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Activation of double-stranded RNA dependent protein kinase by ribosomal RNA precursors

B Bottazzi1, M Clayton, L Varesio

  • 1Istituto di Ricerche Farmacologiche Mario Negri, Via Eritrea 62, 20157, Milano, Italy.

Cytotechnology
|February 24, 2012
PubMed

Insights

Ribosomal RNA precursors activate double-stranded RNA-dependent protein kinase (dsPK). This suggests endogenous RNA controls dsPK activation, potentially influencing macrophage tumoricidal activity.

Area of Science:

  • Molecular Biology
  • Immunology
  • Biochemistry

Background:

  • Macrophages exhibit altered RNA metabolism during tumoricidal activity, including reduced RNA synthesis and accumulation of double-stranded ribosomal RNA (ds rRNA) precursors.
  • The double-stranded RNA-dependent protein kinase (dsPK) is a key regulator of cellular responses to double-stranded RNA (dsRNA).

Purpose of the Study:

  • To investigate the role of endogenous ds rRNA precursors in activating dsPK.
  • To determine if ds rRNA precursors can directly activate dsPK.

Main Methods:

  • A cell-free transcription system was used to generate purified rRNA precursors from the murine rRNA gene.
  • The ability of these purified rRNA precursors to activate dsPK was assessed.
  • Treatment with proteinase K, RNase A, and RNase V(1) was used to characterize the nature of the activating molecule.

Main Results:

  • Purified rRNA precursors potently activated dsPK in a dose-dependent manner.
  • Enzymatic treatments showed that dsRNA structure is essential for activation, as RNase V(1) abrogated the activity.
  • Proteinase K and RNase A treatments did not affect the activating capacity of the rRNA precursors.

Conclusions:

  • Endogenous rRNA precursors, specifically their double-stranded regions, are potent activators of dsPK.
  • This finding suggests that endogenous RNA can regulate dsPK activity.
  • dsPK activation may play a role in controlling macrophage-mediated tumoricidal activity.

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