J Integr Plant Biol. ›› 2023, Vol. 65 ›› Issue (5): 1113-1133.DOI: 10.1111/jipb.13450

• Abiotic Stress Responses • Previous Articles     Next Articles

The spliceophilin CYP18‐2 is mainly involved in the splicing of retained introns under heat stress in Arabidopsis

Areum Lee1, Hyun Ji Park1, Seung Hee Jo1,2, Haemyeong Jung1,2, Hyun‐Soon Kim1, Hyo‐Jun Lee1,3, Youn‐Sung Kim4, Choonkyun Jung5,6 and Hye Sun Cho1,2*   

  1. 1. Plant Systems Engineering Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Korea;
    2. Department of Biosystems and Bioengineering, KRIBB School of Biotechnology, University of Science and Technology (UST), Daejeon 34141, Korea;
    3. Department of Functional Genomics, KRIBB School of Bioscience, UST, Daejeon 34113, Korea;
    4. Department of Biotechnology, NongWoo Bio, Anseong 17558, Korea;
    5. Department of International Agricultural Technology and Crop Biotechnology Institute/Green Bio Science and Technology, Seoul National University, Pyeongchang 25354, Korea;
    6. Department of Agriculture, Forestry, and Bioresources and Integrated Major in Global Smart Farm, College of Agriculture and Life Sciences, Seoul National University, Seoul 08826, Korea
    *Correspondence: Hye Sun Cho (hscho@kribb.re.kr)
  • Received:2022-12-26 Accepted:2023-01-12 Online:2023-02-24 Published:2023-05-01

Abstract: Peptidyl‐prolyl isomerase‐like 1 (PPIL1) is associated with the human spliceosome complex. However, its function in pre‐mRNA splicing remains unclear. In this study, we show that Arabidopsis thaliana CYCLOPHILIN 18‐2 (AtCYP18‐2), a PPIL1 homolog, plays an essential role in heat tolerance by regulating pre‐mRNA splicing. Under heat stress conditions, AtCYP18‐2 expression was upregulated in mature plants and GFP‐tagged AtCYP18‐2 redistributed to nuclear and cytoplasmic puncta. We determined that AtCYP18‐2 interacts with several spliceosome complex BACT components in nuclear puncta and is primarily associated with the small nuclear RNAs U5 and U6 in response to heat stress. The AtCYP18‐2 loss‐of‐function allele cyp18‐2 engineered by CRISPR/Cas9‐mediated gene editing exhibited a hypersensitive phenotype to heat stress relative to the wild type. Moreover, global transcriptome profiling showed that the cyp18‐2 mutation affects alternative splicing of heat stress–responsive genes under heat stress conditions, particularly intron retention (IR). The abundance of most intron‐containing transcripts of a subset of genes essential for thermotolerance decreased in cyp18‐2 compared to the wild type. Furthermore, the intron‐containing transcripts of two heat stress‐related genes, HEAT SHOCK PROTEIN 101 (HSP101) and HEAT SHOCK FACTOR A2 (HSFA2), produced functional proteins. HSP101‐IR‐GFP localization was responsive to heat stress, and HSFA2‐III‐IR interacted with HSF1 and HSP90.1 in plant cells. Our findings reveal that CYP18‐2 functions as a splicing factor within the BACT spliceosome complex and is crucial for ensuring the production of adequate levels of alternatively spliced transcripts to enhance thermotolerance.

Key words: alternative splicing, CYP18‐2, HSFA2‐III, intron retention, spliceophilin, spliceosome complex BACT, thermotolerance

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