TWIK-1 is the first identified member of the two-pore domain potassium (K2P) channels that are involved in neuronal excitability and astrocytic passive conductance in the brain. Despite the physiological roles of TWIK-1, there is still a lack of information on the basic expression patterns of TWIK-1 proteins in the brain. Here, using a modified bacterial artificial chromosome (BAC), we generated a transgenic mouse (Tg mouse) line expressing green fluorescent protein (GFP) under the control of the TWIK-1 promoter (TWIK-1 BAC-GFP Tg mice). We confirmed that nearly all GFP-producing cells co-expressed endogenous TWIK-1 in the brain of TWIK-1 BAC-GFP Tg mice. GFP signals were highly expressed in various brain areas, including the dentate gyrus (DG), lateral entorhinal cortex (LEC), and cerebellum (Cb). In addition, we found that GFP signals were highly expressed in immature granule cells in the DG. Finally, our TWIK-1 BAC-GFP Tg mice mimic the upregulation of TWIK-1 mRNA expression in the hippocampus following the injection of kainic acid (KA). Our data clearly showed that TWIK-1 BAC-GFP Tg mice are a useful animal model for studying the mechanisms regulating TWIK-1 gene expression and the physiological roles of TWIK-1 channels in the brain.

The inner ear is one of the sensory organs of vertebrates and is largely composed of the vestibule, which controls balance, and the cochlea, which is responsible for hearing. In particular, a problem in cochlear development can lead to hearing loss. Although numerous studies have been conducted on genes involved in the development of the cochlea, many areas still need to be discovered regarding factors that control the patterning of the early cochlear duct. Herein, based on the dynamic expression pattern of FOXG1 in the apical and basal regions of the E13.5 cochlear duct, we identified detailed expression regions through an open-source analysis of single-cell RNA analysis data and demonstrated a clinical correlation with hearing loss. The distinct expression patterns of FOXG1 and GATA3 during the patterning process of the cochlear duct provide important clues to understanding how the fates of the apical and basal regions are divided. These results are expected to be extremely important not only for understanding the molecular mechanisms involved in the early development of the cochlear duct, but also for identifying potential genes that cause hearing loss.