BIOLOGY OF THE EPITHELIAL BASEMENT MEMBRANE

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The longterm objective of this grant (R23 conversion to a FIRST award) is to combine morphology, biochemistry and molecular biology to determine the functional and structural relationships between the basement membrane, epithelial cytoskeleton, and epithelial metabolism. This work will be done on a corneal epithelial cell model which can be used to study the biology of the basement membrane zone by these techniques. The basement membrane (basal lamina) is defined here as consisting of a central dense sheet (lamina densa) rich in laminin and type IV collagen surrounded on both sides by laminae rarae containing glycoproteins and most of the proteoglycan of the basement membrane. In the first year of this grant, the epithelia cell model was used to determine basement membrane-cytoskeleton relationships. The cytoskeleton was disrupted with specific drugs in the presence or absence of an intact basement membrane or added extracellular matrix (ECM) molecules. We determined that the actin cytoskeleton was necessary for the increase in epithelial collagen production caused by basal cell contact with basement membrane molecules. This competitive renewal includes specific aims directed toward using probes for the mRNA of collagen and other proteins to determine 1) the location of the mRNA, 2) to make a correlation of mRNA levels with protein synthesis, and 3) the type of protein synthesis regulation (transcription of translation) occurring in epithelial cells. This proposal will address the disease process of EB directly, by studying the relationship between the ECM, cytroskeleton, and protein synthesis of corneal epithelial cells, chick epidermis, and in the future, human epidermis. The results of the proposal will advance our understanding of corneal epithelial metabolism and differentiation and thus and relevant to eye malformations in this and other diseases. We expect these studies to cast light on cell- basement membrane interaction and to open up new pathways for approaching possible effects of abnormal BL on cell metabolism and differentiation.