Hypothalamic loss of Snord116 recapitulates the hyperphagia of Prader-Willi syndrome.

Profound hyperphagia is a major disabling feature of Prader-Willi syndrome (PWS). Characterization of the mechanisms that underlie PWS-associated hyperphagia has been slowed by the paucity of animal models with increased food intake or obesity. Mice with a microdeletion encompassing the Snord116 cluster of noncoding RNAs encoded within the Prader-Willi minimal deletion critical region have previously been reported to show growth retardation and hyperphagia. Here, consistent with previous reports, we observed growth retardation in Snord116+/-P mice with a congenital paternal Snord116 deletion. However, these mice neither displayed increased food intake nor had reduced hypothalamic expression of the proprotein convertase 1 gene PCSK1 or its upstream regulator NHLH2, which have recently been suggested to be key mediators of PWS pathogenesis. Specifically, we disrupted Snord116 expression in the mediobasal hypothalamus in Snord116fl mice via bilateral stereotaxic injections of a Cre-expressing adeno-associated virus (AAV). While the Cre-injected mice had no change in measured energy expenditure, they became hyperphagic between 9 and 10 weeks after injection, with a subset of animals developing marked obesity. In conclusion, we show that selective disruption of Snord116 expression in the mediobasal hypothalamus models the hyperphagia of PWS

Heterogeneity of hypothalamic pro-opiomelanocortin-expressing neurons revealed by single-cell RNA sequencing

$\textbf{Objective}$ Arcuate proopiomelanocortin (POMC) neurons are critical nodes in the control of body weight. Often characterized simply as direct targets for leptin, recent data suggest a more complex architecture. $\textbf{Methods}$ Using single cell RNA sequencing, we have generated an atlas of gene expression in murine POMC neurons. $\textbf{Results}$ Of 163 neurons, 118 expressed high levels of $\textit{Pomc}$ with little/no Agrp expression and were considered “canonical” POMC neurons (P$^{+}$). The other 45/163 expressed low levels of $\textit{Pomc}$ and high levels of $\textit{Agrp}$ (A$^{+}$P$_{+}$). Unbiased clustering analysis of P$^{+}$ neurons revealed four different classes, each with distinct cell surface receptor gene expression profiles. Further, only 12% (14/118) of P$^{+}$ neurons expressed the leptin receptor ($\textit{Lepr}$) compared with 58% (26/45) of A$^{+}$P$_{+}$ neurons. In contrast, the insulin receptor ($\textit{Insr}$) was expressed at similar frequency on P$^{+}$ and A$^{+}$P$_{+}$ neurons (64% and 55%, respectively). $\textbf{Conclusion}$ These data reveal arcuate POMC neurons to be a highly heterogeneous population. Accession Numbers: GSE92707.This work was supported by the UK Medical Research Council (MRC) Metabolic Disease Unit (MRC_MC_UU_12012/1 & MRC_MC_UU_12012/5), a Wellcome Trust Strategic Award (100574/Z/12/Z), and the Helmholtz Alliance ICEMED

Heterogeneity of hypothalamic pro-opiomelanocortin-expressing neurons revealed by single-cell RNA sequencing

$\textbf{Objective}$ Arcuate proopiomelanocortin (POMC) neurons are critical nodes in the control of body weight. Often characterized simply as direct targets for leptin, recent data suggest a more complex architecture. $\textbf{Methods}$ Using single cell RNA sequencing, we have generated an atlas of gene expression in murine POMC neurons. $\textbf{Results}$ Of 163 neurons, 118 expressed high levels of $\textit{Pomc}$ with little/no Agrp expression and were considered “canonical” POMC neurons (P$^{+}$). The other 45/163 expressed low levels of $\textit{Pomc}$ and high levels of $\textit{Agrp}$ (A$^{+}$P$_{+}$). Unbiased clustering analysis of P$^{+}$ neurons revealed four different classes, each with distinct cell surface receptor gene expression profiles. Further, only 12% (14/118) of P$^{+}$ neurons expressed the leptin receptor ($\textit{Lepr}$) compared with 58% (26/45) of A$^{+}$P$_{+}$ neurons. In contrast, the insulin receptor ($\textit{Insr}$) was expressed at similar frequency on P$^{+}$ and A$^{+}$P$_{+}$ neurons (64% and 55%, respectively). $\textbf{Conclusion}$ These data reveal arcuate POMC neurons to be a highly heterogeneous population. Accession Numbers: GSE92707.This work was supported by the UK Medical Research Council (MRC) Metabolic Disease Unit (MRC_MC_UU_12012/1 & MRC_MC_UU_12012/5), a Wellcome Trust Strategic Award (100574/Z/12/Z), and the Helmholtz Alliance ICEMED

Thyroid Hormone Receptor Beta in the Ventromedial Hypothalamus Is Essential for the Physiological Regulation of Food Intake and Body Weight.

The obesity epidemic is a significant global health issue. Improved understanding of the mechanisms that regulate appetite and body weight will provide the rationale for the design of anti-obesity therapies. Thyroid hormones play a key role in metabolic homeostasis through their interaction with thyroid hormone receptors (TRs), which function as ligand-inducible transcription factors. The TR-beta isoform (TRβ) is expressed in the ventromedial hypothalamus (VMH), a brain area important for control of energy homeostasis. Here, we report that selective knockdown of TRβ in the VMH of adult mice results in severe obesity due to hyperphagia and reduced energy expenditure. The observed increase in body weight is of a similar magnitude to murine models of the most extreme forms of monogenic obesity. These data identify TRβ in the VMH as a major physiological regulator of food intake and energy homeostasis

Ueber das Löwenzahnbitter (Taraxacin)

n/