HYPER RECOMBINATION1 of the THO/TREX complex plays a role in controlling transcription of the REVERSION-TO-ETHYLENE SENSITIVITY1 gene in Arabidopsis

PLoS Genet. 2015 Feb 13;11(2):e1004956. doi: 10.1371/journal.pgen.1004956. eCollection 2015 Feb.

Abstract

Arabidopsis REVERSION-TO-ETHYLENE SENSITIVITY1 (RTE1) represses ethylene hormone responses by promoting ethylene receptor ETHYLENE RESPONSE1 (ETR1) signaling, which negatively regulates ethylene responses. To investigate the regulation of RTE1, we performed a genetic screening for mutations that suppress ethylene insensitivity conferred by RTE1 overexpression in Arabidopsis. We isolated HYPER RECOMBINATION1 (HPR1), which is required for RTE1 overexpressor (RTE1ox) ethylene insensitivity at the seedling but not adult stage. HPR1 is a component of the THO complex, which, with other proteins, forms the TRanscription EXport (TREX) complex. In yeast, Drosophila, and humans, the THO/TREX complex is involved in transcription elongation and nucleocytoplasmic RNA export, but its role in plants is to be fully determined. We investigated how HPR1 is involved in RTE1ox ethylene insensitivity in Arabidopsis. The hpr1-5 mutation may affect nucleocytoplasmic mRNA export, as revealed by in vivo hybridization of fluorescein-labeled oligo(dT)45 with unidentified mRNA in the nucleus. The hpr1-5 mutation reduced the total and nuclear RTE1 transcript levels to a similar extent, and RTE1 transcript reduction rate was not affected by hpr1-5 with cordycepin treatment, which prematurely terminates transcription. The defect in the THO-interacting TEX1 protein of TREX but not the mRNA export factor SAC3B also reduced the total and nuclear RTE1 levels. SERINE-ARGININE-RICH (SR) proteins are involved mRNA splicing, and we found that SR protein SR33 co-localized with HPR1 in nuclear speckles, which agreed with the association of human TREX with the splicing machinery. We reveal a role for HPR1 in RTE1 expression during transcription elongation and less likely during export. Gene expression involved in ethylene signaling suppression was not reduced by the hpr1-5 mutation, which indicates selectivity of HPR1 for RTE1 expression affecting the consequent ethylene response. Thus, components of the THO/TREX complex appear to have specific roles in the transcription or export of selected genes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics*
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / biosynthesis
  • Arabidopsis Proteins / genetics*
  • Ethylenes / metabolism
  • Gene Expression Regulation, Plant
  • Hypocotyl / genetics
  • Membrane Proteins / biosynthesis
  • Membrane Proteins / genetics*
  • Phenotype
  • RNA, Messenger / biosynthesis
  • Receptors, Cell Surface / biosynthesis
  • Receptors, Cell Surface / genetics
  • Seedlings / genetics
  • Transcription, Genetic*

Substances

  • Arabidopsis Proteins
  • EMU protein, Arabidopsis
  • ETR1 protein, Arabidopsis
  • Ethylenes
  • Membrane Proteins
  • RNA, Messenger
  • RTE1 protein, Arabidopsis
  • Receptors, Cell Surface
  • ethylene

Grants and funding

This work was supported by the the Chinese Ministry of Science and Technology (2011CB100700 and 2012AA10A302-2; http://program.most.gov.cn/)and National Natural Sciences Foundation of China (31123006 and 31370314; http://www.nsfc.org.cn/) to CKW. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.