Metabolic Reprogramming of Microglia Enhances Proinflammatory Cytokine Release through EphA2/p38 MAPK Pathway in Alzheimer's Disease.

BACKGROUND: The activation of microglia and neuroinflammation has been implicated in the pathogenesis of Alzheimer's disease (AD), but the exact roles of microglia and the underlying mechanisms remain unclear. OBJECTIVE: To clarify how the metabolic reprogramming of microglia induce by amyloid-ß (Aß)1-42 to affect the release of proinflammatory cytokines in AD. METHODS: MTS assay was used to detect the viability of BV2 cells treated with different concentrations of Aß1-42 for different periods of time. The expression levels of proinflammatory cytokines were determined by qRT-PCR and western blot assay in BV2 cells and hippocampus of mice. RNA sequencing was applied to evaluate the gene expression profiles in response to HK2 knockdown in BV2 cells treated with Aß1-42. RESULTS: Low concentrations of Aß1-42 increased the viability of BV2 cells and promoted the release of proinflammatory cytokines, and this process is accompanied by increased glycolysis. Inhibition of glycolysis significantly downregulated the release of proinflammatory cytokines in BV2 cells and hippocampus of mice treated with Aß1-42. The results of RNA sequencing revealed the expression of chemokine ligand 2 (Cxcl2) and ephrin receptor tyrosine kinase A2 (EphA2) were significantly downregulated when knocked down HK2 in BV2 cells. Subsequently, the expression of proinflammatory cytokines was downregulated in BV2 cell after knocking down EphA2. CONCLUSION: This study demonstrated that EphA2/p38 MAPK pathway is involved the release of proinflammatory cytokines in microglia induced by Aß1-42 in AD, which is accompanied by metabolic reprogramming from oxidative phosphorylation (OXPHOS) to glycolysis.

Androgen Plays a Carcinogenic Role in EOC via the PI3K/AKT Signaling Pathway in an AR-Dependent Manner.

Background: Epithelial ovarian cancer (EOC) is one of the most common gynecological cancers with the highest mortality rate. Studies indicate that androgens contribute to initiation or progression of EOC through poorly understood mechanisms, however, in the phase II clinical studies of antiandrogen therapy for EOC, neither flutamide nor bicalutamide showed good antitumor effects. Based on the contradictions, the purpose of this study was to explore the role of androgen receptor (AR) in the androgen pathogenesis of EOC and the possible mechanism, and further to find an indicator to screen the anti-androgen therapy sensitive cases. Methods: In this study, 70 EOC biopsies and 17 para-cancerous tissues with complete medical information were collected and analyzed. The expression of the androgen receptor (AR) was detected by immunohistochemistry. In addition, ovarian cancer cell lines were used for in vitro studies to further explore the role of androgen in cell proliferation and the possible mechanisms. Results: The results showed that the expression of AR in ovarian cancer tissues was significantly elevated compared to the para-cancerous tissues, particularly in low-grade EOC, and the presence of high AR expression often suggested a worse prognosis. The in vitro study indicated that testosterone promoted the proliferation of the AR-positive SKOV3 cell line, which could be blocked by flutamide, but not in the AR-negative A2780 cell line. Next, we showed that testosterone-promoted proliferation in SKOV3 cells was abolished after we knocked out the AR. The mechanism studies revealed that the p-AKT expression in the ovarian cancer tissue was increased compared to the para-cancerous tissues, following a pattern similar to the increase of AR expression. Furthermore, the deletion and overexpression of SKOV3 cells' ARs lead to corresponding changes in the p-AKT levels. In addition, the BEZ235, an inhibitor of the PI3K/AKT signaling pathway blocked the proliferative effect of testosterone in SKOV3 cells. Conclusion: We showed that testosterone was able to promote the proliferation of ovarian cancer cells through activating the PI3K/AKT signaling pathway in an AR dependent manner and AR may be a screening indicator for anti-androgen therapy sensitive cases of EOC.

Non-genomic mechanisms mediate androgen-induced PSD95 expression.

The non-genomic actions of androgen-induced synaptic plasticity have been extensively studied. However, the underlying mechanisms remain controversial. We recently found that testosterone-fetal bovine serum albumin (T-BSA), a cell membrane-impermeable complex, led to a rapid increase in the postsynaptic density 95 (PSD95) protein level through a transcription-independent mechanism in mouse hippocampal HT22 cells. Using T-BSA conjugated FITC, we verified the presence of membrane androgen-binding sites. Here, we show that T-BSA-induced PSD95 expression is mediated by G-protein-coupled receptor (GPCR)-zinc transporter ZIP9 (SLC39A9), one of the androgen membrane binding sites, rather than the membrane-localized androgen receptor. Furthermore, we found that T-BSA induced an interaction between ZIP9 and Gnα11 that lead to the phosphorylation of Erk1/2 MAPK and eIF4E, which are critical in the mRNA translation process. The PSD95 and p-eIF4E expression decreased when knockdown of ZIP9 or Gnα11 expression or inhibition of Erk1/2 activation. Taken together, these findings suggest that ZIP9 mediates the non-genomic action of androgen on synaptic protein PSD95 synthesis through the Gnα11/Erk1/2/eIF4E pathway in HT22 cells. This novel mechanism provides a theoretical basis to understand the neuroprotective mechanism of androgen.