NDP52 tunes cortical actin interaction with astral microtubules for accurate spindle orientation

Abstract

Oriented cell divisions are controlled by a conserved molecular cascade involving Gαi, LGN, and NuMA. Here, we show that NDP52 regulates spindle orientation via remodeling the polar cortical actin cytoskeleton. siRNA-mediated NDP52 suppression surprisingly revealed a ring-like compact subcortical F-actin architecture surrounding the spindle in prophase/prometaphase cells, which resulted in severe defects of astral microtubule growth and an aberrant spindle orientation. Remarkably, NDP52 recruited the actin assembly factor N-WASP and regulated the dynamics of the subcortical F-actin ring in mitotic cells. Mechanistically, NDP52 was found to bind to phosphatidic acid-containing vesicles, which absorbed cytoplasmic N-WASP to regulate local filamentous actin growth at the polar cortex. Our TIRFM analyses revealed that NDP52-containing vesicles anchored N-WASP and shortened the length of actin filaments in vitro. Based on these results we propose that NDP52-containing vesicles regulate cortical actin dynamics through N-WASP to accomplish a spatiotemporal regulation between astral microtubules and the actin network for proper spindle orientation and precise chromosome segregation. In this way, intracellular vesicles cooperate with microtubules and actin filaments to regulate proper mitotic progression. Since NDP52 is absent from yeast, we reason that metazoans have evolved an elaborate spindle positioning machinery to ensure accurate chromosome segregation in mitosis.

Annexin A1 is a polarity cue that directs planar mitotic spindle orientation during mammalian epithelial morphogenesis

“…Thus, our findings indicate that defects in astral microtubules and spindle orientation upon ANXA1 depletion are likely to cause incorrect chromosome segregation. This is consistent with evidence suggesting that unbalanced astral microtubule-cortex cross talk leads to defective chromosome dynamics 4,61 . It will be interesting to explore further the molecular mechanisms linking ANXA1-mediated regulation of astral microtubule dynamics to accurate chromosome segregation.…”

The autophagy adaptor NDP52 and the FIP200 coiled-coil allosterically activate ULK1 complex membrane recruitment

“…The CC membrane binding site is also important for binding, but residual binding still occurs in when the CC membrane binding site is removed. We tested whether NDP52 itself could bind membranes as previously reported (H. Yu et al, 2019). NDP52 was recruited to the GUV membranes either when it was tagged with GST or upon the addition of poly-ubiquitin ( Figure S5).…”

Phase separation drives decision making in cell division

“…Computational modeling of the spindle positioning process suggests a mechanism by which the ring-like F-actin structure regulates astral microtubule dynamics and mitotic spindle orientation. Yu and colleagues found that NDP52, a membrane organelle regulator, regulates spindle orientation by remodeling the polar F-actin structure (81). Mechanistically, NDP52 binds to phosphatidic acid-containing vesicles to enable NDP52-containing vesicles to anchor to the actin assembly factor N-WASP via a physical interaction and thereby shorten actin filaments.…”