Musculoskeletal system

  • Letter |

    Humans are able to throw projectiles with high speed and accuracy largely as a result of anatomical features that enable elastic energy storage and release at the shoulder; features that first appear together approximately 2 million years ago in Homo erectus, possibly as a means to hunt.

    • Neil T. Roach
    • , Madhusudhan Venkadesan
    •  & Daniel E. Lieberman
  • Letter |

    This study describes a mechanotransduction pathway that links the body wall with the epidermis in Caenorhabditis elegans. The pathway involves the p21 activated kinase PAK 1, an adaptor GIT 1 and its partner PIX 1. Tension exerted by muscles or external pressure keeps GIT 1 on station at hemidesmosomes — the small rivet like bodies that attach epidermal cells to the underlying musculature — and stimulates PAK 1 through PIX 1 and Rac GTPase. The C. elegans hemidesmosome is more than a passive attachment structure, therefore, but a sensor that responds to tension by triggering signalling processes.

    • Huimin Zhang
    • , Frédéric Landmann
    •  & Michel Labouesse
  • Letter |

    Here, artificial proteins are described that mimic the molecular architecture of titin — a protein that helps to govern the passive elastic properties of muscle. The new artificial proteins combine structured and unstructured domains, and can be photochemically crosslinked into a solid biomaterial that is resilient at low strains and extensible and tough at high strains. This provides an example of tailoring the macroscopic properties of a material through engineering at the single-molecule level.

    • Shanshan Lv
    • , Daniel M. Dudek
    •  & Hongbin Li
  • Letter |

    Zebrafish are able to replace lost heart muscle efficiently, and are used as a model to understand why natural heart regeneration — after a heart attack, for instance — is blocked in mammals. Here, and in an accompanying paper, genetic fate-mapping approaches reveal which cell population contributes prominently to cardiac muscle regeneration after an injury approximating myocardial infarction. The results show that cardiac muscle regenerates through activation and expansion of existing cardiomyocytes, without involving a stem-cell population.

    • Chris Jopling
    • , Eduard Sleep
    •  & Juan Carlos Izpisúa Belmonte
  • Letter |

    A genome-wide RNA interference screen to systematically test the genetic basis for formation and function of the Drosophila muscle is described. A role in muscle for 2,785 genes is identified; many of these genes are phylogenetically conserved.

    • Frank Schnorrer
    • , Cornelia Schönbauer
    •  & Barry J. Dickson