Extraordinary Seminar – 4th November – Dr. Shih-Shun Lin

Dr. Shih-Shun Lin

Institute of Biotechnology, National Taiwan University, Taiwan

“The unique biological properties of AGO1 reveal the autonomy of gene regulation in RNA silencing”

Abstract

RNA silencing is essential for plant gene regulation and viral defense. Our study reveals that the potyviral viral suppressor HC-Pro inhibits RNA silencing, disrupting microRNA (miRNA)-mediated regulation. To explore the suppression mechanism of HC-Pro, we examined three different potyviral HC-Pros, including turnip mosaic virus (TuMV; HC-Pro^Tu), zucchini yellow mosaic virus (ZYMV; HC-Pro^Zy), and tobacco etch virus (TEV; HC-Pro^Te). We found that HC-Pro^Tu transgenic plants (HC-Pro^Tu plants) demonstrated a higher capability to degrade Arabidopsis AGO1 (AtAGO1) through autophagy than HC-Pro^Zy and HC-Pro^Te plants. Additionally, HC-Pro^Tu plants more effectively inhibit HEN1-mediated miRNA methylation. Our research suggests that HC-Pro triggers autophagic degradation of AGO1, which is linked to the inhibition of miRNA methylation. Unmethylated miRNAs loaded into AtAGO1 induce autophagic AGO1 degradation via an unknown function of HESO1. Moreover, our study on miRNA regulation in Marchantia polymorpha shows that heat stress can influence RNA silencing. Under high temperatures, MpAGO1 and its associated miRNA need to maintain stability within the cell. The autonomy of different miRNAs in loading into AGO1 and regulating target genes varies during heat stress. Investigating the RNA silencing mechanisms in bryophytes and angiosperms has helped us further understand miRNA methylation and AGO1 autonomy.

1. Pan, Z.J., Wei, W.L., Tran, P.A., Fang, R.Y., Pham, T.H., Bowman, J.L., Chung, C.T., Shen, B.N., Yang, J.T., Hong, S.F., Shang, Q.W., Hu, S.F., Lin, P.C., Wu, F.H., Lin, C.S., Shen, T.L., Lin, S.S.* 2024. Turnip mosaic virus HC-Pro suppresses RNA silencing by sequencing HEN1 activity and enhancing autophagic AGO1 degradation. Nature Communications (Major revision) (*Correspond author) https://doi.org/10.21203/rs.3.rs-2131027/v1
2. Hong, S.F., Wei, W.L., Pan, Z.J., Yu, J.Z., Cheng, S., Hung, Y.L., Tjita, V., Wang, H.C., Komatsu, A., Nishihama, R., Kohchi, T., Chen, H.C., Chen, W.C., Lo, J.C., Chiu, Y.H., Yang, H. C., Lu, M.Y., Liu, L.Y.D., and Lin. S.S.* 2024. Molecular insights into MpAGO1 and its regulatory miRNA, miR11707, in the high-temperature acclimation of Marchantia polymorpha. Plant Cell Physiol. 65:1414-1433 (*Correspond author)
3. Hung, Y.L., Hong, S.F., Wei, W.L., Cheng, S., Yu, J.Z., Tjita, V., Yong, Q.Y., Nishihama, R., Kohchi, T., Bowman, J., Chien, Y.C., Chiu, Y.H., Yang, H.C., Lu, M.Y.J., Pan, Z.J.*, Wang, C.N.*, Lin, S.S.* 2024. Dual regulation of cytochrome P450 gene expression by two distinct small RNAs, a novel tasiRNA and miRNA, in Marchantia polymorpha. Plant Cell Physiol. 65:1115-1134 (*Co-correspond author) (Cover photo)

Short Bio

Professor 2018 – now. Institute of Biotechnology, National Taiwan University, Taiwan

Adjunct Research Fellow 2018 – now. Center of Biotechnology, National Taiwan University, Taiwan

Adjunct Research Fellow 2020 – now. Agricultural Biotechnology Research Center, Academia Sinica, Taiwan

Associate Editor of Virology Journal 2021 – now.

Associate Editor of Journal of Plant Research 2022 – now

If anyone is interested in meeting with the speaker, please contact José Antonio Darós (jadaros@ibmcp.upv.es).