2. Academic Validation
  3. Lunapark stabilizes nascent three-way junctions in the endoplasmic reticulum

Lunapark stabilizes nascent three-way junctions in the endoplasmic reticulum

  • Proc Natl Acad Sci U S A. 2015 Jan 13;112(2):418-23. doi: 10.1073/pnas.1423026112.
Shuliang Chen 1,  Tanvi Desai 2,  James A McNew 2,  Patrick Gerard 3,  Peter J Novick 4,  Susan Ferro-Novick 5
Affiliations

Affiliations

  • 1 Department of Cellular and Molecular Medicine and Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093;
  • 2 Department of Biochemistry and Cell Biology, Rice University, Houston, TX 77005; and.
  • 3 Department of Mathematical Sciences, Clemson University, Clemson, SC 29634.
  • 4 Department of Cellular and Molecular Medicine and pnovick@ucsd.edu sfnovick@ucsd.edu.
  • 5 Department of Cellular and Molecular Medicine and Howard Hughes Medical Institute, University of California, San Diego, La Jolla, CA 92093; pnovick@ucsd.edu sfnovick@ucsd.edu.
PMID: 25548161 DOI: 10.1073/pnas.1423026112
Abstract

The endoplasmic reticulum (ER) consists of a polygonal network of sheets and tubules interconnected by three-way junctions. This network undergoes continual remodeling through competing processes: the branching and fusion of tubules forms new three-way junctions and new polygons, and junction sliding and ring closure leads to polygon loss. However, little is known about the machinery required to generate and maintain junctions. We previously reported that yeast Lnp1 localizes to ER junctions, and that loss of Lnp1 leads to a collapsed, densely reticulated ER network. In mammalian cells, only approximately half the junctions contain Lnp1. Here we use live cell imaging to show that mammalian Lnp1 (mLnp1) affects ER junction mobility and hence network dynamics. Three-way junctions with mLnp1 are less mobile than junctions without mLnp1. Newly formed junctions that acquire mLnp1 remain stable within the ER network, whereas nascent junctions that fail to acquire mLnp1 undergo rapid ring closure. These findings imply that mLnp1 plays a key role in stabilizing nascent three-way ER junctions.

Keywords

Lunapark; endoplasmic reticulum; membrane remodeling; organelle morphogenesis; three-way junction.

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