Loss of Snord116 impacts lateral hypothalamus, sleep, and food-related behaviors

Imprinted genes are highly expressed in the hypothalamus, however whether specific imprinted genes affect hypothalamic neuromodulators and their functions is unknown. It has been suggested that Prader-Willi syndrome (PWS), a neurodevelopmental disorder caused by lack of paternal expression at the chromosome 15q11-q13, characterised with a hypothalamic insufficiency. Here we investigate the role of paternally expressed Snord116 gene within the context of sleep and metabolic abnormalities of PWS, and we report a novel role of this imprinted gene in the function and organisation of the two main neuromodulatory systems of the lateral hypothalamus (LH), namely the orexin (OX) and the melanin concentrating hormone (MCH). We observe that the dynamic between neuronal discharge in the LH and sleep-wake states of mice carrying the paternal deletion of the Snord116 (PWScrm+/p-) is compromised. This abnormal state-dependent neuronal activity is paralleled by a significant reduction of OX neurons in LH of mutants. Therefore, we propose that unbalance between OX- and MCH- expressing neurons in the LH of mutants reflects in a series of deficits manifested in the PWS, such as dysregulation of rapid eye movement (REM) sleep, food intake and temperature control. Investigation of the effect of loss of Snord116 and Sleep Deprivation (SD) on the hypothalamus transcriptome in both normal and PWScrm+/p− mutant mice (paternal Snord116 loss) by performing RNA-sequencing (RNA-seq).  The mice (3-5 per condition) were investigated at the beginning of the light period ZT0 (group 1, G1), six hours later at ZT6 (group 2, G2) and at same ZT6 but following 6-hrs of SD (group 3, G3).