Abstract
Serine/arginine-rich (SR) proteins are important splicing factors which play significant roles in spliceosome assembly and splicing regulation. However, little is known regarding their biological functions in plants. Here, we analyzed the phenotypes of mutants upon depleting different subfamilies of Arabidopsis SR proteins. We found that loss of the functions of SC35 and SC35-like (SCL) proteins cause pleiotropic changes in plant morphology and development, including serrated leaves, late flowering, shorter roots and abnormal silique phyllotaxy. Using RNA-seq, we found that SC35 and SCL proteins play roles in the pre-mRNA splicing. Motif analysis revealed that SC35 and SCL proteins preferentially bind to a specific RNA sequence containing the AGAAGA motif. In addition, the transcriptions of a subset of genes are affected by the deletion of SC35 and SCL proteins which interact with NRPB4, a specific subunit of RNA polymerase II. The splicing of FLOWERING LOCUS C (FLC) intron1 and transcription of FLC were significantly regulated by SC35 and SCL proteins to control Arabidopsis flowering. Therefore, our findings provide mechanistic insight into the functions of plant SC35 and SCL proteins in the regulation of splicing and transcription in a direct or indirect manner to maintain the proper expression of genes and development.
Highlights
Alternative splicing (AS) is an important mechanism in the regulation of gene expression by excising introns and ligating different exons to produce multiple mRNA isoforms from a single gene
Genetic analysis revealed that loss of the function of SC35/SCL proteins influences the plant development
This study revealed SC35/SCL proteins regulate alternative splicing, preferentially bind a specific RNA motif, interact with NRPB4, and affect the transcription of a subset of genes
Summary
Alternative splicing (AS) is an important mechanism in the regulation of gene expression by excising introns and ligating different exons to produce multiple mRNA isoforms from a single gene. This post-transcriptional process greatly enhances transcriptome and proteome complexity [1,2]. Pre-mRNAs from >95% protein-coding genes are alternatively spliced to produce mature mRNAs [3,4]. AS plays a key role in the life process by modulating the gene expression in development [7,8,9,10,11]. Aberrant AS may affect their growths and defense responses [13,14,15,16]
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