A N-terminally deleted form of the CK2α' catalytic subunit is sufficient to support cell viability

  • Biochem Biophys Res Commun. 2020 Oct 20;531(3):409-415. doi: 10.1016/j.bbrc.2020.07.112.
Christian Borgo  1 ,  Claudio D'Amore  1 ,  Luca Cesaro  1 ,  Kenichiro Itami  2 ,  Tsuyoshi Hirota  3 ,  Mauro Salvi  4 ,  Lorenzo A Pinna  5
Affiliations
  • 1. Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy.
  • 2. Institute of Transformative Bio-Molecules, Nagoya University, Nagoya, 464-8601, Japan; Department of Chemistry, Graduate School of Science, Nagoya University, Nagoya, 464-8601, Japan.
  • 3. Institute of Transformative Bio-Molecules, Nagoya University, Nagoya, 464-8601, Japan.
  • 4. Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy. Electronic address: [email protected].
  • 5. Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy; CNR Institute of Neuroscience, Viale G. Colombo 3, Padova, Italy. Electronic address: [email protected].
PMID: 32800562 DOI: 10.1016/j.bbrc.2020.07.112
Abstract

Viable clones of C2C12 myoblasts where both catalytic subunits of protein kinase CK2 had been knocked out by the CRISPR/Cas9 methodology have recently been generated, thus challenging the concept that CK2 is essential for cell viability. Here we present evidence that these cells are still endowed with a residual "CK2-like" activity that is able to phosphorylate Ser-13 of endogenous CDC37. Searching for a molecular entity accounting for such an activity we have identified a band running slightly ahead of CK2α' on SDS-PAGE. This band is not detectable by in-gel Casein Kinase assay but it co-immuno-precipitates with the β-subunit being downregulated by specific CK2α' targeting siRNA treatment. Its size and biochemical properties are consistent with those of CK2α' mutants deleted upstream of Glu-15 generated during the knockout process. This mutant sheds light on the role of the CK2 N-terminal segment as a regulator of activity and stability. Comparable cytotoxic efficacy of two selective and structurally unrelated CK2 inhibitors support the view that survival of CK2α/α'-/- cells relies on this deleted form of CK2α', whose discovery provides novel perspectives about the biological role of CK2.

Keywords
CK2α’; CX-4945; Crispr/Cas9; GO289; Protein kinase CK2.
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