title: The calcium-dependent ribonuclease XendoU promotes ER network formation through local RNA degradation.
abstract: 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.
authors.affiliation: Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114 Department of Genetics, Harvard Medical School, Boston, MA 02115.
authors.forename: Dianne S
authors.initials: DS
authors.lastname: Schwarz
authors.affiliation: Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114 Department of Genetics, Harvard Medical School, Boston, MA 02115 blower@molbio.mgh.harvard.edu.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Blower
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D002460:Cell Line; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D004722:Endoribonucleases / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D009685:Nuclear Envelope / Q000378:metabolism*; D010063:Ovum / Q000378:metabolism; D034622:RNA Interference; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D012261:Ribonucleoproteins / Q000378:metabolism; D015398:Signal Transduction / Q000235:genetics; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis / Q000235:genetics / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D034741:RNA, Small Interfering; D012261:Ribonucleoproteins; D029867:Xenopus Proteins; D004722:Endoribonucleases; C475059:ENDOU protein, Xenopus; D002118:Calcium