The long noncoding RNA NEAT1_1 is seemingly dispensable for normal tissue homeostasis and cancer cell growth

  1. Jean-Christophe Marine1,2
  1. 1Laboratory for Molecular Cancer Biology, Center for Cancer Biology, VIB, 3000 Leuven, Belgium
  2. 2Laboratory for Molecular Cancer Biology, Oncology Department, KU Leuven, 3000 Leuven, Belgium
  3. 3Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
  4. 4RNA Systems Biochemistry Laboratory, RIKEN Cluster for Pioneering Research, 351-0198 Saitama, Japan
  5. 5Department of Systems BioMedicine, Tokyo Medical and Dental University, 113-8510 Tokyo, Japan
  6. 6Institute for Genetic Medicine, Hokkaido University, 060-0808 Sapporo, Japan
  7. 7Faculty of Pharmaceutical Sciences, Hokkaido University, 060-0812 Sapporo, Japan
  1. Corresponding author: jeanchristophe.marine{at}kuleuven.vib.be

Abstract

NEAT1 is one of the most studied lncRNAs, in part because its silencing in mice causes defects in mammary gland development and corpus luteum formation and protects them from skin cancer development. Moreover, depleting NEAT1 in established cancer cell lines reduces growth and sensitizes cells to DNA damaging agents. However, NEAT1 produces two isoforms and because the short isoform, NEAT1_1, completely overlaps the 5′ part of the long NEAT1_2 isoform; the respective contributions of each of the isoforms to these phenotypes has remained unclear. Whereas NEAT1_1 is highly expressed in most tissues, NEAT1_2 is the central architectural component of paraspeckles, which are nuclear bodies that assemble in specific tissues and cells exposed to various forms of stress. Using dual RNA-FISH to detect both NEAT1_1 outside of the paraspeckles and NEAT1_2/NEAT1 inside this nuclear body, we report herein that NEAT1_1 levels are dynamically regulated during the cell cycle and targeted for degradation by the nuclear RNA exosome. Unexpectedly, however, cancer cells engineered to lack NEAT1_1, but not NEAT1_2, do not exhibit cell cycle defects. Moreover, Neat1_1-specific knockout mice do not exhibit the phenotypes observed in Neat1-deficient mice. We propose that NEAT1 functions are mainly, if not exclusively, attributable to NEAT1_2 and, by extension, to paraspeckles.

Keywords

  • Received March 28, 2019.
  • Accepted August 30, 2019.

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