5 Cell-Cell Interaction
During Drosophila Embryogenesis:
Novel Mechanisms and Molecules
M. Affolter
5.1
Cell-Cell Interactions in Development ...................... 65
5.2
Cell Migration in Development ............................ 70
5.3
Prospects. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 76
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 77
5.1 Cell-Cell Interactions in Development
During the development of multicellular organisms, cells interact extensiyely in order to generate tissues and organs at a defined time in the
appropriate place. In the past 20 years, numerous cell-cell signaling
systems have been identified and characterized. It has become a general
rule that a given signaling system is used repetitively during development, in the same, as well as in different, cellular contexts. However, the
cellular response to the signal varies in most cases and appears to rely
upon the developmental history of the responding cell.
To better understand cell-cell interactions as they occur in developing multicellular systems, we have focused our studies on the molecular
characterization of genes involved in the formation of two tissues: the
endodermal cell layer and the developing tracheal system. The patterning of the endodermal cell layer depends on induction between two
single-celled sheets and represents a relatively simple situation. In contrast, the development of the tracheal system via cell migration and cell