Generation of an in vitro model to investigate replicative stress as the possible molecular mechanism underlying Schimke immunoosseous dysplasia

Schimke immuno-osseous disease (SIOD) is a rare and severe genetic condition essentially characterized by spondyloepiphyseal dysplasia, which is a delayed and defective development of the bones at the vertebrae level, and nephritis, the latter resulting in renal failure with age. SIOD can arise early in age and have severe symptoms or have a late onset and milder symptoms. SIOD is caused by mutations in the SMARCAL1 gene, which encodes for a protein, SMARCAL1, which is one of the factors the can remodel the structure of DNA undergoing replication when DNA synthesis is perturbed by endogenous or exogenous factors. Although the molecular mechanism underlying the disease in presently unknown, studies on cells in which SMARCAL1 expression was turned-off showed that loss of SMARCAL1 induces replication problems and may result in the so-called replication stress. Replication stress (RS) is a feature of many other genetic diseases and is responsible for the generation of DNA damage during continuous cell proliferation. Our project wants to verify whether mutations resulting in severe or mild SIOD differently affect RS, and whether such condition may result in impaired proliferative potential leading to premature cell death or replicative senescence. To test out hypothesis, we will generate a cell model of SIOD where studying the correlation between SIOD-related mutations, SMARCAL1 function during replication and RS generation. Development or differentiation defects can be appreciated using the power of cell reprogramming, which can derive pluripotent stem-like cells from adult, differentiated, cells. Thus, we will use cells of our model to generate SIOD iPSC (induced pluripotent stem cells). iPSC of SIOD will be powerful tools to study in more details the defect generating the disease and to analyze if other genetic or environmental factors can modulate its progression and/or severity, and to look for therapeutic targets as well