Altered expression of DENND5B in patients with epilepsy and its regulation of seizures in mice

Epilepsy is a high incidence neurological disease, and its repeated attacks cause serious physical and psychological damage to the patient. Differentially expressed in normal and neoplastic cells (DENN) domain containing 5B (DENND5B) is a lipoprotein binding protein that mediates synaptic vesicle transport and regulates neuroplasticity and lipid metabolism. Nevertheless, the effect of DENND5B on seizures remains unclear. We aimed to investigate the association of DENND5B with epilepsy, detect its expression and distribution in the nervous system, and explore its role in epileptogenesis through western blot, immunofluorescence staining, and behavioral studies. In this experiment, two C57BL/6 mice models, which induced seizures by pentylenetetrazole and kainic acid, were established. We observed that the expression of DENND5B was reduced in the brains of patients with temporal lobe epilepsy, and its expression was also similarly decreased in both chronic epileptic mice. The findings strongly suggest that DENND5B may be associated with epileptic seizures. Results of immunofluorescence showed that DENND5B was mainly expressed in the hippocampal region and co-located with neurons but not with astrocytes. Next, we used lentivirus to induce both lentiviral vector-mediated overexpression and knockdown of DENND5B in mice to test the change of susceptibility and severity of seizures in the two chronic seizure models. Knockdown of DENND5B was found to promote epileptic seizures, increase chronic spontaneous recurrent epileptic seizures and epileptic discharge, and reduce the incubation period. However, overexpression of DENND5B showed the opposite effect. These results suggest that DENND5B overexpression decreased the behavioral phenotype of epileptic seizures, but DENND5B downregulation had the opposite effect. In summary, our findings suggest that DENND5B can regulate epileptic seizures and may provide a new target for antiepileptic therapy.