A new player in photomorphogenesis

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Li et al. discover a regulator of alternative splicing during light-regulated plant growth and development https://doi.org/10.1093/plcell/koac235

 By Yang Li and Rongcheng Lin

 Background: Light is one of the most important environmental factors affecting plant growth and developmental processes, such as photomorphogenesis. CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) is a central player in the light signaling pathway that targets several other proteins for degradation. Alternative splicing is a pivotal post-transcriptional process that may produce different protein variants and contributes to proteome diversity and gene regulation. Previous transcriptomic analysis indicated that light induces massive alternative splicing in plants. However, only a few splicing regulators involved in regulating light responses have been identified.

 Question: We were interested in identifying new splicing factors that regulate photomorphogenesis and dissecting their underlying molecular mechanism.

Findings: We show that the RNA helicase UAP56 is a negative regulator of photomorphogenesis in Arabidopsis. UAP56 interacts with COP1 in vitro and in plant cells. RNA sequencing analysis revealed that UAP56 and COP1 co-regulate the expression levels of many genes as well as the splicing of many common pre-mRNAs. RNA immunoprecipitation assays demonstrated that UAP56 and COP1 bind to common small nuclear RNAs and target mRNAs. This study identified a role of UAP56 in regulating light-mediated seedling growth as well as a mechanism by which UAP56 and COP1 modulate pre-mRNA alternative splicing in plants.

Next steps: It would be of interest to determine how UAP56 and COP1 execute their overlapping and distinct roles and their relationship with phytochrome in regulating alternative splicing.

Reference:

Yang Li, Yanxin Du, Junling Huai, Yanjun Jing, Rongcheng Lin (2022). The RNA helicase UAP56 and the E3 ubiquitin ligase COP1 coordinately regulate alternative splicing to repress photomorphogenesis in Arabidopsis. https://doi.org/10.1093/plcell/koac235