Project description:Hypothalamic neuronal populations are central regulators of energy homeostasis and reproductive function. However, the ontogeny of these critical hypothalamic neuronal populations is largely unknown. Here, we reveal novel cellular fates of the hypothalamic Pomc-expressing precursors by combining mouse genetics with a conditional viral ribosome-tagging approach to phenotype neurons. Our results show that the Pomc-expressing precursors differentiate into discrete neuronal subpopulations that mediate not only energy balance (POMC and AgRP) but also reproductive physiology (Kisspeptin). Punches containing the mediobasal hypothalamus of Pomc-Cre:RiboTag mice and Pomc-Cre mice injected with the RiboTag viral vector (AAV-DIO-RiboTag) were homogenized and incubated with anti-hemagglutin (HA) antibodies and protein A/G magnetic beads to isolate the polysome-associated mRNAS in the Pomc-derived lineage and in adult POMC neurons, respectively. To identify differentially expressed transcripts, RNA from the immunoprecipitates was extracted, amplified, labelled and hybridized to MouseRef-8 v2 expression beadchips.
Project description:The activity of the endoribonuclease Dicer is crucial to produce the mature form of most microRNAs (miRNAs). Recent studies indicate that lack of miRNAs in different neuronal types results in a range of anatomical and behavioural phenotypes. In the present study we aimed to investigate the developmental and metabolic consequences of miRNA ablation in hypothalamic POMC neurons studying mice with a conditional deletion of Dicer in this population of neurons (POMCDicerKO). These mice exhibited a progressive obese phenotype characterized by hyperphagia, increased adiposity, hyperleptinemia, defective glucose metabolism and alterations in the pituitary-adrenal axis. The development of the obese phenotype was paralleled by a POMC neuron degenerative process that was complete by 6 weeks of age. Furthermore, immunohistochemistry and gene expression studies in control C57Bl/6 adult mice showed that Dicer was expressed in relevant hypothalamic areas and neurons implicated in energy balance, and that its expression was regulated by nutrient availability. Collectively, our results highlight a crucial role for miRNAs in POMC neuron survival and the consequent development of neurodegenerative obesity. Total RNA was extracted from hypothalamic microdissections of 2-week old control and POMCDicerKO mice using the RNeasy micro spin columns (Qiagen, Venlo, The Netherlands). Ten micrograms of total RNA were converted into cRNA, biotinylated, fragmented, and hybridized to GeneChip Mouse Genome 430 2.0 (Affymetrix, Santa Clara, CA). Six microarrays were hybridized with three independent samples from control and POMCDicerKO mice.
Project description:The hypothalamus contains a remarkable diversity of neurons that orchestrate behavioural and metabolic outputs in a highly plastic manner. Neuronal diversity is key to enabling hypothalamic functions and, according to the neuroscience dogma, it is predetermined during embryonic life. Here, by combining lineage tracing of hypothalamic pro-opiomelanocortin (Pomc) neurons with single-cell profiling approaches in adult male mice, we uncovered subpopulations of 'Ghost' neurons endowed with atypical molecular and functional identity. Compared to 'classical' Pomc neurons, Ghost neurons exhibit negligible Pomc expression and are ‘invisible’ to available neuroanatomical approaches and promoter-based reporter mice for studying Pomc biology. Ghost neuron numbers increase in diet-induced obese mice, independent of neurogenesis or cell death, but weight loss can reverse this shift. Our work challenges the notion of fixed, developmentally programmed neuronal identities in the mature hypothalamus, highlighting the ability of specialized neurons to adapt their funcitonal identity to adult-onset obesogenic stimuli
Project description:Hypothalamic neuronal populations are central regulators of energy homeostasis and reproductive function. However, the ontogeny of these critical hypothalamic neuronal populations is largely unknown. Here, we reveal novel cellular fates of the hypothalamic Pomc-expressing precursors by combining mouse genetics with a conditional viral ribosome-tagging approach to phenotype neurons. Our results show that the Pomc-expressing precursors differentiate into discrete neuronal subpopulations that mediate not only energy balance (POMC and AgRP) but also reproductive physiology (Kisspeptin).
Project description:The in utero environment is a critical determinant of the immediate and future health of the developing fetus. Two of the most commonly used drugs during pregnancy are alcohol and nicotine. While prolonged gestational exposure to alcohol or nicotine has been associated with a range of adverse outcomes in the offspring, the consequences of exposure during early gestation only are less well understood. Here, we use mouse models of relatively moderate early gestational ethanol or nicotine exposure to profile gene expression in whole male embryos at 9.5 days post coitum using an Illumina microarray.
Project description:The activity of the endoribonuclease Dicer is crucial to produce the mature form of most microRNAs (miRNAs). Recent studies indicate that lack of miRNAs in different neuronal types results in a range of anatomical and behavioural phenotypes. In the present study we aimed to investigate the developmental and metabolic consequences of miRNA ablation in hypothalamic POMC neurons studying mice with a conditional deletion of Dicer in this population of neurons (POMCDicerKO). These mice exhibited a progressive obese phenotype characterized by hyperphagia, increased adiposity, hyperleptinemia, defective glucose metabolism and alterations in the pituitary-adrenal axis. The development of the obese phenotype was paralleled by a POMC neuron degenerative process that was complete by 6 weeks of age. Furthermore, immunohistochemistry and gene expression studies in control C57Bl/6 adult mice showed that Dicer was expressed in relevant hypothalamic areas and neurons implicated in energy balance, and that its expression was regulated by nutrient availability. Collectively, our results highlight a crucial role for miRNAs in POMC neuron survival and the consequent development of neurodegenerative obesity.
Project description:Mitofusin 1 (Mfn1) is a transmembrane GTPase protein implicated in mitochondrial fusion. To investigate the potential role of Mfn1 in energy balance and metabolism control we generated mice lacking Mfn1 specifically in hypothalamic POMC neurons (POMCMfn1KO). We used microarrays to determine gene expression changes resulting from deletion of Mfn1 in POMC neurons under fed and fasting conditions
Project description:Maternal unbalanced nutritional habits during embryo development and perinatal stages perturb hypothalamic neuronal programming of the offspring, thus increasing “diabesity” risk. Here we report that exposure to high-fat diet during gestation and lactation did not interfere with progeny’s hypothalamic POMC neuron specification, but significantly impaired their spatial distribution and axonal extension to target areas. Importantly, we established POMC neuron-specific translatome signatures accounting for neuronal aberrant development and axonal growth. These anatomical and molecular alterations caused metabolic dysfunction in early-life and adulthood. Our study provides fundamental insights on the molecular mechanisms underlying POMC neuron malprogramming in obesogenic contexts.
Project description:Developmental exposure to particulate matter air pollution is harmful to cardiovascular health, but the mechanisms by which this exposure mediates susceptibility to heart disease is poorly understood. We have previously shown, in a mouse model, that gestational exposure to diesel exhaust results in increased cardiac hypertrophy, fibrosis and susceptibility to heart failure in the adult offspring following transverse aortic constriction. In this study, we have analyzed gene expression in neonatal cardiomyocytes after gestational exposure by RNA-sequencing and have identified 300 genes that are dysregulated, including many involved in cardiac metabolism.
Project description:We developed a technique for generating hypothalamic neurons from human pluripotent stem cells. Here, as proof-of-principle, we examine the use of these cells in modeling of a monogenic form of severe obesity: PCSK1 deficiency. We generated PCSK1 (PC1/3)-deficient human embryonic stem cell (hESC) lines using both shRNA and CRISPR-Cas9, and investigated pro-opiomelanocortin (POMC) processing using hESC-differentiated hypothalamic neurons.