LIS1 and NDEL1 coordinate the plus-end-directed transport of cytoplasmic dynein

Abstract

LIS1 was first identified as a gene mutated in human classical lissencephaly sequence. LIS1 is required for dynein activity, but the underlying mechanism is poorly understood. Here, we demonstrate that LIS1 suppresses the motility of cytoplasmic dynein on microtubules (MTs), whereas NDEL1 releases the blocking effect of LIS1 on cytoplasmic dynein. We demonstrate that LIS1, cytoplasmic dynein and MT fragments comigrate anterogradely. When LIS1 function was suppressed by a blocking antibody, anterograde movement of cytoplasmic dynein was severely impaired. Immunoprecipitation assay indicated that cytoplasmic dynein forms a complex with LIS1, tubulins and kinesin-1. In contrast, immunoabsorption of LIS1 resulted in disappearance of co-precipitated tubulins and kinesin. Thus, we propose a novel model of the regulation of cytoplasmic dynein by LIS1, in which LIS1 mediates anterograde transport of cytoplasmic dynein to the plus end of cytoskeletal MTs as a dynein-LIS1 complex on transportable MTs, which is a possibility supported by our data.

Rab6a releases LIS1 from a dynein idling complex and activates dynein for retrograde movement

“…Rab6a releases LIS1 from the LIS1-dynein idling complex to allow the resumption of dynein motor activity. On the other hand, NDEL1s are also required for the activation of dynein that is bound with LIS1 as we reported previously 9 . In our present model, Rab6a adequately releases LIS1 from dynein, resulting in LIS1-free dynein molecules.…”

“…We therefore applied FCCS to examine whether dynein and Rab6a-GTP are cis-interacting in DRG neurons from postnatal mice. In the DRG neurons, each MT within the array is particularly oriented with its assemblyfavoured plus end directed away from the cell body 9 . First, we examined the subcelluar localization of Rab6a by immunocytochemistry using a specific antibody and expressing enhanced green fluorescent protein (EGFP)-Rab6a in the DRG neurons.…”

“…We previously demonstrated that LIS1 arrests dynein motility (Fig. 1a: lanes 1 and 2, Supplementary Movies 1 and 2) and that kinesin-1 transports a LIS1-dynein-tubulin complex to plus ends of MTs via mNUDC 9,10 . Before dynein can function as a retrograde motor, idling dynein must be activated to bind cargoes.…”

“…In all of the organisms where they have been examined, LIS1 orthologues are complexed with cytoplasmic dynein, the main cytoplasmic microtubule (MT) 'minus'-end-directed motor. Numerous studies to address the molecular function of LIS1 led to the conclusion that LIS1 is essential for the proper regulation and localization of cytoplasmic dynein [7][8][9] . We previously reported that LIS1 is essential for anterograde transport of cytoplasmic dynein in a kinesin-1-dependent manner and that mammalian nuclear distribution protein C (mNUDC) mediates the interaction between the LIS1-dynein complex and kinesin-1 (refs 9,10).…”

Combinatorial regulation of the balance between dynein microtubule end accumulation and initiation of directed motility

“…However, Lis1 was not required for dynein end tracking in a minimal in vitro reconstitution (Duellberg et al , 2014), raising the question as to why Lis1 is needed for dynein end tracking in cells. Lis1 is a homodimeric 45 kDa protein that binds directly to the dynein motor domain (Mateja et al , 2006; Kardon & Vale, 2009), and was reported to induce a more strongly microtubule‐bound state of dynein (Yamada et al , 2008; McKenney et al , 2010; Torisawa et al , 2011), thereby increasing the force produced by dynein (McKenney et al , 2010; Reddy et al , 2016), and slowing down microtubule transport by surface‐immobilised dynein motors (Yamada et al , 2008; Torisawa et al , 2011; Wang et al , 2013). …”