Our group studies post-transcriptional regulation (RNA biology) in the brain in relation to synapse dynamics over cognitive development and decline. Structural and functional changes of synapses occur in an activity-dependent manner and are mediated by highly orchestrated gene networks. Our goal is to understand the regulation of gene expression within the neural circuits during development, long-term neuronal plasticity, and disease with an emphasis on the spatiotemporal regulation mechanisms. In an essential effort to achieve this goal, we are developing effective RNA live-imaging methods for sensitive and quantitative studies of RNA dynamics in living neural circuits. Our research has a strong orientation to incorporate novel bioactive materials and chemical approaches to biological studies, which drives us to do cross-disciplinary research projects inside and outside iCeMS.
We are currently pursuing to answer the following questions:
How do specific RNA localize to synapses of neurons? The fact that only select RNAs are targeted to synapses and the species of localized RNA differ between cell types, indicates that neurons dedicate their trafficking mechanisms to transport specific RNA species. Sensorin mRNA, encoding a neuropeptide in Aplysia central nervous system, is localized to synapses (red) by presenting a secondary RNA structure within the 5’UTR just upstream of the translation initiation site. More RNAs have been shown to travel to specific locations in cells.
Meer E*, Wang DO*, Kim SM, Barr I, Guo F, and Martin KC. Identification of a cis-element that localizes mRNA to synapses. PNAS, Mar 20;109 (12):4639-44 (2012) (*Equal contribution).
Kashida S, Wang DO*, Saito H, Gueroui Z. Nanoparticle-based local translation reveals mRNA as translation-coupled scaffold with anchoring function. PNAS, 116 (27):13346-51 (2019).
Wang DO, Ninomiya K, Mori C, Koyama A Haan M, Kitabatake M, Hagiwara M, Chida K, Tahakashi S, Ohno M*, Kataoka N*. Transport granules bound with nuclear cap binding protein and exon junction complex imply a role of pioneer round translation in mRNP remodeling in human neuronal processes. Front. Mol Biosci DOI.org/10.3389/fmolb.2017.00093 (2017)
How do localized RNA respond to synaptic activity? A central question of post-transcriptional regulation of RNA within neuronal circuits is how external local stimuli (e.g. synaptic activity) regulate RNA function such as their modification, translation, and degradation. Using Aplysia sensorin mRNA as a model molecule, we found that the translation of sensorin mRNA can be triggered by learning-related stimuli (5HT to induce long-term facilitation of sensory-motor synaptic connection). This regulation is spatially restricted to the stimulated synapses, in a sensitive manner to the type of the stimuli (for example, the regulated translation occurs in response to long-term facilitation, but not to short-term facilitation, or long-term depression stimulus). Intriguingly, a trans-synaptic signal is required for activating the translation, of which the identity remains elusive.
Merkurjev D, Hong WT, Iida K, Goldie BJ, Yamaguti H, Oomoto I, Ohara T, Kawaguchi S, Hirano T, Martin KC, Pellegrini M, Wang DO*. Synaptic N6 methyladenosine (m6A) reveals functional partitioning of localized transcripts. Nature Neuroscience, 21, 1004–1014 (2018)
Wang DO, Kim SM, Zhao Y, Hwang HG, Miura SK, Sossin WS, and Martin KC. Synapse- and stimulus-specific local translation during long-term neuronal plasticity. Science 324(5934): 1536-40 (2009)
How are localized RNA regulated in space and time? Fluorescent proteins such as GFP have transformed our view of protein trafficking in living cells and living organisms. In contrast, effective live-imaging methods to study RNA regulation are yet to be developed. We found that novel photochemical RNA probes with defined sequences may become useful tools that allow us to monitor when, where, in what amount and how much of this amount may change over time for an RNA in living neuronal circuits, especially during learning. As an initial step, we developed a simplified FISH (fluorescent in situ hybridization) procedure that requires no stringency washes in the entire procedure thus can be applied to live-cell imaging, a closed and highly noisy system.
Wang DO and Akimitsu Okamoto. ECHO probes: fluorescence emission control for nucleic acid imaging. Journal of Photochemistry and Photobiology, C: Photochemistry Reviews Jun 13:2 112-23 (2012)
Wang DO*, Matsuno H, Ikeda S, Nakamura A, Yanagisawa H, Hayashi Y and Akimitsu Okamoto*. A Quick and Simple FISH Protocol with Hybridization-sensitive Fluorescent Linear Oligodeoxynucleotide Probes. RNA Jan;18(1):166-75 (2012)
Oomoto I, Hirano-Suzuki A, Umeshima H, Han YW, Yanagisawa H, Carlton P, Harada Y, Kengaku M, Okamoto A, Shimogori T, and Wang DO*. ECHO-liveFISH: in vivo RNA Labeling Reveals Dynamic Regulation of Nuclear RNA Foci in Living Tissues. Nucl Acids Res DOI:10.1093/narlgkv614 (2015)
*This work has been featured in “Nikkei Sangyo Shimbun” and “Weekly Economist”.
Wang DO* Live Imaging of Nuclear RNPs in Mammalian Complex Tissue with ECHO-liveFISH. Methods Mol Biol, 1649:259-272 (2018).
We currently receive funding from the following resources: