Alzheimer’s disease (AD) is the most common dementia. It is known that women with one ApoE4 allele display greater risk and earlier onset of AD compared with men. In mice, we previously showed that follicle–stimulating hormone (FSH), a gonadotropin that rises in post–menopausal females, activates its receptor FSHR in the hippocampus, to drive AD–like pathology and cognitive impairment. Here we show in mice that ApoE4 and FSH jointly trigger AD-like pathogenesis by activating C/EBPβ/δ-secretase signaling. ApoE4 and FSH additively activate C/EBPβ/δ-secretase pathway that mediates APP and Tau proteolytic fragmentation, stimulating Aβ and neurofibrillary tangles. Ovariectomy-provoked AD-like pathologies and cognitive defects in female ApoE4-TR mice are ameliorated by anti-FSH antibody treatment. FSH administration facilitates AD-like pathologies in both young male and female ApoE4-TR mice. Furthermore, FSH stimulates AD-like pathologies and cognitive defects in ApoE4-TR mice, but not ApoE3-TR mice. Our findings suggest that in mice, augmented FSH in females with ApoE4 but not ApoE3 genotype increases vulnerability to AD-like process by activating C/EBPβ/δ-secretase signalling.

The aggregation of Tau protein into neurofibrillary tangles (NFTs), a hallmark of Alzheimer’s disease (AD), is associated with cognitive decline. Recent studies have revealed that neuronal cytoskeletal instability drives early AD pathogenesis. The physiological interaction between tau and the microtubule (MT) is crucial for maintaining axonal transport and stability. However, aberrant post-translational modifications (PTMs) in the MT binding domain—such as phosphorylation, acetylation and ubiquitination—trigger tau dissociation, causing microtubule collapse, transport deficits, and synaptic dysfunction. MT dysregulation also affects actin/cofilin-mediated dendritic spine destabilization and causes the hyperplasia of the glial intermediate filament, which exacerbates neuroinflammation and synaptic toxicity. This review systematically explores the functions of neuronal cytoskeletons, deciphers the molecular crosstalk between tau pathology and cytoskeletal remodeling, and proposes multi-target therapeutic strategies to restore cytoskeletal homeostasis, thereby providing novel perspectives for precision interventions in AD

Background: The pathologic accumulation and aggregation of tau is a hallmark of tauopathies including Alzheimer’s disease (AD). However, the molecular mechanisms mediating tau aggregation in AD remain elusive. The incidence of AD is increased in patients with type 2 diabetes (T2DM), which is characterized by the amyloid deposition of islet amyloid polypeptide (IAPP) in the pancreas. However, the molecular mechanisms bridging AD and T2DM remain unknown.Methods: We first examined the presence of IAPP in the neurofibrillary tangles of AD patients. Then we tested the effect of IAPP on tau aggregation. The biochemical and biological characteristics of the IAPP-tau fibrils were tested in vitro. The seeding activity and neurotoxicity of the IAPP-tau fibrils were confirmed in cultured neurons. Lastly, the effect of IAPP on tau pathology and cognitive impairments was determined by injecting the IAPP-tau fibrils and IAPP fibrils into the hippocampus of tau P301S mice.Results: We found that IAPP interacts with tau and accelerates the formation of a more toxic strain, which shows distinct morphology with enhanced seeding activity and neurotoxicity in vitro. Intrahippocampal injection of the IAPP-tau strain into the tau P301S transgenic mice substantially promoted the spreading of tau pathology and induced more severe synapse loss and cognitive deficits, when compared with tau fibrils. Furthermore, intracerebral injection of synthetic IAPP fibrils initiated tauopathy in the brain of tau P301S transgenic mice.Conclusions: These observations indicate that IAPP acts as a crucial mediator of tau pathology in AD, and provide a mechanistic explanation for the higher risk of AD in individuals with T2DM.

Brain-derived neurotrophic factor (BDNF) and its tropomyosin-related kinase B receptor (TrkB) are expressed in human osteoblasts and mediate fracture healing. BDNF/TrkB signaling activates Akt that phosphorylates and inhibits asparagine endopeptidase (AEP), which regulates the differentiation fate of human bone marrow stromal cells (hBMSC) and is altered in postmenopausal osteoporosis. Here we show that R13, a small molecular TrkB receptor agonist prodrug, inhibits AEP and promotes bone formation. Though both receptor activator of nuclear factor kappa-Β ligand (RANK-L) and osteoprotegerin (OPG) induced by ovariectomy (OVX) remain comparable between WT and BDNF+/− mice, R13 treatment significantly elevates OPG in both mice without altering RANKL, blocking trabecular bone loss. Strikingly, both R13 and anti-RANK-L exhibit equivalent therapeutic efficacy. Moreover, OVX increases RANK-L and OPG in WT and AEP KO mice with RANK-L/OPG ratio lower in the latter than the former, attenuating bone turnover. 7,8-DHF, released from R13, activates TrkB and its downstream effector CREB, which is critical for OPG augmentation. Consequently, 7,8-DHF represses C/EBPβ/AEP pathway, inhibiting RANK-L-induced RAW264.7 osteoclastogenesis. Therefore, our findings support that R13 exerts its therapeutic efficacy toward osteoporosis via inhibiting AEP and escalating OPG.

Lipid metabolism disorders represent a significant risk factor for the pathogenesis of Alzheimer’s disease (AD). Apolipoprotein E (APOE) has been regarded as a pivotal regulator of lipid homeostasis in the central nervous system (CNS), with polymorphic alleles identified as genetic risk factors for late-onset AD. Despite advances in APOE research and the development of numerous pharmaceutical approaches targeting distinct APOE isoforms, there remain limited treatment approaches for AD that focus on lipid metabolic homeostasis. Consequently, it is necessary to reevaluate the lipid metabolic process in the CNS. Apolipoprotein A1 (APOA-I), a major component of high-density lipoprotein (HDL), plays a crucial role in reverse cholesterol transport from tissues to the liver to maintain lipid homeostasis. Over the past few decades, numerous studies have suggested a connection between reduced APOA-I levels and a higher risk of AD. APOA-I is synthesized exclusively in the liver and intestines, and there is a lack of conclusive evidence supporting its functional significance within the central nervous system, in contrast to APOE, which is produced locally by glial cells and neurons within the CNS. Moreover, APOA-I’s ability to penetrate the blood-brain barrier (BBB) is still poorly understood, which causes its significance in central lipid metabolism and AD pathophysiology to be mainly disregarded. Recent advancements in tracing methodologies have underscored the essential role of APOA-I in regulating lipid metabolism in the CNS. This review aims to elucidate the physiological functions and metabolic pathways of APOA-I, integrating its associations with AD-related pathologies, risk factors, and potential therapeutic targets. Through this discourse, we aim to provide novel insights into the intricate relationship between AD and APOA-I, paving the way for future research in this field.

Depression is one of the most common affective disorders in people’s life. Women are susceptibility to depression during puberty, peripartum and menopause transition, when they are suffering from sex hormone fluctuation. A lot of studies have demonstrated the neuroprotective effect of estrogen on depression in women, however, the effect of FSH on depression is unclear. In this study, we investigated the role of FSH on depression in mice. Our study demonstrated that FSH induced depression-like behaviors in mice in a dose-dependent manner. This induction was associated with elevated levels of pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α in both serum and hippocampal tissues. Additionally, FSH treatment resulted in impaired synaptic plasticity and a reduction in the expression of key synaptic proteins. It is noteworthy that the depression-like behaviors, inflammatory cytokines expression and synaptic plasticity impairment induced by FSH could be alleviated by knocking down the expression of FSH receptor (FSHR) in the hippocampus of the mice. Therefore, our findings reveal that FSH may play an important role in the pathogenesis of depression and targeting FSH may be a potential therapeutic strategy for depression during hormone fluctuation in women.