Biology subjects

Kim, I.-B.

Publications and source records attributed to Kim, I.-B..

2 recordsLinked to original sources

bioRxiv2024

IK channel confers fine-tuning of rod bipolar cell excitation and synaptic transmission in the retina

During retinal visual processing, rod bipolar cells (RBCs) transfer scotopic signals from rods to AII amacrine cells as second-order neurons. Elucidation of the RBC excitation/inhibition is essential for understanding the visual signal transmission. Although excitation and extrinsic inhibitory mechanisms have been studied, intrinsic inhibitory mechanisms remain unclear. We focused on RBCs prominent K+ current, which exhibits voltage and Ca2+ dependence. We isolated and confirmed intermediate-conductance Ca2+-activated K+ channels (IK) and in RBCs using the patch-clamp method with IK inhibitors (clotrimazole and TRAM34). The regulation of the IK current primarily relies on Ca2+ influx via low-threshold Ca2+ channels during RBC excitation. It mediates RBC repolarization and oscillation, enabling fast and transient synaptic transmission to AII amacrine cells. Our findings highlight the unique role of the IK channel in RBC, suggesting that it plays a critical role in the scotopic pathway by fine-tuning RBC activity.

neuroscience↗

bioRxiv2022

Amplification of Olfactory Signals by Anoctamin 9 is Essential for Mammalian Olfaction: a Risk Factor for the Covid-19-associated Anosmia

Sensing smells of foods, prey, or predators determines animal survival. Olfactory sensory neurons in the olfactory epithelium (OE) detect odorants, where cAMP and Ca2+ play a significant role in transducing odorant inputs to electrical activity. Here we show Anoctamin 9, a cation channel activated by cAMP/PKA pathway, is expressed in the OE and amplifies olfactory signals. Ano9- deficient mice had reduced olfactory behavioral sensitivity, electro-olfactogram signals, and neural activity in the olfactory bulb. In line with the difference in olfaction between birds and other vertebrates, chick ANO9 failed to respond to odorants, whereas chick CNGA2, a major transduction channel, showed greater responses to cAMP. Importantly, single-cell transcriptome data from Covid-19 patients revealed that Ano9 transcripts were markedly suppressed among genes in the olfactory signal pathway. The signal amplification by ANO9 is essential for mammalian olfactory transduction, whose downregulation may be a risk factor for the olfactory dysfunction in Covid-19 patients.

cell biology↗