Heterogeneous Nuclear Ribonucleoprotein H1 Coordinates with Phytochrome and the U1 snRNP Complex to Regulate Alternative Splicing in Physcomitrella patens

Abstract

Plant photoreceptors tightly regulate gene expression to control photomorphogenic responses. Although gene expression is modulated by photoreceptors at various levels, the regulatory mechanism at the pre-mRNA splicing step remains unclear. Alternative splicing, a widespread mechanism in eukaryotes that generates two or more mRNAs from the same pre-mRNA, is largely controlled by splicing regulators, which recruit spliceosomal components to initiate pre-mRNA splicing. The red/ far-red light photoreceptor phytochrome participates in light-mediated splicing regulation, but the detailed mechanism remains unclear. Here, using protein-protein interaction analysis, we demonstrate that in the moss Physcomitrella patens, phytochrome4 physically interacts with the splicing regulator heterogeneous nuclear ribonucleoprotein H1 (PphnRNP-H1) in the nucleus, a process dependent on red light. We show that PphnRNP-H1 is involved in red light-mediated phototropic responses in P. patens and that it binds with higher affinity to the splicing factor pre-mRNA-processing factor39-1 (PpPRP39-1) in the presence of red light-activated phytochromes. Furthermore, PpPRP39-1 associates with the core component of U1 small nuclear RNP in P. patens. Genome-wide analyses demonstrated the involvement of both PphnRNP-H1 and PpPRP39-1 in lightmediated splicing regulation. Our results suggest that phytochromes target the early step of spliceosome assembly via a cascade of protein-protein interactions to control pre-mRNA splicing and photomorphogenic responses.

Molecular mechanisms underlying phytochrome-controlled morphogenesis in plants

“…Post-transcriptionally, phytochromes may control alternative splicing (AS) (extensively reviewed in Cheng et al 114 ). In Physcomitrella patens phytochromes appear to directly regulate AS 115 . In Arabidopsis, despite the identification of a number of splicing factors that can interact with phytochromes 116,117 , it remains debated whether AS is due to direct phytochrome regulation, is an indirect metabolic consequence of de-etiolation or a combination of both 114,118 .…”

Differential Transcription and Alternative Splicing in Cotton Underly Specialized Defense Responses Against Pests

“…AS is a conserved gene regulation in eukaryotes and has been thought to be involved in many biological processes. In recent years the AS regulation in stress has been reported (Laloum et al, 2018;de Francisco Amorim et al, 2018;Calixto et al, 2018;Shih et al, 2019). Here, we found that most DAS genes caused by insect damage were not affected at the transcription level.…”

Genomewide SNP marker identification associated with drought tolerance in oil palm

“…A SNP was located in the intron sequence of each RNP1 and SNRNP59. These genes were nuclear ribonucleoprotein, that have mRNA processing function in the plant (Shih et al 2019). Two SNPs were located in the intron of AHL1 gene.…”