A HIERARCHY OF ECM-MEDIATED SIGNALING REGULATES TISSUE-SPECIFIC GENE-EXPRESSION

A dynamic and reciprocal flow of information between cells and the ext racellular matrix contributes significantly to the regulation of form and function in developing systems. Signals generated by the extracell ular matrix do not act in isolation. Instead, they are processed withi n the context of global signalling hierarchies whose constituent input s and outputs are constantly modulated by all the factors present in t he cell's surrounding microenvironment. This is particularly evident i n the mammary gland, where the construction and subsequent destruction of such a hierarchy regulates changes in tissue-specific gene express ion, morphogenesis and apoptosis during each developmental cycle of pr egnancy, lactation and involution.