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The role of inte~rins in Drosophila development. Michael Wilcox, Maria Leptin, Aaron DiAntonio, Nicholas Brown and Thierry Bogaert. MRC Lab. Mol Biol., Cambridge and LHarvard Biolabs.

The integrin receptor family is one of the major classes of surface protein involved in cell migration and adhesion during morphogenesis. Integrins are receptors for a variety of different ligands, most notably extracellular matrix (ECM) components llke fibroneetin and laminin. Like their vertebrate counterparts, the Drosophil a position-specific integrins PSI and PS2 are

8 heterodimers; each has the same 8 subunit associated with different subunits. Analysis of lethal mutants in both ~ and 8 PS snbunits has demonstrated a role for these molecules during embryogenesls in the attachment of mesoderm and ectoderm and in ECM assembly. Viable mutations in these genes lead to defects in the adult wing, indicating a further role for the integrins in wing morphogenesis. In these cases, and elsewhere in the embryo and larva, the PSI and PS2 integrins are expressed on cells on either side of tissue attachment sites, suggesting that they may cooperate in their function. These and other findings will be discussed.

179

The Exnressinn of Matrix Recentor Svndecan Is Suonressed In Hormonallv TransformedS 115 (2ells. Sim-a Dahlstedt*.Pirkko H~lrk6nen** and Markku Jalkanen*. Departments of Medical Biochemistry* and Anatomy**, Institute of Biomedicine, University of Turku, SF-20520 Turku, Finland.

The expression ofsyndecan during bormonally induced phenotype shift from fibroblastic to epithelial one in S 115 cell line was studied. In the absence of androgen Sl15 cells expressed an epithelial phenotype and syndecan was localized on these cells at the cell borders, organized in long fibers at the edges of the cells but also as small concentrates (adhesion plaques) beneath the cells. Testosterone treatment, which also induced these cells to become fibroblastic and anchorage- independent in their growth, revealed less intense and unorganized stain. Furthermore, quantitation ofsyndecan express ion by rad io- immunoassay revealed almost undetectable amounts of matrix binding ectodomain of syndecan on the surfaces of these malignant cells. Western-blot analysis indicated that Sl15 cell-derived syndecan both from epithelial-like and the small detectable amount from fibroblastic-like ceils was similar in size with syndecan from normal mouse mammary epithelial cells, indicating that also malignant S115 cells were able to carry out the fully glycosylation of syndecan. However, malignant S115 cells were observed to contain only minimal amounts of syndecan mRNA (2.6 kb). Thus we propose that the inactivation of syndeean gene prevents syndecan expression in hormonally transformed cells, and that this inactivation is one of the reasons for malignant morphology of S 115 cells under hormone influence.

180

In situ hybridization of collagen and Anchorin mRNA during cartilage development.

C. Hofmann and K. yon der Mark Max-Planck-Clinical Research Group, Erlangen Collagen type II, produced by the noto- chord, stimulates the chondrogenic differentiation in the adjacent sclerotome (the prechondrogenic region) of embryonic chick somites (Strudel, 1973). This cell-matrix interaction is possibly mediated by the collagen-binding protein Anchorin CII, which was isolated from chondrocyte membranes in our group (Mollenhauer et al., 1983). We demonstrate by immunoprecipitation, Western blotting and Northern blotting, that somites, isolated from chick embryos of different stages, do express Anchorin CII mRNA as well as the protein before and at the time of interaction with the Notochord (stage ll-20). The distribution of Anchorin mRNA during cartilage development was studied in correlation with the mRNA of type I and type II collagen by in situ hybridization. Anchorin mRNA was localized first at stage 24 in the sclerotome and in the otic vesicle. O~l(I) mRNA was also found in the sclerotome untile stage 24; thereafter ~ 1(II) mRNA appeared and increased dramatically.

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