Genetic requirements for PIE-1 localization and inhibition of gene expression in the embryonic germ lineage of Caenorhabditis elegans

Dev Biol. 1998 Aug 15;200(2):212-24. doi: 10.1006/dbio.1998.8940.

Abstract

In early Caenorhabditis elegans embryos, production of new mRNAs is inhibited in the germ lineage. This inhibition requires the germline factor PIE-1, and correlates with the absence in germline blastomeres of a phosphoepitope on RNA polymerase II (RNAPII-H5). We show that PIE-1 is uniformly distributed in oocytes and newly fertilized eggs, and becomes localized asymmetrically in the late one-cell stage. To begin to dissect the mechanisms required for PIE-1 localization and inhibition of RNAPII-H5 expression, we have examined the distribution of PIE-1 and RNAPII-H5 in maternal-effect mutants that disrupt embryonic development. We find that mutants that disrupt the asymmetric divisions of germline blastomeres mislocalize PIE-1, and activate RNAPII-H5 expression in the germ lineage. In contrast, mutants that alter somatic cell identities do not affect PIE-1 localization or RNAPII-H5 expression. Our observations suggest that PIE-1 represses mRNA transcription in each germline blastomere in a concentration-dependent manner. We also show that in wild-type, and in mutants where PIE-1 is mislocalized, the cellular and subcellular distribution of PIE-1 remarkably parallels that of the P granules, suggesting that the localizations of these two germline components are coordinately regulated.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antibodies, Monoclonal / metabolism
  • Caenorhabditis elegans / embryology*
  • Caenorhabditis elegans Proteins*
  • Cytoplasmic Granules / metabolism
  • DNA / analysis
  • Fluorescent Antibody Technique
  • Gene Expression Regulation, Developmental / genetics*
  • Germ Cells / metabolism*
  • Heterozygote
  • In Situ Hybridization
  • Mutation / genetics
  • Nuclear Proteins / immunology
  • Nuclear Proteins / metabolism*
  • Oocytes / chemistry
  • Phenotype
  • RNA Polymerase II / metabolism
  • RNA, Messenger / metabolism
  • Transcriptional Activation / physiology

Substances

  • Antibodies, Monoclonal
  • Caenorhabditis elegans Proteins
  • Nuclear Proteins
  • RNA, Messenger
  • pie-1 protein, C elegans
  • DNA
  • RNA Polymerase II