Patrick Willey - Academia.edu (original) (raw)

Papers by Patrick Willey

Research paper thumbnail of Minus-End-Directed Kinesin-14 Motors Align Antiparallel Microtubules to Control Metaphase Spindle Length

Developmental Cell, 2014

During cell division, a microtubule-based mitotic spindle mediates the faithful segregation of du... more During cell division, a microtubule-based mitotic spindle mediates the faithful segregation of duplicated chromosomes into daughter cells. Proper length control of the metaphase mitotic spindle is critical to this process and is thought to be achieved through a mechanism in which spindle pole separation forces from plus-end-directed motors are balanced by forces from minus-end-directed motors that pull spindle poles together. However, in contrast to this model, metaphase mitotic spindles with inactive kinesin-14 minus-end-directed motors often have shorter spindle lengths, along with poorly aligned spindle microtubules. A mechanistic explanation for this paradox is unknown. Using computational modeling, in vitro reconstitution, live-cell fluorescence microscopy, and electron microscopy, we now find that the budding yeast kinesin-14 molecular motor Kar3-Cik1 can efficiently align spindle microtubules along the spindle axis. This then allows plus-end-directed kinesin-5 motors to efficiently exert the outward microtubule sliding forces needed for proper spindle bipolarity.

Research paper thumbnail of TorsinA Mediates Distinct Mechanisms of Nuclear-Cytoplasmic Communication By Adopting Different Functional Assembly States

Research paper thumbnail of The luminal AAA+ ATPase torsinA mediates distinct mechanisms of nuclear-cytoplasmic communication by adopting different functional assembly states

Chemical and mechanical nuclear-cytoplasmic communication across the nuclear envelope (NE) is lar... more Chemical and mechanical nuclear-cytoplasmic communication across the nuclear envelope (NE) is largely mediated by the nuclear pore complex (NPC) and the linker of nucleoskeleton and cytoskeleton (LINC) complex, respectively. While NPC and LINC complex assembly are functionally related, the mechanisms responsible for this relationship remain poorly understood. Here, we investigated how the luminal ATPases associated with various cellular activities (AAA+) protein torsinA promotes NPC and LINC complex assembly using fluorescence fluctuation spectroscopy (FFS), quantitative photobleaching analyses, and functional cellular assays. We report that torsinA controls LINC complex-dependent nuclear-cytoskeletal coupling as a soluble hexameric AAA+ protein and interphase NPC biogenesis as a membrane-associated helical polymer. These findings help resolve the conflicting models of torsinA function that were recently proposed based on in vitro structural studies. Our results will enable future s...

Research paper thumbnail of Correction: A synthetic biology platform for the reconstitution and mechanistic dissection of LINC complex assembly (doi:10.1242/jcs.219451)

Journal of Cell Science, 2019

The labels for the N-terminus and C-terminus in Fig. 3A were incorrectly swapped, and Fig. 5 had ... more The labels for the N-terminus and C-terminus in Fig. 3A were incorrectly swapped, and Fig. 5 had labels stating that the constructs were from SUN1 when in fact they were from SUN2. The online full-text and PDF versions of the paper have been updated.

Research paper thumbnail of A synthetic biology platform for the reconstitution and mechanistic dissection of LINC complex assembly

Journal of Cell Science, 2018

The linker of nucleoskeleton and cytoskeleton (LINC) is a conserved nuclear envelope-spanning mol... more The linker of nucleoskeleton and cytoskeleton (LINC) is a conserved nuclear envelope-spanning molecular bridge that is responsible for the mechanical integration of the nucleus with the cytoskeleton. LINC complexes are formed by a transluminal interaction between the outer and inner nuclear membrane KASH and SUN proteins, respectively. Despite recent structural insights, our mechanistic understanding of LINC complex assembly remains limited by the lack of an experimental system for its in vitro reconstitution and manipulation. Here, we describe artificial nuclear membranes (ANMs) as a synthetic biology platform based on mammalian cell-free expression for the rapid reconstitution of SUN proteins in supported lipid bilayers. We demonstrate that SUN1 and SUN2 are oriented in ANMs with solvent-exposed C-terminal KASH-binding SUN domains. We also find that SUN2 possesses a single transmembrane domain, while SUN1 possesses three. Finally, SUN protein-containing ANMs bind synthetic KASH pe...

Research paper thumbnail of TorsinA controls TAN line assembly and the retrograde flow of dorsal perinuclear actin cables during rearward nuclear movement

The Journal of cell biology, Jan 6, 2017

The nucleus is positioned toward the rear of most migratory cells. In fibroblasts and myoblasts p... more The nucleus is positioned toward the rear of most migratory cells. In fibroblasts and myoblasts polarizing for migration, retrograde actin flow moves the nucleus rearward, resulting in the orientation of the centrosome in the direction of migration. In this study, we report that the nuclear envelope-localized AAA+ (ATPase associated with various cellular activities) torsinA (TA) and its activator, the inner nuclear membrane protein lamina-associated polypeptide 1 (LAP1), are required for rearward nuclear movement during centrosome orientation in migrating fibroblasts. Both TA and LAP1 contributed to the assembly of transmembrane actin-associated nuclear (TAN) lines, which couple the nucleus to dorsal perinuclear actin cables undergoing retrograde flow. In addition, TA localized to TAN lines and was necessary for the proper mobility of EGFP-mini-nesprin-2G, a functional TAN line reporter construct, within the nuclear envelope. Furthermore, TA and LAP1 were indispensable for the retro...

Research paper thumbnail of Minus-End-Directed Kinesin-14 Motors Align Antiparallel Microtubules to Control Metaphase Spindle Length

Developmental Cell, 2014

During cell division, a microtubule-based mitotic spindle mediates the faithful segregation of du... more During cell division, a microtubule-based mitotic spindle mediates the faithful segregation of duplicated chromosomes into daughter cells. Proper length control of the metaphase mitotic spindle is critical to this process and is thought to be achieved through a mechanism in which spindle pole separation forces from plus-end-directed motors are balanced by forces from minus-end-directed motors that pull spindle poles together. However, in contrast to this model, metaphase mitotic spindles with inactive kinesin-14 minus-end-directed motors often have shorter spindle lengths, along with poorly aligned spindle microtubules. A mechanistic explanation for this paradox is unknown. Using computational modeling, in vitro reconstitution, live-cell fluorescence microscopy, and electron microscopy, we now find that the budding yeast kinesin-14 molecular motor Kar3-Cik1 can efficiently align spindle microtubules along the spindle axis. This then allows plus-end-directed kinesin-5 motors to efficiently exert the outward microtubule sliding forces needed for proper spindle bipolarity.

Research paper thumbnail of TorsinA Mediates Distinct Mechanisms of Nuclear-Cytoplasmic Communication By Adopting Different Functional Assembly States

Research paper thumbnail of The luminal AAA+ ATPase torsinA mediates distinct mechanisms of nuclear-cytoplasmic communication by adopting different functional assembly states

Chemical and mechanical nuclear-cytoplasmic communication across the nuclear envelope (NE) is lar... more Chemical and mechanical nuclear-cytoplasmic communication across the nuclear envelope (NE) is largely mediated by the nuclear pore complex (NPC) and the linker of nucleoskeleton and cytoskeleton (LINC) complex, respectively. While NPC and LINC complex assembly are functionally related, the mechanisms responsible for this relationship remain poorly understood. Here, we investigated how the luminal ATPases associated with various cellular activities (AAA+) protein torsinA promotes NPC and LINC complex assembly using fluorescence fluctuation spectroscopy (FFS), quantitative photobleaching analyses, and functional cellular assays. We report that torsinA controls LINC complex-dependent nuclear-cytoskeletal coupling as a soluble hexameric AAA+ protein and interphase NPC biogenesis as a membrane-associated helical polymer. These findings help resolve the conflicting models of torsinA function that were recently proposed based on in vitro structural studies. Our results will enable future s...

Research paper thumbnail of Correction: A synthetic biology platform for the reconstitution and mechanistic dissection of LINC complex assembly (doi:10.1242/jcs.219451)

Journal of Cell Science, 2019

The labels for the N-terminus and C-terminus in Fig. 3A were incorrectly swapped, and Fig. 5 had ... more The labels for the N-terminus and C-terminus in Fig. 3A were incorrectly swapped, and Fig. 5 had labels stating that the constructs were from SUN1 when in fact they were from SUN2. The online full-text and PDF versions of the paper have been updated.

Research paper thumbnail of A synthetic biology platform for the reconstitution and mechanistic dissection of LINC complex assembly

Journal of Cell Science, 2018

The linker of nucleoskeleton and cytoskeleton (LINC) is a conserved nuclear envelope-spanning mol... more The linker of nucleoskeleton and cytoskeleton (LINC) is a conserved nuclear envelope-spanning molecular bridge that is responsible for the mechanical integration of the nucleus with the cytoskeleton. LINC complexes are formed by a transluminal interaction between the outer and inner nuclear membrane KASH and SUN proteins, respectively. Despite recent structural insights, our mechanistic understanding of LINC complex assembly remains limited by the lack of an experimental system for its in vitro reconstitution and manipulation. Here, we describe artificial nuclear membranes (ANMs) as a synthetic biology platform based on mammalian cell-free expression for the rapid reconstitution of SUN proteins in supported lipid bilayers. We demonstrate that SUN1 and SUN2 are oriented in ANMs with solvent-exposed C-terminal KASH-binding SUN domains. We also find that SUN2 possesses a single transmembrane domain, while SUN1 possesses three. Finally, SUN protein-containing ANMs bind synthetic KASH pe...

Research paper thumbnail of TorsinA controls TAN line assembly and the retrograde flow of dorsal perinuclear actin cables during rearward nuclear movement

The Journal of cell biology, Jan 6, 2017

The nucleus is positioned toward the rear of most migratory cells. In fibroblasts and myoblasts p... more The nucleus is positioned toward the rear of most migratory cells. In fibroblasts and myoblasts polarizing for migration, retrograde actin flow moves the nucleus rearward, resulting in the orientation of the centrosome in the direction of migration. In this study, we report that the nuclear envelope-localized AAA+ (ATPase associated with various cellular activities) torsinA (TA) and its activator, the inner nuclear membrane protein lamina-associated polypeptide 1 (LAP1), are required for rearward nuclear movement during centrosome orientation in migrating fibroblasts. Both TA and LAP1 contributed to the assembly of transmembrane actin-associated nuclear (TAN) lines, which couple the nucleus to dorsal perinuclear actin cables undergoing retrograde flow. In addition, TA localized to TAN lines and was necessary for the proper mobility of EGFP-mini-nesprin-2G, a functional TAN line reporter construct, within the nuclear envelope. Furthermore, TA and LAP1 were indispensable for the retro...