Cytosolic Adaptation to Mitochondrial Precursor Overaccumulation Stress Induces Progressive Muscle Wasting

  1. Xiaowen Wang
  2. Frank A. Middleton
  3. Rabi Tawil
  4. Xin Jie Chen

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Abstract

Mitochondrial dysfunction causes muscle wasting (or atrophy) in many diseases and probably also during aging. The underlying mechanism is unclear. Accumulating evidence suggests that substantial levels of bioenergetic deficiency and oxidative stress are insufficient by themselves to intrinsically cause muscle wasting, raising the possibility that non-bioenergetic factors may contribute to mitochondria-induced muscle wasting. In this report, we show that chronic adaptation to mitochondria-induced proteostatic stress in the cytosol induces muscle wasting. We generated transgenic mice with unbalanced mitochondrial protein loading and import, by a two-fold increase in the expression of the nuclear-encoded mitochondrial carrier protein, Ant1. We found that the ANT1 -transgenic mice progressively lose muscle mass. Skeletal muscle is severely atrophic in older mice without affecting the overall lifespan. Mechanistically, Ant1 overloading induces aggresome-like structures and the expression of small heat shock proteins in the cytosol. The data support mitochondrial Precursor Overaccumulation Stress (mPOS), a recently discovered cellular stress mechanism caused by the toxic accumulation of unimported mitochondrial precursors/preproteins. Importantly, the ANT1 -transgenic muscles have a drastically remodeled transcriptome that appears to be trying to counteract mPOS, by repressing protein synthesis, and by stimulating proteasomal function, autophagy and lysosomal amplification. These anti-mPOS responses collectively reduce protein content, which is known to decrease myofiber size and muscle mass. Our work therefore revealed that a subtle imbalance between mitochondrial protein load and import is sufficient to induce mPOS in vivo , and that anti-mPOS adaptation is a robust mechanism of muscle wasting. This finding may help improve the understanding of how mitochondria contribute to muscle wasting. It could have direct implications for several human diseases associated with ANT1 overexpression, including Facioscapulohumeral Dystrophy (FSHD).

One Sentence Summary

Proteostatic adaptations to proteostatic stress in the cytosol caused by unbalanced mitochondrial protein loading and import lead to progressive muscle wasting.

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  1. Review Commons

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    Reply to the reviewers

    OVERALL RESPONSE

    We showed that chronic adaptation to mPOS, a new mechanism of cell stress initially discovered in yeast, induces muscle atrophy in a mouse model. We are pleased to see the overall enthusiasm from the reviewers about our work. The reviewers are unanimous in (1) that the work represents “a huge amount of work” that “has been well conducted regarding the characterization of the Ant1(TG/+) murine model that exhibits a muscle loss phenotype”, and (2) that our study linking mitochondria-induced proteostatic stress to muscle atrophy opens “a new field of investigation” and “is of interest to the scientific communities studying skeletal muscle pathophysiology and mitochondrial homeostasis”.

    Mitochondrial alterations are important hallmarks in skeletal muscles under many pathological conditions. Given that bioenergetic deficiency alone is not sufficient to explain muscle wasting as shown by other groups, the reviewers commented that our work “is original and opens new perspectives in the field of mitochondrial dysfunction related to myopathies”.

    Additional strengths noted by the reviewers include the demonstration of mPOS in an animal model, and the potential implication of our work for FSHD that is one of the most common muscle disease in humans.

    We are also pleased to learn that the reviewers reached “cross-referee” recommendations to improve the paper. We are excited to see these recommendations. We are motivated and have the capacity to implement all the four series of experiments recommended by the reviewers as outlined below.

    REVIEWERS’ COMMENTS AND OUR RESPONSE

    __1. It would also be useful to perform cell fractionation and measure the accumulation of Ant1 and other unimported mitochondrial precursor proteins in the cytosol (reviewer 1). Characterizing the aggregates observed in muscles, to see whether they contain ANT1, ubiquitin, p62 and unimported mitochondrial proteins (reviewer 2 & 3). It would be informative to measure the formation of soluble and insoluble protein aggregates (reviewer 1&2). __

    Response

            We propose to perform subcellular fractionation of muscle lysates using sucrose gradient centrifugation, coupled with western-blot. This will enable us to learn whether Ant1-induced stress increases the retention of unimported mitochondrial (pre)proteins (e.g., Ant1, Tom20, MDH2, TFAM, SDHA and Aco2) in the cytosol or extramitochondrial aggregates. We routinely practice this technique and we have all these antibodies validated in the lab.

        Our previous work showed that the giant aggresomes induced by ANT1 overexpression contain Ant1 and mitochondrial proteins in HEK293T cells (Liu et al., 2019, MBoC 30:1272-1284). However, the aggresomes we observed in the ANT1-transgenic muscles have sizes often comparable to mitochondria. Protein import stress may also lead to the accumulation and misfolding of precursors on the mitochondrial surface that are subject to ubiquitination and autophagic removal. It would be difficult to distinguish between aggresomes and mitochondria by IHC using antibodies against Ant1, ubiquitin, p62 and unimported mitochondrial proteins. To overcome this, we will take advantage of the subcellular fractionation technique described above.  This should enable us to clarify whether the cytosolic small aggregates co-fractionate with p62 and ubiquitin.

        As suggested by reviewer 1 & 2, we will determine whether NP-40 insoluble but SDS-soluble aggregates can be detected in the Ant1-transgenic muscles, using the dot blot technique as we previously published (Liu et al., 2019, MBoC 30:1272-1284). Antibodies against mitochondrial proteins, p62 and ubiquitin will be used to determine whether the aggregates are enriched in mitochondrial protein, p62 and ubiquitin.

        Collectively, the experiments proposed about will provide biochemical support for the retention, and possibly ubiquitination and p62-mediated aggregation of unimported mitochondrial proteins in the cytosol of Ant1-transgenic muscles.

    2. Finalizing the characterization of the EM analysis (reviewer 2 & 3) – The reviewers suggested that we should try to quantify the different aggresomal/autophagic/vacuolar structures in the transgenic and control muscles in the TEM experiments.

    Response

      Yes, we will perform the quantitation with the grids we prepared as suggested by the reviewers.

    3. Evidence reduced altered protein synthesis rate (Reviewer 1 & 3) – Reviewer 1 suggested that it may be helpful to provide biochemical evidence for potential changes to protein synthesis rate, in order the validate the RNA-Seq data. This is also echoed by reviewer 3. The non-radioactive SUnSET technique (FASEB J. 2011 Mar;25(3):1028-39. doi: 10.1096/fj.10-168799) was recommended for measuring protein synthesis rate in vivo.

    Response

      We appreciate reviewers’ suggestions and will be happy to set up this experiment. Briefly, we will inject the mice (n=3 for the transgenic and control mice) with puromycin to bind neosynthesized peptides. Muscle tissues will be collected and analyzed by western blot using an anti-puromycin antibody (#MABE343, Millipore Sigma). Quantitation of the western blot signals will inform whether relative protein synthesis rate is decreased in transgenic muscles compared with wild-type controls.

    4. Quantifying different lysosomal markers (reviewer 2) – Reviewer 2 suggested that we should quantify the levels of LC3I/II, Lmap2 and other lysosomal markers (e.g, Beclin1).

    Response

      We agree with this and the western blot experiments will be performed accordingly, using frozen muscle samples that we collected. We will also extend to the analysis using antibodies against CTSL (Abcam, #ab103574) and V-ATPase subunits such as ATP6V1H (Abcam, #ab187706) and ATP6V1G2 (Sigma, # WH0000534M2) that are upregulated in the transgenic muscles as revealed by RNA-Seq.

    ADDITIONAL RECOMMENDATIONS.

    The reviewers made additional minor recommendations that we found very constructive and helpful for improving the manuscript. These include providing for details of animal number and muscle types used in the experiments, statistical analysis, image analysis, and method sections for protein extraction and western blot. The reviewers also made suggestions for reorganization of some of the Figures. We have implemented some of these suggestions in the revised version of the manuscript.

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    Referee #3

    Evidence, reproducibility and clarity

    Summary:

    In this study the authors generated a transgenic mouse model of impaired mitochondrial import/loading by overexpressing ANT1, a mitochondrial carrier protein. The moderate overexpression of ANT1 was sufficient to cause progressive muscle wasting, characterized by a reduction of myofiber size. By transmission electron microscopy, the authors observed that aggresome-like structures in the cytosol of ANT1 Tg muscle cells, suggesting that occurrence of mitochondrial Precursor Over-accumulation Stress (mPOS). The authors characterized the transcriptional profile of the muscle of ANT1 Tg and WT mice by RNA-sequencing. The data supports that mPOS leads to changes in gene expression to promote: 1) mitochondrial protein import and proteostasis; 2) inhibition of protein synthesis; and 3) protein degradation. The authors speculate that this is an adaptative response to cope with the cytosolic proteostatic stress induced by ANT1 overloading but that, if chronically sustained, leads to a reduction of protein content and consequent muscle wasting.

    Major comments:

    The key conclusions of this work are that ANT1 overexpression induces accumulation of proteins in aggresomes in the cytosol, supporting the existence of overaccumulation of unimported mitochondrial precursor proteins (or mPOS) in an in vivo animal model. As an adaptive response, the cell's transcription profile changes to inhibit protein synthesis and promote protein degradation. This adaptation creates a protein imbalance that leads to muscle wasting.

    The data and methods are clearly presented. However, this work would benefit from more evidence to strengthen the main conclusions. I have the following comments:

    1. By transmission electron microscopy, the authors detected aggresome-like structures in the cytosol of ANT1Tg/+ but not in that of WT muscles. Is it possible to quantify the frequency of each type of structure in WT and ANT1Tg/+? Does this frequency increase with age or correlate with the degree of myofiber phenotype (reduction in size)?

    2. mPOS is characterised by the accumulation of unimported mitochondrial precursor proteins. Is there any evidence either that the aggresome-like structures contain unimported mitochondrial proteins or that mitochondrial precursor proteins, still containing their mitochondrial targeting sequence, accumulate in the cytosol? Does unimported Ant1 precursor protein accumulate in ANT1Tg/+ mice?

    3. Previous studies have shown that expression of mutant Ant1 protein causes mitochondrial morphology defects and mtDNA deletions. Do ANT1Tg/+ mice have altered mitochondrial morphology or deletions/loss of mtDNA in muscle?

    4. The transcriptomic data and the amplification of the lysosomal compartment suggest an activation of multiple protein degradation processes, that could contribute to the reduced protein content in ANT1Tg/+ muscles. The increase in P-4E-BP and eIF2alpha expression in ANT1Tg/+ muscles suggest protein synthesis may be decreased. These data are consistent with unbalanced protein synthesis versus degradation. Figure 7A demonstrates a reduction in steady state protein levels in ANT1Tg/+ muscles. However, Figure 7A is insufficient to confirm a mechanistic explanation of the muscle wasting phenotype as the authors state at the end of the Results. This would require direct evidence of altered protein synthesis rates and protein degradation, which, although challenging in vivo, have not been directly demonstrated. The authors should therefore modify the final sentence in the Results.

    Minor comments:

    Suggestions to improve the presentation of data and conclusions: On page 7, it reads "No myofiber type grouping was observed in muscle samples stained for mitochondrial activities, suggesting the lack of chronic neuropathy." This sentence is lacking a reference to a figure (maybe Fig 2, D?).

    On page 12, the authors say "These genes are known to be activated as an important regulatory circuit in the Integrated Stress Response (ISR), an elaborating signaling network that is stimulated by divers cellular stresses to decrease global protein synthesis and to activate selected genes in the benefit of cellular recovery (42)." The word diverse is misspelled.

    On page 13, the authors wrote: "First, we found that the transcription of genes encoding proteasomal subunits, NFE2L1 and NFE2L2 are upregulated (Fig. 6A & 6B). NFE2L1 and NFE2L2 activate the transcription of proteasomal genes." This section could be rephrased for clarity. The first sentence suggests that NFE2L1 and NFE2L2 are proteasomal subunits. But then the authors say they activate transcription. I believe what the authors meant was that the genes encoding proteasomal subunits were upregulated (Fig. 6A), as well as NFE2L1 and NFE2L2 (Fig. 6B), that activate the transcription of proteasomal genes.

    On page 13 (last paragraph), the authors mention that "numerous genes involved in autophagy, cytoskeletal organization and intracellular trafficking are upregulated in ANT1Tg/+ muscles" but they only explain what STBD1, ARHGAP33 and ARHGEF2 do. The other genes are not mentioned. If the authors want to speculate that the differences in gene expression are relevant, they should explain the role of the different genes/proteins.

    On page 14, where it reads "we found that Lamp2-possitive lysosomes and/or lysosome-derived structures are amplified in the ANT1Tg/+ muscles", the word positive is misspelled.

    Regarding Fig 1: in C there are two Tg bars, do they represent the two independent transgenic mice referred in the text? Or are these males and females, like in the following graphs? The authors should clarify this. What do the values and error bars represent and which statistical tests were used?

    Regarding Fig 2: How was the coefficient of variability calculated? A sentence explaining this might be helpful in the methods' section. There is no scale bar in D. Which statistical test was used in I-J? The authors mention " P values were calculated by unpaired Student's t test." for E-H but no for I-J.

    Fig 3. is missing a scale bar.

    In Fig 5, B-C: the labelling of males and females is missing from the graphs. Authors should indicate which statistical test was performed for each graph.

    In Fig S1: Why split A from B? Why only showing 1 of the Tg for each timepoint and not both? If the images are representative of both transgenics, then it should be mentioned. Suggestion: adding the timepoint info (3, 6, 17 months) above each panel makes it easier to understand the figure without reading the legend. E-H: the graphs show grouped variables, wouldn't a Two-way ANOVA be more appropriate to test for statistical significance?

    Significance

    mPOS has been observed in yeast (Wang and Chen 2015) and human cells (Liu et al. 2019). This works shows, for the first time, evidence for mPOS is an in vivo animal model. This work suggests that a moderate overexpression of ANT1 is sufficient to impair mitochondrial import and loading, causing mPOS and an adaptative response to cytosolic proteostatic stress. These findings are relevant to understand pathologies where ANT1 is affected, such as facioscapulohumeral muscular dystrophy (FSHD) (Laoudj-Chenivesse et al 2005). mPOS represents a novel mechanism through which mitochondrial dysfunction impacts on muscle wasting. Moreover, since impairment of the mitochondrial import and loading machinery is observed in aging and disease (MacKenzie and Payne 2007), these findings are relevant to better understand the impact of mitochondrial dysfunction in different cell types.

  3. Review Commons

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    Referee #2

    Evidence, reproducibility and clarity

    Summary:

    The authors investigate the role of mitochondria - other than bioenergetic or oxidative stress - in the loss of muscle mass. They hypothesize that the accumulation of immature mitochondrial proteins in the cytosol is responsible for muscle atrophy, independently to mitochondria metabolism. For this purpose, they generated a murine model that over-expresses ANT1, a mitochondrial protein. The two-fold increase in Ant1 protein level leads to an overload in mitochondria import machinery, thus an accumulation of ANT1 in the cytosol, and thus to mitochondrial Precursor Over-accumulation Stress (mPOS). Consequently, the protein degradation pathway is stimulated, leading to an imbalance between protein synthesis/degradation, and in long term in muscle wasting.

    Major comments:

    The authors have executed a huge amount of work. Before fully reaching the conclusion that mPOS induce an imbalance between protein degradation/protein synthesis, by mainly increasing the lysosomal pathway, the authors should test/validate few more things:

    1-Quantify the increase in LAMP2 muscle (WB and/or immunolabeling quantifications

    2-Quantify other lysosomal markers

    3-Characterize better the aggresomes observed in ANT1Tg/+ muscles

    4-Add details for the methods (details are missing and make it difficult to judge this section, see comments below) These experiments should be easily done, 3 months of work: regular WB analysis, immunohistology and analyses EM images the authors already have, cost for supply <$2000.

    Results:

    Figure 1, movie 1-3 and paragraph "Moderate Ant1 overexpression causes progressive muscle wasting." The authors generated two independent hemizygous transgenic mice (ANT1Tg/+) and characterized them. The authors show a greater level of ANT1 in the transgenic mice. Could they show the localization of ANT1 in ANT1Tg/+ muscles: cytosol? Near the mitochondria? Sub-sarcolemmal mitochondria or else? Does ANT1 form aggregates? If yes, do the aggregates co-localised with ubiquitin? Proteasome? Lysosomal markers?

    Figure 3 and paragraph "Cytosolic aggresome formation supports mPOS." The authors show EM images of muscle section of ANT1Tg/+ muscles at 1 and 2 years old. The authors wrote that there is an increase of aggresomes: they show in figure 3Q and M structures that look like mature lysosomes, or in 3F and 3R early mitophagy ... The authors should try to classify the different structures they observed and quantify these structures (eg number of autophagic vacuole per sarcomere). They should then perform some immunostaining on muscle sections at same age to confirm an increase in lyosomal markers for example. They still should do the same analysis (quantification and immunostaining) in WT muscle tissue same age. Figure 3 B and C suggest lipid vacuoles. Can the authors check using Oil red-O staining for example (or another staining)? The accumulation of lipid drops in transgenic muscle would suggest an impact on the metabolism, and more specifically on the lipid metabolism. All these structures are classic and should be observable in WT muscle, but probably at a lower frequency. Attempting to quantify these parameters and confirm by histochemistry would help to characterise better the murine model.

    Figure 4, Supplemental Figure 4, Supplemental Table1 and paragraph "Ant1 overloading activates genes involved in mitochondrial protein import and proteostasis, and those encoding small heat shock family B chaperones consistent with mPOS." The authors generated Supplemental table 2 but never mentioned it in the text. Figure 4 and supplemental Figure 4, can the authors add the stat. The authors conclude from these figures (Figure 4 and Supplemental Figure 4) that ANT1 overexpression causes a protein import stress on the mitochondria. This is based on transcriptomic analysis and RTqPCR. They should validate at the protein level: eg level of HSPBs, NACA and HsP90 by WB and localisation in muscle section by immunostaining (counterstaining with mitochondria marker)

    Figure 6 and 7 and paragraph "Activation of multiple protein degradation processes and reduced protein content in ANT1Tg/+ muscles." Figure 6H: the authors should quantify LAMP2 level. Other markers of the lysosomal should be assessed at the protein level (LC3I/II, Beclin1 etc) The proteasome pathway does not seem strongly stimulated as no increase in ubiquitinylation nor in P62 are observed by Western blot. However, the authors should check whether The aggresomes observed, do they colocalise with ubiquitin and/or P62 proteins in muscle section (if yes try to find a way to quantify this if there is some colocalization). Are the aggresomes soluble or non-soluble proteins? The latter could interfere on the absence of detection n of increases in protein ubiquitinylation.

    Material and methods

    Paragraph describing the statistical analysis is missing. Number of mice, sample used for each experiment should be added in the Mat and Methods as well.Which muscle was used for which experiments (for histology, EM and RNAseq in Mat & Methods)? The procedure for image analysing is missing: objective used, number of images analysis per sample, how many muscle were studied? Protein extraction and Western blot procedures is missing

    Minor comments:

    -Figure 1I: typo in the x axe legend: quadriceps instead of quadrucep

    -Figure 2 and paragraph "Mitochondrial respiration is moderately decreased in ANT1Tg/+ muscles." Figure 2A-B-C: the authors should move the supplemental figure 2A and B in the main figure, and place figure 2Band C in sup data. To confirm that there is a difference in fiber size distribution, the authors should perform a Kolmogorov Smirnov test. Can the author clarify if whether they are using minimum diameter of fibres throughout the results (figure 2c and supplemental figure 2A and B), and if this is what is meant by the term "lesser diameter"? Figure 2I-J: It would be interesting to compare the different respiratory state at different age using an ANOVA2 factor and post-hoc test.

    -Page 13: full stop missing after the reference (49): "ligases respectively, are frequently upregulated (49),"

    -Supplemental Figure 4: reorganise the plot: put the reference ANT1 in first position, then organise per pathway involvement (eg: put together SLC7A1, SLC7A5 and ASNS for the acid transport, MTHFD2 and PSAT1 together for the one-carbon metabolism etc).

    -The authors describe figure 6E and F before A,B,C,D... they thus may need to switch them around.

    Significance

    Muscle loss associated with cachexia, sarcopenia, or neuromuscular disorders, if of current interest to the field, with much work ongoing to study the role of inflammation, denervation, REDOX homeostasis and proteostasis. The current paper suggests a new mechanism that could be involved in muscle atrophy: mitochondrial protein load and import. The authors generated a new murine model that would be useful to the muscle community to investigate pathways involved in muscle wasting, in different physiological and pathological context. Working on different neuromuscular disorders and muscle ageing, the existence of such a model would be an interesting tool to investigate the role of mitochondrial dysfunctions (dysfunctions other than mitochondrial metabolism) in muscle wasting.

    REFEREES CROSS COMMENTING

    Reading the comments from other reviewers, it seems that there is general agreement that this paper has been well conducted regarding the characterization of Ant1TG/+ murine model, and muscle loss.

    Similarly, all the reviewers seem to agree that: Finalizing the characterization of the EM analysis, characterizing the aggregates observed in muscles (containing ANT1?, ub?, p62?, soluble or non-soluble aggregates), as well as quantifying the protein synthesis and different lysosomal markers would improve the paper.

  4. Review Commons

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    Referee #1

    Evidence, reproducibility and clarity

    Summary In this manuscript, Wang and colleagues show that chronic adaptation to mitochondria-dependent proteostatic stress in the cytosol induces muscle atrophy. Although mitochondrial dysfunction is known to cause muscle wasting, the underlying mechanism is unclear. The authors generated a transgenic mouse (ANT1Tg/+) in which the expression of the nuclear-encoded mitochondrial carrier protein Ant1 is increased by two-fold. These mice are characterized by the progressive loss of body weight and muscle mass. As revealed by muscle histology and immunocytochemistry analysis, ANT1Tg/+ mice have decreased myofiber size and increased myofiber size variability. Consistent with muscle wasting, ANT1Tg/+ mice are characterized by decreased home cage activities and exercise tolerance. Mechanistically, the authors found that ANT1 overexpression has a relatively mild effect on mitochondrial respiration. However, ANT1 overexpression induces cytosolic proteostasis stress (mPOS), the formation of aggresome-like structures and the activation of small heat shock proteins in the cytosol accompanied by the upregulation of the stress-activated transcriptions factors. The drastically remodeled transcriptome of ANT1Tg/+ mice muscles is indicated by the authors as an adaptive response to counteract mPOS.

    Major comments

    The phenotypic characterization of the ANT1Tg/+ skeletal muscle is well conducted and detailed. However, the key conclusions are mainly based on the interpretation of RNA-seq data with little experimental evidence of the underlying mechanism. For this reason, the authors should qualify some of their claims as preliminary or speculative. For instance, they find upregulation of SENS2 gene, which has been demonstrated to take part in mitophagy. In addition, they corroborate this data with electron microscopy images where mitophagy structures are present. However, these two data are not enough to state that mitophagy is involved. It would be advisable to focus on fewer genes but with a stronger validation process.

    I recommend performing the following experiments:

    To better characterize the effects of Ant1 overexpression on mitochondrial function, the author should address whether ANT1Tg/+ mitochondria are more prone to depolarize or not.

    It would be informative to measure the formation of soluble and insoluble protein aggregates.

    It would also be useful to perform cell fractionation and measure the accumulation of Ant1 and other mitochondrial proteins in the cytosol.

    Finally, I would suggest to measure protein synthesis by the non-radioactive SUNSET technique (FASEB J. 2011 Mar;25(3):1028-39. doi: 10.1096/fj.10-168799).

    Minor comments: The author should mention how many muscles were used for the EM studies. I would encourage discussion of the atrophic (and not dystrophic) phenotype of the ANT1Tg/+ mice related to the connection between Ant1 and FSHD.

    Significance

    The authors investigate a still poorly explored mechanism underlying muscle wasting based on mitochondrial import machinery dysfunction. The work is original and opens new perspectives in the field of mitochondrial dysfunction related to myopathies.

    Mitochondria alterations play a key role in the context of muscle decline in many diseases and in aging. It is well known that the alteration of mitochondrial respiration and the oxidative stress increase are hallmarks of mitochondria dysfunction in skeletal muscles under pathological conditions. However, there is evidence that these features are not sufficient to explain the severe phenotype of muscle wasting. This work opens the way to the possibility that non-bioenergetics factors could take part in the pathological scenario. In detail, the involvement of the mitochondrial import mechanism, which causes a cytosolic proteostatic stress, is a new field of investigation. A few years ago, the same authors demonstrated that the mitochondrial precursor over-accumulation stress (mPOS) triggers a cytosolic proteostatic stress in yeast, however until now there was no evidence whether this phenomenon could occur in animals and which tissues would be involved. Thanks to this work, the authors demonstrated that mPOS occurs in skeletal muscle.

    This study is of interest to the scientific communities studying skeletal muscle pathophysiology and mitochondrial homeostasis. My main research field is the role of mitochondrial homeostasis in skeletal muscle function in health and disease.

  5. Version published to 10.1101/733097 on bioRxiv