Role of proteoglycans in fetal lung maturation

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The survival of a baby at birth is crtically dependent upon the ability of the lungs to successfully take over the role of exchanging oxygen and carbon dioxide between the air and blood. To perform this task, during fetal life the lung must have grown properly and near the end of gestation it must mature both structurally and biochemically. Thus, babies that are born early, before the expected time of birth, are born before the lungs have had the opportunity to mature. It is not surprising, therefore, that an inability to breathe is one of the primary problems faced by a prematurely born infant. During late gestation the lung changes dramatically in order to increase its ability to exchange gases. There is an increase in surface area and a reduction in the barrier thickness between the airspace and the blood stream. The molecular mechanisms involved in this remodelling are unknown, but it is known that the administration of corticosteroids to women at risk of preterm labour causes a large decrease in this barrier thickness and increases the distensibility of the lung. This project seeks to understand how the structure of the lung matures in late gestation and to determine whether corticosteroids regulate these changes by altering the structure of a specialised molecule, called versican. Versican resides in the tissue space outside of cells and has special properties that allow it to retain water and help organise the surrounding matrix. We propose that alterations in the structure of versican will reduce its ability to retain water, thereby reducing the tissue volume and contributing to a reduction in the air-blood tissue barrier within the lung.