Altered Fibronectin-α5β1 Integrin-Src Signalling Pathway Drives Network Hyperexcitability in the Hippocampal...

Fibronectin (FN1), a vital extracellular matrix protein, has been reported to be elevated in blood and cerebrospinal fluid in epileptic patients exhibiting recent seizure activity. A transcriptomic study from MTLE-HS patients has identified FN1 as a potential gene linked to MTLE. Nonetheless, the function of FN1 and the participation of the FN1/α5β1-Integrin/Src kinase signaling pathway are yet to be fully investigated in both pre-clinical and clinical investigations of TLE. Furthermore, its role in NMDA receptor-mediated hyperexcitability in TLE requires investigation. This study evaluates the contribution of the FN1/α5β1-Integrin/Src kinase axis in facilitating NMDA-induced hyperexcitability in temporal lobe epilepsy. Hippocampal formation and ATL tissues from MTLE-HS patients, as well as acute and chronic Li-pilocarpine TLE rat models, were examined using qRT-PCR, immunoblotting, and ex vivo immunolabeling to evaluate the expression of FN1, α5β1 Integrin, Src kinase, and NMDA receptor subunits. To assess the functions of FN1 and Src in NMDA receptor-induced hyperexcitability, siRNA-mediated knockdown was conducted in TLE rats. Following knockdown, behavioral assessments, molecular studies, and in vivo EEG were employed to examine the FN1/α5β1 Integrin/Src axis in seizure-related hyperexcitability.In MTLE-HS patients and TLE rat models, FN1 and Src kinase showed upregulation in both the hippocampal formation and ATL, together with increased α5β1 Integrin levels in rats. Elevated Src activity was associated with augmented phosphorylation of NMDA receptors. The siRNA-mediated knockdown of FN1 or Src diminished NMDA receptor phosphorylation and markedly reduced seizure activity in TLE animals. Our research suggests that FN1 has a role in MTLE pathophysiology and may regulate NMDAR-mediated hyperexcitability via the FN1/α5β1 Integrin/Src kinase pathway. This pathway regulates seizures via the hippocampal formation and anterior temporal lobe networks. The therapeutic potential of targeting this signaling pathway for epilepsy needs additional investigation.