{
  "id": 10285350,
  "title": "Not all TOP RNAs are created equal: 3'UTR length and TSS selection predict the translational regulation of LARP1-bound mRNAs in CD4+ T cells",
  "url": "https://urgent.news/2026/09/27/not-all-top-rnas-are-created-equal-3utr-length-and-tss-selection",
  "topic": "science",
  "section": "Science",
  "published": "2026-09-27T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.09.25.754325v1?rss=1"
  },
  "original_language": "en",
  "account": "Translationally repressed ribosomal protein mRNA, known as TOP RNAs, play a crucial role in supporting protein synthesis, cell growth, and proliferation in naive T cells. These RNAs are regulated by an RNA binding protein called LARP1, which stabilizes the transcript and represses translation. In this study, researchers generated cross-linking immunoprecipitation (CLIP) datasets to investigate LARP1 function in T cell activation, specifically focusing on naive and activated CD4+ T cells.\n\nThe analysis identified novel TOP RNAs with varying levels of regulation. RP mRNAs, a typical member of this class, exhibited high stability and translational repression in naive T cells, which increased MTORC1-dependent translation following T cell activation. However, other TOP RNAs demonstrated different patterns of regulation. Specifically, TOP RNAs with longer 3' untranslated regions (3 UTRs) displayed a reduced dependency on LARP1 for stability and MTORC1 for translation. Additionally, the position of the transcription start site (TSS) influenced TOP RNA regulation by creating a mixture of transcript isoforms with varying TOP motif lengths. Longer terminal oligo pyrimidine stretches were linked to a greater dependency on MTORC1 for translation.\n\nThese findings suggest that the differential regulation of TOP RNAs enables fine-tuned translational responses to MTORC1 signaling. This indicates potential roles for LARP1 beyond translation regulation and stability, highlighting the complexity of TOP RNA dynamics in T cell activation.",
  "summary": "Naive T cells are poised for activation and contain a pool of translationally repressed ribosomal protein (RP) mRNA prepared to induce ribosome biogenesis to support protein synthesis, cell growth and proliferation. RP mRNA are the prototypical members of a class of transcripts initiating at cytosine followed by a CU rich element called terminal oligo pyrimidine (TOP) RNAs. TOP RNAs are regulated…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}