APOE4/4 is linked to damaging lipid droplets in Alzheimer's disease microglia.

Several genetic risk factors for Alzheimer's disease implicate genes involved in lipid metabolism and many of these lipid genes are highly expressed in glial cells1. However, the relationship between lipid metabolism in glia and Alzheimer's disease pathology remains poorly understood. Through single-nucleus RNA sequencing of brain tissue in Alzheimer's disease, we have identified a microglial state defined by the expression of the lipid droplet-associated enzyme ACSL1 with ACSL1-positive microglia being most abundant in patients with Alzheimer's disease having the APOE4/4 genotype. In human induced pluripotent stem cell-derived microglia, fibrillar Aß induces ACSL1 expression, triglyceride synthesis and lipid droplet accumulation in an APOE-dependent manner. Additionally, conditioned media from lipid droplet-containing microglia lead to Tau phosphorylation and neurotoxicity in an APOE-dependent manner. Our findings suggest a link between genetic risk factors for Alzheimer's disease with microglial lipid droplet accumulation and neurotoxic microglia-derived factors, potentially providing therapeutic strategies for Alzheimer's disease.

Cell type-specific roles of APOE4 in Alzheimer disease.

The ɛ4 allele of the apolipoprotein E gene (APOE), which translates to the APOE4 isoform, is the strongest genetic risk factor for late-onset Alzheimer disease (AD). Within the CNS, APOE is produced by a variety of cell types under different conditions, posing a challenge for studying its roles in AD pathogenesis. However, through powerful advances in research tools and the use of novel cell culture and animal models, researchers have recently begun to study the roles of APOE4 in AD in a cell type-specific manner and at a deeper and more mechanistic level than ever before. In particular, cutting-edge omics studies have enabled APOE4 to be studied at the single-cell level and have allowed the identification of critical APOE4 effects in AD-vulnerable cellular subtypes. Through these studies, it has become evident that APOE4 produced in various types of CNS cell - including astrocytes, neurons, microglia, oligodendrocytes and vascular cells - has diverse roles in AD pathogenesis. Here, we review these scientific advances and propose a cell type-specific APOE4 cascade model of AD. In this model, neuronal APOE4 emerges as a crucial pathological initiator and driver of AD pathogenesis, instigating glial responses and, ultimately, neurodegeneration. In addition, we provide perspectives on future directions for APOE4 research and related therapeutic developments in the context of AD.

Alzheimer mechanisms and therapeutic strategies.

There are still no effective treatments to prevent, halt, or reverse Alzheimer's disease, but research advances over the past three decades could change this gloomy picture. Genetic studies demonstrate that the disease has multiple causes. Interdisciplinary approaches combining biochemistry, molecular and cell biology, and transgenic modeling have revealed some of its molecular mechanisms. Progress in chemistry, radiology, and systems biology is beginning to provide useful biomarkers, and the emergence of personalized medicine is poised to transform pharmaceutical development and clinical trials. However, investigative and drug development efforts should be diversified to fully address the multifactoriality of the disease.

Kynurenine 3-monooxygenase inhibition in blood ameliorates neurodegeneration.

Metabolites in the kynurenine pathway, generated by tryptophan degradation, are thought to play an important role in neurodegenerative disorders, including Alzheimer's and Huntington's diseases. In these disorders, glutamate receptor-mediated excitotoxicity and free radical formation have been correlated with decreased levels of the neuroprotective metabolite kynurenic acid. Here, we describe the synthesis and characterization of JM6, a small-molecule prodrug inhibitor of kynurenine 3-monooxygenase (KMO). Chronic oral administration of JM6 inhibits KMO in the blood, increasing kynurenic acid levels and reducing extracellular glutamate in the brain. In a transgenic mouse model of Alzheimer's disease, JM6 prevents spatial memory deficits, anxiety-related behavior, and synaptic loss. JM6 also extends life span, prevents synaptic loss, and decreases microglial activation in a mouse model of Huntington's disease. These findings support a critical link between tryptophan metabolism in the blood and neurodegeneration, and they provide a foundation for treatment of neurodegenerative diseases.

Report of the APOE4 National Institute on Aging/Alzheimer Disease Sequencing Project Consortium Working Group: Reducing APOE4 in Carriers is a Therapeutic Goal for Alzheimer's Disease.

Alzheimer's disease (AD) is the most common neurodegenerative disorder and one of the leading causes of disability worldwide. The apolipoprotein E4 gene (APOE4) is the strongest genetic risk factor for AD. In 2023, the APOE4 National Institute on Aging/Alzheimer's Disease Sequencing Project working group came together to gather data and discuss the question of whether to reduce or increase APOE4 as a therapeutic intervention for AD. It was the unanimous consensus that cumulative data from multiple studies in humans and animal models support that lowering APOE4 should be a target for therapeutic approaches for APOE4 carriers. ANN NEUROL 2024;95:625-634.

UDP-glucosyltransferase HvUGT13248 confers type II resistance to Fusarium graminearum in barley.

Fusarium head blight (FHB) of barley (Hordeum vulgare) causes yield losses and accumulation of trichothecene mycotoxins (e.g. deoxynivalenol [DON]) in grains. Glucosylation of DON to the nontoxic DON-3-O-glucoside (D3G) is catalyzed by UDP-glucosyltransferases (UGTs), such as barley UGT13248. We explored the natural diversity of UGT13248 in 496 barley accessions and showed that all carried potential functional alleles of UGT13248, as no genotypes showed strongly increased seedling sensitivity to DON. From a TILLING population, we identified 2 mutant alleles (T368I and H369Y) that, based on protein modeling, likely affect the UDP-glucose binding of UGT13248. In DON feeding experiments, DON-to-D3G conversion was strongly reduced in spikes of these mutants compared to controls, and plants overexpressing UGT13248 showed increased resistance to DON and increased DON-to-D3G conversion. Moreover, field-grown plants carrying the T368I or H369Y mutations inoculated with Fusarium graminearum showed increased FHB disease severity and reduced D3G production. Barley is generally considered to have type II resistance that limits the spread of F. graminearum from the infected spikelet to adjacent spikelets. Point inoculation experiments with F. graminearum showed increased infection spread in T368I and H369Y across the spike compared to wild type, while overexpression plants showed decreased spread of FHB symptoms. Confocal microscopy revealed that F. graminearum spread to distant rachis nodes in T368I and H369Y mutants but was arrested at the rachis node of the inoculated spikelet in wild-type plants. Taken together, our data reveal that UGT13248 confers type II resistance to FHB in barley via conjugation of DON to D3G.

Recombinantly expressed rhFEB remodeled the skin defect of db/db mice.

Fibronectin (FN) and collagen are vital components of the extracellular matrix (ECM). These proteins are essential for tissue formation and cell alignment during the wound healing stage. In particular, FN interacts with collagens to activate various intracellular signaling pathways to maintain ECM stability. A novel recombinant extra domain-B fibronectin (EDB-FN)-COL3A1 fusion protein (rhFEB) was designed to mimic the ECM to promote chronic and refractory skin ulcer wound healing. rhFEB significantly enhanced cell adhesion and migration, vascular ring formation, and the production of new collagen I (COL1A1) in vitro. rhFEB decreased M1 macrophages and further modulated the wound microenvironment, which was confirmed by the treatment of db/db mice with rhFEB. Accelerated wound healing was shown during the initial stages in rhFEB-treated db/db mice, as was enhanced follicle regeneration, re-epithelialization, collagen deposition, granulation, inflammation, and angiogenesis. The wound chronicity of diabetic foot ulcers (DFUs) remains the main challenge in current and future treatment. rhFEB may be a candidate molecule for regulating M1 macrophages during DFU healing. KEY POINTS: • A recombinant protein EDB-FN-collagen III (rhFEB) was highly expressed in Escherichia coli • rhFEB protein induces COL1A1 secretion in human skin fibroblasts • rhFEB protein accelerates diabetic wound healing.

APOE Christchurch-mimetic therapeutic antibody reduces APOE-mediated toxicity and tau phosphorylation.

INTRODUCTION: We discovered that the APOE3 Christchurch (APOE3Ch) variant may provide resistance to Alzheimer's disease (AD). This resistance may be due to reduced pathological interactions between ApoE3Ch and heparan sulfate proteoglycans (HSPGs). METHODS: We developed and characterized the binding, structure, and preclinical efficacy of novel antibodies targeting human ApoE-HSPG interactions. RESULTS: We found that one of these antibodies, called 7C11, preferentially bound ApoE4, a major risk factor for sporadic AD, and disrupts heparin-ApoE4 interactions. We also determined the crystal structure of a Fab fragment of 7C11 and used computer modeling to predict how it would bind to ApoE. When we tested 7C11 in mouse models, we found that it reduced recombinant ApoE-induced tau pathology in the retina of MAPT*P301S mice and curbed pTau S396 phosphorylation in brains of systemically treated APOE4 knock-in mice. Targeting ApoE-HSPG interactions using 7C11 antibody may be a promising approach to developing new therapies for AD.

Advancements in APOE and dementia research: Highlights from the 2023 AAIC Advancements: APOE conference.

INTRODUCTION: The apolipoprotein E gene (APOE) is an established central player in the pathogenesis of Alzheimer's disease (AD), with distinct apoE isoforms exerting diverse effects. apoE influences not only amyloid-beta and tau pathologies but also lipid and energy metabolism, neuroinflammation, cerebral vascular health, and sex-dependent disease manifestations. Furthermore, ancestral background may significantly impact the link between APOE and AD, underscoring the need for more inclusive research. METHODS: In 2023, the Alzheimer's Association convened multidisciplinary researchers at the "AAIC Advancements: APOE" conference to discuss various topics, including apoE isoforms and their roles in AD pathogenesis, progress in apoE-targeted therapeutic strategies, updates on disease models and interventions that modulate apoE expression and function. RESULTS: This manuscript presents highlights from the conference and provides an overview of opportunities for further research in the field. DISCUSSION: Understanding apoE's multifaceted roles in AD pathogenesis will help develop targeted interventions for AD and advance the field of AD precision medicine. HIGHLIGHTS: APOE is a central player in the pathogenesis of Alzheimer's disease. APOE exerts a numerous effects throughout the brain on amyloid-beta, tau, and other pathways. The AAIC Advancements: APOE conference encouraged discussions and collaborations on understanding the role of APOE.

Hormone Regulation in Testicular Development and Function.

The testes serve as the primary source of androgens and the site of spermatogenesis, with their development and function governed by hormonal actions via endocrine and paracrine pathways. Male fertility hinges on the availability of testosterone, a cornerstone of spermatogenesis, while follicle-stimulating hormone (FSH) signaling is indispensable for the proliferation, differentiation, and proper functioning of Sertoli and germ cells. This review covers the research on how androgens, FSH, and other hormones support processes crucial for male fertility in the testis and reproductive tract. These hormones are regulated by the hypothalamic-pituitary-gonad (HPG) axis, which is either quiescent or activated at different stages of the life course, and the regulation of the axis is crucial for the development and normal function of the male reproductive system. Hormonal imbalances, whether due to genetic predispositions or environmental influences, leading to hypogonadism or hypergonadism, can precipitate reproductive disorders. Investigating the regulatory network and molecular mechanisms involved in testicular development and spermatogenesis is instrumental in developing new therapeutic methods, drugs, and male hormonal contraceptives.

Modulating of Bouligand Structure and Chirality Constructed Bionically Based on the Self-Assembly of Chitin Whiskers.

Chitin can self-assemble into a liquid crystal phase with supramolecular chirality and Bouligand structure, which is widely found in the exoskeletons of arthropods. However, bionically replicating this structure via the self-assembly of chitin whiskers (CHWs) is still a challenge. Here, the effects of several internal and external parameters on the self-assembly of CHWs were revealed based on liquid crystal phase, chirality, Bouligand structure, and rheological properties. The formation of chiral liquid crystal phase and Bouligand structure largely depends on the concentration of CHWs and, meanwhile, is affected by the aspect ratio and zeta potential of CHWs and the self-assembly time. Impressively, introducing electrolytes and changing pH significantly affect the thickness of the electrical double layer, thereby also affecting the self-assembly of CHWs. This study offers a comprehensive understanding of CHWs' self-assembly process, which is beneficial for the bionic design of new nature-inspired functional materials with chiral characteristic and Bouligand structure.

miR-143-3p Promotes Ovarian Granulosa Cell Senescence and Inhibits Estradiol Synthesis by Targeting UBE2E3 and LHCGR.

The ovary is a highly susceptible organ to senescence, and granulosa cells (GCs) have a crucial role in oocyte development promotion and overall ovarian function maintenance. As age advances, GCs apoptosis and dysfunction escalate, leading to ovarian aging. However, the molecular mechanisms underpinning ovarian aging remain poorly understood. In this study, we observed a correlation between the age-related decline of fertility and elevated expression levels of miR-143-3p in female mice. Moreover, miR-143-3p was highly expressed in senescent ovarian GCs. The overexpression of miR-143-3p in GCs not only hindered their proliferation and induced senescence-associated secretory phenotype (SASP) but also impeded steroid hormone synthesis by targeting ubiquitin-conjugating enzyme E2 E3 (Ube2e3) and luteinizing hormone and human chorionic gonadotropin receptor (Lhcgr). These findings suggest that miR-143-3p plays a substantial role in senescence and steroid hormone synthesis in GCs, indicating its potential as a therapeutic target for interventions in the ovarian aging process.

Sertoli cell-derived exosome-mediated transfer of miR-145-5p inhibits Leydig cell steroidogenesis by targeting steroidogenic factor 1.

In the mammalian testis, two distinct populations of Sertoli cells (SCs), the immature SCs (ISCs) and adult SCs (ASCs), play significant roles in regulating the development and function of Leydig cells. However, the effect of different SC types on the function of Leydig cells is poorly understood. Here, our study showed that miR-145-5p expression was significantly different in SCs at different stages, with the highest expression observed in ISCs. Exosomes mediate the transfer of miR-145-5p from ISCs to Leydig cells. Overexpression of miR-145-5p in Leydig cells significantly downregulated steroidogenic gene expression and inhibited testosterone synthesis. Additionally, miR-145-5p functioned by directly targeted steroidogenic factor-1 (Sf-1) and downregulated the expression of SF-1, which further downregulated the expression of steroidogenic genes, induced accumulation of lipid droplets, and eventually suppressed testosterone production. These findings demonstrate that SC-derived miR-145-5p plays a significant role in regulating the functions of Leydig cells and may therefore serve as a diagnostic biomarker for male hypogonadism developmental abnormalities during puberty.

Recombinant expression a novel fibronectin-collage fusion peptide modulating stem cell stemness via integrin ß3.

Constructing bionic extracellular matrix (ECM) is an attractive proposition for tissue engineering and clinical regeneration therapy involving the stemness of stem cells. Here, a novel recombinant protein fibronectin-collagen peptide (FCP) was designed to modulate the function of ECM expressed by Picha. pastoris strain X33. This FCP promotes cell migration and adhesion and maintains rBMSC stemness by binding integrin ß3. Its effects were blocked by both integrin ß3 siRNA and the integrin ß3 inhibitor Cilengitide. A template-independent ab initio prediction modeling approach is the best approach to construct a stable FCP protein model, which predicts the binding sites between FCP and integrin ß3. FCP may be used in the in vitro culture and clinical regeneration of stem cells that highly express integrin ß3, such as hematopoietic stem cells. The study provides information on the molecular structure of FCP and its bioactivity, which can be used to design new compounds. KEY POINTS: • Design a novel recombinant fibronectin-collagen peptide biomimetic ECM. • FCP promotes cell adhesion, migration, and proliferation. • Predicted and verified FCP structure and affinity with integrin ß3. • FCP binds integrin ß3 to maintain rBMSC stemness.

CORO1A regulates lipoprotein uptake in Leydig cells exposed to cadmium.

Cadmium (Cd) is one of the most common environmental pollutants, which has a long biological half-life. Maternal Cd-exposure in the natural environment causes steroidogenesis defects resulting in spermatogenesis disorder in male offspring. For better understanding its underlying mechanism, we have employed iTRAQ to screen the differentially expressed protein and found that the expression of CORO1A and Cofilin 1 was up-regulated approximately 2 fold in Leydig cells of maternal Cd-exposure offspring. As the major source of steroid hormone, cholesterol is transported to cells via receptor-mediated endocytosis which relies on the remodel of cytoskeleton, then stores in lipid droplets (LDs). However, few studies have focused on the role of cytoskeleton in abnormal steroidogenesis. This study was performed to explore the role of CORO1A in androgen deficiency caused by Cd exposure and its involvement of low-density lipoprotein (LDL) uptake and effects on LDs. We found that Cd resulted in the up-regulation of CORO1A and Cofilin 1, and down-regulation of Profilin 1 in the testis of male offspring with maternal exposure. The structure of filamentous actin was broken, disordered and even crumpled up in Cd-treated R2C cells. F-actin disassembly led to a low uptake of LDL with a reduced number of LDs, followed by decreased total cholesterol and low progesterone production. When CORO1A was silenced, the expression of Cofilin 1 was down-regulated and Profilin 1 was up-regulated in Cd-treated R2C cells. The filamentous actin was rescued and the integrated cytoskeleton prompted LDL uptake, which resulted in the increased total cholesterol and high progesterone production. These findings highlight the crucial role of CORO1A as a cytoskeleton regulatory protein in steroidogenesis, which may help to better understand Cd-induced steroid hormone deficiency in children.

Deletion of the miR-25/93/106b cluster induces glomerular deposition of immune complexes and renal fibrosis in mice.

IgA nephropathy (IgAN), the most common form of primary glomerulonephritis, is caused by immune system dysfunction and affects only the kidneys. miRNA was involved in IgAN, in which their roles are still unknown. Herein, we found increased glomerular medulla size, proteinuria, kidney artery resistance, kidney fibrosis and immune complex deposition in 5-month miR-25/93/106b cluster knockout (miR-TKO) mice. In vitro, the inhibition of miR-25 cluster could promote cell proliferation and increase fibrosis-related protein and transferrin receptor (TFRC) expression in human renal glomerular mesangial cell (HRMC). Luciferase assay revealed that inhibition of miR-93/106b cluster could upregulate Ccnd1 expression through direct binding with the 3'UTR of Ccnd1. Conversely, inhibition of Ccnd1 expression prevented miR-93/106b-induced effect in HRMC. These findings suggested that miR-25 cluster played an important role in the progression of IgAN, which provided new insights into the pathogenesis and treatment of IgAN.

Sertoli cell-derived exosomal MicroRNA-486-5p regulates differentiation of spermatogonial stem cell through PTEN in mice.

Self-renewal and differentiation of spermatogonial stem cell (SSC) are critical for male fertility and reproduction, both of which are highly regulated by testicular microenvironment. Exosomal miRNAs have emerged as new components in intercellular communication. However, their roles in the differentiation of SSC remain unclear. Here, we observed miR-486-5p enriched in Sertoli cell and Sertoli cell-derived exosomes. The exosomes mediate the transfer of miR-486-5p from Sertoli cells to SSCs. Exosomes release miR-486-5p, thus up-regulate expression of Stra8 (stimulated by retinoic acid 8) and promote differentiation of SSC. And PTEN was identified as a target of miR-486-5p. Overexpression of miR-486-5p in SSCs down-regulates PTEN expression, which up-regulates the expression of STRA8 and SYCP3, promotes SSCs differentiation. In addition, blocking the exosome-mediated transfer of miR-486-5p inhibits differentiation of SSC. Our findings demonstrate that miR-486-5p acts as a communication molecule between Sertoli cells and SSCs in modulating differentiation of SSCs. This provides a new insight on molecular mechanisms that regulates SSC differentiation and a basis for the diagnosis, treatment, and prevention of male infertility.

Genetic dissection of a pericentromeric region of barley chromosome 6H associated with Fusarium head blight resistance, grain protein content and agronomic traits.

KEY MESSAGE: Fine mapping of barley 6H pericentromeric region identified FHB QTL with opposite effects, and high grain protein content was associated with increased FHB severity. Resistance to Fusarium head blight (FHB), kernel discoloration (KD), deoxynivalenol (DON) accumulation and grain protein content (GPC) are important traits for breeding malting barley varieties. Previous work mapped a Chevron-derived FHB QTL to the pericentromeric region of 6H, coinciding with QTL for KD resistance and GPC. The Chevron allele reduced FHB and KD, but unfavorably increased GPC. To determine whether the correlations are caused by linkage or pleiotropy, a fine mapping approach was used to dissect the QTL underlying these quality and disease traits. Two populations, referred to as Gen10 and Gen10/Lacey, derived from a recombinant near-isogenic line (rNIL) were developed. Recombinants were phenotyped for FHB, KD, DON, GPC and other agronomic traits. Three FHB, two DON and two KD QTLs were identified. One of the three FHB QTLs, one DON QTL and one KD QTL were coincident with the GPC QTL, which contains the Hv-NAM1 locus affecting grain protein accumulation. The Chevron allele at the GPC QTL increased GPC and FHB and decreased DON and KD. The other two FHB QTL and the other DON and KD QTL were identified in the regions flanking the Hv-NAM1 locus, and the Chevron alleles decreased FHB, DON and KD. Our results suggested that the QTL associated with FHB, KD, DON and GPC in the pericentromeric region of 6H was controlled by both pleiotropy and tightly linked loci. The rNILs identified in this study with low FHB severity and moderate GPC may be used for breeding malting barley cultivars.

Chitinophaga silvatica sp. nov., isolated from forest soil, and reclassification of Chitinophaga extrema as a later heterotypic synonym of Chitinophaga solisilvae.

A novel bacterial strain, designated K2CV101002-2T, was isolated from forest soil collected at Dinghushan Biosphere Reserve, Guangdong Province, PR China. Phylogenetic analyses based on 16S rRNA gene sequences showed that it belonged to the genus Chitinophaga and was most closely related to Chitinophaga terrae KP01T (99.0 %), followed by Chitinophaga extrema Mgbs1T (98.3 %) and Chitinophaga solisilvae O9T (98.1 %). The draft genome sequence was 6.8 Mb long with a relative low G+C content of 39.8 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between the novel strain and closely related type strains were 71.4‒76.2 % and 18.4‒19.6 %, respectively. Meanwhile the corresponding values between C. extrema Mgbs1T and C. solisilvae O9T were 98.6 and 88.1 %, respectively. The novel strain contained iso-C15:0, C16:1 ω5c and iso-C17:0 3-OH as the major fatty acids and MK-7 as the predominant respiratory quinone. The polyphasic study clearly supported that strain K2CV101002-2T represents a new species of the genus Chitinophaga, for which the name Chtinophaga silvatica sp. nov. (type strain K2CV101002-2T=GDMCC 1.1288T=JCM 32696T) is proposed. In addition, Chitinophaga extrema Goh et al. 2020 should be taken as a later heterotypic synonym of Chitinophaga solisilvae Ping et al. 2020.

Polygalaxanthone III downregulates inflammation in the lipopolysaccharide-stimulated RAW264.7 macrophages: A quantibody array analysis.

Polygala japonica Houtt. (PJ), a member of the Polygala L. family that is suggested to exhibit detoxification properties in traditional Chinese medicine, is often used to treat upper respiratory tract infections. The anti-inflammatory effects of four main components of PJ (POL, PS-XLIX, PS-E, and PS-F) were examined using the LPS(0.3 µg·mL-1)-stimulated RAW264.7 macrophage model. The levels of NO, ROS, and iNOS were examined to analyze the anti-inflammatory activity of POL. Additionally, the levels of extracellular inflammation-related cytokines and chemokines were measured using quantibody array. The KEGG pathway analysis was performed to examine the anti-inflammatory mechanism of POL. The levels of NO in the POL-pretreated group were significantly downregulated when compared with those in the PS-E-pretreated, PS-F-pretreated, and PS-XLIX-pretreated groups. POL significantly inhibited the changes of iNOS, ROS, and inflammatory factors caused by LPS stimulation (p < 0.001). The expression levels of IL21 and GM-CSF were examined using qPCR, while those of JAK-STAT signaling pathway-related proteins in the LPS-stimulated RAW264.7 macrophages were analyzed using western blotting. POL significantly downregulated the expression of IL-21 and GM-CSF. The anti-inflammatory mechanism of POL is mediated through the JAK-STAT pathway. Thus, this study demonstrated that POL is an anti-inflammatory component of PJ and elucidated its mechanism.