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LwaCas13a indiscriminately targets the human transcriptome

Aguilar-Martinez E1, Tonthat G1, Antony Adamson1

  • 1Faculty of Biology. Medicine and Health, University of Manchester, Manchester, Greater Manchester, M13 9PT, UK.

Wellcome Open Research
|May 4, 2026
PubMed
Abstract

Insights

Leptotrichia wadei Cas13a (LwCas13a) causes cell toxicity and death in mammalian cells due to non-specific RNA targeting. This finding indicates LwCas13a is unsuitable for targeted mRNA downregulation in these systems.

Area of Science:

  • Molecular Biology
  • Gene Regulation
  • RNA Interference

Background:

  • CRISPR-Cas13a systems offer RNA-targeting gene silencing.
  • Leptotrichia wadei Cas13a (LwCas13a) exhibits RNA degradation in bacteria.
  • Trans-collateral RNA degradation by LwCas13a is reportedly absent in mammalian cells.

Purpose of the Study:

  • To investigate the efficacy of LwCas13a for mRNA downregulation in mammalian cells.
  • To assess the potential off-target effects of LwCas13a in human cell lines.

Main Methods:

  • A doxycycline-inducible system was established to express LwCas13a in HEK293T cells.
  • RNA sequencing (RNA-seq) was employed to analyze LwCas13a off-target activity.

Main Results:

  • LwCas13a activation in HEK293T cells resulted in widespread, non-specific RNA targeting.
  • This non-specific activity led to significant cellular toxicity and cell death.

Conclusions:

  • LwCas13a exhibits detrimental off-target activity in mammalian cells.
  • The observed toxicity renders LwCas13a inappropriate for specific mRNA downregulation applications in human cells.
Keywords:
LwaCas13a; down-regulation; off-target; trans-collateral activity; RNA

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