Downregulation of IRS-1 in adipose tissue of offspring of obese mice is programmed cell-autonomously through post-transcriptional mechanisms.

We determined the effects of maternal diet-induced obesity on offspring adipose tissue insulin signalling and miRNA expression in the aetiology of insulin resistance in later life. Although body composition and glucose tolerance of 8-week-old male offspring of obese dams were not dysregulated, serum insulin was significantly (p<0.05) elevated. Key insulin signalling proteins in adipose tissue were down-regulated, including the insulin receptor, catalytic (p110β) and regulatory (p85α) subunits of PI3K as well as AKT1 and 2 (all p<0.05). The largest reduction observed was in IRS-1 protein (p<0.001), which was regulated post-transcriptionally. Concurrently, miR-126, which targets IRS-1, was up-regulated (p<0.05). These two features were maintained in isolated primary pre-adipocytes and differentiated adipocytes in-vitro. We have therefore established that maternal diet-induced obesity programs adipose tissue insulin resistance. We hypothesise that maintenance of the phenotype in-vitro strongly suggests that this mechanism is cell autonomous and may drive insulin resistance in later life.