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Tau proteins with FTDP-17 mutations have a reduced ability to promote microtubule assembly
M Hasegawa1, M J Smith, M Goedert
1Medical Research Council Laboratory of Molecular Biology, Cambridge, UK.
Abstract:
Recently exonic and intronic mutations in the gene for microtubule-associated protein tau have been discovered in cases of familial frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17). Intronic mutations have been shown to lead to an abnormal preponderance of four-repeat tau isoforms. The effects of the exonic mutations are unknown. We report here that the G272V, P301L, V337M and R406W mutations lead to a marked reduction in the ability of tau to promote microtubule assembly. This partial loss-of-function may be the primary effect of the known missense mutations in tau.
Insights
Missense mutations in the tau gene reduce its ability to assemble microtubules. This loss-of-function may explain familial frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17).
Area of Science:
- Neuroscience
- Genetics
- Molecular Biology
Background:
- Familial frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) is associated with mutations in the tau gene.
- Intronic mutations in tau lead to an abnormal increase in four-repeat tau isoforms.
- The impact of exonic tau mutations on protein function remains largely unknown.
Purpose of the Study:
- To investigate the functional consequences of known exonic missense mutations in the tau gene.
- To determine if these mutations affect the tau protein's ability to promote microtubule assembly.
Main Methods:
- Site-directed mutagenesis was used to introduce specific tau mutations (G272V, P301L, V337M, R406W).
- In vitro assays were performed to assess the ability of mutated tau proteins to promote microtubule assembly.
Main Results:
- The G272V, P301L, V337M, and R406W tau mutations significantly reduced the protein's capacity to promote microtubule assembly.
- This indicates a partial loss-of-function for these specific tau variants.
Conclusions:
- The studied missense mutations in the tau gene impair its microtubule-binding and assembly-promoting functions.
- This partial loss-of-function is a potential primary mechanism underlying FTDP-17 in patients with these tau mutations.