Introns Regulate Gene Expression in Cryptococcus Neoformans in a Pab2p Dependent Pathway

PLoS Genet. 2013;9(8):e1003686. doi: 10.1371/journal.pgen.1003686. Epub 2013 Aug 15.

Abstract

Most Cryptococccus neoformans genes are interrupted by introns, and alternative splicing occurs very often. In this study, we examined the influence of introns on C. neoformans gene expression. For most tested genes, elimination of introns greatly reduces mRNA accumulation. Strikingly, the number and the position of introns modulate the gene expression level in a cumulative manner. A screen for mutant strains able to express functionally an intronless allele revealed that the nuclear poly(A) binding protein Pab2 modulates intron-dependent regulation of gene expression in C. neoformans. PAB2 deletion partially restored accumulation of intronless mRNA. In addition, our results demonstrated that the essential nucleases Rrp44p and Xrn2p are implicated in the degradation of mRNA transcribed from an intronless allele in C. neoformans. Double mutant constructions and over-expression experiments suggested that Pab2p and Xrn2p could act in the same pathway whereas Rrp44p appears to act independently. Finally, deletion of the RRP6 or the CID14 gene, encoding the nuclear exosome nuclease and the TRAMP complex associated poly(A) polymerase, respectively, has no effect on intronless allele expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Nucleus / genetics
  • Cell Nucleus / metabolism
  • Cryptococcus neoformans / genetics
  • Gene Expression Regulation, Fungal*
  • Introns / genetics*
  • Metabolic Networks and Pathways / genetics
  • Poly A / genetics
  • Poly(A)-Binding Protein II / genetics*
  • RNA Splicing / genetics
  • RNA Stability / genetics*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism

Substances

  • Poly(A)-Binding Protein II
  • RNA, Messenger
  • Poly A

Grant support

CG was a recipient of a scholarship from the Pasteur-Paris University International Doctoral Program/Institut Carnot Maladies Infectieuses. THB was supported by a fellowship from the Australian Research Council. This work was supported by a grant from ANR (2010-BLAN-1620-01 programme YeastIntrons) to GJ. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.