Nekouei M, Aliahmadi A, Kiaei M, Ghassempour A R. Mutant Profilin1 Aggregation in Amyotrophic Lateral Sclerosis: An in Vivo Biochemical Analysis. BCN 2021; 12 (2) :213-222
URL:
http://bcn.iums.ac.ir/article-1-1383-en.html
1- Department of Phytochemistry, Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, Tehran, Iran.
2- Department of Biology, Medicinal Plants and Drugs Research Institute, Shahid Beheshti University, Tehran, Iran.
3- Department of Pharmacology and Toxicology, Department of Neurology, Department of Geriatrics, University of Arkansas for Medical Sciences, Little Rock, USA.
Abstract:
Introduction: Profilin1 (PFN1) is a ubiquitously expressed protein known for its function as a regulator of actin polymerization and dynamics. A recent discovery linked mutant PFN1 to Amyotrophic Lateral Sclerosis (ALS), which is a fatal and progressive motor neuron disease. We have also demonstrated that Gly118Val mutation in PFN1 is a cause of ALS, and the formation of aggregates containing mutant PFN1 may be a mechanism for motor neuron death. Hence, we were interested in investigating the aggregation of PFN1 further and searching for co-aggregated proteins in our mouse model overexpressing mutant PFN1.
Methods: We investigated protein aggregation in several tissues of transgenic and no-transgenic mice using western blotting. To further understand the neurotoxicity of mutant PFN1, we conducted a pull-down assay using an insoluble fraction of spinal cord lysates from hPFN1G118V transgenic mice. For this assay, we expressed His6-tagged PFN1WT and PFN1G118V in E. coli and purified these proteins using the Ni-NTA column.
Results: In this study, we demonstrated that mutant PFN1 forms aggregate in the brain and spinal cord of hPFN1G118V mice, while WT-PFN1 remains soluble. Among these tissues, spinal cord lysates were found to have PFN1 bands at higher molecular weights recognized with anti-PFN1. Moreover, the pull-down assay using His6-PFN1G118V showed that Myelin Binding Protein (MBP) was present in the insoluble fraction.
Conclusion: Our analysis of PFN1 aggregation in vivo revealed further details of mutant PFN1 aggregation and its possible complex formation with other proteins, providing new insights into the ALS mechanism.
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Highlights
● Recombinant His6-tagged PFN1 proteins were purified for pull-down assay.
● Mutant PFN1 forms aggregate and complexes with myelin binding protein in hPFN1G118V mice.
● Misfolding of mutant PFN1 protein occurs earlier, and aggregation is the final product.
Plain Language Summary
Amyotrophic Lateral Sclerosis (ALS) or motor neuron disease affects 3-5 per 100000 people worldwide. Despite the discovery of causative genes accounting for ~50% of familial ALS, the mechanism of how and why motor neurons degenerate has not been fully understood yet. Currently, there are no effective therapies available for patients suffering from this devastating disease. The mutation in the PFN1 gene, encoding PFN1 protein, was recently discovered as a new cause of ALS, and its study may provide new clues on how nerve cells will die in ALS. PFN1 protein is of great interest for its crucial functions contributing to neuronal morphology and long axons. In this report, our results showed that ALS-linked mutant PFN1 protein forms clumps in the CNS region of ALS-linked mouse models that may damage the neurons and push them to die. We also found that clumping of PFN1 may form complexes with other essential proteins that may further cause stress and damage to neurons.
Type of Study:
Original |
Subject:
Cellular and molecular Neuroscience Received: 2019/12/15 | Accepted: 2020/01/23 | Published: 2021/03/1