Replicative stress induces intragenic transcription of the ASE1 gene that negatively regulates Ase1 activity
Article, Other literature type
- Publisher: Elsevier BV
Agricultural and Biological Sciences(all) | Biochemistry, Genetics and Molecular Biology(all) | Article
Intragenic transcripts initiate within the coding region of a gene, thereby producing shorter mRNAs and proteins. Although intragenic transcripts are widely expressed , their role in the functional regulation of genes remains largely unknown. In budding yeast, DNA replication stress activates the S-phase checkpoint that stabilizes replication forks and arrests cells in S-phase with a short spindle [2-4]. When yeast cells were treated with hydroxyurea (HU) to block DNA synthesis and induce replication stress, we found that Ase1, a conserved spindle midzone protein , appeared as two short protein isoforms in addition to the full-length protein. We further demonstrated that the short isoforms result from intragenic transcription of ASE1, which depends on the S-phase checkpoint. Blocking generation of the short isoforms leads to a destabilized S-phase spindle, characterized by increased spindle dynamics and frequent spindle collapse. Because the short Ase1 isoforms localize at the spindle in HU-treated cells and overexpression of the short Ase1 isoforms impairs the spindle midzone localization of full-length Ase1, it is likely that the presence of short Ase1 isoforms stabilizes the spindle by antagonizing full-length Ase1. Together, our results reveal intragenic transcription as a unique mechanism to down-regulate gene functions in response to DNA replication stress.