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Prader-Willi syndrome (PWS) is caused by a loss of paternally expressed genes in an imprinted region of chromosome 15q. Among the canonical PWS phenotypes are hyperphagic obesity, central hypogonadism, and low growth hormone (GH). Rare microdeletions in PWS patients define a 91-kb minimum critical deletion region encompassing 3 genes, including the noncoding RNA gene SNORD116. Here, we found that protein and transcript levels of nescient helix loop helix 2 (NHLH2) and the prohormone convertase PC1 (encoded by PCSK1) were reduced in PWS patient induced pluripotent stem cell-derived (iPSC-derived) neurons. Moreover, Nhlh2 and Pcskl expression were reduced in hypothalami of fasted Snord116 paternal knockout ([Snord116.sup.p/m+]) mice. Hypothalamic Agrp and Npy remained elevated following refeeding in association with relative hyperphagia in Snord116p/m+ mice. Nhlh2-deficient mice display growth deficiencies as adolescents and hypogonadism, hyperphagia, and obesity as adults. Nhlh2 has also been shown to promote Pcsk1 expression. Humans and mice deficient in PC1 display hyperphagic obesity, hypogonadism, decreased GH, and hypoinsulinemic diabetes due to impaired prohormone processing. Here, we found that [Snord116.sup.p/m+] mice displayed in vivo functional defects in prohormone processing of proinsulin, pro-GH-releasing hormone, and proghrelin in association with reductions in islet, hypothalamic, and stomach PC1 content. Our findings suggest that the major neuroendocrine features of PWS are due to PC1 deficiency., Introduction Prader-Willi syndrome (PWS) is the most common syndromic obesity, affecting 1 in 25,000 live births (1, 2). PWS results from a loss of paternally expressed genes at 15q11.2-q13 (Figure [...]

Noncoding polymorphisms in the fat mass and obesity-associated (FTO) gene represent common alleles that are strongly associated with effects on food intake and adiposity in humans. Previous studies have suggested that the obesity- risk allele rs8050136 in the first intron of FTO alters a regulatory element recognized by the transcription factor CUX1, thereby leading to decreased expression of FTO and retinitis pigmentosa GTPase regulator-interacting protein-1 like (RPGRIP1L). Here, we evaluated the effects of rs8050136 and another potential CUX1 element in rs1421085 on expression of nearby genes in human induced pluripotent stem cell-derived (iPSC-derived) neurons. There were allele-dosage effects on FTO, RPGRIP1L, and AKT-interacting protein (AKTIP) expression, but expression of other vicinal genes, including IRX3, IRX5, and RBL2, which have been implicated in mediating functional effects, was not altered. In vivo manipulation of CUX1, Fto, and/or RpgripH expression in mice affected adiposity in a manner that was consistent with CUX1 influence on adiposity via remote effects on Fto and Rpgrip1l expression. In support of a mechanism, mice hypomorphic for RpgripH exhibited hyperphagic obesity, as the result of diminished leptin sensitivity in Leprb-expressing neurons. Together, the results of this study indicate that the effects of FTO-associated SNPs on energy homeostasis are due in part to the effects of these genetic variations on hypothalamic FTO, RPGRIP1L, and possibly other genes., Introduction The strongest GWAS signal yet detected for common obesity is generated by SNPs located within an approximately 47-kb interval in the first intron of fat mass and obesity-associated (FTO) [...]