1. A small proportion of Talin molecules transmit forces at developing muscle attachments in vivo
- Author
-
Frank Schnorrer, Anna-Lena Cost, Carsten Grashoff, Thomas Weidemann, Sandra B. Lemke, Max Planck Institute of Biochemistry (MPIB), Max-Planck-Gesellschaft, Research Group 'Molecular Mechanotransduction', Max-Planck-Gesellschaft-Max-Planck-Gesellschaft, Institut de Biologie du Développement de Marseille (IBDM), Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Centre National de la Recherche Scientifique (CNRS), and Max-Planck-Institut für Biochemie = Max Planck Institute of Biochemistry (MPIB)
- Subjects
Male ,Talin ,0301 basic medicine ,Life Cycles ,Integrins ,Muscle Physiology ,Physiology ,[SDV]Life Sciences [q-bio] ,Muscle Fibers, Skeletal ,Muscle Proteins ,Muscle Development ,Biochemistry ,Fluorophotometry ,Tendons ,Spectrum Analysis Techniques ,0302 clinical medicine ,Animal Cells ,Fluorescence Resonance Energy Transfer ,Medicine and Health Sciences ,Myocyte ,Biology (General) ,Musculoskeletal System ,Cells, Cultured ,ComputingMilieux_MISCELLANEOUS ,biology ,Cell adhesion molecule ,Muscles ,General Neuroscience ,Muscle Biochemistry ,Cell migration ,Muscle Analysis ,Adhesion ,Extracellular Matrix ,Actin Cytoskeleton ,Bioassays and Physiological Analysis ,Spectrophotometry ,Drosophila ,Anatomy ,Cellular Types ,General Agricultural and Biological Sciences ,Research Article ,Protein Binding ,Sarcomeres ,Imaging Techniques ,QH301-705.5 ,Blotting, Western ,Integrin ,Muscle Tissue ,Cell fate determination ,Research and Analysis Methods ,Muscle Fibers ,General Biochemistry, Genetics and Molecular Biology ,03 medical and health sciences ,Fluorescence Imaging ,Muscle attachment ,Animals ,Focal Adhesions ,General Immunology and Microbiology ,Biology and Life Sciences ,Proteins ,Pupae ,Cell Biology ,Actin cytoskeleton ,Biological Tissue ,030104 developmental biology ,biology.protein ,Biophysics ,030217 neurology & neurosurgery ,Developmental Biology - Abstract
Cells in developing organisms are subjected to particular mechanical forces that shape tissues and instruct cell fate decisions. How these forces are sensed and transmitted at the molecular level is therefore an important question, one that has mainly been investigated in cultured cells in vitro. Here, we elucidate how mechanical forces are transmitted in an intact organism. We studied Drosophila muscle attachment sites, which experience high mechanical forces during development and require integrin-mediated adhesion for stable attachment to tendons. Therefore, we quantified molecular forces across the essential integrin-binding protein Talin, which links integrin to the actin cytoskeleton. Generating flies expressing 3 Förster resonance energy transfer (FRET)-based Talin tension sensors reporting different force levels between 1 and 11 piconewton (pN) enabled us to quantify physiologically relevant molecular forces. By measuring primary Drosophila muscle cells, we demonstrate that Drosophila Talin experiences mechanical forces in cell culture that are similar to those previously reported for Talin in mammalian cell lines. However, in vivo force measurements at developing flight muscle attachment sites revealed that average forces across Talin are comparatively low and decrease even further while attachments mature and tissue-level tension remains high. Concomitantly, the Talin concentration at attachment sites increases 5-fold as quantified by fluorescence correlation spectroscopy (FCS), suggesting that only a small proportion of Talin molecules are mechanically engaged at any given time. Reducing Talin levels at late stages of muscle development results in muscle–tendon rupture in the adult fly, likely as a result of active muscle contractions. We therefore propose that a large pool of adhesion molecules is required to share high tissue forces. As a result, less than 15% of the molecules experience detectable forces at developing muscle attachment sites at the same time. Our findings define an important new concept of how cells can adapt to changes in tissue mechanics to prevent mechanical failure in vivo., The protein Talin links the transmembrane cell adhesion molecule integrin to the actin cytoskeleton. Quantitative FRET-based force measurements across Talin in vivo reveal that only few Talin molecules are under force during the development of muscle attachment sites., Author summary Cells in our body are constantly exposed to mechanical forces, which they need to sense and react to. In previous studies, fluorescent force sensors were developed to demonstrate that individual proteins in adhesion structures of a cell experience forces in the piconewton (pN) range. However, these cells were analyzed in isolation in an artificial plastic or glass environment. Here, we explored forces on adhesion proteins in their natural environment within a developing animal and used the muscle–tendon tissue in the fruit fly Drosophila as a model system. We made genetically modified fly lines with force sensors or controls inserted into the gene that produces the essential adhesion protein Talin. Using these force sensor flies, we found that only a small proportion of all the Talin proteins (
- Published
- 2019
- Full Text
- View/download PDF