Disruption of tubulin-alpha4a polyglutamylation prevents aggregation of hyper-phosphorylated tau and microglia activation in mice

Abstract

Dissociation of hyper-phosphorylated Tau from neuronal microtubules and its pathological aggregates, are hallmarks in the etiology of tauopathies. The Tau-microtubule interface is subject to polyglutamylation, a reversible posttranslational modification, increasing negative charge at tubulin C-terminal tails. Here, we asked whether tubulin polyglutamylation may contribute to Tau pathology in vivo. Since polyglutamylases modify various proteins other than tubulin, we generated a knock-in mouse carrying gene mutations to abolish Tuba4a polyglutamylation in a substrate-specific manner. We found that Tuba4a lacking C-terminal polyglutamylation prevents the binding of Tau and GSK3 kinase to neuronal microtubules, thereby strongly reducing phospho-Tau levels. Notably, crossbreeding of the Tuba4a knock-in mouse with the hTau tauopathy model, expressing a human Tau transgene, reversed hyper-phosphorylation and oligomerization of Tau and normalized microglia activation in brain. Our data highlight tubulin polyglutamylation as a potential therapeutic strategy in fighting tauopathies.

Polyglutamylation of microtubules drives neuronal remodeling

“…Indeed, our work strengthens the long-sought link between developmental neurite remodeling and axon degeneration 50 . Many of the enzymes of the remodeling mechanism that we describe here are linked to neurodegenerative disease: Spastin to hereditary spastic paraplegia 8 , CCP1 to infantile-onset neurodegeneration 70 , and Tuba4a to motor neuron disease 41 . A unifying mechanism could involve alterations on microtubule dynamics, followed by altered organelle and enzyme transport, which again could feed back to cytoskeletal stability 71 .…”

“…In light of this expression pattern, we investigated the effect of Tuba4a-specific polyglutamylation loss in neuronal remodeling. For this, we utilized Tuba4a knock-in mice (Tuba4a KI ), which carry a mutated Tuba4a allele, which prohibits glutamylation of this specific tubulin isoform 41 . Using confocal analysis of double immunostainings for PolyE and Tubb3 in terminal axons in Tuba4a KI triangularis sterni muscles, we found a phenotype resembling to that of TTLL1 mnKO : Tubb3 intensity increased (1.2-fold; normalized to neurofilament; Fig.…”

Monoallelic loss of the F-actin-binding protein radixin facilitates startle reactivity and pre-pulse inhibition in mice

“…Western blot analysis was carried out as described before ( Hausrat et al, 2022 ). Briefly, all primary antibodies were incubated in TRIS-buffered saline (TBS) supplemented with Tween-20 (TBS-T) containing 5% (w/v) dry milk (Roth, Karlsruhe, Germany) for 1 h at room temperature or, respectively, overnight at 4°C.…”

Intrinsic microtubule destabilization of multiciliated choroid plexus epithelial cells during postnatal lifetime

“…Tubulin assembly and disassembly depend on tubulin posttranslational modification (PTM) events 11 , such as acetylation, glutamylation and glycylation. Glutamylation, the reversible addition of a single or multiple glutamates to the tubulin C-terminal tails, is the most abundant tubulin modification in the mammalian brain, occurring mainly during postnatal brain maturation 16,17,18,19 . The addition and removal of glutamate residues are regulated processes which depend on selective enzymes, such as tubulin-tyrosine ligase-like (TTLL) family and deglutamylase cytosolic carboxypeptidase-like proteins (CCP), respectively 20 .…”