Tension and Force-Resistant Attachment Are Essential for Myofibrillogenesis in Drosophila Flight Muscle

BACKGROUND Higher animals generate an elaborate muscle-tendon network to perform their movements. To build a functional network, developing muscles must establish stable connections with tendons and assemble their contractile apparatuses. Current myofibril assembly models do not consider the impact of muscle-tendon attachment on myofibrillogenesis. However, if attachment and myofibrillogenesis are not properly coordinated, premature muscle contractions can destroy an unstable myotendinous system, leading to severe myopathies. RESULTS Here, we use Drosophila indirect flight muscles to investigate how muscle-tendon attachment and myofibrillogenesis are coordinated. We find that flight muscles first stably attach to tendons and then assemble their myofibrils. Interestingly, this myofibril assembly is triggered simultaneously throughout the entire muscle, suggesting a self-assembly mechanism. By applying laser-cutting experiments, we show that muscle attachment coincides with an increase in mechanical tension before periodic myofibrils can be detected. We manipulated tension buildup within the myotendinous system either by genetically compromising attachment initiation and integrin recruitment to the myotendinous junction or by optically severing tendons from muscle. Both treatments cause strong myofibrillogenesis defects. We find that myosin motor activity is required for both tension formation and myofibril assembly, suggesting that myofibril assembly itself contributes to tension buildup. CONCLUSIONS Our results demonstrate that force-resistant attachment enables a stark tension increase in the myotendinous system. Subsequently, this tension increase triggers simultaneous myofibril self-assembly throughout the entire muscle fiber. As myofibril and sarcomeric architecture as well as their molecular components are evolutionarily conserved, we propose a similar tension-based mechanism to regulate myofibrillogenesis in vertebrates.

[1]  Julien Colombelli,et al.  Pulsed Forces Timed by a Ratchet-like Mechanism Drive Directed Tissue Movement during Dorsal Closure , 2009, Cell.

[2]  T. Hunter,et al.  Focal adhesion kinase is not required for integrin function or viability in Drosophila , 2004, Development.

[3]  R. Fässler,et al.  The Tail of Integrins, Talin, and Kindlins , 2009, Science.

[4]  D. Coombs,et al.  Mechanical force regulates integrin turnover in Drosophila in vivo , 2012, Nature Cell Biology.

[5]  M. Gautel,et al.  The sarcomere and sarcomerogenesis. , 2008, Advances in experimental medicine and biology.

[6]  T. Uemura,et al.  Shortstop Recruits EB1/APC1 and Promotes Microtubule Assembly at the Muscle-Tendon Junction , 2003, Current Biology.

[7]  M. Martín-Bermudo,et al.  The localized assembly of extracellular matrix integrin ligands requires cell-cell contact. , 2000, Journal of cell science.

[8]  Garland L. Crawford,et al.  Scaffolds and chaperones in myofibril assembly: putting the striations in striated muscle , 2011, Biophysical Reviews.

[9]  J. Vigoreaux,et al.  Characterization of components of Z-bands in the fibrillar flight muscle of Drosophila melanogaster , 1989, The Journal of cell biology.

[10]  B. Wehrle-Haller.  Structure and function of focal adhesions. , 2012, Current opinion in cell biology.

[11]  Michael Mende,et al.  Context-specific requirements of functional domains of the Spectraplakin Short stop in vivo , 2009, Mechanisms of Development.

[12]  Frank Jülicher,et al.  Increased Cell Bond Tension Governs Cell Sorting at the Drosophila Anteroposterior Compartment Boundary , 2009, Current Biology.

[13]  Frank Schnorrer,et al.  Muscle building; mechanisms of myotube guidance and attachment site selection. , 2004, Developmental cell.

[14]  R. Lehmann,et al.  The function of PS integrins during Drosophila embryogenesis , 1989, Cell.

[15]  J. Joanny,et al.  Polarity patterns of stress fibers. , 2010, Physical review letters.

[16]  J. Sanger,et al.  Assembly and Dynamics of Myofibrils , 2010, Journal of biomedicine & biotechnology.

[17]  M. Reedy,et al.  Ultrastructure of developing flight muscle in Drosophila. I. Assembly of myofibrils. , 1993, Developmental biology.

[18]  K. Tokuyasu.  Immunocytochemical studies of cardiac myofibrillogenesis in early chick embryos. III. Generation of fasciae adherentes and costameres , 1989, The Journal of cell biology.

[19]  M. Bate,et al.  Absence of PS integrins or laminin A affects extracellular adhesion, but not intracellular assembly, of hemiadherens and neuromuscular junctions in Drosophila embryos. , 1998, Developmental biology.

[20]  Frank Schnorrer,et al.  The transmembrane protein Kon-tiki couples to Dgrip to mediate myotube targeting in Drosophila. , 2007, Developmental cell.

[21]  M. Martín-Bermudo,et al.  Integrins as mediators of morphogenesis in Drosophila. , 2000, Developmental biology.

[22]  Hans-Ulrich Dodt,et al.  Spalt mediates an evolutionarily conserved switch to fibrillar muscle fate in insects , 2011, Nature.

[23]  N H Brown,et al.  Genetic analysis of the Drosophila alphaPS2 integrin subunit reveals discrete adhesive, morphogenetic and sarcomeric functions. , 1998, Genetics.

[24]  P. D. De Deyne.  Formation of sarcomeres in developing myotubes: role of mechanical stretch and contractile activation. , 2000, American journal of physiology. Cell physiology.

[25]  F. Protasi,et al.  Independent assembly of 1.6 microns long bipolar MHC filaments and I-Z-I bodies. , 1997, Cell structure and function.

[26]  Nir S. Gov,et al.  Sarcomeric Pattern Formation by Actin Cluster Coalescence , 2012, PLoS Comput. Biol..

[27]  N. Perrimon,et al.  Sarcomere Formation Occurs by the Assembly of Multiple Latent Protein Complexes , 2010, PLoS Genetics.

[28]  N. Sato,et al.  Effects of BTS (N-benzyl-p-toluene sulphonamide), an Inhibitor for Myosin-Actin Interaction, on Myofibrillogenesis in Skeletal Muscle Cells in Culture , 2006, Zoological science.

[29]  Wayne L. Rickoll,et al.  Multiple Forces Contribute to Cell Sheet Morphogenesis for Dorsal Closure in Drosophila , 2000, The Journal of cell biology.

[30]  F. Schöck,et al.  The initial steps of myofibril assembly: integrins pave the way , 2009, Nature Reviews Molecular Cell Biology.

[31]  M. Bate,et al.  Development of the indirect flight muscles of Drosophila. , 1991, Development.

[32]  T. Volk,et al.  A role for integrin in the formation of sarcomeric cytoarchitecture , 1990, Cell.

[33]  W. Danthanarayana,et al.  Insect Flight , 1986, Proceedings in Life Sciences.

[34]  J C Perriard,et al.  Myofibrillogenesis in the developing chicken heart: assembly of Z-disk, M-line and the thick filaments. , 1999, Journal of cell science.

[35]  Michael Bate,et al.  Founder myoblasts and fibre number during adult myogenesis in Drosophila , 2004, Development.

[36]  Stephen S. Gisselbrecht,et al.  The transmembrane protein Perdido interacts with Grip and integrins to mediate myotube projection and attachment in the Drosophila embryo , 2007, Development.

[37]  Adam J. Engler,et al.  Myotubes differentiate optimally on substrates with tissue-like stiffness , 2004, The Journal of cell biology.

[38]  V. Beneš,et al.  Modular proteins from the Drosophila sallimus (sls) gene and their expression in muscles with different extensibility. , 2007, Journal of molecular biology.

[39]  R. Cripps,et al.  Assembly of thick filaments and myofibrils occurs in the absence of the myosin head , 1999, The EMBO journal.

[40]  S. Celniker,et al.  Development of the indirect flight muscle attachment sites in Drosophila: role of the PS integrins and the stripe gene. , 1996, Developmental biology.

[41]  M. Reedy,et al.  Ultrastructure of developing flight muscle in Drosophila. II. Formation of the myotendon junction. , 1993, Developmental biology.

[42]  The role of LamininB2 (LanB2) during mesoderm differentiation in Drosophila , 2011, Cellular and Molecular Life Sciences.

[43]  N. Brown,et al.  Integrins in development: moving on, responding to, and sticking to the extracellular matrix. , 2002, Developmental cell.

[44]  Taekjip Ha,et al.  Measuring mechanical tension across vinculin reveals regulation of focal adhesion dynamics , 2010, Nature.

[45]  Stephan Lange,et al.  From A to Z and back? Multicompartment proteins in the sarcomere. , 2006, Trends in cell biology.

[46]  Robert A. H. White,et al.  Talin is essential for integrin function in Drosophila. , 2002, Developmental cell.

[47]  J. Telleria.  [Mechanism of muscular contraction]. , 1951, Medicina.

[48]  Aiping Du,et al.  Cardiac myofibrillogenesis inside intact embryonic hearts. , 2008, Developmental biology.

[49]  U. Müller,et al.  Beta1 integrins regulate myoblast fusion and sarcomere assembly. , 2003, Developmental cell.

[50]  R. Schweitzer,et al.  Connecting muscles to tendons: tendons and musculoskeletal development in flies and vertebrates , 2010, Development.

[51]  Cornelia Schönbauer,et al.  Systematic genetic analysis of muscle morphogenesis and function in Drosophila , 2010, Nature.

[52]  K. Leonard,et al.  The function of the M-line protein obscurin in controlling the symmetry of the sarcomere in the flight muscle of Drosophila , 2012, Journal of Cell Science.

[53]  A. Mogilner,et al.  Motor-induced sliding of microtubule and actin bundles. , 2009, Physical chemistry chemical physics : PCCP.