Motor protein binding and mitochondrial transport are altered by pathogenic TUBB4A variants

Franca Vulinovic, Victor Krajka, Torben J. Hausrat, Philip Seibler, Daniel Alvarez-Fischer, Harutyun Madoev, Jin Sung Park, Kishore R. Kumar, Carolyn M. Sue, Katja Lohmann, Matthias Kneussel, Christine Klein*, Aleksandar Rakovic

*Corresponding author for this work


Mutations in TUBB4A have been identified to cause a wide phenotypic spectrum of diseases ranging from hereditary generalized dystonia with whispering dysphonia (DYT-TUBB4A) and hereditary spastic paraplegia (HSP) to leukodystrophy hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC). TUBB4A encodes the brain-specific β-tubulin isotype, β-tubulin 4A. To elucidate the pathogenic mechanisms conferred by TUBB4A mutations leading to the different phenotypes, we functionally characterized three pathogenic TUBB4A variants (c.4C>G,p.R2G; c.745G>A,p.D249N; c.811G>A, p.A271T) as representatives of the mutational and disease spectrum) in human neuroblastoma cells and human induced pluripotent stem cell (iPSC)-derived neurons. We showed that mRNA stability was not affected by any of the TUBB4A variants. Although two mutations (p.R2G and p.D249N) are located at the α/β-tubulin interdimer interface, we confirmed incorporation of all TUBB4A mutants into the microtubule network. However, we showed that the mutations p.D249N and p.A271T interfered with motor protein binding to microtubules and impaired neurite outgrowth and microtubule dynamics. Finally, TUBB4A mutations, as well as heterozygous knockout of TUBB4A, disrupted mitochondrial transport in iPSC-derived neurons. Taken together, our findings suggest that functional impairment of microtubule-associated transport is a shared pathogenic mechanism by which the TUBB4A mutations studied here cause a spectrum of diseases.

Original languageEnglish
JournalHuman Mutation
Issue number12
Pages (from-to)1901-1915
Number of pages15
Publication statusPublished - 01.12.2018

Research Areas and Centers

  • Research Area: Medical Genetics


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