Inhibition of transcription by the Caenorhabditis elegans germline protein PIE-1: Genetic evidence for distinct mechanisms targeting initiation and elongation

Dolan Ghosh, Geraldine Seydoux

Research output: Contribution to journalArticle

Abstract

In Caenorhabditis elegans embryos, specification of the germ lineage depends on PIE-1, a maternal protein that blocks mRNA transcription in germline blastomeres. Studies in mammalian cell culture have suggested that PIE-1 inhibits P-TEFb, a kinase that phosphorylates serine 2 in the carboxyl-terminal domain (CTD) repeats of RNA polymerase II during transcriptional elongation. We have tested this hypothesis using an in vivo complementation assay for PIE-1 function. Our results support the view that PIE-1 inhibits P-TEFb using the CTD-like motif YAPMAPT. This activity is required to block serine 2 phosphorylation in germline blastomeres, but unexpectedly is not essential for transcriptional repression or specification of the germline. We find that sequences outside of the YAPMAPT are required to inhibit serine 5 phosphorylation, and that this second inhibitory mechanism is essential for transcriptional repression and specification of the germ lineage. Our results suggest that PIE-1 uses partially redundant mechanisms to block transcription by targeting both the initiation and elongation phases of the transcription cycle.

Original languageEnglish (US)
Pages (from-to)235-243
Number of pages9
JournalGenetics
Volume178
Issue number1
DOIs
StatePublished - Jan 2008

ASJC Scopus subject areas

  • Genetics

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