Oral Presentation Annual Meetings of the Endocrine Society of Australia and Society for Reproductive Biology and Australia and New Zealand Bone and Mineral Society 2016

Glucocorticoids repress the extracellular matrix proteoglycan versican v1 isoform during murine lung development (#76)

Kelly Short 1 , Anthony Bird 1 , Judy Ng 1 , Timothy Cole 1
  1. Biochemistry , Monash , Clayton, Vic, Australia

Development of the functional human lung requires regulation of cellular proliferation and differentiation. Important endocrine regulators of lung development are glucocorticoid (GC) steroids. Previous work using global or conditional mouse knockouts of the glucocorticoid receptor (GR) gene have established that GR activity in the mesenchymal compartment of the lung is crucial to normal respiratory development. Previous screens for differentially expressed target gene in mesenchymal GR-deficient lung (GRmesKO) have identified Versican (Vcan) as a strongly GR-regulated gene target.


We hypothesised that the severe mesenchymal cell hyperplasia observed in saccular-stage GRmesKO fetal mouse lungs is partially or wholly due to the lack of GR-mediated repression of Vcan. GRmesKO mice were used to investigate Vcan as a potential direct GR regulated gene target. Alternative exon splicing of the Vcan gene generates 5 isoforms V0, V1, V2, V3 and V4 that vary in structure and function. Using isoform specific qPCR we observed that mRNA levels for all Vcan isoforms in the fetal mouse lung decline from E14.5 to P0.5. We also showed by immunohistochemistry that the V1 isoform containing the β GAG domain of Vcan is far more abundant in E16.5 lung than E18.5 suggesting that the β domain is spatially regulated in late lung development.


All four isoform mRNA levels showed an increase in E18.5 GRmesKO lungs relative to controls. Surprising, we did not detect a large degree of difference in protein expression of Vcan between GRmesKO, GRnull and controls. However we observed localised regions of β GAG overexpression in both the E18.5 GRmesKO and total GR deficient lung. In summary, GC steroids regulated repression of the ECM protein Vcan V1 isoform to contribute to the coordinated regulation of normal respiratory development in mammals.