title: The cytoplasmic poly(A) polymerases GLD-2 and GLD-4 promote general gene expression via distinct mechanisms.
abstract: Post-transcriptional gene regulation mechanisms decide on cellular mRNA activities. Essential gatekeepers of post-transcriptional mRNA regulation are broadly conserved mRNA-modifying enzymes, such as cytoplasmic poly(A) polymerases (cytoPAPs). Although these non-canonical nucleotidyltransferases efficiently elongate mRNA poly(A) tails in artificial tethering assays, we still know little about their global impact on poly(A) metabolism and their individual molecular roles in promoting protein production in organisms. Here, we use the animal model Caenorhabditis elegans to investigate the global mechanisms of two germline-enriched cytoPAPs, GLD-2 and GLD-4, by combining polysome profiling with RNA sequencing. Our analyses suggest that GLD-2 activity mediates mRNA stability of many translationally repressed mRNAs. This correlates with a general shortening of long poly(A) tails in gld-2-compromised animals, suggesting that most if not all targets are stabilized via robust GLD-2-mediated polyadenylation. By contrast, only mild polyadenylation defects are found in gld-4-compromised animals and few mRNAs change in abundance. Interestingly, we detect a reduced number of polysomes in gld-4 mutants and GLD-4 protein co-sediments with polysomes, which together suggest that GLD-4 might stimulate or maintain translation directly. Our combined data show that distinct cytoPAPs employ different RNA-regulatory mechanisms to promote gene expression, offering new insights into translational activation of mRNAs.
authors.affiliation: Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstrasse 108, Dresden, 01307, Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Nousch
authors.affiliation: Max Planck Institute of Biochemistry (MPIB), Am Klopferspitz 18, Martinsried, 82152, Germany.
authors.forename: Assa
authors.initials: A
authors.lastname: Yeroslaviz
authors.affiliation: Max Planck Institute of Biochemistry (MPIB), Am Klopferspitz 18, Martinsried, 82152, Germany.
authors.forename: Bianca
authors.initials: B
authors.lastname: Habermann
authors.affiliation: Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG), Pfotenhauerstrasse 108, Dresden, 01307, Germany eckmann@mpi-cbg.de.
authors.forename: Christian R
authors.initials: CR
authors.lastname: Eckmann
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics; D029742:Caenorhabditis elegans Proteins / Q000502:physiology*; D011061:Poly A / Q000378:metabolism; D011062:Polynucleotide Adenylyltransferase / Q000502:physiology*; D011132:Polyribosomes / Q000378:metabolism; D014176:Protein Biosynthesis; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism*
chemical_list: D029742:Caenorhabditis elegans Proteins; D012333:RNA, Messenger; D011061:Poly A; C491056:GLD-2 protein, C elegans; C000594512:GLD-4 protein, C elegans; D011062:Polynucleotide Adenylyltransferase