ALDOC modulates astrocytic glycolysis and AMPK/mTOR/HIF-1α signaling in Alzheimer's disease

Astrocytes provide crucial metabolic support for neurons and undergo significant metabolic changes in Alzheimer's disease (AD). Aldolase C (ALDOC), an astrocyte-enriched glycolytic enzyme, may play a role in this process. This study aimed to investigate whether ALDOC modulates astrocytic metabolism to support neuronal energy supply in patients with AD and to assess its therapeutic potential.

Hippocampal and cortical tissues from 6-month-old APP/PS1 and wild-type mice were subjected to western blotting, qPCR, and immunofluorescence staining for ALDOC and glycolytic proteins. An in vitro AD model was created using oligomeric β-amyloid (oAβ)-treated SVGp12 astrocytes. ALDOC was overexpressed or knocked down via plasmid or siRNA. Downstream effects on AMPK/mTOR/HIF-1α signaling and the expression of glycolytic markers (LDHA and PKM2) were evaluated by western blot and qPCR, as well as by lactate/ATP assays and extracellular acidification rate (ECAR) measurements. Neuron-astrocyte interactions were assessed in an SVGp12/SH-SY5Y coculture. Furthermore, the ability of magnesium ions to restore ALDOC expression was tested.

ALDOC was specifically expressed in astrocytes but was downregulated in APP/PS1 mice, accompanied by reduced HIF-1α and LDHA levels, suggesting glycolytic impairment. Similar downregulation occurred in oAβ-treated SVGp12 cells. ALDOC overexpression was associated with altered AMPK/mTOR/HIF-1α signaling, enhanced glycolysis, and increased lactate and ATP production, whereas its knockdown had the opposite effects. These outcomes appeared to depend on HIF-1α, as suggested by the rescue experiments. In coculture, ALDOC overexpression in astrocytes supported neuronal metabolic function. Moreover, magnesium ions restored ALDOC activity and glycolysis in oAβ-treated astrocytes.

These results suggest that ALDOC is downregulated in APP/PS1 mice and is associated with glycolytic impairment. In oAβ-treated astrocytes, ALDOC appears to regulate glycolysis through the AMPK/mTOR/HIF-1α axis and may support neuronal energy via the lactate shuttle. Magnesium ions appear to offer a potential strategy for addressing the metabolic deficits in AD.