TDP-43 causes neurotoxicity and cytoskeletal dysfunction in primary cortical neurons
Authors: Pranetha Baskaran
Christopher Shaw
Sarah Guthrie
Journal: PLoS ONE (2018)
Discipline: Multidisciplinary
Keywords: TDP-43; proteinopathy; amyotrophic lateral sclerosis; cytoskeleton; axons
Affiliations: Department of Developmental Neurobiology, King's College, Guy's Campus, London, United Kingdom., Maurice Wohl Clinical Neuroscience Institute, King's College, London, United Kingdom.

Abstract:  TDP-43-mediated proteinopathy is a key factor in the pathology of amyotrophic lateral sclerosis (ALS). A potential underlying mechanism is dysregulation of the cytoskeleton. Here we investigate the effects of expressing TDP-43 wild-type and M337V and Q331K mutant isoforms on cytoskeletal integrity and function, using rat cortical neurons in vitro. We find that TDP-43 protein becomes mislocalised in axons over 24-72 hours in culture, with protein aggregation occurring at later timepoints (144 hours). Quantitation of cell viability showed toxicity of both wild-type and mutant constructs which increased over time, especially of the Q331K mutant isoform. Analysis of the effects of TDP-43 on axonal integrity showed that TDP-43-transfected neurons had shorter axons than control cells, and that growth cone sizes were smaller. Axonal transport dynamics were also impaired by transfection with TDP-43 constructs. Taken together these data show that TDP-43 mislocalisation into axons precedes cell death in cortical neurons, and that cytoskeletal structure and function is impaired by expression of either TDP-43 wild-type or mutant constructs in vitro. These data suggest that dysregulation of cytoskeletal and neuronal integrity is an important mechanism for TDP-43-mediated proteinopathy. 

Retracted: Yes

PubPeer comments:
 Figure 4A has some ROIs copied and pasted several times throughout the image. Observe the similar shape of several of the bright spots and the tell tale changes in contrast, in the shape of squares, around the bright spots. ![file] , 
 Figure 4B. Much more similar than expected. https: imgur.com eDveIhC , 
 Figure 4C. Much more similar than expected. https: imgur.com OI9230Q , 
 Figure 4D. Much more similar than expected. https: imgur.com wF0hTHM , 
 #2 Figure 4B continued. https: imgur.com PCQZXwc , 
 #1 Figure 4A. https: imgur.com ZHnzTjh , 
 On social media, the journal has replied to mention of these concerns: u201cThanks, we will look into this.u201d , 
 #5 Figure 4B. Additional doublet signal. https: imgur.com j9j2NlX , 
 Retraction: TDP-43 causes neurotoxicity and cytoskeletal dysfunction in primary cortical neurons Following the publication of this article [1], concerns were raised regarding the results presented in Fig 4. Specifically, In Fig 4A-D, there are cells within each panel that are highly similar to one another. In many cases, the background around the similar cells appears discontinuous with neighbouring background such that there appear to be rectangles of differently shaded background around these cells. Underlying data provided by the authors confirm that additional cell images were pasted into all four figure panels, affecting the number of bright and dark cells shown. Furthermore, the underlying data provided for Fig 4C did not match the panel presented in the published figure, raising further concerns about the validity of the data reported in this panel. The number of TUNEL-positive cells in the underlying images provided by the authors do not appear to reflect the quantitative trend reported in the 72-h histogram (Fig 4E) for panels B, C, and D. Furthermore, the underlying data provided to support this figure do not indicate the counted TUNEL-positive cells were normalised to total cell numbers, as was reported in the Methods section. The authors clarified that the quantification of the Fig 4 results took place under the microscope and that only representative images were saved. The authors stated that the data underlying the other results reported in this article are still available. This issue was reviewed by the Research Integrity Office and Dean for Research Governance, Ethics and Integrity at Kings College London. The institution did not find evidence of intent to deceive but noted some issues around lack of awareness of good practice standards. Overall, the data and comments provided did not fully resolve the above concerns nor provide adequate assurance as to the reliability of the results reported in Fig 4. In light of these issues, the PLOS ONE Editors retract this article. PB agreed with the retraction and apologises for the issues with the published article. CS and SG either did not respond directly or could not be reached. https: journals.plos.org plosone article?id=10.1371 journal.pone.0252752 ,