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bioRxiv · 10.1101/2021.05.26.445899

Microtubules Promote the Non-cell Autonomy of MicroRNAs by Inhibiting their Cytoplasmic Loading into ARGONAUTE1 in Arabidopsis

Fan, L.·Zhang, C.·Zhang, Y.·Stewart, E.·Jez, J.·Nakajima, K.·Chen, X.
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Abstract

Mobile microRNAs (miRNAs) serve as local and long-distance signals in developmental patterning and stress responses in plants. However, mechanisms governing the non-cell autonomous activities of miRNAs remain elusive. Here, we show that mutations that disrupt microtubule dynamics are specifically defective for the non-cell autonomous actions of mobile miRNAs, including miR165/6 that is produced in the endodermis and moves to the vasculature to pattern xylem cell fates in Arabidopsis roots. We show that KTN1, a subunit of a microtubule-severing enzyme, is required in source and intermediary cells to inhibit the loading of miR165/6 into ARGONUATE1 (AGO1), which is cell-autonomous, to enable the miRNA"s cell exit. Microtubule disruption enhances the association of miR165/6 with AGO1 in the cytosol. These findings suggest that, while cell-autonomous miRNAs load into AGO1 in the nucleus, cytoplasmic AGO1 loading of mobile miRNAs is a key step regulated by microtubules to promote the range of miRNA"s cell-to-cell movement.

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Fan, L., Zhang, C., Zhang, Y., Stewart, E., Jez, J., Nakajima, K., Chen, X.. 2021-05-27. Microtubules Promote the Non-cell Autonomy of MicroRNAs by Inhibiting their Cytoplasmic Loading into ARGONAUTE1 in Arabidopsis. https://doi.org/10.1101/2021.05.26.445899

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