title: Dissecting Torsin/cofactor function at the nuclear envelope: a genetic study.
abstract: The human genome encodes four Torsin ATPases, the functions of which are poorly understood. In this study, we use CRISPR/Cas9 engineering to delete all four Torsin ATPases individually and in combination. Using nuclear envelope (NE) blebbing as a phenotypic measure, we establish a direct correlation between the number of inactivated Torsin alleles and the occurrence of omega-shaped herniations within the lumen of the NE. A similar, although not identical, redundancy is observed for LAP1 and LULL1, which serve as regulatory cofactors for a subset of Torsin ATPases. Unexpectedly, deletion of Tor2A in a TorA/B/3A-deficient background results in a stark increase of bleb formation, even though Tor2A does not respond to LAP1/LULL1 stimulation. The robustness of the observed phenotype in Torsin-deficient cells enables a structural analysis via electron microscopy tomography and a compositional analysis via immunogold labeling. Ubiquitin and nucleoporins were identified as distinctively localizing components of the omega-shaped bleb structure. These findings suggest a functional link between the Torsin/cofactor system and NE/nuclear pore complex biogenesis or homeostasis and establish a Torsin-deficient cell line as a valuable experimental platform with which to decipher Torsin function.
authors: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520.
authors: Ethan
authors: E
authors: Laudermilch
authors: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520.
authors: Pei-Ling
authors: PL
authors: Tsai
authors: Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520.
authors: Morven
authors: M
authors: Graham
authors: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520.
authors: Elizabeth
authors: E
authors: Turner
authors: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520.
authors: Chenguang
authors: C
authors: Zhao
authors: Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520 christian.schlieker@yale.edu.|Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520.
authors: Christian
authors: C
authors: Schlieker
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D015778:Minor Histocompatibility Antigens / Q000235:genetics / Q000378:metabolism; D018832:Molecular Chaperones / Q000235:genetics* / Q000378:metabolism; D009685:Nuclear Envelope / Q000378:metabolism* / Q000502:physiology; D022022:Nuclear Pore / Q000378:metabolism; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D015778:Minor Histocompatibility Antigens; D018832:Molecular Chaperones; D028861:Nuclear Pore Complex Proteins; C108175:TOR1A protein, human; C491547:TOR1B protein, human; C478739:TOR2A protein, human; D000251:Adenosine Triphosphatases; C486741:TOR3A protein, human