COLLAGEN TYPE-VI IN NEURAL CREST DEVELOPMENT - DISTRIBUTION IN-SITU AND INTERACTION WITH CELLS IN-VITRO

We have examined the spatio-temporal distribution of collagen type VI (Col VI) during neural crest development in vivo and its ability to pr omote neural crest cell attachment and migration in vitro. An affinity purified antiserum and chain-specific monoclonal antibodies against c hicken Col VI were employed to immunolocalize the collagen in tissue s ections and by immunoblotting. At stages of initial neural crest cell migration, the al(VI) and alpha2(VI) chains were immunolocalized in ap position with basement membranes of the neural tube, somites, notochor d and ectoderm, whereas no immunoreactivity was seen for the alpha3(VI ) chain. Immunoblotting analysis confirmed the expression of alpha1(VI ) and alpha2(VI) chains and the lack of detectable immunoreactivity fo r the alpha3(VI) chain at these early phases of neural crest developme nt. Conversely, at advanced phases of migration and following gangliog enesis, expression of alpha3(VI) chain coincided with that of alpha1(V I) and alpha2(VI) chains in apposition with basement membranes, around the dorsal root ganglia, and in fibrillar arrangements within the dev eloping dermis and ventral sclerotome. The ability of Col VI to promot e neural crest cell attachment and migration was tested in vitro using quantitative assays for these processes. Both native microfilaments a nd isolated tetramers of Col VI strongly promoted neural crest cell at tachment and migration. Optimal stimulation of neural crest cell adhes ion and migration was dependent upon structural integrity of Col VI si nce unfolded and disassembled alpha chains only weakly promoted cell a ttachment and were virtually inactive in supporting cell movement. The importance of a native macromolecular organization of Col VI further was analyzed in experiments in which dissociated tetramers were reasso ciated by Ca2+- and temperature-dependent self-aggregation. In contras t to native microfilaments, these oligomeric complexes were less effec tive in promoting neural crest cell movement, but still retained the a bility to stimulate maximal cell attachment. The results indicate that Col VI is a primary component of the extracellular matrix deposited a long neural crest migratory pathways, where it may participate in the regulation of cell movement by functioning as a migratory substrate. T he ability of Col VI to promote neural crest cell adhesion and motilit y is highly dependent upon maintainance of a native macromolecular arr angement. (C) 1993 Wiley-Liss, Inc.