Hypothermia Alleviates TBI-Induced Tau Hyperphosphorylation Through RBM3-Dependent GSK-3β and AMPK Pathways

Traumatic brain injury (TBI) often results in tau hyperphosphorylation, a key pathological feature of neurodegenerative diseases such as Alzheimer's disease. Hypothermia (HT) is a promising therapeutic intervention for TBI, but the underlying molecular mechanisms remain unclear. This study investigates the role of RNA-binding motif protein 3 (RBM3) in mediating the neuroprotective effects of HT on tau phosphorylation and its involvement in glycogen synthase kinase 3 beta (GSK-3β) and AMP-activated protein kinase (AMPK) signaling.

We used a TBI mouse model to assess the effects of HT on tau phosphorylation using Western blotting and immunohistochemistry. The phosphorylation status of GSK-3β (Ser9) and AMPK (Thr172) was also analyzed to explore key signaling pathways. RBM3 expression was modulated using RBM3 short hairpin RNA (knockdown) and adenovirus-RBM3 plasmid (overexpression) to determine its role in HT-induced changes in tau phosphorylation.

Hypothermia treatment significantly reduced tau hyperphosphorylation in TBI mice compared with controls. Western blotting revealed a significant increase in GSK-3β Ser9 phosphorylation (p < 0.01) and AMPK Thr172 phosphorylation (p < 0.05) in the HT group. Manipulation of RBM3 expression showed that both RBM3 knockdown and overexpression affected the extent of tau dephosphorylation mediated by HT. Specifically, RBM3 overexpression enhanced the protective effects of HT, whereas knockdown diminished its efficacy.

Our findings suggest that RBM3 is a crucial mediator of the neuroprotective effects of hypothermia in TBI, acting through modulation of GSK-3β and AMPK signaling pathways. These results provide new insights into the molecular mechanisms of TBI treatment and highlight RBM3 as a potential therapeutic target for neurodegenerative diseases associated with tauopathies. Limitations include the need for further validation in clinical models.