Altering lamina assembly reveals lamina-dependent and -independent functions for A-type lamins.
Lamins are intermediate filament proteins that form a fibrous meshwork, called the nuclear lamina, between the inner nuclear membrane and peripheral heterochromatin of metazoan cells. The assembly and incorporation of lamin A/C into the lamina, as well as their various functions, are still not well understood. Here, we employed designed ankyrin repeat proteins (DARPins) as new experimental tools for lamin research. We screened for DARPins that specifically bound to lamin A/C, and interfered with lamin assembly in vitro and with incorporation of lamin A/C into the native lamina in living cells. The selected DARPins inhibited lamin assembly and delocalized A-type lamins to the nucleoplasm without modifying lamin expression levels or the amino acid sequence. Using these lamin binders, we demonstrate the importance of proper integration of lamin A/C into the lamina for nuclear mechanical properties and nuclear envelope integrity. Finally, our study provides evidence for cell-type-specific differences in lamin functions.
Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland.
Monika
M
Zwerger
Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland.
Heidi
H
Roschitzki-Voser
Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland.
Reto
R
Zbinden
Cornell University, Weill Institute for Cell and Molecular Biology, Department of Biomedical Engineering, Weill Hall, Ithaca, NY 14853, USA.
Celine
C
Denais
Functional Architecture of the Cell, German Cancer Research Center (DKFZ), Heidelberg 69120, Germany.
Harald
H
Herrmann
Cornell University, Weill Institute for Cell and Molecular Biology, Department of Biomedical Engineering, Weill Hall, Ithaca, NY 14853, USA.
Jan
J
Lammerding
Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland.
Markus G
MG
Grütter
Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, Zurich 8057, Switzerland Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University, Beer-Sheva 84105, Israel omedalia@bioc.uzh.ch.
Ohad
O
Medalia
D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D034904:Lamin Type A / Q000378:metabolism; D034921:Lamin Type B / Q000378:metabolism; D034882:Lamins / Q000378:metabolism*; D009685:Nuclear Envelope / Q000378:metabolism*
D034904:Lamin Type A; D034921:Lamin Type B; D034882:Lamins
Assembly; DARPins; Lamina; Lamins; Nuclear envelope; Nucleus