Bridging the Gap: The Importance of TUBA1A α-Tubulin in Forming Midline Commissures

Abstract

Developing neurons undergo dramatic morphological changes to appropriately migrate and extend axons to make synaptic connections. The microtubule cytoskeleton, made of α/β-tubulin dimers, drives neurite outgrowth, promotes neuronal growth cone responses, and facilitates intracellular transport of critical cargoes during neurodevelopment. TUBA1A constitutes the majority of α-tubulin in the developing brain and mutations to TUBA1A in humans cause severe brain malformations accompanied by varying neurological defects, collectively termed tubulinopathies. Studies of TUBA1A function in mammalian cells have been limited by the presence of multiple genes encoding highly similar tubulin proteins, which leads to α-tubulin antibody promiscuity and makes genetic manipulation challenging. Here, we test mutant tubulin levels and assembly activity and analyze the impact of TUBA1A reduction on growth cone composition, neurite extension, and commissural axon architecture during brain development. We present a novel tagging method for studying and manipulating TUBA1A in cells without impairing tubulin function. Using this tool, we show that a TUBA1A loss-of-function mutation TUBA1AN102D (TUBA1AND), reduces TUBA1A protein levels and prevents incorporation of TUBA1A into microtubule polymers. Reduced Tuba1a α-tubulin in heterozygous Tuba1aND/+ mice leads to grossly normal brain formation except a significant impact on axon extension and impaired formation of forebrain commissures. Neurons with reduced Tuba1a as a result of the Tuba1aND mutation exhibit slower neuron outgrowth compared to controls. Neurons deficient in Tuba1a failed to localize microtubule associated protein-1b (Map1b) to the developing growth cone, likely impacting stabilization of microtubules. Overall, we show that reduced Tuba1a is sufficient to support neuronal migration and cortex development but not commissure formation, and provide mechanistic insight as to how TUBA1A tunes microtubule function to support neurodevelopment.

Chemogenetic approaches reveal dual functions of microglia in epilepsy

“…Additionally, increased expression of Tuba1a gene was observed in the Gi-Dreadd group as compared to the controls. Tuba1a gene encodes for the microtubule protein α-Tubulin which is essential for cytoskeleton organization and cell motility in neurons [58][59][60]. This supports our observation of a more ramified morphology of microglia after chronic Gi-activation.…”

Artificial Intelligence-Enabled AlphaFold II Pipeline Guides Functional Fluorescence Labeling of Tubulin Across Species

“…Previous studies have elucidated that insertion of up to 17 amino acids into the H1-S2 loop had no apparent functional disruption on tubulins (Schatz et al, 1987). Therefore, affinity tags have been inserted into this loop for biochemical preparation or IF imaging of individual tubulin isotypes (Buscaglia et al, 2022; Johnson et al, 2011; Sirajuddin et al, 2014; Valenstein and Roll-Mecak, 2016). To identify the most appropriate insertion site within this loop, we performed multiple sequence alignment (MSA) for each set of α- and β-tubulin isotypes to acquire the least conserved and most structurally flexible sites amenable for manipulation (Fig.…”

TUBA1A licenses APC/C‐mediated mitotic progression to drive glioblastoma growth by inhibiting PLK3

“…Most important, cell cycle arrest induced by TUBA1A knockdown seems to be permanent, as transient inhibition of TUBA1A expression could significantly inhibit the growth of GBM in vivo over 46 days, further confirming the pivotal role of TUBA1A for cell proliferation of GBM cells. Additionally, reduced TUBA1A had been shown to be sufficient to support neuron survival during brain development in Tuba1a ND/+ heterozygous mutant mice [27], highlighting that TUBA1A targeting agents might be less toxic to neurons and have potential application for GBM treatment. Since TUBA1C silencing also leads to significant mitotic arrest and apoptosis in glioma cells [6], it is worthy of investigating whether simultaneously targeting TUBA1A and TUBA1C or other subtypes of α‐tubulin overexpressed in GBM would exhibit more potent anti‐GBM efficacy.…”