Biology subjects

Haineault, J. A. G.

Publications and source records attributed to Haineault, J. A. G..

2 recordsLinked to original sources

bioRxiv2026

Doublecortin mutation disrupts lattice-dependent proximity to reveal cytoskeletal networks in developing neurons

Doublecortin (DCX) is a microtubule-associated protein (MAP) required for neuronal migration and cortical development. However, DCX is not sufficient to direct these processes on its own. Instead, nucleokinesis, growth cone advancement, collateral branching, and polarity depend on the coordination of different MAPs and cytoskeletal proteins, including DCX, to define distinct polymer properties and cytoskeletal interfaces. While many of these proteins have been investigated for their mechanistic cytoskeletal engagement, the spatiotemporal proteomic landscape of developing neurons remains largely uncharacterized. Here, we explore DCX-centric cytoskeletal networks using BioID accumulated throughout the differentiation of cortical neurons from induced pluripotent stem cells (iPSCs). Using the morphological staging of these cells as temporal landmarks, we generate a time-resolved proteomic atlas that charts DCX's molecular environment throughout differentiation. From this atlas, we identify a cluster of cytoskeletal proteins whose persistent proximity to DCX is disrupted with the disease-associated mutation, DCX p.Arg178Leu (R178L). Consistent with R178L's diminished cooperativity, we find many of these species are implicated in modulating microtubule stability and intracellular transport, including proteins EML4 and MAP7D1. Together, our findings place DCX at the interface of distinct microtubule populations and cytoskeletal systems throughout neuronal development.

developmental biology↗

bioRxiv2025

Competition for microtubule lattice spacing between a microtubule expander and compactor.

Microtubules exist in expanded and compacted states, as defined by the lattice spacing of {beta}-tubulin dimers. Changes in lattice spacing has been linked to factors such as GTP-hydrolysis, the binding of microtubule-associated proteins (MAPs), the tubulin code, and microtubule bending. These diverse factors exert opposing molecular driving forces on the microtubule lattice that push lattice spacing towards expanded or compacted states. To better understand how these opposing forces are reconciled, we developed in vitro and cell-based model systems for the competition between a microtubule expander (paclitaxel) and a microtubule compactor (Doublecortin, or DCX). Using an in vitro reconstitution approach, we show that paclitaxel expands microtubules cooperatively. In cells, high concentrations of paclitaxel cause DCX to relocalize to compacted lattices found at concave bends. When the concentration of DCX is increased, however, we find that DCX re-compacts the previously expanded microtubules in vitro. Consistently, high expression levels of DCX prevent its relocalization in paclitaxel treated cells. When the competition between paclitaxel and DCX is "balanced", we observe a complex phenotype: DCX simultaneously localized to both long, straight clusters and concave bends, while other regions on the microtubule network remained DCX-free. We conclude that multiple lattice spacings can coexist in cells. Our results indicate that competition for microtubule lattice spacing is a critical aspect of microtubule physiology.

cell biology↗