Background: Progressive neuronal death is the key pathological feature of Alzheimer’s disease (AD). However, the molecular mechanisms underlying the neuronal death in AD patients have not been fully elucidated. Necroptosis reportedly activates and induces neuronal death in patients with Alzheimer’s disease (AD); however, the main mediators and mechanisms underlying necroptosis induction in AD remain elusive. Methods: The function of hyperphosphorylated tau (pTau) in inducing necroptosis in neuronal cell was examined using Western blotting, RT-PCR and flow cytometry. Tau-induced inflammation was identified via RNA sequencing and transwell assay. Pharmacological methods and CRISPR–Cas9 technology were used to verify the role of necrosome proteins in pTau-stimulated neuronal death and inflammation. TauP301S model mice were treated with Nec-1 s to evaluate the role of necroptosis in tau pathology. Results: Hyperphosphorylated tau could induce necroptosis in neuronal cells by promoting the formation of the RIPK1/RIPK3/MLKL necrosome. In addition, pTau significantly stimulated cell-autonomous overexpression of cytokines and chemokines via the intracellular nuclear factor kappa B (NF-κB) signaling pathway. Importantly, the RIPK1/RIPK3/MLKL axis was essential for the pTau-mediated NF-κB activation and cytokine storm. Furthermore, necroptosis stimulation, NF-κB activation, and cytokine induction have been detected in TauP301S mice and blocking necroptosis markedly ameliorated behavioral defects and excessive neuroinflammation in AD mice. Conclusions: Our study, for the first time, revealed that pTau contributes to neuronal death by inducing necroptosis and inflammation, mediated by activating the RIPK1/RIPK3/MLKL and NF-κB pathways, thereby delineating the hierarchical molecular network of neuronal necroptosis induction in AD.

Background: Tau hyper-phosphorylation has been considered a major contributor to neurodegeneration in Alzheimer’s disease (AD) and related tauopathies, and has gained prominence in therapeutic development for AD. To elucidate the pathogenic mechanisms underlying AD and evaluate therapeutic approaches targeting tau, numerous transgenic mouse models that recapitulate critical AD-like pathology have been developed. Tau P301S transgenic mice is one of the most widely used mouse models in AD research. Extensive studies have demonstrated that sex significantly influences AD pathology, behavioral status, and therapeutic outcomes, suggesting that studies using mouse models of AD must consider sex- and age-related differences in neuropathology, behavior, and plasma content. Method: We systematically investigated differences in tau P301S transgenic mice (PS19 line) and wildtype littermates of different sex behavioral performance, tau neuropathology, and biomarkers in plasma and brain. Results: Male P301S transgenic mice exhibited significant changes in weight loss, survival rate, clasping, kyphosis, composite phenotype assessment, nest building performance, tau phosphorylation at Ser202/Thr205, and astrocyte activation compared to that of wild-type littermates. In contrast, female P301S transgenic mice were only sensitive in the Morris water maze and open field test. In addition, we characterized the absence of macrophage-inflammatory protein (MIP-3α) and the upregulation of interferon (IFN)-γ, interleukin (IL)-5, and IL-6 in the plasma of P301S transgenic mice, which can be served as potential plasma biomarkers in P301S Tg mice. Male P301S transgenic mice expressed more monokine induced by IFN-γ (MIG), tumor necrosis factor-α (TNF-α), IL-10, and IL-13 than those of female P301S mice. Conclusion: Our findings highlight sexual dimorphism in the behavior, neuropathology, and plasma proteins in tau P301S transgenic AD mice, indicating that the use of male P301S transgenic mice may be more suitable for assessing anti-phosphorylated tau therapeutic strategies for AD and related tauopathies, and the MIP-3α may be a new potential plasma biomarker.

GLP and G9a are major H3K9 dimethylases and are essential for mouse early embryonic development. GLP and G9a both harbor ankyrin repeat domains that are capable of binding H3K9 methylation. However, the functional significance of their recognition of H3K9 methylation is unknown. Here, we report that the histone methyltransferase activities of GLP and G9a are stimulated by neighboring nucleosomes that are premethylated at H3K9. These stimulation events function in cis and are dependent on the H3K9 methylation binding activities of ankyrin repeat domains of GLP and G9a. Disruption of the H3K9 methylation-binding activity of GLP in mice causes growth retardation of embryos, ossification defects of calvaria, and postnatal lethality due to starvation of the pups. In mouse embryonic stem cells (ESCs) harboring a mutant GLP that lacks H3K9me1-binding activity, critical pluripotent genes, including Oct4 and Nanog, display inefficient establishment of H3K9me2 and delayed gene silencing during differentiation. Collectively, our study reveals a new activation mechanism for GLP and G9a that plays an important role in ESC differentiation and mouse viability.

The transcription factor Snail2 is a repressor of E-cadherin expression during carcinogenesis; however, the specific mechanisms involved in this process in human colorectal cancer (CRC) remain largely unknown. We checked the expression of Snail2 in several clinical CRC specimens. Then, we established Snail2-overexpressing and knockdown cell lines to determine the function of Snail2 during EMT and metastasis processes in CRC. In addition, we used luciferase reporter assay to explore how Snail2 inhibits the expression of E-cadherin and induces EMT. We found that the expression of Snail2 was higher in clinical specimens of colorectal cancer (CRC) compared to non-cancerous tissues. Overexpression of Snail2 induced migration and metastatic properties in CRC cells in vitro and in vivo. Furthermore, overexpression of Snail2 promoted the occurrence of the epithelial–mesenchymal transition (EMT), downregulating the expression of E-cadherin and upregulating that of vimentin. Specifically, Snail2 could interact with HDAC6 and then recruited HDAC6 and PRC2 to the promoter of E-cadherin and thus inhibited the expression of E-cadherin, promoting EMT and inducing invasion and metastasis of CRC. Our study reveals that Snail2 might epigenetically suppress the expression of E-cadherin during CRC metastasis.

Functional E‐cadherin loss, a hallmark of epithelial‐mesenchymal transition (EMT), is important for metastasis. However, the mechanism of Snail2 in hepatocellular carcinoma (HCC) EMT and metastasis remains unclear. Here, we showed that Snail2 was upregulated in primary HCC, and significantly increased during transforming growth factor‐β‐induced liver cell EMT. Snail2‐overexpressing and knockdown cell lines have been established to determine its function in EMT in HCC. H3K9 methylation was upregulated and H3K4 and H3K56 acetylation were downregulated at the E‐cadherin promoter in Snail2‐overexpressing cancer cells. Furthermore, Snail2 interacted with G9a and histone deacetylases (HDACs) to form a complex to suppress E‐cadherin transcription. Snail2 overexpression enhanced migration and invasion in HCC cells, whereas G9a and HDAC inhibition significantly reversed this effect. Moreover, Snail2 overexpression in cancer cells increased tumor metastasis and shortened survival time in mice, whereas G9a and HDAC inhibitors extended survival. Our study not only reveals a critical mechanism underlying the epigenetic regulation of EMT but also suggests novel treatment strategies for HCC.