Human prefoldin modulates co-transcriptional pre-mRNA splicing

Abstract

Prefoldin is a heterohexameric complex conserved from archaea to humans that plays a cochaperone role during the cotranslational folding of actin and tubulin monomers. Additional functions of prefoldin in the cell nucleus have been described, including a positive contribution to transcription elongation and chromatin dynamics in yeast. Here we show that prefoldin depletion provoked transcriptional alterations across the genome of human cells. Severe pre-mRNA splicing defects were also detected, particularly under serum stimulation conditions. We found a significant impairment of co-transcriptional splicing during transcription elongation, that explains why the expression of long genes with a high number of introns was affected the most. We detected prefoldin binding to the gene body of transcribed genes and found that its lack caused significant decrease in the levels of Ser2 phosphorylation of the RNA polymerase II carboxiterminal domain. Moreover, lack of prefoldin reduced the association of splicing factor U2AF65 with chromatin, an association that is known to be dependent on Ser2 phosphorylation. Considered altogether the reported results indicate that human prefoldin is able to modulate gene expression by influencing phosphorylation of elongating RNA polymerase II, and thereby regulating co-transcriptional splicing efficiency.

A role for prefoldins in H2A.Z deposition inArabidopsis

“…This may occur, for instance, by facilitating the recruitment of the remodeler to the chromatin. Although PFDs do not seem to bind DNA directly, they have been found bound to the chromatin by ChIP in yeast and humans (Wang et al, 2017;Payán-Bravo et al, 2020;Millan-Zambrano et al, 2013), and by cell fractioning in Arabidopsis (Locascio et al, 2013). The molecular mechanism that provides specificity to PFDs' action on H2A.Z deposition is, therefore, a matter for future research.…”

“…Work in Arabidopsis has demonstrated that PFDs participate in the splicing of a particular set of pre-mRNAs by promoting the stability of the core spliceosome complex LSM2-8 (Esteve-Bruna et al, 2020). In humans, depletion of PFDN5 affects co-transcriptional splicing of long genes by preventing the recruitment of the splicing factor U2AF65 to the target loci (Payán-Bravo et al, 2020).…”