The calcium-dependent ribonuclease XendoU promotes ER network formation through local RNA degradation

J Cell Biol. 2014 Oct 13;207(1):41-57. doi: 10.1083/jcb.201406037. Epub 2014 Oct 6.


How cells shape and remodel organelles in response to cellular signals is a poorly understood process. Using Xenopus laevis egg extract, we found that increases in cytosolic calcium lead to the activation of an endogenous ribonuclease, XendoU. A fraction of XendoU localizes to the endoplasmic reticulum (ER) and is required for nuclear envelope assembly and ER network formation in a catalysis-dependent manner. Using a purified vesicle fusion assay, we show that XendoU functions on the surface of ER membranes to promote RNA cleavage and ribonucleoprotein (RNP) removal. Additionally, RNA removal from the surface of vesicles by RNase treatment leads to increased ER network formation. Using human tissue culture cells, we found that hEndoU localizes to the ER, where it promotes the formation of ER tubules in a catalysis-dependent manner. Together, these results demonstrate that calcium-activated removal of RNA from membranes by XendoU promotes and refines ER remodeling and the formation of tubular ER.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism
  • Calcium Signaling
  • Cell Line
  • Cell Membrane / enzymology
  • Cell Membrane / metabolism
  • Endoplasmic Reticulum / metabolism*
  • Endoribonucleases / metabolism*
  • HeLa Cells
  • Humans
  • Nuclear Envelope / metabolism*
  • Ovum / metabolism
  • RNA Interference
  • RNA Stability*
  • RNA, Messenger / metabolism*
  • RNA, Small Interfering / genetics
  • Ribonucleoproteins / metabolism
  • Signal Transduction / genetics
  • Xenopus Proteins / metabolism*
  • Xenopus laevis / genetics
  • Xenopus laevis / metabolism*


  • RNA, Messenger
  • RNA, Small Interfering
  • Ribonucleoproteins
  • Xenopus Proteins
  • Endoribonucleases
  • ENDOU protein, Xenopus
  • Calcium