Publications by authors named "Camilla Scheele"

60 Publications

Endogenous Fatty Acid Synthesis Drives Brown Adipose Tissue Involution.

Cell Rep 2021 Jan;34(2):108624

Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. Electronic address:

Thermoneutral conditions typical for standard human living environments result in brown adipose tissue (BAT) involution, characterized by decreased mitochondrial mass and increased lipid deposition. Low BAT activity is associated with poor metabolic health, and BAT reactivation may confer therapeutic potential. However, the molecular drivers of this BAT adaptive process in response to thermoneutrality remain enigmatic. Using metabolic and lipidomic approaches, we show that endogenous fatty acid synthesis, regulated by carbohydrate-response element-binding protein (ChREBP), is the central regulator of BAT involution. By transcriptional control of lipogenesis-related enzymes, ChREBP determines the abundance and composition of both storage and membrane lipids known to regulate organelle turnover and function. Notably, ChREBP deficiency and pharmacological inhibition of lipogenesis during thermoneutral adaptation preserved mitochondrial mass and thermogenic capacity of BAT independently of mitochondrial biogenesis. In conclusion, we establish lipogenesis as a potential therapeutic target to prevent loss of BAT thermogenic capacity as seen in adult humans.
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http://dx.doi.org/10.1016/j.celrep.2020.108624DOI Listing
January 2021

Brown Adipose Tissue: A Metabolic Regulator in a Hypothalamic Cross Talk?

Annu Rev Physiol 2021 02 6;83:279-301. Epub 2020 Nov 6.

Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark; email:

Since the discovery of functionally competent, energy-consuming brown adipose tissue (BAT) in adult humans, much effort has been devoted to exploring this tissue as a means for increasing energy expenditure to counteract obesity. However, despite promising effects on metabolic rate and insulin sensitivity, no convincing evidence for weight-loss effects of cold-activated human BAT exists to date. Indeed, increasing energy expenditure would naturally induce compensatory feedback mechanisms to defend body weight. Interestingly, BAT is regulated by multiple interactions with the hypothalamus from regions overlapping with centers for feeding behavior and metabolic control. Therefore, in the further exploration of BAT as a potential source of novel drug targets, we discuss the hypothalamic orchestration of BAT activity and the relatively unexplored BAT feedback mechanisms on neuronal regulation. With a holistic view on hypothalamic-BAT interactions, we aim to raise ideas and provide a new perspective on this circuit and highlight its clinical relevance.
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http://dx.doi.org/10.1146/annurev-physiol-032420-042950DOI Listing
February 2021

Calsyntenin 3β Is Dynamically Regulated by Temperature in Murine Brown Adipose and Marks Human Multilocular Fat.

Front Endocrinol (Lausanne) 2020 25;11:579785. Epub 2020 Sep 25.

Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.

Activation of thermogenic adipose tissue is linked to improved metabolic outcomes in mice and humans. Dissipation of energy as heat during thermogenesis relies on sufficient innervation of fat by sympathetic nerve fibers, a process recently proposed to be regulated by the adipose-specific calsyntenin3β (Clstn3β)-S100b axis. Here we aimed 1) to assess enrichment patterns of , as well as the previously annotated neuronal in perirenal brown and subcutaneous white human fat specimens, and 2) to investigate if the novel is dynamically regulated by changes in environmental temperatures and nutritional stress in thermogenic adipose tissues in mice. We provide evidence for enrichment in multilocular perirenal fat located anatomically in the proximity to both the adrenal gland and sympathetic nerve bundles innervating the kidney in humans. Moreover, transcript levels of , but not or , positively correlate with uncoupling protein 1 () expression in human adipose tissue. Our results further show that is preferentially expressed in brown adipocytes and is highly responsive to changes in environmental temperature and obesity state in mice. Collectively, this brief communication highlights as a hallmark of thermogenic adipose depots in mice and humans.
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http://dx.doi.org/10.3389/fendo.2020.579785DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7546853PMC
September 2020

Human Brown Adipocyte Thermogenesis Is Driven by β2-AR Stimulation.

Cell Metab 2020 Aug;32(2):287-300.e7

Centre de Recherche du Centre Hospitalier Universitaire de Sherbrooke, Sherbrooke, QC, Canada; Department of Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada. Electronic address:

Stimulation of brown adipose tissue (BAT) thermogenesis in humans has emerged as an attractive target to improve metabolic health. Pharmacological stimulations targeting the β-adrenergic receptor (β-AR), the adrenergic receptor believed to mediate BAT thermogenesis, have historically performed poorly in human clinical trials. Here we report that, in contrast to rodents, human BAT thermogenesis is not mediated by the stimulation of β-AR. Oral administration of the β-AR agonist mirabegron only elicited increases in BAT thermogenesis when ingested at the maximal allowable dose. This led to off-target binding to β-AR and β-AR, thereby increasing cardiovascular responses and white adipose tissue lipolysis, respectively. ADRB2 was co-expressed with UCP1 in human brown adipocytes. Pharmacological stimulation and inhibition of the β-AR as well as knockdown of ADRB1, ADRB2, or ADRB3 in human brown adipocytes all confirmed that BAT lipolysis and thermogenesis occur through β-AR signaling in humans (ClinicalTrials.govNCT02811289).
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http://dx.doi.org/10.1016/j.cmet.2020.07.005DOI Listing
August 2020

Human brown adipose tissue is phenocopied by classical brown adipose tissue in physiologically humanized mice.

Nat Metab 2019 08 19;1(8):830-843. Epub 2019 Aug 19.

Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.

Human and rodent brown adipose tissues (BAT) appear morphologically and molecularly different. Here we compare human BAT with both classical brown and brite/beige adipose tissues of 'physiologically humanized' mice: middle-aged mice living under conditions approaching human thermal and nutritional conditions, that is, prolonged exposure to thermoneutral temperature (approximately 30 °C) and to an energy-rich (high-fat, high-sugar) diet. We find that the morphological, cellular and molecular characteristics (both marker and adipose-selective gene expression) of classical brown fat, but not of brite/beige fat, of these physiologically humanized mice are notably similar to human BAT. We also demonstrate, both in silico and experimentally, that in physiologically humanized mice only classical BAT possesses a high thermogenic potential. These observations suggest that classical rodent BAT is the tissue of choice for translational studies aimed at recruiting human BAT to counteract the development of obesity and its comorbidities.
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http://dx.doi.org/10.1038/s42255-019-0101-4DOI Listing
August 2019

Adenosine/A2B Receptor Signaling Ameliorates the Effects of Aging and Counteracts Obesity.

Cell Metab 2020 Jul 25;32(1):56-70.e7. Epub 2020 Jun 25.

Institute of Pharmacology and Toxicology, University Hospital, University of Bonn, 53127 Bonn, Germany. Electronic address:

The combination of aging populations with the obesity pandemic results in an alarming rise in non-communicable diseases. Here, we show that the enigmatic adenosine A2B receptor (A2B) is abundantly expressed in skeletal muscle (SKM) as well as brown adipose tissue (BAT) and might be targeted to counteract age-related muscle atrophy (sarcopenia) as well as obesity. Mice with SKM-specific deletion of A2B exhibited sarcopenia, diminished muscle strength, and reduced energy expenditure (EE), whereas pharmacological A2B activation counteracted these processes. Adipose tissue-specific ablation of A2B exacerbated age-related processes and reduced BAT EE, whereas A2B stimulation ameliorated obesity. In humans, A2B expression correlated with EE in SKM, BAT activity, and abundance of thermogenic adipocytes in white fat. Moreover, A2B agonist treatment increased EE from human adipocytes, myocytes, and muscle explants. Mechanistically, A2B forms heterodimers required for adenosine signaling. Overall, adenosine/A2B signaling links muscle and BAT and has both anti-aging and anti-obesity potential.
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http://dx.doi.org/10.1016/j.cmet.2020.06.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7437516PMC
July 2020

Exercise and browning of white adipose tissue - a translational perspective.

Curr Opin Pharmacol 2020 06 29;52:18-24. Epub 2020 May 29.

Centre of Inflammation and Metabolism/Centre for Physical Activity Research (CIM/CFAS), Rigshospitalet, University of Copenhagen, Copenhagen, Denmark. Electronic address:

Browning of white adipose tissue is a cold-induced phenomenon in rodents, constituted by the differentiation of a subset of thermogenic adipocytes among existing white adipocytes. Emerging evidence in the literature points at additional factors and environmental conditions stimulating browning in rodents, including physical exercise training. Exercise engages sympathetic activation which during cold activation promotes proliferation and differentiation of brown preadipocytes. Exercise also stimulates the release of multiple growth factors and cytokines. Importantly, there are clear discrepancies between human and rodents with regard to thermogenic capacity and browning potential. Here we provide a translational perspective on exercise-induced browning and review recent findings on the role of myokines and hepatokines in this process.
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http://dx.doi.org/10.1016/j.coph.2020.04.004DOI Listing
June 2020

Human thermogenic adipocyte regulation by the long noncoding RNA LINC00473.

Nat Metab 2020 05 21;2(5):397-412. Epub 2020 May 21.

The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.

Human thermogenic adipose tissue mitigates metabolic disease, raising much interest in understanding its development and function. Here, we show that human thermogenic adipocytes specifically express a primate-specific long non-coding RNA, which is highly correlated with UCP1 expression and decreased in obesity and type-2 diabetes. is detected in progenitor cells, and increases upon differentiation and in response to cAMP. In contrast to other known adipocyte LincRNAs, LINC00473 shuttles out of the nucleus, colocalizes and can be crosslinked to mitochondrial and lipid droplet proteins. Up- or down- regulation of results in reciprocal alterations in lipolysis, respiration and transcription of genes associated with mitochondrial oxidative metabolism. Depletion of PLIN1 results in impaired cAMP-responsive expression and lipolysis, indicating bidirectional interactions between PLIN1, LINC00473 and mitochondrial oxidative functions. Thus, we suggest that is a key regulator of human thermogenic adipocyte function, and reveals a role for a LincRNA in inter-organelle communication and human energy metabolism.
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http://dx.doi.org/10.1038/s42255-020-0205-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7241442PMC
May 2020

Proteomics-Based Comparative Mapping of the Secretomes of Human Brown and White Adipocytes Reveals EPDR1 as a Novel Batokine.

Cell Metab 2019 11 24;30(5):963-975.e7. Epub 2019 Oct 24.

Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen 2200, Denmark; The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen 2100, Denmark. Electronic address:

Adipokines secreted from white adipose tissue play a role in metabolic crosstalk and homeostasis, whereas the brown adipose secretome is less explored. We performed high-sensitivity mass-spectrometry-based proteomics on the cell media of human adipocytes derived from the supraclavicular brown adipose and from the subcutaneous white adipose depots of adult humans. We identified 471 potentially secreted proteins covering interesting categories such as hormones, growth factors, extracellular matrix proteins, and proteins of the complement system, which were differentially regulated between brown and white adipocytes. A total of 101 proteins were exclusively quantified in brown adipocytes, and among these was ependymin-related protein 1 (EPDR1). EPDR1 was detected in human plasma, and functional studies suggested a role for EPDR1 in thermogenic determination during adipogenesis. In conclusion, we report substantial differences between the secretomes of brown and white human adipocytes and identify novel candidate batokines that can be important regulators of human metabolism.
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http://dx.doi.org/10.1016/j.cmet.2019.10.001DOI Listing
November 2019

Brown Adipose Crosstalk in Tissue Plasticity and Human Metabolism.

Endocr Rev 2020 01;41(1)

Institute of Food, Nutrition, and Health, ETH Zürich, Schorenstrasse, Schwerzenbach, Switzerland.

Infants rely on brown adipose tissue (BAT) as a primary source of thermogenesis. In some adult humans, residuals of brown adipose tissue are adjacent to the central nervous system and acute activation increases metabolic rate. Brown adipose tissue (BAT) recruitment occurs during cold acclimation and includes secretion of factors, known as batokines, which target several different cell types within BAT, and promote adipogenesis, angiogenesis, immune cell interactions, and neurite outgrowth. All these processes seem to act in concert to promote an adapted BAT. Recent studies have also provided exciting data on whole body metabolic regulation with a broad spectrum of mechanisms involving BAT crosstalk with liver, skeletal muscle, and gut as well as the central nervous system. These widespread interactions might reflect the property of BAT of switching between an active thermogenic state where energy is highly consumed and drained from the circulation, and the passive thermoneutral state, where energy consumption is turned off. (Endocrine Reviews 41: XXX - XXX, 2020).
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http://dx.doi.org/10.1210/endrev/bnz007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7006230PMC
January 2020

Epigenome- and Transcriptome-wide Changes in Muscle Stem Cells from Low Birth Weight Men.

Endocr Res 2020 Feb 30;45(1):58-71. Epub 2019 Sep 30.

Department of Endocrinology, Diabetes and Bone-metabolic Research Unit, Copenhagen, Denmark.

: Being born with low birth weight (LBW) is a risk factor for muscle insulin resistance and type 2 diabetes (T2D), which may be mediated by epigenetic mechanisms programmed by the intrauterine environment. Epigenetic mechanisms exert their prime effects in developing cells. We hypothesized that muscle insulin resistance in LBW subjects may be due to early differential epigenomic and transcriptomic alterations in their immature muscle progenitor cells.: Muscle progenitor cells were obtained from 23 healthy young adult men born at term with LBW, and 15 BMI-matched normal birth weight (NBW) controls. The cells were subsequently cultured and differentiated into myotubes. DNA and RNA were harvested before and after differentiation for genome-wide DNA methylation and RNA expression measurements.After correcting for multiple comparisons (q ≤ 0.05), 56 CpG sites were found to be significantly, differentially methylated in myoblasts from LBW compared with NBW men, of which the top five gene-annotated CpG sites () previously have been associated to regulation of cholesterol, fatty acid and glucose metabolism and muscle development or hypertrophy. LBW men displayed markedly decreased myotube gene expression levels of the AMPK-repressing tyrosine kinase gene and the histone deacetylase gene . Silencing of and was associated with impaired myotube formation, which for reduced muscle glucose uptake.: The data provides evidence of impaired muscle development predisposing LBW individuals to T2D is linked to and potentially caused by distinct DNA methylation and transcriptional changes including down regulation of and in their immature myoblast stem cells.
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http://dx.doi.org/10.1080/07435800.2019.1669160DOI Listing
February 2020

Diverse repertoire of human adipocyte subtypes develops from transcriptionally distinct mesenchymal progenitor cells.

Proc Natl Acad Sci U S A 2019 09 16;116(36):17970-17979. Epub 2019 Aug 16.

Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01655;

Single-cell sequencing technologies have revealed an unexpectedly broad repertoire of cells required to mediate complex functions in multicellular organisms. Despite the multiple roles of adipose tissue in maintaining systemic metabolic homeostasis, adipocytes are thought to be largely homogenous with only 2 major subtypes recognized in humans so far. Here we report the existence and characteristics of 4 distinct human adipocyte subtypes, and of their respective mesenchymal progenitors. The phenotypes of these distinct adipocyte subtypes are differentially associated with key adipose tissue functions, including thermogenesis, lipid storage, and adipokine secretion. The transcriptomic signature of "brite/beige" thermogenic adipocytes reveals mechanisms for iron accumulation and protection from oxidative stress, necessary for mitochondrial biogenesis and respiration upon activation. Importantly, this signature is enriched in human supraclavicular adipose tissue, confirming that these cells comprise thermogenic depots in vivo, and explain previous findings of a rate-limiting role of iron in adipose tissue browning. The mesenchymal progenitors that give rise to beige/brite adipocytes express a unique set of cytokines and transcriptional regulators involved in immune cell modulation of adipose tissue browning. Unexpectedly, we also find adipocyte subtypes specialized for high-level expression of the adipokines adiponectin or leptin, associated with distinct transcription factors previously implicated in adipocyte differentiation. The finding of a broad adipocyte repertoire derived from a distinct set of mesenchymal progenitors, and of the transcriptional regulators that can control their development, provides a framework for understanding human adipose tissue function and role in metabolic disease.
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http://dx.doi.org/10.1073/pnas.1906512116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6731669PMC
September 2019

Heterogeneity in the perirenal region of humans suggests presence of dormant brown adipose tissue that contains brown fat precursor cells.

Mol Metab 2019 06 15;24:30-43. Epub 2019 Mar 15.

The Centre of Inflammation and Metabolism and Centre for Physical Activity Research Rigshospitalet, University Hospital of Copenhagen, 2100, Denmark; Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark. Electronic address:

Objective: Increasing the amounts of functionally competent brown adipose tissue (BAT) in adult humans has the potential to restore dysfunctional metabolism and counteract obesity. In this study, we aimed to characterize the human perirenal fat depot, and we hypothesized that there would be regional, within-depot differences in the adipose signature depending on local sympathetic activity.

Methods: We characterized fat specimens from four different perirenal regions of adult kidney donors, through a combination of qPCR mapping, immunohistochemical staining, RNA-sequencing, and pre-adipocyte isolation. Candidate gene signatures, separated by adipocyte morphology, were recapitulated in a murine model of unilocular brown fat induced by thermoneutrality and high fat diet.

Results: We identified widespread amounts of dormant brown adipose tissue throughout the perirenal depot, which was contrasted by multilocular BAT, primarily found near the adrenal gland. Dormant BAT was characterized by a unilocular morphology and a distinct gene expression profile, which partly overlapped with that of subcutaneous white adipose tissue (WAT). Brown fat precursor cells, which differentiated into functional brown adipocytes were present in the entire perirenal fat depot, regardless of state. We identified SPARC as a candidate adipokine contributing to a dormant BAT state, and CLSTN3 as a novel marker for multilocular BAT.

Conclusions: We propose that perirenal adipose tissue in adult humans consists mainly of dormant BAT and provide a data set for future research on factors which can reactivate dormant BAT into active BAT, a potential strategy for combatting obesity and metabolic disease.
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http://dx.doi.org/10.1016/j.molmet.2019.03.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6531810PMC
June 2019

Author Correction: Osteogenesis depends on commissioning of a network of stem cell transcription factors that act as repressors of adipogenesis.

Nat Genet 2019 04;51(4):766

Functional Genomics and Metabolism Research Unit, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark.

In the version of this article initially published, in the graph keys in Fig. 1i, the colors indicating 'Ob' and 'Ad' were red and blue, respectively, but should have been blue and red, respectively; the shapes indicating 'MUS' and 'BM' were a triangle and a square, respectively, but should have been a square and a triangle, respectively. The errors have been corrected in the HTML and PDF versions of the article.
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http://dx.doi.org/10.1038/s41588-019-0400-4DOI Listing
April 2019

Osteogenesis depends on commissioning of a network of stem cell transcription factors that act as repressors of adipogenesis.

Nat Genet 2019 04 4;51(4):716-727. Epub 2019 Mar 4.

Functional Genomics and Metabolism Research Unit, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark.

Mesenchymal (stromal) stem cells (MSCs) constitute populations of mesodermal multipotent cells involved in tissue regeneration and homeostasis in many different organs. Here we performed comprehensive characterization of the transcriptional and epigenomic changes associated with osteoblast and adipocyte differentiation of human MSCs. We demonstrate that adipogenesis is driven by considerable remodeling of the chromatin landscape and de novo activation of enhancers, whereas osteogenesis involves activation of preestablished enhancers. Using machine learning algorithms for in silico modeling of transcriptional regulation, we identify a large and diverse transcriptional network of pro-osteogenic and antiadipogenic transcription factors. Intriguingly, binding motifs for these factors overlap with SNPs related to bone and fat formation in humans, and knockdown of single members of this network is sufficient to modulate differentiation in both directions, thus indicating that lineage determination is a delicate balance between the activities of many different transcription factors.
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http://dx.doi.org/10.1038/s41588-019-0359-1DOI Listing
April 2019

Sex influences DNA methylation and gene expression in human skeletal muscle myoblasts and myotubes.

Stem Cell Res Ther 2019 01 15;10(1):26. Epub 2019 Jan 15.

Department of Clinical Sciences, Lund University Diabetes Centre, Lund University, Scania University Hospital, 20502, Malmö, Sweden.

Background: Sex differences are known to impact muscle phenotypes, metabolism, and disease risk. Skeletal muscle stem cells (satellite cells) are important for muscle repair and to maintain functional skeletal muscle. Here we studied, for the first time, effects of sex on DNA methylation and gene expression in primary human myoblasts (activated satellite cells) before and after differentiation into myotubes.

Method: We used an array-based approach to analyse genome-wide DNA methylation and gene expression in myoblasts and myotubes from 13 women and 13 men. The results were followed up with a reporter gene assay.

Results: Genome-wide DNA methylation and gene expression differences between the sexes were detected in both myoblasts and myotubes, on the autosomes as well as the X-chromosome, despite lack of exposure to sex hormones and other factors that differ between sexes. Pathway analysis revealed higher expression of oxidative phosphorylation and other metabolic pathways in myoblasts from women compared to men. Oxidative phosphorylation was also enriched among genes with higher expression in myotubes from women. Forty genes in myoblasts and 9 in myotubes had differences in both DNA methylation and gene expression between the sexes, including LAMP2 and SIRT1 in myoblasts and KDM6A in myotubes. Furthermore, increased DNA methylation of LAMP2 promoter had negative effects on reporter gene expression. Five genes (CREB5, RPS4X, SYAP1, XIST, and ZRSR2) showed differential DNA methylation and gene expression between the sexes in both myoblasts and myotubes. Interestingly, differences in DNA methylation and expression between women and men were also found during differentiation (myoblasts versus myotubes), e.g., in genes involved in energy metabolism. Interestingly, more DNA methylation changes occur in women compared to men on autosomes.

Conclusion: All together, we show that epigenetic and transcriptional differences exist in human myoblasts and myotubes as well as during differentiation between women and men. We believe that these intrinsic differences might contribute to sex dependent differences in muscular phenotypes.
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http://dx.doi.org/10.1186/s13287-018-1118-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6332625PMC
January 2019

Gamma-Aminobutyric Acid Signaling in Brown Adipose Tissue Promotes Systemic Metabolic Derangement in Obesity.

Cell Rep 2018 09;24(11):2827-2837.e5

Department of Cardiovascular Biology and Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan. Electronic address:

Brown adipose tissue (BAT) is a metabolically active organ that contributes to the maintenance of systemic metabolism. The sympathetic nervous system plays important roles in the homeostasis of BAT and promotes its browning and activation. However, the role of other neurotransmitters in BAT homeostasis remains largely unknown. Our metabolomic analyses reveal that gamma-aminobutyric acid (GABA) levels are increased in the interscapular BAT of mice with dietary obesity. We also found a significant increase in GABA-type B receptor subunit 1 (GABA-BR1) in the cell membranes of brown adipocytes of dietary obese mice. When administered to obese mice, GABA induces BAT dysfunction together with systemic metabolic disorder. Conversely, the genetic inactivation or inhibition of GABA-BR1 leads to the re-browning of BAT under conditions of metabolic stress and ameliorated systemic glucose intolerance. These results indicate that the constitutive activation of GABA/GABA-BR1 signaling in obesity promotes BAT dysfunction and systemic metabolic derangement.
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http://dx.doi.org/10.1016/j.celrep.2018.08.024DOI Listing
September 2018

Single Cell Analysis Identifies the miRNA Expression Profile of a Subpopulation of Muscle Precursor Cells Unique to Humans With Type 2 Diabetes.

Front Physiol 2018 11;9:883. Epub 2018 Jul 11.

Centre for Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.

MicroRNAs (miRNAs) take part in regulating central cellular processes such as differentiation and metabolism. We have previously shown that muscle progenitor cells derived from individuals with type 2 diabetes (T2DM) have a dysregulated miRNA profile. We hypothesized that the T2DM muscle progenitor population is heterogeneous in its miRNA expression and differs from the progenitor population of healthy controls. MiRNA expression profiles of CD56+ muscle progenitor cells from people with T2DM and from healthy controls were therefore investigated at a single cell level. Single-cell analysis revealed three subpopulations expressing distinct miRNA profiles: two subpopulations including both T2DM and healthy control muscle precursors presented miRNA expression profiles mostly overlapping between groups. A distinct third subpopulation consisted solely of cells from donors with T2DM and showed enriched expression of miRNAs previously shown to be associated with type 2 diabetes. Among the enriched miRNAs was miR-29, a regulator of mRNA expression. Interestingly, this subpopulation also revealed several miRNAs with predicted targets in the PI3K/Akt pathway, not previously described in relation to T2DM muscle dysfunction. We concluded that a subpopulation of T2DM muscle precursor cells is severely dysregulated in terms of their miRNA expression, and accumulation of this population might thus contribute to the dysfunctional muscular phenotype in type 2 diabetes.
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http://dx.doi.org/10.3389/fphys.2018.00883DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6050405PMC
July 2018

Adipogenesis in Primary Cell Culture.

Handb Exp Pharmacol 2019 ;251:73-84

The Centre of Inflammation and Metabolism and Centre for Physical Activity Research Rigshospitalet, University Hospital of Copenhagen, Copenhagen, Denmark.

Obesity involves a contrasting expansion of the energy-storing white fat and loss of functionally competent brown fat, an energy-consuming thermogenic adipose. Leveraging our understanding of white and brown adipocyte recruitment and investigating factors that regulate these processes might reveal novel targets for counteracting obesity. In vitro differentiation of primary preadipocytes mimics many of the morphological and transcriptional events occurring during adipogenesis in vivo. Moreover, preadipocytes isolated from a specific depot maintain features of their originating niche. This makes in vitro adipogenesis a valuable model for identifying differential regulation patterns between brown and white adipogenesis. In this chapter, we describe step-by-step how to isolate brown and white preadipocytes from human tissue biopsies and how to culture and differentiate them in vitro. We discuss this process, what to consider, and how this in vitro system can be used to model in vivo adipogenesis.
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http://dx.doi.org/10.1007/164_2018_142DOI Listing
July 2019

Cardiolipin Synthesis in Brown and Beige Fat Mitochondria Is Essential for Systemic Energy Homeostasis.

Cell Metab 2018 Jul 31;28(1):159-174.e11. Epub 2018 May 31.

Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen 2200, Denmark; Department of Biomedical Sciences, University of Copenhagen, Copenhagen 2200, Denmark. Electronic address:

Activation of energy expenditure in thermogenic fat is a promising strategy to improve metabolic health, yet the dynamic processes that evoke this response are poorly understood. Here we show that synthesis of the mitochondrial phospholipid cardiolipin is indispensable for stimulating and sustaining thermogenic fat function. Cardiolipin biosynthesis is robustly induced in brown and beige adipose upon cold exposure. Mimicking this response through overexpression of cardiolipin synthase (Crls1) enhances energy consumption in mouse and human adipocytes. Crls1 deficiency in thermogenic adipocytes diminishes inducible mitochondrial uncoupling and elicits a nuclear transcriptional response through endoplasmic reticulum stress-mediated retrograde communication. Cardiolipin depletion in brown and beige fat abolishes adipose thermogenesis and glucose uptake, which renders animals insulin resistant. We further identify a rare human CRLS1 variant associated with insulin resistance and show that adipose CRLS1 levels positively correlate with insulin sensitivity. Thus, adipose cardiolipin has a powerful impact on organismal energy homeostasis through thermogenic fat bioenergetics.
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http://dx.doi.org/10.1016/j.cmet.2018.05.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6038052PMC
July 2018

Brown Fat AKT2 Is a Cold-Induced Kinase that Stimulates ChREBP-Mediated De Novo Lipogenesis to Optimize Fuel Storage and Thermogenesis.

Cell Metab 2018 01 16;27(1):195-209.e6. Epub 2017 Nov 16.

Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605, USA. Electronic address:

Brown adipose tissue (BAT) is a therapeutic target for metabolic diseases; thus, understanding its metabolic circuitry is clinically important. Many studies of BAT compare rodents mildly cold to those severely cold. Here, we compared BAT remodeling between thermoneutral and mild-cold-adapted mice, conditions more relevant to humans. Although BAT is renowned for catabolic β-oxidative capacity, we find paradoxically that the anabolic de novo lipogenesis (DNL) genes encoding ACLY, ACSS2, ACC, and FASN were among the most upregulated by mild cold and that, in humans, DNL correlates with Ucp1 expression. The regulation and function of adipocyte DNL and its association with thermogenesis are not understood. We provide evidence suggesting that AKT2 drives DNL in adipocytes by stimulating ChREBPβ transcriptional activity and that cold induces the AKT2-ChREBP pathway in BAT to optimize fuel storage and thermogenesis. These data provide insight into adipocyte DNL regulation and function and illustrate the metabolic flexibility of thermogenesis.
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http://dx.doi.org/10.1016/j.cmet.2017.10.008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5762420PMC
January 2018

NFIA co-localizes with PPARγ and transcriptionally controls the brown fat gene program.

Nat Cell Biol 2017 Sep 14;19(9):1081-1092. Epub 2017 Aug 14.

Department of Diabetes and Metabolic Diseases, Graduate School of Medicine, The University of Tokyo, Tokyo 113-8655, Japan.

Brown fat dissipates energy as heat and protects against obesity. Here, we identified nuclear factor I-A (NFIA) as a transcriptional regulator of brown fat by a genome-wide open chromatin analysis of murine brown and white fat followed by motif analysis of brown-fat-specific open chromatin regions. NFIA and the master transcriptional regulator of adipogenesis, PPARγ, co-localize at the brown-fat-specific enhancers. Moreover, the binding of NFIA precedes and facilitates the binding of PPARγ, leading to increased chromatin accessibility and active transcription. Introduction of NFIA into myoblasts results in brown adipocyte differentiation. Conversely, the brown fat of NFIA-knockout mice displays impaired expression of the brown-fat-specific genes and reciprocal elevation of muscle genes. Finally, expression of NFIA and the brown-fat-specific genes is positively correlated in human brown fat. These results indicate that NFIA activates the cell-type-specific enhancers and facilitates the binding of PPARγ to control the brown fat gene program.
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http://dx.doi.org/10.1038/ncb3590DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5885759PMC
September 2017

Dysregulation of a novel miR-23b/27b-p53 axis impairs muscle stem cell differentiation of humans with type 2 diabetes.

Mol Metab 2017 07 27;6(7):770-779. Epub 2017 Apr 27.

The Centre of Inflammation and Metabolism and the Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen Denmark.

Objective: MicroRNAs (miRNAs) are increasingly recognized as fine-tuning regulators of metabolism, and are dysregulated in several disease conditions. With their capacity to rapidly change gene expression, miRNAs are also important regulators of development and cell differentiation. In the current study, we describe an impaired myogenic capacity of muscle stem cells isolated from humans with type 2 diabetes (T2DM) and assess whether this phenotype is regulated by miRNAs.

Methods: We measured global miRNA expression during in vitro differentiation of muscle stem cells derived from T2DM patients and healthy controls.

Results: The mir-23b/27b cluster was downregulated in the cells of the patients, and a pro-myogenic effect of these miRNAs was mediated through the p53 pathway, which was concordantly dysregulated in the muscle cells derived from humans with T2DM.

Conclusions: Our results indicate that we have identified a novel pathway for coordination of myogenesis, the miR-23b/27b-p53 axis that, when dysregulated, potentially contributes to a sustained muscular dysfunction in T2DM.
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http://dx.doi.org/10.1016/j.molmet.2017.04.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5485225PMC
July 2017

Type 2 diabetes and obesity induce similar transcriptional reprogramming in human myocytes.

Genome Med 2017 05 25;9(1):47. Epub 2017 May 25.

Department of Biology and Biological Engineering, Chalmers University of Technology, 41296, Gothenburg, Sweden.

Background: Skeletal muscle is one of the primary tissues involved in the development of type 2 diabetes (T2D). The close association between obesity and T2D makes it difficult to isolate specific effects attributed to the disease alone. Therefore, here we set out to identify and characterize intrinsic properties of myocytes, associated independently with T2D or obesity.

Methods: We generated and analyzed RNA-seq data from primary differentiated myotubes from 24 human subjects, using a factorial design (healthy/T2D and non-obese/obese), to determine the influence of each specific factor on genome-wide transcription. This setup enabled us to identify intrinsic properties, originating from muscle precursor cells and retained in the corresponding myocytes. Bioinformatic and statistical methods, including differential expression analysis, gene-set analysis, and metabolic network analysis, were used to characterize the different myocytes.

Results: We found that the transcriptional program associated with obesity alone was strikingly similar to that induced specifically by T2D. We identified a candidate epigenetic mechanism, H3K27me3 histone methylation, mediating these transcriptional signatures. T2D and obesity were independently associated with dysregulated myogenesis, down-regulated muscle function, and up-regulation of inflammation and extracellular matrix components. Metabolic network analysis identified that in T2D but not obesity a specific metabolite subnetwork involved in sphingolipid metabolism was transcriptionally regulated.

Conclusions: Our findings identify inherent characteristics in myocytes, as a memory of the in vivo phenotype, without the influence from a diabetic or obese extracellular environment, highlighting their importance in the development of T2D.
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http://dx.doi.org/10.1186/s13073-017-0432-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5444103PMC
May 2017

FGF21 Is a Sugar-Induced Hormone Associated with Sweet Intake and Preference in Humans.

Cell Metab 2017 May;25(5):1045-1053.e6

Section of Metabolic Genetics, Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark. Electronic address:

The liking and selective ingestion of palatable foods-including sweets-is biologically controlled, and dysfunction of this regulation may promote unhealthy eating, obesity, and disease. The hepatokine fibroblast growth factor 21 (FGF21) reduces sweet consumption in rodents and primates, whereas knockout of Fgf21 increases sugar consumption in mice. To investigate the relevance of these findings in humans, we genotyped variants in the FGF21 locus in participants from the Danish Inter99 cohort (n = 6,514) and examined their relationship with a detailed range of food and ingestive behaviors. This revealed statistically significant associations between FGF21 rs838133 and increased consumption of candy, as well as nominal associations with increased alcohol intake and daily smoking. Moreover, in a separate clinical study, plasma FGF21 levels increased acutely after oral sucrose ingestion and were elevated in fasted sweet-disliking individuals. These data suggest the liver may secrete hormones that influence eating behavior.
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http://dx.doi.org/10.1016/j.cmet.2017.04.009DOI Listing
May 2017

Metabolic regulation and the anti-obesity perspectives of human brown fat.

Redox Biol 2017 08 11;12:770-775. Epub 2017 Apr 11.

The Centre of Inflammation and Metabolism and Centre for Physical Activity Research Rigshospitalet, University Hospital of Copenhagen, Denmark.

Activation of brown adipose tissue (BAT) in adult humans increase glucose and fatty acid clearance as well as resting metabolic rate, whereas a prolonged elevation of BAT activity improves insulin sensitivity. However, substantial reductions in body weight following BAT activation has not yet been shown in humans. This observation raise the possibility for feedback mechanisms in adult humans in terms of a brown fat-brain crosstalk, possibly mediated by batokines, factors produced by and secreted from brown fat. Batokines also seems to be involved in BAT recruitment by stimulating proliferation and differentiation of brown fat progenitors. Increasing human BAT capacity could thus include inducing brown fat biogenesis as well as identifying novel batokines. Another attractive approach would be to induce a brown fat phenotype, the so-called brite or beige fat, within the white fat depots. In adult humans, white fat tissue transformation into beige has been observed in patients with pheochromocytoma, a norepinephrine-producing tumor. Interestingly, human beige fat is predominantly induced in regions that were BAT during early childhood, possibly reflecting that a presence of human beige progenitors is depot specific and originating from BAT. In conclusion, to utilize the anti-obesity potential of human BAT focus should be directed towards identifying novel regulators of brown and beige fat progenitor cells, as well as feedback mechanisms of BAT activation. This would allow for identification of novel anti-obesity targets.
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http://dx.doi.org/10.1016/j.redox.2017.04.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5397125PMC
August 2017

Abnormal epigenetic changes during differentiation of human skeletal muscle stem cells from obese subjects.

BMC Med 2017 02 22;15(1):39. Epub 2017 Feb 22.

Department of Clinical Sciences, Lund University Diabetes Centre, Lund University, Malmö, 205 02, Sweden.

Background: Human skeletal muscle stem cells are important for muscle regeneration. However, the combined genome-wide DNA methylation and expression changes taking place during adult myogenesis have not been described in detail and novel myogenic factors may be discovered. Additionally, obesity is associated with low relative muscle mass and diminished metabolism. Epigenetic alterations taking place during myogenesis might contribute to these defects.

Methods: We used Infinium HumanMethylation450 BeadChip Kit (Illumina) and HumanHT-12 Expression BeadChip (Illumina) to analyze genome-wide DNA methylation and transcription before versus after differentiation of primary human myoblasts from 14 non-obese and 14 obese individuals. Functional follow-up experiments were performed using siRNA mediated gene silencing in primary human myoblasts and a transgenic mouse model.

Results: We observed genome-wide changes in DNA methylation and expression patterns during differentiation of primary human muscle stem cells (myoblasts). We identified epigenetic and transcriptional changes of myogenic transcription factors (MYOD1, MYOG, MYF5, MYF6, PAX7, MEF2A, MEF2C, and MEF2D), cell cycle regulators, metabolic enzymes and genes previously not linked to myogenesis, including IL32, metallothioneins, and pregnancy-specific beta-1-glycoproteins. Functional studies demonstrated IL-32 as a novel target that regulates human myogenesis, insulin sensitivity and ATP levels in muscle cells. Furthermore, IL32 transgenic mice had reduced insulin response and muscle weight. Remarkably, approximately 3.7 times more methylation changes (147,161 versus 39,572) were observed during differentiation of myoblasts from obese versus non-obese subjects. In accordance, DNMT1 expression increased during myogenesis only in obese subjects. Interestingly, numerous genes implicated in metabolic diseases and epigenetic regulation showed differential methylation and expression during differentiation only in obese subjects.

Conclusions: Our study identifies IL-32 as a novel myogenic regulator, provides a comprehensive map of the dynamic epigenome during differentiation of human muscle stem cells and reveals abnormal epigenetic changes in obesity.
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http://dx.doi.org/10.1186/s12916-017-0792-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5320752PMC
February 2017

Fetal Hyperglycemia Changes Human Preadipocyte Function in Adult Life.

J Clin Endocrinol Metab 2017 04;102(4):1141-1150

Department of Endocrinology, Diabetes and Metabolism, Rigshospitalet, Copenhagen, 2200 Denmark.

Context: Offspring of women with gestational diabetes (O-GDM) or type 1 diabetes mellitus (O-T1DM) have been exposed to hyperglycemia in utero and have an increased risk of developing metabolic disease in adulthood.

Design: In total, we recruited 206 adult offspring comprising the two fetal hyperglycemic groups, O-GDM and O-T1DM, and, as a control group, offspring from the background population (O-BP). Subcutaneous fat biopsies were obtained and preadipocyte cell cultures were established from adult male O-GDM (n = 18, age 30.1 ± 2.5 years), O-T1DM (n = 18, age 31.6 ± 2.2 years), and O-BP (n = 16; age, 31.5 ± 2.7 years) and cultured in vitro.

Main Outcome Measures: First, we studied in vivo adipocyte histology. Second, we studied in vitro preadipocyte leptin secretion, gene expression, and LEP DNA methylation. This was studied in combination with in vitro preadipocyte lipogenesis, lipolysis, and mitochondrial respiration.

Results: We show that subcutaneous adipocytes from O-GDM are enlarged compared with O-BP adipocytes. Preadipocytes isolated from male O-GDM and O-T1DM and cultured in vitro displayed decreased LEP promoter methylation, increased leptin gene expression, and elevated leptin secretion throughout differentiation, compared with adipocytes established from male O-BP. In addition, the preadipocytes demonstrated functional defects including decreased maximal mitochondrial capacity with increased lipolysis and decreased ability to store fatty acids when challenged with 3 days of extra fatty acid supply.

Conclusions: Taken together, these findings show that intrinsic epigenetic and functional changes exist in preadipocyte cultures from individuals exposed to fetal hyperglycemia who are at increased risk of developing metabolic disease.
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http://dx.doi.org/10.1210/jc.2016-3907DOI Listing
April 2017

Epigenetic programming of adipose-derived stem cells in low birthweight individuals.

Diabetologia 2016 12 14;59(12):2664-2673. Epub 2016 Sep 14.

Department of Endocrinology, Diabetes and Metabolism, Rigshospitalet - Section 7652, Tagensvej 20, DK-2200, Copenhagen, Denmark.

Aims/hypothesis: Low birthweight (LBW) is associated with dysfunctions of adipose tissue and metabolic disease in adult life. We hypothesised that altered epigenetic and transcriptional regulation of adipose-derived stem cells (ADSCs) could play a role in programming adipose tissue dysfunction in LBW individuals.

Methods: ADSCs were isolated from the subcutaneous adipose tissue of 13 normal birthweight (NBW) and 13 LBW adult men. The adipocytes were cultured in vitro, and genome-wide differences in RNA expression and DNA methylation profiles were analysed in ADSCs and differentiated adipocytes.

Results: We demonstrated that ADSCs from LBW individuals exhibit multiple expression changes as well as genome-wide alterations in methylation pattern. Reduced expression of the transcription factor cyclin T2 encoded by CCNT2 may play a key role in orchestrating several of the gene expression changes in ADSCs from LBW individuals. Indeed, silencing of CCNT2 in human adipocytes decreased leptin secretion as well as the mRNA expression of several genes involved in adipogenesis, including MGLL, LIPE, PPARG, LEP and ADIPOQ. Only subtle genome-wide mRNA expression and DNA methylation changes were seen in mature cultured adipocytes from LBW individuals.

Conclusions/interpretation: Epigenetic and transcriptional changes in LBW individuals are most pronounced in immature ADSCs that in turn may programme physiological characteristics of the mature adipocytes that influence the risk of metabolic diseases. Reduced expression of CCNT2 may play a key role in the developmental programming of adipose tissue.
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http://dx.doi.org/10.1007/s00125-016-4099-9DOI Listing
December 2016