STRUCTURES AND FUNCTIONS OF COLLAGENS IN CAENORHABDITIS-ELEGANS

Two types of collagens have been identified in Caenorhabditis elegans corresponding to two types of extracellular matrix, the cuticle and ba sement membranes. Cuticle collagens are encoded by a developmentally r egulated family of similar to 100 genes. Mutations in cuticle collagen s can produce animals that are longer or shorter than normal and/or th at are helically twisted. Mutations in different collagens can cause d ifferent morphological abnormalities, as can different mutations in th e same collagen. Genetic interactions between collagen genes have been described and may identify collagens that interact to form the cuticl e. Two basement membrane (type IV) collagen genes have been identified in C. elegans. They encode proteins similar in structure to vertebrat e type IV collagen. One of the genes produces two alternatively splice d forms, one predominantly expressed in embryos and the other in larva e and adults, suggesting that embryonic basement membranes may have un ique properties. Most mutations in the type IV genes cause embryonic l ethality, indicating that normal basement membranes are required for e mbryogenesis. Temperature-sensitive mutations have been used to show t hat type IV collagen function is also required for larval development and adult fertility.