Long-term expression of zinc transporters in hippocampus following penicillin-induced developmental seizures and its regulation by E-64d

Abstract

Autophagy has been shown to be involved in the pathophysiology of developmental seizure-induced brain damage. The present study aimed to examine whether E-64d, an autophagy inhibitor, was able to facilitate developmental seizure-induced hippocampal mossy fiber sprouting, in particular sprouting-associated zinc transporter signals. Recurrent seizures were induced by penicillin every other day in Sprague-Dawley rats from postnatal day 21 (P21). Rats were randomly assigned into the control group (CONT), recurrent seizure group (RS) and the seizure plus E-64d group (E64D). The expression levels of beclin-1 and B-cell lymphoma 2 were analyzed at 1.5, 3, 6 and 24 h after the last seizures using western blot analysis. At P51, mossy fiber sprouting and the mRNA expression levels of zinc transporter 2 (ZnT-2), ZnT-4, ZnT-5, ZnT-6, ZnT-7, divalent cation transporter 1, Zrt-Irt-like protein 6 (ZIP-6), ZIP-7, cathepsin D and cathepsin L in the rat hippocampus were assessed using Timm staining and reverse transcription-quantitative polymerase chain reaction analysis, respectively. Reduced hippocampal mossy fiber sprouting were detected in the E-64d-treated rats compared with the non-treated control. In parallel with these observations, there was a marked reduction in the mRNA expression levels of ZnT-4 at P51 in the E-64d-treated rat hippocampus compared with the non-treated seizure group. Linear correlation analysis showed significant inter-relationship among ZIP-7, ZnT-4, ZnT-5, ZnT-7, cathepsin D and cathepsin L. These results indicate that the ZnT-4/ZIP-7/cathepsin signaling pathway serves a crucial function in the neuroprotective effects of E-64d. Thus, E-64d may offer a novel strategy for the development of therapeutic interventions for developmental seizure-induced brain damage.

The Protective Role of E-64d in Hippocampal Excitotoxic Neuronal Injury Induced by Glutamate in HT22 Hippocampal Neuronal Cells

“…Our results indicated that E-64d protected HT22 cells against glutamate-induced injury. To evaluate the effects of E-64d on neuronal cells, we first established an in vitro model by exposing HT22 cells and primary mouse astrocytes to 15 mM glutamate for 24 h. Our findings are consistent with our previous work, suggesting that E-64d exerts a neuroprotective effect against epilepsy-induced neuronal damage [ 41 , 62 ]. Using this glutamate-induced injury model, we then investigated the mechanisms by which E-64d exerts protective effects.…”

Transition metals and metal complexes in autophagy and diseases

“…This contradiction may be related to the different types and quantities of Zn transporters, differences in Zn accumulation in cells, and external stimulation; Zn oxide nanoparticles can also increase the activity of lysosomal proteases in skin cells to activate autophagy flux (Rudolf & Rudolf, 2017). In contrast, Zn accumulation in the lysosomes of dopamine neurons has little effect on autophagy flux or acid protease expression (Ni et al, 2016). In mussels, in addition to increasing the activity of lysosomal proteases, Zn nanoparticles disrupt membrane stability, releasing large quantities of proteases into the cytoplasm, thus blocking later stages of autophagy (Falfushynska et al, 2019).…”

Quantitative interactome proteomics identifies proteostasis network for GABAAreceptors

“…Dedicator of cytokinesis protein 7 (DOCK7), which is localized to the developing axons, activates Rac1 and Rac3 small GTPases and regulates neuronal polarity; moreover, its variants cause developmental and epileptic encephalopathy 23 (DEE23) (63,64). SLC39A7 (ZIP-7) is a Zn 2+ efflux transporter in the ER membrane; ZIP7 depletion causes neurodevelopmental impairments and ZIP7 signaling pathway provides neuroprotective effects in recurrent seizures (65,66).…”