Regulated specific proteolysis of the Cajal body marker protein coilin

Chromosoma. 2012 Dec;121(6):629-42. doi: 10.1007/s00412-012-0387-4. Epub 2012 Oct 14.

Abstract

Cajal bodies (CB) are subnuclear domains that contain various proteins with diverse functions including the CB marker protein coilin. In this study, we investigate the proteolytic activity of calpain on coilin. Here, we report a 28-kDa cleaved coilin fragment detected by two coilin antibodies that is cell cycle regulated, with levels that are consistently reduced during mitosis. We further show that an in vitro calpain assay with full-length or C-terminal coilin recombinant protein releases the same size cleaved fragment. Furthermore, addition of exogenous RNA to purified coilin induces proteolysis by calpain. We also report that the relative levels of this cleaved coilin fragment are susceptible to changes induced by various cell stressors, and that coilin localization is affected by inhibition or knockdown of calpain both under normal and stressed conditions. Collectively, our data suggest that coilin is subjected to regulated specific proteolysis by calpain, and this processing may play a role in the regulation of coilin activity and CB formation.

Publication types

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

MeSH terms

  • Calpain / antagonists & inhibitors
  • Calpain / metabolism
  • Cell Cycle / physiology
  • Cell Nucleolus / metabolism
  • Coiled Bodies / drug effects
  • Coiled Bodies / metabolism*
  • HeLa Cells / drug effects
  • Humans
  • Leupeptins / pharmacology
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Proteolysis

Substances

  • Leupeptins
  • Nuclear Proteins
  • acetylleucyl-leucyl-norleucinal
  • p80-coilin
  • Calpain
  • CAPNS1 protein, human