High-throughput analysis of downstream effects of activating Gsalpha mutations in skeletal progenitor/stem cells

Fibrous dysplasia (FD) of bone is a genetic disease caused by mutations of the α subunit of the stimulatory G protein, Gs (Gsα). The mutation results in enhanced cAMP production, and in a subversion of the structure of bone/bone marrow, mediated by the effects on skeletal stem cells (SSC). To investigate the downstream effects of the mutation in stem cells, we transduced phenotype-purified SSC with a LV vector encoding one of the two mutations causing the disease in humans (R201C). De novo transduction of normal SSC (as opposed to isolation of SSC from bone lesions) and the use of the parent untransduced cell strain as control, allowed to approach a high-throughput analysis of transcriptome changes downstream of mutated Gsα, with a statistical power which would not be permitted by natural variability of clinical material and rarity of the disease. This revealed the up- or down regulation of multiple genes specifically involved in excess bone formation, bone resorption, angiogenesis, hematopoietic control, and adipogenesis. Among these, individual genes were identified which could directly explain the emergence of specific histopathological changes.