Dynamics of axonal β‐actin mRNA in live hippocampal neurons. (31st August 2022)

• Record Type: Journal Article
• Authors: Lee, Byung Hun; Bang, Seokyoung; Lee, Seung‐Ryeol; Jeon, Noo Li; Park, Hye Yoon
• Is Part Of: Traffic. Volume 23:Number 10(2022)
• Page Start: 496
• Page End: 505
• Publication Date: 2022-08-31
• Subjects: actin patch -- axonal β‐actin mRNA -- live‐cell imaging -- microfluidic device -- mRNA localization process; Biological transport -- Periodicals; 571.6
• DOI: 10.1111/tra.12865
• Languages: English
• ISSNs: 1398-9219

Abstract

Abstract: Localization of mRNA facilitates spatiotemporally controlled protein expression in neurons. In axons, mRNA transport followed by local protein synthesis plays a critical role in axonal growth and guidance. However, it is not yet clearly understood how mRNA is transported to axonal subcellular sites and what regulates axonal mRNA localization. Using a transgenic mouse model in which endogenous β‐actin mRNA is fluorescently labeled, we investigated β‐actin mRNA movement in axons of hippocampal neurons. We cultured neurons in microfluidic devices to separate axons from dendrites and performed single‐particle tracking of axonal β‐actin mRNA. Compared with dendritic β‐actin mRNA, axonal β‐actin mRNA showed less directed motion and exhibited mostly subdiffusive motion, especially near filopodia and boutons in mature dissociated hippocampal neurons. We found that axonal β‐actin mRNA was likely to colocalize with actin patches (APs), regions that have a high density of filamentous actin (F‐actin) and are known to have a role in branch initiation. Moreover, simultaneous imaging of F‐actin and axonal β‐actin mRNA in live neurons revealed that moving β‐actin mRNA tended to be docked in the APs. Our findings reveal that axonal β‐actin mRNA localization is facilitated by actin networks and suggest that localized β‐actin mRNA plays a potential role in axon branch formation. Abstract : In this study, we imaged β‐actin mRNA in live axons of hippocampal neurons. Compared with β‐actin mRNA in dendrites, axonal β‐actin mRNAs exhibited less directed motion with slower speed. The majority of them were localized to actin patches (APs) which are precursors of the axonal branch and showed confined diffusive motion within the APs.