Profilin 1 with the amyotrophic lateral sclerosis associated mutation T109M displays unaltered actin binding and does not affect the actin cytoskeleton.

Axel Freischmidt,Marisa S Feiler,Albert C Ludolph,Jochen H Weishaupt,Ann-Katrin Fleck,Marcel Schöpflin

doi:10.1186/s12868-015-0214-y

Axel Freischmidt, Marisa S Feiler + Show 4 more

Open Access

https://doi.org/10.1186/s12868-015-0214-y

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Journal: BMC neuroscience	Publication Date: Nov 16, 2015
Citations: 21	License type: cc-by

Affiliation: University of Ulm

Abstract

BackgroundThe recent identification of several mutations in PFN1, a protein involved in actin dynamics, strengthens the hypothesis that pathology of amyotrophic lateral sclerosis is linked to cytoskeletal defects. Impaired actin binding is a common denominator of several PFN1 mutations associated with amyotrophic lateral sclerosis, although further mechanisms may also contribute to the death of motor neurons. In this study we examine the actin binding properties of PFN1 carrying the causal T109M mutation and its effects on the actin cytoskeleton.MethodsActin binding of PFN1 T109M was examined by co-immunoprecipitation experiments, a split luciferase complementation assay and a pulldown assay with recombinant PFN1. The actin cytoskeleton was investigated by fluorescence microscopy and by ultracentrifuge separation of globular and filamentous actin fractions followed by Western blotting.ResultsUsing different technical approaches we show that PFN1 T109M displays unaltered actin binding. Furthermore we show that the actin cytoskeleton is not affected by PFN1 carrying the T109M mutation.ConclusionOur data suggest that actin independent mechanisms contribute to the pathogenicity of PFN1 T109M and possibly other PFN1 mutations.

Highlights

The recent identification of several mutations in PFN1, a protein involved in actin dynamics, strength‐ ens the hypothesis that pathology of amyotrophic lateral sclerosis is linked to cytoskeletal defects
In order to further elucidate the relevance of altered actin binding for amyotrophic lateral sclerosis (ALS)-associated PFN1 mutant proteins, we studied in detail the actin binding properties of the PFN1 T109M variant as well as its impact on the actin cytoskeleton
Not predicted by splice site prediction software, we wanted to rule out the possibility that pathogenicity of the PFN1 T109M mutation is due to a haploinsufficiency caused by impaired splicing of the mRNA

Summary

Introduction

The recent identification of several mutations in PFN1, a protein involved in actin dynamics, strength‐ ens the hypothesis that pathology of amyotrophic lateral sclerosis is linked to cytoskeletal defects. Impaired actin binding is a common denominator of several PFN1 mutations associated with amyotrophic lateral sclerosis, further mechanisms may contribute to the death of motor neurons. Mutations in several other genes, e.g. PFN1 [2] or HNRNPA1 [3], have been shown to be a rare cause of ALS. Analysis of these rare causal mutations is a valuable tool for the uncovering of altered pathways possibly common to ALS pathogenesis. Chronic cellular stress and a pathogenic transition of transient stress granules to permanent aggregates of RNA-binding proteins are thought to be important in ALS [9]

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