Partial cloning and sequencing of chick fibrillin-1 cDNA

The recent identification of numerous matrix genes and gene products has al lowed a detailed examination of their roles in development. Two of these ex tracellular matrix proteins, fibrillin-1 and fibrillin-2, are components of the elastin-associated microfibrils. Given what is known about the distrib ution of the fibrillins in normal tissues and the abnormalities that result when mutations occur, a basic hypothesis has emerged: fibrillin-1 is prima rily responsible for load bearing and providing structural integrity, where as fibrillin-2 may be a director of elastogenesis. Nevertheless, examinatio n of phenotypes in disorders caused by mutations in fibrillin-1 or fibrilli n-2 suggests some common functions. To better understand these similar and diverse roles, it would be helpful to examine these proteins during chick d evelopment. To accomplish this goal, it is first necessary to characterize the chick homologs of the known fibrillins. In this study, the partial chic k FBN1 cDNA was identified by polymerase chain reaction-aided cloning as a first step toward elucidating these goals. Sequence analysis indicated that there is striking conservation between chick and mammalian fibrillin-1 at the DNA and protein levels. Antisense and sense riboprobes were synthesized and used in in situ hybridization in stage 14 chick embryos and high level s of FBN1 transcripts were observed in the heart.