Cellular hormetic response to 27-hydroxycholesterol promotes neuroprotection through AICD induction of MAST4 abundance and kinase activity

MAST4 regulates stem cell maintenance with DLX3 for epithelial development and amelogenesis

The asymmetric division of stem cells permits the maintenance of the cell population and differentiation for harmonious progress. Developing mouse incisors allows inspection of the role of the stem cell niche to provide specific insights into essential developmental phases. Microtubule-associated serine/threonine kinase family member 4 (Mast4) knockout (KO) mice showed abnormal incisor development with low hardness, as the size of the apical bud was decreased and preameloblasts were shifted to the apical side, resulting in amelogenesis imperfecta. In addition, Mast4 KO incisors showed abnormal enamel maturation, and stem cell maintenance was inhibited as amelogenesis was accelerated with Wnt signal downregulation. Distal-Less Homeobox 3 (DLX3), a critical factor in tooth amelogenesis, is considered to be responsible for the development of amelogenesis imperfecta in humans. MAST4 directly binds to DLX3 and induces phosphorylation at three residues within the nuclear localization site (NLS) that promotes the nuclear translocation of DLX3. MAST4-mediated phosphorylation of DLX3 ultimately controls the transcription of DLX3 target genes, which are carbonic anhydrase and ion transporter genes involved in the pH regulation process during ameloblast maturation. Taken together, our data reveal a novel role for MAST4 as a critical regulator of the entire amelogenesis process through its control of Wnt signaling and DLX3 transcriptional activity.

Nuclear MAST4 Suppresses FOXO3 through Interaction with AKT3 and Induces Chemoresistance in Pancreatic Ductal Carcinoma

Pancreatic ductal adenocarcinoma (PDAC) is highly malignant, with a 5-year survival rate of less than 10%. Furthermore, the acquisition of anticancer drug resistance makes PDAC treatment difficult. We established MIA-GEM cells, a PDAC cell line resistant to gemcitabine (GEM), a first-line anticancer drug, using the human PDAC cell line-MIA-PaCa-2. Microtubule-associated serine/threonine kinase-4 (MAST4) expression was increased in MIA-GEM cells compared with the parent cell line. Through inhibitor screening, dysregulated AKT signaling was identified in MIA-GEM cells with overexpression of AKT3. MAST4 knockdown effectively suppressed AKT3 overexpression, and both MAST4 and AKT3 translocation into the nucleus, phosphorylating forkhead box O3a (FOXO3) in MIA-GEM cells. Modulating FOXO3 target gene expression in these cells inhibited apoptosis while promoting stemness and proliferation. Notably, nuclear MAST4 demonstrated higher expression in GEM-resistant PDAC cases compared with that in the GEM-sensitive cases. Elevated MAST4 expression correlated with a poorer prognosis in PDAC. Consequently, nuclear MAST4 emerges as a potential marker for GEM resistance and poor prognosis, representing a novel therapeutic target for PDAC.

Identification of novel candidate genes associated with non-syndromic tooth agenesis in Mongolian families

OBJECTIVES

This study aimed to identify genetic variants associated with non-syndromic tooth agenesis (TA) in nine families from Mongolia using whole-exome sequencing (WES) and bioinformatics analysis.

MATERIAL AND METHODS

The study enrolled 41 participants, including three inherited and six non-inherited families. WES analysis was performed on 14 saliva samples from individuals with non-syndromic TA. The potential candidate genes were identified through variant filtering and segregation analysis. The filtered variants were then analyzed in silico mutation impact analysis.

RESULTS

WES analysis identified 21 variants associated with TA, and 5 of these variants met all filtering criteria. These variants were located in the exome region of MAST4, ITGA6, PITX2, CACNA1S, and CDON genes. The variant in PITX2 was found in eight participants from inherited and non-inherited families, while the MAST4 variant was identified in 6 participants from inherited families.

CONCLUSIONS

The study identified various genetic variant candidates associated with TA in different family groups, with PITX2 being the most commonly identified. Our findings suggest that MAST4 may also be a novel candidate gene for TA due to its association with the Wnt signaling pathway. Additionally, we found that five candidate genes related to focal adhesion and calcium channel complex were significant and essential in tooth development.

CLINICAL RELEVANCE

Identifying new pathogenic genes associated with TA can improve our understanding of the molecular mechanisms underlying the disease, leading to better diagnosis, prevention, and treatment. Early detection of TA based on biomarkers can improve dental management and facilitate orthodontic and prosthetic treatment.

MAST4 promotes primary ciliary resorption through phosphorylation of Tctex-1

The primary cilium undergoes cell cycle-dependent assembly and disassembly. Dysregulated ciliary dynamics are associated with several pathological conditions called ciliopathies. Previous studies showed that the localization of phosphorylated Tctex-1 at Thr94 (T94) at the ciliary base critically regulates ciliary resorption by accelerating actin remodeling and ciliary pocket membrane endocytosis. Here, we show that microtubule-associated serine/threonine kinase family member 4 (MAST4) is localized at the primary cilium. Suppressing MAST4 blocks serum-induced ciliary resorption, and overexpressing MAST4 accelerates ciliary resorption. Tctex-1 binds to the kinase domain of MAST4, in which the R503 and D504 residues are key to MAST4-mediated ciliary resorption. The ciliary resorption and the ciliary base localization of phospho-(T94)Tctex-1 are blocked by the knockdown of MAST4 or the expression of the catalytic-inactive site-directed MAST4 mutants. Moreover, MAST4 is required for Cdc42 activation and Rab5-mediated periciliary membrane endocytosis during ciliary resorption. These results support that MAST4 is a novel kinase that regulates ciliary resorption by modulating the ciliary base localization of phospho-(T94)Tctex-1. MAST4 is a potential new target for treating ciliopathies causally by ciliary resorption defects.

Unraveling the impact of 27-hydroxycholesterol in autoimmune diseases: Exploring promising therapeutic approaches

The role of 27-hydroxycholesterol (27-OHC) in autoimmune diseases has become a subject of intense research in recent years. This oxysterol, derived from cholesterol, has been identified as a significant player in modulating immune responses and inflammation. Its involvement in autoimmune pathogenesis has drawn attention to its potential as a therapeutic target for managing autoimmune disorders effectively. 27-OHC, an oxysterol derived from cholesterol, has emerged as a key player in modulating immune responses and inflammatory processes. It exerts its effects through various mechanisms, including activation of nuclear receptors, interaction with immune cells, and modulation of neuroinflammation. Additionally, 27-OHC has been implicated in the dysregulation of lipid metabolism, neurotoxicity, and blood-brain barrier (BBB) disruption. Understanding the intricate interplay between 27-OHC and autoimmune diseases, particularly neurodegenerative disorders, holds promise for developing targeted therapeutic strategies. Additionally, emerging evidence suggests that 27-OHC may interact with specific receptors and transcription factors, thus influencing gene expression and cellular processes in autoimmune disorders. Understanding the intricate mechanisms by which 27-OHC influences immune dysregulation and tissue damage in autoimmune diseases is crucial for developing targeted therapeutic interventions. Further investigations into the molecular pathways and signaling networks involving 27-OHC are warranted to unravel its full potential as a therapeutic target in autoimmune diseases, thereby offering new avenues for disease intervention and management.

ApoE Modifier Alleles for Alzheimer's Disease Discovered by Information Theory Dependency Measures: MIST Software Package

Information theory-based measures of variable dependency (previously published) have been implemented into a software package, MIST. The design of the software and its potential uses are described, and a demonstration is presented in the discovery of modifier alleles of the ApoE gene in affecting Alzheimer's disease (AD) by analyzing the UK Biobank dataset. The modifier genes uncovered overlap strongly with genes found to be associated with AD. Others include many known to influence AD. We discuss a range of uses of the dependency calculations using MIST that can uncover additional genetic effects in similar complex datasets, like higher degrees of interaction and phenotypic pleiotropy.

De novo variants in MAST4 related to neurodevelopmental disorders with developmental delay and infantile spasms: Genotype-phenotype association

Objective

This study aims to prove that the de novo variants in MAST4 gene are associated with neurodevelopmental disorders (NDD) with developmental delay (DD) and infantile spasm (IS) and to determine the genotype-phenotype correlations.

Methods

Trio-based exome sequencing (ES) was performed on the four families enrolled in this study. We collected and systematically reviewed the four probands' clinical data, magnetic resonance images (MRI), and electroencephalography (EEG). We also carried out bioinformatics analysis by integrating published exome/genome sequencing data and human brain transcriptomic data.

Results

We described four patients whose median age of seizure onset was 5 months. The primary manifestation was infantile spasms with typical hypsarrhythmia on EEG. Developmental delays or intellectual disabilities varied among the four individuals. Three de novo missense variants in MAST4 gene were identified from four families, including chr5:66438324 (c.2693T > C: p.Ile898Thr) z, chr5:66459419 (c.4412C > T: p.Thr1471Ile), and chr5:66462662 (c.7655C > G:p.Ser2552Trp). The missense variant p.Ile898Thr is mapped to the AGC-kinase C-terminal with phosphatase activity. The other variant p.Ser2552Trp is located in a phosphoserine-modified residue which may affect cell membrane stability and signal transduction. Besides, the variant p.Thr1471Ile is a recurrent site screened out in two unrelated patients. Compared to private mutations (found only in a single family or a small population) of MAST4 in the gnomAD non-neuro subset, all de novo variants were predicted to be damaging or probably damaging through different bioinformatic analyses. Significantly higher CADD scores of the variant p.Thr1471Ile indicate more deleteriousness of the recurrent site. And the affected amino acids are highly conserved across multiple species. According to the Brainspan Atlas database, MAST4 is expressed primarily in the mediodorsal nucleus of the thalamus and medial prefrontal cortex during the prenatal period, potentially contributing to embryonic brain development.

Conclusion

Our results revealed that the variants of MAST4 gene might lead to neurodevelopmental disorders with developmental delay and infantile spasm. Thus, MAST4 variants should be considered the potential candidate gene in patients with neurodevelopmental disorders clinically marked by infantile spasms.

From bugs to bedside: functional annotation of human genetic variation for neurological disorders using invertebrate models

The exponential accumulation of DNA sequencing data has opened new avenues for discovering the causative roles of single-nucleotide polymorphisms (SNPs) in neurological diseases. The opportunities emerging from this are staggering, yet only as good as our abilities to glean insights from this surplus of information. Whereas computational biology continues to improve with respect to predictions and molecular modeling, the differences between in silico and in vivo analysis remain substantial. Invertebrate in vivo model systems represent technically advanced, experimentally mature, high-throughput, efficient and cost-effective resources for investigating a disease. With a decades-long track record of enabling investigators to discern function from DNA, fly (Drosophila) and worm (Caenorhabditis elegans) models have never been better poised to serve as living engines of discovery. Both of these animals have already proven useful in the classification of genetic variants as either pathogenic or benign across a range of neurodevelopmental and neurodegenerative disorders-including autism spectrum disorders, ciliopathies, amyotrophic lateral sclerosis, Alzheimer's and Parkinson's disease. Pathogenic SNPs typically display distinctive phenotypes in functional assays when compared with null alleles and frequently lead to protein products with gain-of-function or partial loss-of-function properties that contribute to neurological disease pathogenesis. The utility of invertebrates is logically limited by overt differences in anatomical and physiological characteristics, and also the evolutionary distance in genome structure. Nevertheless, functional annotation of disease-SNPs using invertebrate models can expedite the process of assigning cellular and organismal consequences to mutations, ascertain insights into mechanisms of action, and accelerate therapeutic target discovery and drug development for neurological conditions.

Oxysterols are potential physiological regulators of ageing

Delaying and even reversing ageing is a major public health challenge with a tremendous potential to postpone a plethora of diseases including cancer, metabolic syndromes and neurodegenerative disorders. A better understanding of ageing as well as the development of innovative anti-ageing strategies are therefore an increasingly important field of research. Several biological processes including inflammation, proteostasis, epigenetic, oxidative stress, stem cell exhaustion, senescence and stress adaptive response have been reported for their key role in ageing. In this review, we describe the relationships that have been established between cholesterol homeostasis, in particular at the level of oxysterols, and ageing. Initially considered as harmful pro-inflammatory and cytotoxic metabolites, oxysterols are currently emerging as an expanding family of fine regulators of various biological processes involved in ageing. Indeed, depending of their chemical structure and their concentration, oxysterols exhibit deleterious or beneficial effects on inflammation, oxidative stress and cell survival. In addition, stem cell differentiation, epigenetics, cellular senescence and proteostasis are also modulated by oxysterols. Altogether, these data support the fact that ageing is influenced by an oxysterol profile. Further studies are thus required to explore more deeply the impact of the "oxysterome" on ageing and therefore this cholesterol metabolic pathway constitutes a promising target for future anti-ageing interventions.

Estrogen-Responsive Gene MAST4 Regulates Myeloma Bone Disease

Our previous data showed that young female multiple myeloma (MM) patients had a low frequency of osteolytic lesions. Based on this clinical observation, we found that estrogen cell signaling played a regulatory role in MM bone disease (MMBD), and the estrogen-responsive gene microtubule-associated serine/threonine kinase family member 4 (MAST4) was a critical factor. The presence of estrogen in cell cultures promoted MAST4 expression in MM cells, while knocking down estrogen receptor 1 (ESR1) inhibited MAST4 expression. Chromatin immunoprecipitation assay suggested a binding site of ESR1 on the MAST4 promoter. Bisphosphonates, such as zoledronic acid (ZOL), which was widely used in MMBD control, could stimulate MAST4 expression in MM cells by promoting ESR1 expression. MAST4 interacted with phosphatase and tensin homolog (PTEN), therefore regulating the PI3K-Akt-mTOR pathway and the expression of downstream cytokines, such as CCL2/3/4. MAST4 knockdown (MAST4-KD) or ESR1 knockdown (ESR1-KD) MM cells had repressed PTEN activity, elevated PI3K-Akt-mTOR activity, and increased CCL2/3/4 expressions. Coculture of MAST4-KD or ESR1-KD MM cells with pre-osteoclasts (pre-OCs) stimulated OC formation in vitro, whereas neutralizing antibodies of CCL2/3/4 attenuated such stimulation. In mouse models, mice inoculated with MAST4-KD or ESR1-KD MM cells had severer MMBD than control knockdown (CTR-KD). The correlations between MAST4 and ESR1 expressions in MMBD, as well as related cell signaling pathways, were confirmed in analyses using gene expression profiles (GEPs) of patients' MM cells. The negative correlation of MAST4 expression and occurrence of MMBD was further validated by patients' immunohistochemical tissue array. Overall, our data suggested that estrogen cell signaling negatively regulated MMBD through MAST4. © 2022 American Society for Bone and Mineral Research (ASBMR).

Loss of APP in mice increases thigmotaxis and is associated with elevated brain expression of IL-13 and IP-10/CXCL10

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that leads to memory loss and is often accompanied by increased anxiety. Although AD is a heterogeneous disease, dysregulation of inflammatory pathways is a consistent event. Interestingly, the amyloid precursor protein (APP), which is the source of the amyloid peptide Aβ, is also necessary for the efficient regulation of the innate immune response. Here, we hypothesize that loss of APP function in mice would lead to cognitive loss and anxiety behavior, both of which are typically present in AD, as well as changes in the expression of inflammatory mediators. To test this hypothesis, we performed open field, Y-maze and novel object recognition tests on 12-18-week-old male and female wildtype and App^KO mice to measure thigmotaxis, short-term spatial memory and long-term recognition memory. We then performed a quantitative multiplexed immunoassay to measure levels of 32 cytokines/chemokines associated with AD and anxiety. Our results showed that App^KO mice, compared to wildtype controls, experienced increased thigmotactic behavior but no memory impairments, and this phenotype correlated with increased IP-10 and IL-13 levels. Future studies will determine whether dysregulation of these inflammatory mediators contributes to pathogenesis in AD.

Detecting the Multiomics Signatures of Factor-Specific Inflammatory Effects on Airway Smooth Muscles

Smooth muscles are a specific muscle subtype that is widely identified in the tissues of internal passageways. This muscle subtype has the capacity for controlled or regulated contraction and relaxation. Airway smooth muscles are a unique type of smooth muscles that constitute the effective, adjustable, and reactive wall that covers most areas of the entire airway from the trachea to lung tissues. Infection with SARS-CoV-2, which caused the world-wide COVID-19 pandemic, involves airway smooth muscles and their surrounding inflammatory environment. Therefore, airway smooth muscles and related inflammatory factors may play an irreplaceable role in the initiation and progression of several severe diseases. Many previous studies have attempted to reveal the potential relationships between interleukins and airway smooth muscle cells only on the omics level, and the continued existence of numerous false-positive optimal genes/transcripts cannot reflect the actual effective biological mechanisms underlying interleukin-based activation effects on airway smooth muscles. Here, on the basis of newly presented machine learning-based computational approaches, we identified specific regulatory factors and a series of rules that contribute to the activation and stimulation of airway smooth muscles by IL-13, IL-17, or the combination of both interleukins on the epigenetic and/or transcriptional levels. The detected discriminative factors (genes) and rules can contribute to the identification of potential regulatory mechanisms linking airway smooth muscle tissues and inflammatory factors and help reveal specific pathological factors for diseases associated with airway smooth muscle inflammation on multiomics levels.

Mast4 knockout shows the regulation of spermatogonial stem cell self-renewal via the FGF2/ERM pathway

Spermatogenesis is an important cellular differentiation process that produces the male gametes and remains active throughout the individual's lifespan. Sertoli cell-only syndrome (SCO) refers to the dysfunction of the male reproductive system, including infertility. Accurate self-renewal of spermatogonial stem cells (SSCs) is essential to prevent SCO syndrome. This study investigated the role of microtubule-associated serine/threonine kinase family member 4 (MAST4) in spermatogenesis in mice. MAST4 was localized in Sertoli cells before puberty, providing a somatic niche for spermatogenesis in mice and MAST4 expression shifted to Leydig cells and spermatids throughout puberty. Mast4 knockout (KO) testes were reduced in size compared to wild-type testes, and germ cell depletion associated with an increase in apoptosis and subsequent loss of tubular structure were similar to the SCO phenotype. In addition, MAST4 phosphorylated the Ets-related molecule (ERM), specifically the serine 367 residue. The phosphorylation of ERM ultimately controls the transcription of ERM target genes related to SSC self-renewal. The expression of spermatogenesis-associated proteins was significantly decreased whereas Sertoli cell markers were increased in Mast4 KO testes, which was well-founded by RNA-sequencing analysis. Therefore, MAST4 is associated with the fibroblast growth factor 2 (FGF2)/ERM pathway and this association helps us explore the capacity of SSCs to maintain a vertebrate stem cell niche.

Orphan Nuclear Receptor RORα Regulates Enzymatic Metabolism of Cerebral 24S-Hydroxycholesterol through CYP39A1 Intronic Response Element Activation

Oxysterols, important regulators of cholesterol homeostasis in the brain, are affected by neurodegenerative diseases. Early-onset Alzheimer’s disease is associated with higher levels of circulating brain-derived 24S-hydroxycholesterol (24S-OHC). Conversion of cholesterol to 24S-OHC is mediated by cholesterol 24S-hydroxylase in the brain, which is the major pathway for oxysterol elimination, followed by oxidation through hepatic first-pass metabolism by CYP39A1. Abnormal CYP39A1 expression results in accumulation of 24S-OHC, influencing neurodegenerative disease-related deterioration; thus, it is important to understand the normal elimination of 24S-OHC and the system regulating CYP39A1, a selective hepatic metabolic enzyme of 24S-OHC. We examined the role of transcriptional regulation by retinoic acid receptor-related orphan receptor α (RORα), a nuclear receptor that responds to oxysterol ligands. In humans, the promoter and first intronic regions of CYP39A1 contain two putative RORα response elements (ROREs). RORα binding and responses of these ROREs were assessed using electrophoretic mobility shift, chromatin immunoprecipitation, and luciferase reporter assays. CYP39A1 was upregulated by RORα overexpression in HEK293 cells, while RORα knockdown by siRNA significantly downregulated CYP39A1 expression in human hepatoma cells. Additionally, CYP39A1 was induced by RORα agonist treatment, suggesting that CYP39A1 expression is activated by RORα nuclear receptors. This may provide a way to increase CYP39A1 activity using RORα agonists, and help halt 24S-OHC accumulation in neurodegenerative illnesses.

Loss of amyloid precursor protein exacerbates early inflammation in Niemann-Pick disease type C

BACKGROUND

Niemann-Pick disease type C (NPC) is a progressive neurodegenerative condition that results in early fatality. NPC is inherited in an autosomal recessive pattern from mutations in NPC1 or NPC2 genes. The etiology of NPC is poorly defined. In that regard, neuroinflammation occurs early in the disease and we have recently unveiled an atypical pattern of interferon signaling in pre-symptomatic Npc1^-/- mice, with microglial activation, anti-viral response, activation of antigen-presenting cells, and activation and chemotaxis of T lymphocytes as the key affected pathologic pathways. Furthermore, IP-10/CXCL10, a potent IFN-γ-responsive cytokine, was identified as the potential mediator of these early inflammatory abnormalities. Here, we asked whether this aberrant signaling may be exacerbated by the loss of amyloid precursor protein (APP) function, a loss known to shorten lifespan and accelerate neurodegeneration in Npc1^-/- mice.

METHODS

We carried out genome-wide comparative transcriptome analyses of pre-symptomatic Npc1^+/+/App^+/+, Npc1^-/-/App^+/+, Npc1^+/+/App^-/-, and Npc1^-/-/App^-/- mouse cerebella to identify biological pathways in the NPC brain further affected by the loss of APP. Gene Set Enrichment Analysis and Ingenuity Pathway Analysis were utilized for molecular mapping and functional upstream pathway analyses of highly differentially expressed genes. We simultaneously measured the expression of 32 inflammatory cytokines and chemokines in the cerebella from these mice, including those identified in our genome-wide analyses. Finally, we used immunohistochemistry to measure T cell infiltration in the cerebellum.

RESULTS

Expression of IFN-γ- and IFN-α-responsive genes in pre-symptomatic Npc1^-/-/App^-/- cerebella is upregulated compared with Npc1^-/-/App^+/+ mice, compounding the dysregulation of microglial activation, anti-viral response, activation of antigen-presenting cells, and T-lymphocyte activation and chemotaxis pathways present in the NPC brain. Multiplex protein analysis further showed elevated expression of IP-10/CXCL10, a potent downstream effector of IFN-γ, as well as RANTES/CCL5, eotaxin/CCL11 and IL-10, prior to symptomatic onset in Npc1^-/-/App^-/- cerebella, compared with Npc1^-/-/App^+/+mice. In the terminal disease stage, loss of APP caused pleiotropic differential expression of the vast majority of cytokines evaluated. Finally, we present evidence of T cell infiltration in Npc1^-/-/App^-/- cerebella.

CONCLUSIONS

Loss of APP exacerbates the pathogenic neuroinflammation that occurs prior to symptomatic onset in the NPC brain. These findings shed new light on the function of APP as a cytoprotective modulator in the CNS, offering potential evidence-based therapies against NPC.

27-hydroxycholesterol promotes Aβ accumulation via altering Aβ metabolism in mild cognitive impairment patients and APP/PS1 mice

The oxysterol 27-hydroxycholesterol (27-OHC) has been considered to play a key role in the pathogenesis of Alzheimer's disease (AD). Because β-amyloid peptide (Aβ) is the pathological hallmark of AD, the aim of this study is to verify whether 27-OHC could lead to cognitive impairment through modulating Aβ accumulation and deposition. Regulation of Aβ metabolism was explored as the pathogenic mechanism of 27-OHC. Furthermore, microRNAs (miRNAs) and their relations with 27-OHC were also detected. In present study, matched case-control study and APP/PS1 transgenic mice research were conducted. The results showed that the 27-OHC and Aβ in plasma were increased in mild cognitive impairment patients, and a slight correlation was found between 27-OHC and Aβ1-40. This relationship was also proved by the research of APP/PS1 mice. More severe learning and memory impairment and higher Aβ1-40 expression in brain and plasma were detected in the APP/PS1 mice of 27-OHC treatment group. In addition, increased amyloid plaques were also found in the hippocampus of 27-OHC-treated mice. In order to find out the mechanism of 27-OHC on regulating Aβ metabolism, the factors of Aβ production (APP, BACE1 and ADAM10), transport (LRP1 and RAGE) and elimination (NEP and IDE) were tested respectively. The gene and protein expressions of APP, BACE1 and RAGE were increased while LRP1 and IDE were decreased in the brain of 27-OHC-treated mice. At last, down-regulated expression of miRNA let-7g-5p was found after 27-OHC treatment. In conclusion, these findings suggested that excessive 27-OHC could enhance the accumulation and deposition of Aβ both in brain and blood, resulting in a severe impairment of cognition, especially in the modulation of Aβ1-40. The mechanism might be associated with the regulation of Aβ metabolism, and miRNA let-7g-5p was likely to play a vital role in this pathological process induced by 27-OHC.