title: Integrins modulate the Egfr signaling pathway to regulate tendon cell differentiation in the Drosophila embryo.
abstract: Changes in the extracellular matrix (ECM) govern the differentiation of many cell types during embryogenesis. Integrins are cell matrix receptors that play a major role in cell-ECM adhesion and in transmitting signals from the ECM inside the cell to regulate gene expression. In this paper, it is shown that the PS integrins are required at the muscle attachment sites of the Drosophila embryo to regulate tendon cell differentiation. The analysis of the requirements of the individual alpha subunits, alphaPS1 and alphaPS2, demonstrates that both PS1 and PS2 integrins are involved in this process. In the absence of PS integrin function, the expression of tendon cell-specific genes such as stripe and beta1 tubulin is not maintained. In addition, embryos lacking the PS integrins also exhibit reduced levels of activated MAPK. This reduction is probably due to a downregulation of the Epidermal Growth Factor receptor (Egfr) pathway, since an activated form of the Egfr can rescue the phenotype of embryos mutant for the PS integrins. Furthermore, the levels of the Egfr ligand Vein at the muscle attachment sites are reduced in PS mutant embryos. Altogether, these results lead to a model in which integrin-mediated adhesion plays a role in regulating tendon cell differentiation by modulating the activity of the Egfr pathway at the level of its ligand Vein.
authors.affiliation: Department of Anatomy, Cambridge University, Downing Street, Cambridge CB2 3DY, UK. mdmb@mole.bio.cam.ac.uk
authors.forename: M D
authors.initials: MD
authors.lastname: Martin-Bermudo
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D002454:Cell Differentiation; D004268:DNA-Binding Proteins / Q000235:genetics; D004330:Drosophila / Q000196:embryology*; D029721:Drosophila Proteins; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000502:physiology; D066246:ErbB Receptors / Q000502:physiology*; D005109:Extracellular Matrix / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D019476:Insect Proteins / Q000378:metabolism; D016023:Integrins / Q000502:physiology*; D009024:Morphogenesis; D020880:Neuregulins; D013710:Tendons / Q000196:embryology*; D014157:Transcription Factors / Q000235:genetics; D014404:Tubulin / Q000235:genetics; D016335:Zinc Fingers
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D019476:Insect Proteins; D016023:Integrins; D020880:Neuregulins; D014157:Transcription Factors; D014404:Tubulin; C096359:sr protein, Drosophila; C102104:vn protein, Drosophila; D066246:ErbB Receptors