Ttyh1 protein is expressed in glia in vitro and shows elevated expression in activated astrocytes following status epilepticus.

Abstract

In a previous study, we showed that Ttyh1 protein is expressed in neurons in vitro and in vivo in the form of punctuate structures, which are localized to neuropil and neuronal somata. Herein, we provide the first description of Ttyh1 protein expression in astrocytes, oligodendrocytes and microglia in vitro. Moreover, using double immunofluorescence, we show Ttyh1 protein expression in activated astrocytes in the hippocampus following amygdala stimulation-induced status epilepticus. We demonstrate that in migrating astrocytes in in vitro wound model Ttyh1 concentrates at the edges of extending processes. These data suggest that Ttyh1 not only participates in shaping neuronal morphology, as previously described, but may also play a role in the function of activated glia in brain pathology. To localize Ttyh1 expression in the cellular compartments of neurons and astrocytes, we performed in vitro double immunofluorescent staining using markers for the following subcellular structures: endoplasmic reticulum (GRP78), Golgi apparatus (GM130), clathrin-coated vehicles (clathrin), early endosomes (Rab5 and APPL2), recycling endosomes (Rab11), trans-Golgi network (TGN46), endoplasmic reticulum membrane (calnexin), late endosomes and lysosomes (LAMP1) and synaptic vesicles (synaptoporin and synaptotagmin 1). We found that Ttyh1 is present in the endoplasmic reticulum, Golgi apparatus and clathrin-coated vesicles (clathrin) in both neurons and astrocytes and also in late endosomes or lysosomes in astrocytes. The presence of Ttyh1 was negligible in early endosomes, recycling endosomes, trans-Golgi network, endoplasmic reticulum membrane and synaptic vesicles.