RESUMO
The organization and stability of higher order structures that form in the extracellular matrix (ECM) to mediate the attachment of muscles are poorly understood. We have made the surprising discovery that a subset of clotting factor proteins are also essential for muscle attachment in the model organism Drosophila melanogaster One such coagulation protein, Fondue (Fon), was identified as a novel muscle mutant in a pupal lethal genetic screen. Fon accumulates at muscle attachment sites and removal of this protein results in decreased locomotor behavior and detached larval muscles. A sensitized genetic background assay reveals that fon functions with the known muscle attachment genes Thrombospondin (Tsp) and Tiggrin (Tig). Interestingly, Tig is also a component of the hemolymph clot. We further demonstrate that an additional clotting protein, Larval serum protein 1γ (Lsp1γ), is also required for muscle attachment stability and accumulates where muscles attach to tendons. While the local biomechanical and organizational properties of the ECM vary greatly depending on the tissue microenvironment, we propose that shared extracellular protein-protein interactions influence the strength and elasticity of ECM proteins in both coagulation and muscle attachment.
Assuntos
Fatores de Coagulação Sanguínea/metabolismo , Proteínas Sanguíneas/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Músculo Esquelético/metabolismo , Tendões/metabolismo , Animais , Fatores de Coagulação Sanguínea/genética , Proteínas Sanguíneas/genética , Proteínas de Drosophila/genética , Drosophila melanogaster/metabolismo , Proteínas da Matriz Extracelular/genética , Proteínas da Matriz Extracelular/metabolismo , Hemolinfa/metabolismo , Músculo Esquelético/fisiologia , Ligação Proteica , Tendões/fisiologia , Trombospondinas/genética , Trombospondinas/metabolismoRESUMO
Drosophila larval coagulation factors have been identified in vitro. Better understanding of insect hemolymph coagulation calls for experiments in vivo. We have characterized a fondue (fon) mutation and null alleles isolated by imprecise excision of a transposable element. Loss of fon was pupal lethal, but adults could be recovered by expressing the UAS::fonGFP construct of Lindgren et al. (2008). Despite their lethality, fon mutations did not affect larval survival after wounding either when tested alone or in combination with a mutation in the hemolectin clotting factor gene. This reinforces the idea of redundant hemostatic mechanisms in Drosophila larvae, and independent pleiotropic functions of the fondue protein in coagulation and a vital process in metamorphosis.