Adult-onset deletion of the Prader-Willi syndrome susceptibility gene in mice results in reduced feeding and increased fat mass.

Background: The imprinted small nucleolar RNA (snoRNA) Snord116 is implicated in the aetiology of Prader-Willi syndrome (PWS), a disease associated with hyperphagia and obesity. Germline deletion of in mice has been found to lead to increased food intake but not to the development of obesity. To determine the role of Snord116 independent of potential compensatory developmental factors, we investigated the effects of conditional adult-onset deletion of in mice.

Methods: Deletion of was induced at 8 weeks of age by oral administration of tamoxifen to male Snord; ROSA mice, with vehicle-treated mice used as controls. Body weight (BW) was monitored weekly and body composition was measured by dual-energy X-ray absorptiometry and tissue dissection. Non-fasted and fasting-induced food intake was determined, and glucose and insulin tolerance tests were performed. Twenty-four-hour energy expenditure and physical activity were assessed by indirect calorimetry.

Results: Adult-onset deletion of led to reduced food intake and increased adiposity, albeit with no concomitant change in BW or lean mass compared to controls. Adult onset Snord116 deletion was also associated with worsened glucose tolerance and insulin sensitivity.

Conclusions: This study identified a key role for in feeding behaviour and growth. Further, it is likely that the effects of this gene are modulated by developmental stage, as mice with adult-onset deletion showed an opposite phenotype, with respect to food intake and body composition, to previously published data on mice with germline deletion.