EMBO Workshop Report: Molecular genetics of muscle development and neuromuscular diseases Kloster Irsee, Germany, September 26-October 1, 1999.

Abstract

The meeting held at the Irsee Convent in Southern Germany was organized by Hans‐Henning Arnold (Braunschweig), Renate Renkawitz‐Pohl (Marburg), Anna Starzinski‐Powitz (Frankfurt) and Bodo Christ (Freiburg). A total of 150 participants, 47 of whom were invited speakers, created an atmosphere of intense progress in a multifaceted field of research. This comprised somite patterning and determination of cell lineages as a paradigm of muscle precursor cell specification, cardiac myogenesis, signals involved in myogenesis, differentiation and the control of muscle‐specific gene expression, as well as the molecular genetics of myopathies and repair processes. Eric Olson (Dallas, TX) gave the keynote address on the transcriptional control of myogenesis. ### More signals and complexity: the somites The paraxial mesoderm is the source of cells that can differentiate into skeletal muscle. It is the primary structure in the vertebrate body showing segmentation when the somites form in a periodic sequence of cranio‐caudal subdivisions from the presomitic mesoderm in mice and the segmental plate in birds. Three years ago, Pourquie's group (Palmeirim et al ., 1997) presented the first experimental evidence for a periodic molecular event prefiguring the synchronous formation of subsequent somite pairs. They described the oscillating expression of c‐hairy1 in the segmental plate prior to somite formation. Such an oscillation had been postulated in theoretical models of somitogenesis. While an ortholog of c‐hairy1 in mouse has not been found yet, new oscillating genes have been described and attempts are being made to arrange them in a sequence of events. The most prominent gene with oscillating expression is lunatic fringe , an ortholog of Drosophila fringe , which modulates the Delta‐Notch pathway (O.Pourquie, Marseille, France; R.Johnson, Houston, TX). Mice homozygous for a targeted deletion in lunatic fringe lack caudal somites, and markers of a cranio‐caudal polarization such as uncx 4.1 are expressed irregularly (Evrard et al ., 1998; Pourquie, 1999). It appears that …