ABSTRACT
Light Sheet Fluorescence Microscopy (LSFM) of whole organs, in particular the brain, offers a plethora of biological data imaged in 3D. This technique is however often hindered by cumbersome non-automated analysis methods. Here we describe an approach to fully automate the analysis by integrating with data from the Allen Institute of Brain Science (AIBS), to provide precise assessment of the distribution and action of peptide-based pharmaceuticals in the brain. To illustrate this approach, we examined the acute central nervous system effects of the glucagon-like peptide-1 (GLP-1) receptor agonist liraglutide. Peripherally administered liraglutide accessed the hypothalamus and brainstem, and led to activation in several brain regions of which most were intersected by projections from neurons in the lateral parabrachial nucleus. Collectively, we provide a rapid and unbiased analytical framework for LSFM data which enables quantification and exploration based on data from AIBS to support basic and translational discovery.
Subject(s)
Brain Mapping , Hypoglycemic Agents/pharmacology , Liraglutide/pharmacology , Nervous System/drug effects , Animals , Brain Stem/metabolism , Brain Stem/pathology , Eating , Glucagon-Like Peptide-1 Receptor/agonists , Hypothalamus/metabolism , Hypothalamus/pathology , Mice , Mice, Inbred C57BL , Microscopy, Fluorescence , Nervous System/metabolism , Proto-Oncogene Proteins c-fos/metabolismABSTRACT
To date, it remains largely unclear to what extent chromatin machinery contributes to the susceptibility and progression of complex diseases. Here, we combine deep epigenome mapping with single-cell transcriptomics to mine for evidence of chromatin dysregulation in type 2 diabetes. We find two chromatin-state signatures that track ß cell dysfunction in mice and humans: ectopic activation of bivalent Polycomb-silenced domains and loss of expression at an epigenomically unique class of lineage-defining genes. ß cell-specific Polycomb (Eed/PRC2) loss of function in mice triggers diabetes-mimicking transcriptional signatures and highly penetrant, hyperglycemia-independent dedifferentiation, indicating that PRC2 dysregulation contributes to disease. The work provides novel resources for exploring ß cell transcriptional regulation and identifies PRC2 as necessary for long-term maintenance of ß cell identity. Importantly, the data suggest a two-hit (chromatin and hyperglycemia) model for loss of ß cell identity in diabetes.
Subject(s)
Chromatin/metabolism , Diabetes Mellitus, Type 2/metabolism , Diet, High-Fat , Gene Silencing , Insulin-Secreting Cells/metabolism , Polycomb Repressive Complex 2/physiology , Animals , Cell Differentiation/genetics , Cells, Cultured , Chromosome Mapping , Diabetes Mellitus, Type 2/genetics , Epigenomics , Histone-Lysine N-Methyltransferase/genetics , Histone-Lysine N-Methyltransferase/metabolism , Humans , Hyperglycemia/genetics , Mice , Mice, Inbred C57BL , Mice, Knockout , Myeloid-Lymphoid Leukemia Protein/genetics , Myeloid-Lymphoid Leukemia Protein/metabolism , Polycomb Repressive Complex 2/genetics , Single-Cell AnalysisABSTRACT
More than one-half billion people are obese, and despite progress in genetic research, much of the heritability of obesity remains enigmatic. Here, we identify a Trim28-dependent network capable of triggering obesity in a non-Mendelian, "on/off" manner. Trim28(+/D9) mutant mice exhibit a bi-modal body-weight distribution, with isogenic animals randomly emerging as either normal or obese and few intermediates. We find that the obese-"on" state is characterized by reduced expression of an imprinted gene network including Nnat, Peg3, Cdkn1c, and Plagl1 and that independent targeting of these alleles recapitulates the stochastic bi-stable disease phenotype. Adipose tissue transcriptome analyses in children indicate that humans too cluster into distinct sub-populations, stratifying according to Trim28 expression, transcriptome organization, and obesity-associated imprinted gene dysregulation. These data provide evidence of discrete polyphenism in mouse and man and thus carry important implications for complex trait genetics, evolution, and medicine.
Subject(s)
Epigenesis, Genetic , Haploinsufficiency , Nuclear Proteins/genetics , Obesity/genetics , Repressor Proteins/genetics , Thinness/genetics , Adolescent , Animals , Body Mass Index , Child , Child, Preschool , Humans , Mice , Nutrition Surveys , Polymorphism, Genetic , Tripartite Motif-Containing Protein 28ABSTRACT
Obesity and diabetes affect more than half a billion individuals worldwide. Interestingly, the two conditions do not always coincide and the molecular determinants of "healthy" versus "unhealthy" obesity remain ill-defined. Chronic metabolic inflammation (metaflammation) is believed to be pivotal. Here, we tested a hypothesized anti-inflammatory role for heme oxygenase-1 (HO-1) in the development of metabolic disease. Surprisingly, in matched biopsies from "healthy" versus insulin-resistant obese subjects we find HO-1 to be among the strongest positive predictors of metabolic disease in humans. We find that hepatocyte and macrophage conditional HO-1 deletion in mice evokes resistance to diet-induced insulin resistance and inflammation, dramatically reducing secondary disease such as steatosis and liver toxicity. Intriguingly, cellular assays show that HO-1 defines prestimulation thresholds for inflammatory skewing and NF-κB amplification in macrophages and for insulin signaling in hepatocytes. These findings identify HO-1 inhibition as a potential therapeutic strategy for metabolic disease.
