐type control neurons in fluorescent FM1‐43 assays. Live imaging of neurons loaded with FM2‐10 dye revealed differences in synaptic release dynamics of readily‐releasable pool between female and male h‐Aβ KI mice with sucrose stimulation. Immunohistology revealed no amyloid deposit at these age and needs further investigation at older ages of this animal model.ConclusionOur data demonstrate that expression of wild‐type human Aβ in mice is sufficient to drive synaptic and cognitive changes during aging without plaque deposition.

Case report: A 50 year‐old Down syndrome man exhibiting no Alzheimer’s disease biomarker profile nor cognitive impairment. Experience from the Argentine Initiative for the Study of Down syndrome and Alzheimer’s

AbstractBackgroundDown Syndrome (DS) is the most common genetic form of intellectual disability. In recent years, there has been a significant increase in the life expectancy of individuals with DS, currently reaching the age of 60 or over. However, it has been observed that as of age 40, these individuals experience higher risk of developing dementia, and almost all of them exhibit histopathological characteristics of Alzheimer's disease (AD) in their brains.As part of the first Latin American initiative for the study of Alzheimer’s disease in adults with Down syndrome (IASDA), we recruited a 50‐year‐old participant identified as SD8, who did not exhibit beta‐amyloid brain deposition and showed no signs of cognitive impairment.MethodThe absence of beta‐amyloid brain deposition was determined by positron‐emission tomography (PET) using an amyloid‐binding compound (PiB) and quantification of cerebrospinal fluid biomarkers. To explore the possibility that lack of Aβ deposition could be due to an interstitial deletion of the APP gene, we performed Array‐CGH and MLPA assays. Additionally, an exome analysis was conducted to assess the presence of Alzheimer's protective gene variants. Induced pluripotent stem cells (iPSCs) were generated from SD8 peripheral blood mononuclear cells and subsequently differentiated into neurons. This approach will enable a more in‐depth study to gain further insights into this case.ResultThese investigations revealed that SD8 possessed three copies of the APP gene, thus eliminating the possibility of an interstitial deletion. However, the exome analysis yielded no significant findings.ConclusionIn summary, in this study we present the strategies employed to delve into the possible mechanisms of SD8 being an AD “escapee” and outline our planned steps for further investigation.

Copper Dysmetabolism is Connected to Epithelial-Mesenchymal Transition: A Pilot Study in Colorectal Cancer Patients.

Colorectal cancer (CRC) is among the most diagnosed cancers worldwide, whose risk of mortality is associated with the development of metastases to the liver, lungs, and peritoneum. Of note, CRC is highly dependent on copper to sustain its proliferation and aggressiveness. Copper acts not only as a pivotal cofactor for several cuproproteins but also as an allosteric modulator of kinases essential to fulfill the epithelial-to-mesenchymal-transition (EMT), the main mechanism driving cancer cell spreading. System biology identified the APP and SOD1 genes among the top 10 genes shared between CRC and copper metabolism, as confirmed by the upregulation of the protein/mRNA levels of APP observed in CRC tissues. The significant increase of copper found in the sera of CRC patients was paralleled by a strong reduction of copper in the CRC tissues, in agreement with the decreased level of the high-affinity copper transporter CTR1 mRNA (SLC31A1) and LOXL2. As expected, in CRC tissues the mesenchymal marker fibronectin was significantly increased, whereas vimentin and vinculin protein levels were decreased compared to adjacent healthy mucosa. Interestingly, correlation analysis showed an interconnection between vinculin and both CCS and APP. A positive correlation was also observed between APP mRNA and both CDH1 and SOD1 mRNAs. Overall, we demonstrate a correlation between cell copper imbalance and CRC progression via EMT. The results obtained lay the scientific basis for further investigation to describe the kinetics of copper dysregulation during CRC progression and to identify the main cuproproteins involved in the modulation of EMT.

Relationship of Retroelements with Antiviral Proteins and Epigenetic Factors in Alzheimer's Disease

Genetic factors such as allelic variants of the PSEN1, PSEN2, APP, and APOE genes play an important role in Alzheimer's disease development. Still, they cannot explain all cases of the disease and cannot form the basis for effective treatment methods for the pathology. Alzheimer's disease is the most common neurodegenerative disease, so identifying new mechanisms of pathogenesis may reveal new ways of treating it. Since Alzheimer's disease is associated with aging, the hypothesis is proposed that an important trigger mechanism for it is the pathological activation of retroelements during aging, leading to epigenetic changes. This is due to the role of retroelements in gene expression regulation and the origin of long noncoding RNAs and microRNAs from transposons, changes in the expression of which are observed both during aging and Alzheimer's disease. Normally, activation of retroelements is observed in hippocampal neuronal stem cells, which is necessary for epigenetic programming during neuronal differentiation. Direct changes in the expression of retroelements in Alzheimer's disease have also been described. It has been suggested that aging is a trigger for the development of Alzheimer's disease due to the pathological activation of retroelements. To confirm this hypothesis, an analysis of specific microRNAs associated with Alzheimer's disease and aging in the MDTE DB (microRNAs derived from Transposable elements) database was conducted. As a result, identified expression changes in Alzheimer's disease of 37 individual microRNAs derived from retroelements (25 from LINE, 7 from SINE, 5 from HERV), of which 12 changes expression during physiological aging, which confirms my hypothesis that the activation of retroelements during physiological aging is a driver for Alzheimer's disease. This is evidenced by the defeat of diseases mainly by the elderly and older adults. Since 3 of the 12 miRNAs associated with aging and Alzheimer's disease originated from SINE/MIRs that evolved from tRNAs, the role of tRNAs and the tRFs and tRNA halves derived from them in the development of Alzheimer's disease, which are evolutionarily closely related to retroelements was described. These results are promising for targeted disease therapy in the mechanisms of RNA-directed DNA methylation with possible complex use of retroelement enzyme inhibitors. Additional evidence for the role of retroelements in the development of Alzheimer's disease is that overexpression of tau, which has antiviral properties, with its interaction with beta-amyloid leads to dysregulation of retroelements, and in tauopathies, activation of ERV is determined. At the same time, the effect of retroelements as inducers of proteinopathy and tau aggregation has been described. In addition, HIV and herpes viruses, which affect beta-amyloid and tau protein, are also activators of retroelements. Also, polymorphisms associated with Alzheimer's disease are located mainly in intronic and intergenic regions where retroelements are located, affecting changes in their activity.

Amyloid pathology and cognitive impairment in hAβ-KI and APPSAA-KI mouse models of Alzheimer's disease

The hAβ-KI and APPSAA-KI are two amyloid models that harbor mutations in the endogenous mouse App gene. Both hAβ-KI and APPSAA-KI mice contain a humanized Aβ sequence, and APPSAA-KI mice carry three additional familial AD mutations. We herein report that the Aβ levels and Aβ42/Aβ40 ratio in APPSAA-KI homozygotes are dramatically higher than those in hAβ-KI homozygotes at 14 months of age. In addition, APPSAA-KI mice display a widespread distribution of amyloid plaques in the brain, whereas the plaques are undetectable in hAβ-KI mice. Moreover, there are no sex differences in amyloid pathology in APPSAA-KI mice. Both APPSAA-KI and hAβ-KI mice exhibit cognitive impairments, wherein no significant differences are found between these two models, although APPSAA KI mice show a trend towards worse cognitive function. Notably, female hAβ-KI and APPSAA-KI mice have a more pronounced cognitive impairments compared to their respective males. Our findings suggest that Aβ humanization contributes to cognitive deficits in APPSAA-KI mice, and that amyloid deposition might not be closely associated with cognitive impairments in APPSAA-KI mice.

Alzheimer's Disease: Exploring the Landscape of Cognitive Decline.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, memory loss, and impaired daily functioning. The pathology of AD is marked by the accumulation of amyloid beta plaques and tau protein tangles in the brain, along with neuroinflammation and synaptic dysfunction. Genetic factors, such as mutations in APP, PSEN1, and PSEN2 genes, as well as the APOE ε4 allele, contribute to increased risk of acquiring AD. Currently available treatments provide symptomatic relief but do not halt disease progression. Research efforts are focused on developing disease-modifying therapies that target the underlying pathological mechanisms of AD. Advances in identification and validation of reliable biomarkers for AD hold great promise for enhancing early diagnosis, monitoring disease progression, and assessing treatment response in clinical practice in effort to alleviate the burden of this devastating disease. In this paper, we analyze data from the CAS Content Collection to summarize the research progress in Alzheimer's disease. We examine the publication landscape in effort to provide insights into current knowledge advances and developments. We also review the most discussed and emerging concepts and assess the strategies to combat the disease. We explore the genetic risk factors, pharmacological targets, and comorbid diseases. Finally, we inspect clinical applications of products against AD with their development pipelines and efforts for drug repurposing. The objective of this review is to provide a broad overview of the evolving landscape of current knowledge regarding AD, to outline challenges, and to evaluate growth opportunities to further efforts in combating the disease.

8414 Utilization of Cell Free DNA Integrity Index to Differentiate Benign from Malignant Thyroid Nodules

Abstract Disclosure: S. Tarafdar: None. S. Dutta: None. P. Mukhopadhyay: None. N.P. Bhattacharya: None. S. Ghosh: None. Introduction: Recent advances in molecular genetics have evaluated a potential role for plasma cell-free DNA (cfDNA) integrity index as a non-invasive cancer marker. Data on cfDNA integrity in differentiated thyroid cancer is sparse and needs to be investigated further. Aim of the study: The purpose of this study is to investigate the hypothesis that longer DNA strands in plasma may serve as a marker for thyroid cancer. Methods: Patients presenting with thyroid nodules underwent ultrasonography with Thyroid Image Reporting and Data Systems (TIRADS) scoring and FNAC (Bethesda classification).Patients with Bethesda 3, 4, 5, and 6 had surgery and confirmation by histopathology. Patients with Bethesda 2 presenting with compressive symptoms and cosmetic concerns underwent surgery; the remaining patients were considered benign based on clinical follow-up, USG, and FNAC characteristics. Blood sample collected prior to FNAC was used to extract and quantify cfDNA. To assess the integrity index 180/67, 306/67, and 476/67 for the APP gene, we used a quantitative real-time PCR (qPCR) method based on the quantification of four amplicons of varying lengths (67, 180, 306, and 476 bp, respectively). Because culture cells had extremely intact genomic DNA, the genomic DNA obtained from the MDA-T32 papillary thyroid cancer cell line was utilised as a reference to estimate the relative DNA strand integrity in plasma DNA. To determine the (ΔCt) value for 67,180, 306, and 476 bp, the Ct value of the sample was subtracted from that of the MDA-T32 control. Results: A total of 161 subjects were recruited, of these 92 were benign and 69 had differentiated thyroid cancer(confirmed by histopathology). Using the 180/67 bp integrity index benign thyroid nodule patients had significant lower value (median 0.39, 95% CI: 0.33-0.46) compared to patients with differentiated thyroid cancer (median 0.62, 95% CI: 0.56-0.68). A cfDNA integrity index of 180/67 bp could significantly differentiate between benign and malignant thyroid nodules (P<0.001). However, there was no significant difference between malignant and benign thyroid nodules based on the cell free DNA integrity indexes of 306/67 and 476/67. Conclusions: The cfDNA integrity score of 180/67 exhibits potential as a circulating marker for the detection of thyroid nodules and as a means of monitoring cfDNA fragmentation in patients with thyroid cancer. However, further confirmation through prospective trials is necessary. Presentation: 6/3/2024

8414 Utilization Of Cell Free DNA Integrity Index To Differentiate Benign From Malignant Thyroid Nodules

Abstract Disclosure: S. Tarafdar: None. S. Dutta: None. P. Mukhopadhyay: None. N.P. Bhattacharya: None. S. Ghosh: None. Introduction: Recent advances in molecular genetics have evaluated a potential role for plasma cell-free DNA (cfDNA) integrity index as a non-invasive cancer marker. Data on cfDNA integrity in differentiated thyroid cancer is sparse and needs to be investigated further. Aim of the study: The purpose of this study is to investigate the hypothesis that longer DNA strands in plasma may serve as a marker for thyroid cancer. Methods: Patients presenting with thyroid nodules underwent ultrasonography with Thyroid Image Reporting and Data Systems (TIRADS) scoring and FNAC (Bethesda classification).Patients with Bethesda 3, 4, 5, and 6 had surgery and confirmation by histopathology. Patients with Bethesda 2 presenting with compressive symptoms and cosmetic concerns underwent surgery; the remaining patients were considered benign based on clinical follow-up, USG, and FNAC characteristics. Blood sample collected prior to FNAC was used to extract and quantify cfDNA. To assess the integrity index 180/67, 306/67, and 476/67 for the APP gene, we used a quantitative real-time PCR (qPCR) method based on the quantification of four amplicons of varying lengths (67, 180, 306, and 476 bp, respectively). Because culture cells had extremely intact genomic DNA, the genomic DNA obtained from the MDA-T32 papillary thyroid cancer cell line was utilised as a reference to estimate the relative DNA strand integrity in plasma DNA. To determine the (ΔCt) value for 67,180, 306, and 476 bp, the Ct value of the sample was subtracted from that of the MDA-T32 control. Results: A total of 161 subjects were recruited, of these 92 were benign and 69 had differentiated thyroid cancer(confirmed by histopathology). Using the 180/67 bp integrity index benign thyroid nodule patients had significant lower value (median 0.39, 95% CI: 0.33-0.46) compared to patients with differentiated thyroid cancer (median 0.62, 95% CI: 0.56-0.68). A cfDNA integrity index of 180/67 bp could significantly differentiate between benign and malignant thyroid nodules (P<0.001). However, there was no significant difference between malignant and benign thyroid nodules based on the cell free DNA integrity indexes of 306/67 and 476/67. Conclusions: The cfDNA integrity score of 180/67 exhibits potential as a circulating marker for the detection of thyroid nodules and as a means of monitoring cfDNA fragmentation in patients with thyroid cancer. However, further confirmation through prospective trials is necessary. Presentation: 6/3/2024

Novel insights into presenilin 1 mutation associated with a distinctive dementia phenotype and cotton wool plaques.

The mutations in the presenilin 1 gene (PSEN1) are the main cause of familial Alzheimer's disease. PSEN1 mutations affect amyloid-beta peptide production, which accumulates in the brain as senile plaque and cotton wool plaques (CWPs) and relates to other neurodegenerative disorders. Here we report the second case of the PSEN1 G266S mutation, which showed distinctive neuropathological features, including abundant CWPs. Lewy body pathology, and altered amyloid-beta production. Using the proband's samples, we performed genetic analysis of the PSEN1, APP, MAPT, and APOE genes, histopathological and immunohistochemical analysis of the brain tissue, and biochemical analysis of Aβ production in COS cells transfected with wild-type or mutant PSEN1. The patient presented with memory loss, abnormal behavior, and visual hallucinations. Brain scans showed reduced blood flow, mild atrophy, and white matter lesions. Genetic analysis revealed a heterozygous mutation at codon 266 (G266S) of PSEN1 and polymorphism of MAPT (Q230R). The brain had many CWPs, severe cerebral amyloid angiopathy (CAA), senile plaque, Lewy bodies, and neurites. Electron microscopy displayed myelinated fiber degeneration, mitochondrial damage, and amyloid fibrils in the white matter. The production level of Aβ42 in PSEN1 G266S-transfected cells significantly increased. Our findings suggest that the PSEN1 G266S mutation may cause a heterogeneous clinical and pathological phenotype, influenced by other genetic or environmental factors.

Sex-dependent effects of amyloidosis on functional network hub topology is associated with downregulated neuronal gene signatures in the APPswe/PSEN1dE9 double transgenic mouse.

Extracellular beta-amyloid (Aβ) is thought to cause impairments in brain-wide functional connectivity, although mechanisms linking Aβ to broader functional network processing remain elusive. In the present study, we evaluated the effects of Aβ on fear memory and functional connectome measures in male and female mice. Middle-aged (9-11mo) double transgenic APP-PS1 mice and age and sex-matched controls were tested on a fear conditioning protocol and then imaged at 11.1 Tesla. Brains were harvested and processed for analysis of Aβ plaques and Iba1 immunolabeling in neocortical areas, hippocampus, and basolateral amygdala. Additional RNA sequencing data from separate age, strain, and sex-matched mice were analyzed for differentially expressed genes (DEGs) and weighted gene co-expression networks. In both male and female mice, we observed increased functional connectivity in a dorsal striatal/amygdala network as a result of Aβ. Increased functional connectivity within this network was matched by increases in APP gene expression, Aβ and Iba1 immunolabeling, and an upregulated cluster of DEGs involved in the immune response. Conversely, the network measure representing node hubness, eigenvector centrality, was increased in prefrontal cortical brain regions, but only in female APP-PS1 mice. This female-specific effect of amyloid was associated with down-regulation of a cluster of DEGs involved in cortical and striatal GABA transmission, anxiogenic responses, and motor activity, in female APP-PS1 mice, but not males. Our results contribute to a growing literature linking between Aβ, immune activation, and functional network connectivity. Furthermore, our results reveal outcomes of Aβ on gene expression patterns in female mice that may contribute to amyloidosis-induced dysregulation of non-cognitive circuitry.

Novel genetic variants in the NLRP3 inflammasome-related PANX1 and APP genes predict survival of patients with hepatitis B virus-related hepatocellular carcinoma

BackgroundThe nod-like receptor protein 3 (NLRP3) is one of the most characterized inflammasomes involved in the pathogenesis of several cancers, including hepatocellular carcinoma (HCC). However, the effects of genetic variants in the NLRP3 inflammasome-related genes on survival of hepatitis B virus (HBV)-related HCC patients are unclear.MethodsWe performed multivariable Cox proportional hazards regression analysis to evaluate associations between 299 single-nucleotide polymorphisms (SNPs) in 16 NLRP3 inflammasome-related genes and overall survival (OS) of 866 patients with HBV-related HCC. We further performed expression quantitative trait loci (eQTL) analysis using the data from the GTEx project and 1000 Genomes projects, and performed differential expression analysis using the TCGA dataset to explore possible molecular mechanisms underlying the observed associations.ResultsWe found that two functional SNPs (PANX1 rs3020013 A > G and APP rs9976425 C > T) were significantly associated with HBV-related HCC OS with the adjusted hazard ratio (HR) of 0.83 [95% confidence interval (CI) = 0.73–0.95, P = 0.008], and 1.26 (95% CI = 1.02–1.55, P = 0.033), respectively. Moreover, the eQTL analysis revealed that the rs3020013 G allele was correlated with decreased mRNA expression levels of PANX1 in both normal liver tissues (P = 0.044) and whole blood (P < 0.001) in the GTEx dataset, and PANX1 mRNA expression levels were significantly higher in HCC samples and associated with a poorer survival of HCC patients. However, we did not observe such correlations for APP rs9976425.ConclusionsThese results indicated that SNPs in the NLRP3 inflammasome-related genes may serve as potential biomarkers for HBV-related HCC survival, once replicated by additional larger studies.

Tetramethylpyrazine Nitrone (TBN) Reduces Amyloid β Deposition in Alzheimer's Disease Models by Modulating APP Expression, BACE1 Activity, and Autophagy Pathways.

Alzheimer's disease (AD) is a neurodegenerative disorder associated with age. A wealth of evidence indicates that the amyloid β (Aβ) aggregates result from dyshomeostasis between Aβ production and clearance, which plays a pivotal role in the pathogenesis of AD. Consequently, therapies targeting Aβ reduction represent a promising strategy for AD intervention. Tetramethylpyrazine nitrone (TBN) is a novel tetramethylpyrazine derivative with potential for the treatment of AD. Previously, we demonstrated that TBN markedly enhanced cognitive functions and decreased the levels of Aβ, APP, BACE 1, and hyperphosphorylated tau in 3×Tg-AD mice. However, the mechanism by which TBN inhibits Aβ deposition is still unclear. In this study, we employed APP/PS1 mice treated with TBN (60 mg/kg, ig, bid) for six months, and N2a/APP695swe cells treated with TBN (300 μM) to explore the mechanism of TBN in Aβ reduction. Our results indicate that TBN significantly alleviated cognitive impairment and reduced Aβ deposition in APP/PS1 mice. Further investigation of the underlying mechanisms revealed that TBN decreased the expression of APP and BACE1, activated the AMPK/mTOR/ULK1 autophagy pathway, inhibited the PI3K/AKT/mTOR/ULK1 autophagy pathway, and decreased the phosphorylation levels of JNK and ERK in APP/PS1 mice. Moreover, TBN was found to significantly reduce the mRNA levels of APP and BACE1, as well as those of SP1, CTCF, TGF-β, and NF-κB, transcription factors involved in regulating gene expression. Additionally, TBN was observed to decrease the level of miR-346 and increase the levels of miR-147 and miR-106a in the N2a/APP695swe cells. These findings indicate that TBN may reduce Aβ levels likely by reducing APP expression by regulating APP gene transcriptional factors and miRNAs, reducing BACE1 expression, and promoting autophagy activities.