β-TrCP-Mediated Proteolysis of Mis18β Prevents Mislocalization of CENP-A and Chromosomal Instability

Mol Cell Biol. 2024;44(10):429-442. doi: 10.1080/10985549.2024.2382445. Epub 2024 Aug 13.

Abstract

Restricting the localization of evolutionarily conserved histone H3 variant CENP-A to the centromere is essential to prevent chromosomal instability (CIN), an important hallmark of cancers. Overexpressed CENP-A mislocalizes to non-centromeric regions and contributes to CIN in yeast, flies, and human cells. Centromeric localization of CENP-A is facilitated by the interaction of Mis18β with CENP-A specific chaperone HJURP. Cellular levels of Mis18β are regulated by β-transducin repeat containing protein (β-TrCP), an F-box protein of SCF (Skp1, Cullin, F-box) E3-ubiquitin ligase complex. Here, we show that defects in β-TrCP-mediated proteolysis of Mis18β contributes to the mislocalization of endogenous CENP-A and CIN in a triple-negative breast cancer (TNBC) cell line, MDA-MB-231. CENP-A mislocalization in β-TrCP depleted cells is dependent on high levels of Mis18β as depletion of Mis18β suppresses mislocalization of CENP-A in these cells. Consistent with these results, endogenous CENP-A is mislocalized in cells overexpressing Mis18β alone. In summary, our results show that β-TrCP-mediated degradation of Mis18β prevents mislocalization of CENP-A and CIN. We propose that deregulated expression of Mis18β may be one of the key mechanisms that contributes to chromosome segregation defects in cancers.

Keywords: CENP-A; E3 ubiquitin ligase; Mis18β; centromere; chromosomal instability; β-TrCP.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Autoantigens / genetics
  • Autoantigens / metabolism
  • Cell Cycle Proteins* / genetics
  • Cell Cycle Proteins* / metabolism
  • Cell Line, Tumor
  • Centromere / metabolism
  • Centromere Protein A* / genetics
  • Centromere Protein A* / metabolism
  • Chromosomal Instability*
  • Chromosomal Proteins, Non-Histone* / genetics
  • Chromosomal Proteins, Non-Histone* / metabolism
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Humans
  • Proteolysis*
  • beta-Transducin Repeat-Containing Proteins* / genetics
  • beta-Transducin Repeat-Containing Proteins* / metabolism

Substances

  • Adaptor Proteins, Signal Transducing
  • Autoantigens
  • beta-Transducin Repeat-Containing Proteins
  • BTRC protein, human
  • CENPA protein, human
  • Centromere Protein A
  • Chromosomal Proteins, Non-Histone
  • DNA-Binding Proteins
  • HJURP protein, human
  • OIP5 protein, human
  • Cell Cycle Proteins