Nanobodies combined with DNA-PAINT super-resolution reveal a staggered titin nano-architecture in flight muscles
- Max Planck Institute of Biochemistry, Germany
- Aix Marseille University, CNRS, IDBM, France
- Max Planck Institute for Multidisciplinary Sciences, Germany
- Ludwig Maximilian University, Germany
Abstract
Sarcomeres are the force producing units of all striated muscles. Their nanoarchitecture critically depends on the large titin protein, which in vertebrates spans from the sarcomeric Z-disc to the M-band and hence links actin and myosin filaments stably together. This ensures sarcomeric integrity and determines the length of vertebrate sarcomeres. However, the instructive role of titins for sarcomeric architecture outside of vertebrates is not as well understood. Here, we used a series of nanobodies, the Drosophila titin nanobody toolbox, recognising specific domains of the two Drosophila titin homologs Sallimus and Projectin to determine their precise location in intact flight muscles. By combining nanobodies with DNA-PAINT super-resolution microscopy, we found that, similar to vertebrate titin, Sallimus bridges across the flight muscle I-band, whereas Projectin is located at the beginning of the A-band. Interestingly, the ends of both proteins overlap at the I-band/A-band border, revealing a staggered organisation of the two Drosophila titin homologs. This architecture may help to stably anchor Sallimus at the myosin filament and hence ensure efficient force transduction during flight.
Data availability
All source data for all figures are provided.Figure 3 - Source Data 1Figure 4 - Source Data 1Figure 5 - Source Data 1Figure 6 - Source Data 1All new code has been uploaded to a public database and the link is provided.
Article and author information
Author details
Funding
Centre National de la Recherche Scientifique
- Frank Schnorrer
Human Frontier Science Program (RGP0052/2018)
- Frank Schnorrer
Agence Nationale de la Recherche (ANR-10-INBS-04-01)
- Frank Schnorrer
Agence Nationale de la Recherche (ANR-16-CONV-0001,Turing Centre for Living Systems)
- Frank Schnorrer
Aix-Marseille Université
- Pierre Mangeol
Max-Planck-Gesellschaft
- Dirk Görlich
Max-Planck-Gesellschaft
- Ralf Jungmann
European Research Council (ERC-2019-SyG 856118)
- Dirk Görlich
European Research Council (ERC-2019-SyG 856118)
- Frank Schnorrer
European Research Council (ERC-2015-StG 680241)
- Ralf Jungmann
Aix-Marseille Université (ANR-11-IDEX-0001-02)
- Frank Schnorrer
Agence Nationale de la Recherche (ACHN MUSCLE-FORCES)
- Frank Schnorrer
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2023, Schueder et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
Metrics
-
- 2,723
- views
-
- 360
- downloads
-
- 19
- citations
Views, downloads and citations are aggregated across all versions of this paper published by eLife.
Download links
A two-part list of links to download the article, or parts of the article, in various formats.
Downloads (link to download the article as PDF)
Open citations (links to open the citations from this article in various online reference manager services)
Cite this article (links to download the citations from this article in formats compatible with various reference manager tools)
Nanobodies combined with DNA-PAINT super-resolution reveal a staggered titin nano-architecture in flight muscles
eLife 12:e79344.
https://doi.org/10.7554/eLife.79344
Further reading
-
- Developmental Biology
Apical constriction is a basic mechanism for epithelial morphogenesis, making columnar cells into wedge shape and bending a flat cell sheet. It has long been thought that an apically localized myosin generates a contractile force and drives the cell deformation. However, when we tested the increased apical surface contractility in a cellular Potts model simulation, the constriction increased pressure inside the cell and pushed its lateral surface outward, making the cells adopt a drop shape instead of the expected wedge shape. To keep the lateral surface straight, we considered an alternative model in which the cell shape was determined by cell membrane elasticity and endocytosis, and the increased pressure is balanced among the cells. The cellular Potts model simulation succeeded in reproducing the apical constriction, and it also suggested that a too strong apical surface tension might prevent the tissue invagination.
-
- Cancer Biology
- Developmental Biology
Missense ‘hotspot’ mutations localized in six p53 codons account for 20% of TP53 mutations in human cancers. Hotspot p53 mutants have lost the tumor suppressive functions of the wildtype protein, but whether and how they may gain additional functions promoting tumorigenesis remain controversial. Here, we generated Trp53Y217C, a mouse model of the human hotspot mutant TP53Y220C. DNA damage responses were lost in Trp53Y217C/Y217C (Trp53YC/YC) cells, and Trp53YC/YC fibroblasts exhibited increased chromosome instability compared to Trp53-/- cells. Furthermore, Trp53YC/YC male mice died earlier than Trp53-/- males, with more aggressive thymic lymphomas. This correlated with an increased expression of inflammation-related genes in Trp53YC/YC thymic cells compared to Trp53-/- cells. Surprisingly, we recovered only one Trp53YC/YC female for 22 Trp53YC/YC males at weaning, a skewed distribution explained by a high frequency of Trp53YC/YC female embryos with exencephaly and the death of most Trp53YC/YC female neonates. Strikingly, however, when we treated pregnant females with the anti-inflammatory drug supformin (LCC-12), we observed a fivefold increase in the proportion of viable Trp53YC/YC weaned females in their progeny. Together, these data suggest that the p53Y217C mutation not only abrogates wildtype p53 functions but also promotes inflammation, with oncogenic effects in males and teratogenic effects in females.
