bims-mimbat 2022-06-05 papers

bims-mimbat

Biomed News

on Mitochondrial metabolism in brown adipose tissue

Issue of 2022–06–05
thirteen papers selected by
José Carlos de Lima-Júnior, University of California San Francisco

Quantifying proton-induced membrane polarization in single biomimetic giant vesicles.
Brown adipose tissue - a translational perspective.
Silk Hydrogel-Mediated Delivery of Bone Morphogenetic Protein 7 Directly to Subcutaneous White Adipose Tissue Increases Browning and Energy Expenditure.
Comprehensive Transcriptional Profiling and Mouse Phenotyping Reveals Dispensable Role for Adipose Tissue Selective Long Noncoding RNA Gm15551.
Brown Adipocyte ADRB3 Mediates Cardioprotection via Suppressing Exosomal iNOS.
The effects of graded levels of calorie restriction XVIII: tissue specific changes in cell size and number in response to calorie restriction.
Influences of ovarian hormones on physiological responses to cold in women.
Proteasome dysfunction disrupts adipogenesis and induces inflammation via ATF3.
Chronic Cold Exposure Leads to Daytime Preference in the Circadian Expression of Hepatic Metabolic Genes.
Reassessing Human Adipose Tissue.
Endothelial Cells Induced Progenitors Into Brown Fat to Reduce Atherosclerosis.
Novel targets for ameliorating energy metabolism disorders in depression through stable isotope-resolved metabolomics.
Constitutive loss of DNMT3A causes morbid obesity through misregulation of adipogenesis.

Biophys J. 2022 May 27. pii: S0006-3495(22)00434-9. [Epub ahead of print]

Quantifying proton-induced membrane polarization in single biomimetic giant vesicles.

Ran Tivony, Marcus Fletcher, Ulrich F Keyser.

  Proton gradients are utilized by cells to power the transport activity of many membrane proteins. Synthetic cells, like proteo-giant unilamellar vesicles, offer an advanced approach for studying the functionality of membrane proteins in isolation. However, understanding of protein-based transport in vitro, requires accurate measurements of proton flux and its accompanying electrochemical gradient across the lipid bilayer. We present an approach to directly quantify the flux of protons across single cell-sized lipid vesicles under modulated electrochemical gradients. Our measurements reveal the corresponding association between proton permeation and transmembrane potential development and its relation to the chemical nature of the conjugated anion (base). In the case of a formic acid, we showed that, out of the total amount of permeated protons, a fraction of ∼0.2 traverse the lipid bilayer as H+ while the rest (∼0.8) in the form of a neutral acid. For strong acids (HCl or HNO3), proton permeation was governed by translocation of H+. Accordingly, a larger proton motive force (pmf) was generated for strong acids (pmf=14.2 mV) relative to formic acid (pmf=1.3 mV). We anticipate that our approach will guide the development of protein-based transport driven by proton gradient in artificial cell models and enable a deeper understanding of how vital acids, such as fatty acids, amino acids, bile acids, and carboxylic acid-containing drugs, traverse the lipid bilayer.

Keywords:  artificial cells; electrochemical gradient; lipid bilayer; proton flux; transmembrane potential

DOI:  https://doi.org/10.1016/j.bpj.2022.05.041
Endocr Rev. 2022 May 29. pii: bnac015. [Epub ahead of print]

Brown adipose tissue - a translational perspective.

André C Carpentier, Denis P Blondin, François Haman, Denis Richard.

  Brown adipose tissue (BAT) displays the unique capacity to generate heat through uncoupled oxidative phosphorylation that makes it a very attractive therapeutic target for cardiometabolic diseases. Here, we review BAT cellular metabolism, its regulation by the central nervous and endocrine systems and circulating metabolites, the plausible roles of this tissue in human thermoregulation, energy balance and cardiometabolic disorders, and the current knowledge on its pharmacological stimulation in humans. The current definition and measurement of BAT in human studies relies almost exclusively on BAT glucose uptake from positron emission tomography (PET) with 18F-fluorodeoxiglucose ( 18FDG), which can be dissociated from BAT thermogenic activity, as for example in insulin resistant states. The most important energy substrate for BAT thermogenesis is its intracellular fatty acid content mobilized from sympathetic stimulation of intracellular triglyceride (TG) lipolysis. This lipolytic BAT response is intertwined with that of white adipose and other metabolic tissues, and cannot be independently stimulated with the drugs tested thus far. BAT is an interesting and biologically plausible target that has yet to be fully and selectively activated to increase the body's thermogenic response and shift energy balance. The field of human BAT research is in need of methods able to directly, specifically and reliably measure BAT thermogenic capacity while also tracking the related thermogenic responses in white adipose and other tissues. Until this is achieved, uncertainty will remain about the role played by this fascinating tissue in human cardiometabolic diseases.

Keywords:  Brown adipose tissue; adipose tissues; diabetes; energy metabolism; glucose metabolism; insulin resistance; lipid metabolism; obesity; thermogenesis

DOI:  https://doi.org/10.1210/endrev/bnac015
Front Bioeng Biotechnol. 2022 ;10 884601

Silk Hydrogel-Mediated Delivery of Bone Morphogenetic Protein 7 Directly to Subcutaneous White Adipose Tissue Increases Browning and Energy Expenditure.

Kristy L Townsend, Eleanor Pritchard, Jeannine M Coburn, Young Mi Kwon, Magdalena Blaszkiewicz, Matthew D Lynes, David L Kaplan, Yu-Hua Tseng.

  Objective: Increasing the mass and/or activity of brown adipose tissue (BAT) is one promising avenue for treating obesity and related metabolic conditions, given that BAT has a high potential for energy expenditure and is capable of improving glucose and lipid homeostasis. BAT occurs either in discrete "classical" depots, or interspersed in white adipose tissue (WAT), termed "inducible/recruitable" BAT, or 'beige/brite' adipocytes. We and others have demonstrated that bone morphogenetic protein 7 (BMP7) induces brown adipogenesis in committed and uncommitted progenitor cells, resulting in increased energy expenditure and reduced weight gain in mice. BMP7 is therefore a reliable growth factor to induce browning of WAT. Methods: In this study, we sought to deliver BMP7 specifically to subcutaneous (sc)WAT in order to induce tissue-resident progenitor cells to differentiate into energy-expending recruitable brown adipocytes, without off-target effects like bone formation, which can occur when BMPs are in the presence of bone progenitor cells (outside of WAT). BMP7 delivery directly to WAT may also promote tissue innervation, or directly activate mitochondrial activity in brown adipocytes, as we have demonstrated previously. We utilized silk protein in the form of an injectable hydrogel carrying BMP7. Silk scaffolds are useful for in vivo delivery of substances due to favorable material properties, including controlled release of therapeutic proteins in an active form, biocompatibility with minimal immunogenic response, and prior FDA approval for some medical materials. For this study, the silk was engineered to meet desirable release kinetics for BMP7 in order to mimic our prior in vitro brown adipocyte differentiation studies. Fluorescently-labeled silk hydrogel loaded with BMP7 was directly injected into WAT through the skin and monitored by non-invasive in vivo whole body imaging, including in UCP1-luciferase reporter mice, thereby enabling an approach that is translatable to humans. Results: Injection of the BMP7-loaded silk hydrogels into the subcutaneous WAT of mice resulted in "browning", including the development of multilocular, uncoupling protein 1 (UCP1)-positive brown adipocytes, and an increase in whole-body energy expenditure and skin temperature. In diet-induced obese mice, BMP7-loaded silk delivery to subcutaneous WAT resulted in less weight gain, reduced circulating glucose and lower respiratory exchange ratio (RER). Conclusions: In summary, BMP7 delivery via silk scaffolds directly into scWAT is a novel translational approach to increase browning and energy expenditure, and represents a potential therapeutic avenue for delivering substances directly to adipose depots in pursuit of metabolic treatments.

Keywords:  BMP7; adipose tissue; browning; intraadipose delivery; silk hydrogel; thermogenesis

DOI:  https://doi.org/10.3389/fbioe.2022.884601
Noncoding RNA. 2022 May 06. pii: 32. [Epub ahead of print]8(3):

Comprehensive Transcriptional Profiling and Mouse Phenotyping Reveals Dispensable Role for Adipose Tissue Selective Long Noncoding RNA Gm15551.

Christoph Andreas Engelhard, Chien Huang, Sajjad Khani, Petr Kasparek, Jan Prochazka, Jan Rozman, David Pajuelo Reguera, Radislav Sedlacek, Jan-Wilhelm Kornfeld.

  Cold and nutrient-activated brown adipose tissue (BAT) is capable of increasing systemic energy expenditure via the uncoupled respiration and secretion of endocrine factors, thereby protecting mice against diet-induced obesity and improving insulin response and glucose tolerance in men. Long non-coding RNAs (lncRNAs) have recently been identified as fine-tuning regulators of cellular function. While certain lncRNAs have been functionally characterised in adipose tissue, their overall contribution in the activation of BAT remains elusive. We identified lncRNAs correlating to interscapular brown adipose tissue (iBAT) function in a high fat diet (HFD) and cold stressed mice. We focused on Gm15551, which has an adipose tissue specific expression profile, is highly upregulated during adipogenesis, and downregulated by β-adrenergic activation in mature adipocytes. Although we performed comprehensive transcriptional and adipocyte physiology profiling in vitro and in vivo, we could not detect an effect of gain or loss of function of Gm15551.

Keywords:  adipose tissue remodelling; brown adipose tissue; long noncoding RNAs

DOI:  https://doi.org/10.3390/ncrna8030032
Circ Res. 2022 Jun 02. 101161CIRCRESAHA121320470

Brown Adipocyte ADRB3 Mediates Cardioprotection via Suppressing Exosomal iNOS.

Jing-Rong Lin, Li-Li-Qiang Ding, Lian Xu, Jun Huang, Ze-Bei Zhang, Xiao-Hui Chen, Yu-Wen Cheng, Cheng-Chao Ruan, Ping-Jin Gao.

   BACKGROUND: The ADRB3 (β3-adrenergic receptors), which is predominantly expressed in brown adipose tissue (BAT), can activate BAT and improve metabolic health. Previous studies indicate that the endocrine function of BAT is associated with cardiac homeostasis and diseases. Here, we investigate the role of ADRB3 activation-mediated BAT function in cardiac remodeling.
METHODS: BKO (brown adipocyte-specific ADRB3 knockout) and littermate control mice were subjected to Ang II (angiotensin II) for 28 days. Exosomes from ADRB3 antagonist SR59230A (SR-exo) or agonist mirabegron (MR-exo) treated brown adipocytes were intravenously injected to Ang II-infused mice.
RESULTS: BKO markedly accelerated cardiac hypertrophy and fibrosis compared with control mice after Ang II infusion. In vitro, ADRB3 KO rather than control brown adipocytes aggravated expression of fibrotic genes in cardiac fibroblasts, and this difference was not detected after exosome inhibitor treatment. Consistently, BKO brown adipocyte-derived exosomes accelerated Ang II-induced cardiac fibroblast dysfunction compared with control exosomes. Furthermore, SR-exo significantly aggravated Ang II-induced cardiac remodeling, whereas MR-exo attenuated cardiac dysfunction. Mechanistically, ADRB3 KO or SR59230A treatment in brown adipocytes resulted an increase of iNOS (inducible nitric oxide synthase) in exosomes. Knockdown of iNOS in brown adipocytes reversed SR-exo-aggravated cardiac remodeling.
CONCLUSIONS: Our data illustrated a new endocrine pattern of BAT in regulating cardiac remodeling, suggesting that activation of ADRB3 in brown adipocytes offers cardiac protection through suppressing exosomal iNOS.

Keywords:  brown adipocytes; cardiovascular disease; fibroblast; fibrosis; homeostasis

DOI:  https://doi.org/10.1161/CIRCRESAHA.121.320470
J Gerontol A Biol Sci Med Sci. 2022 May 26. pii: glac110. [Epub ahead of print]

The effects of graded levels of calorie restriction XVIII: tissue specific changes in cell size and number in response to calorie restriction.

Daniel Phillips, Hayleigh Mathers, Sharon E Mitchell, John R Speakman.

  Calorie restriction (CR) without malnutrition increases the health- and lifespan of diverse taxa. The mechanism(s) behind CR are debated but may be directly linked to body composition changes that maintain energy balance. During a deficit, energy is primarily obtained from white adipose tissue (WAT; utilized) whilst other tissues remain unchanged (protected) or grow (invested) relative to body mass. The changes in mass of 6 tissues from 48 male C57BL/6 mice following 3-months graded (10, 20, 30, or 40%) CR or fed ad libitum for 12 or 24hr a day were related to cell size (hypo/hypertrophy) and/or number (hypo/hyperplasia). Tissues studied were: retroperitoneal and subcutaneous WAT, brown adipose tissue (BAT) (utilized); lungs (protected), and stomach and caecum (invested). Methodology was based on number of nuclei/ tissue equalling the number of cells. Extracted DNA was quantified and used to estimate cell numbers (Total DNA/DNA per diploid nucleus) and size (Tissue mass/nuclei number). WAT utilization was caused solely by hypotrophy whereas BAT utilization resulted from reduced cell number and size. WAT cell size positively correlated with circulating hormones related to energy balance and BAT cell number and size positively correlated with body temperature. No changes were found in the lungs, consistent with their protected status, whereas hyperplasia appeared to be the dominant mechanism for invested alimentary-tract tissues. These findings indicate the pattern of change of cell size and number across increasing levels of short-term CR is tissue-specific.

Keywords:  Calorie restriction; Hyper/ hypoplasia; hyper/hypotrophy; tissue utilization; weight loss

DOI:  https://doi.org/10.1093/gerona/glac110
Temperature (Austin). 2022 ;9(1): 23-45

Influences of ovarian hormones on physiological responses to cold in women.

Andrew M Greenfield, Nisha Charkoudian, Billie K Alba.

  While it is clear that the ovarian hormones estradiol and progesterone have important influences on physiological thermoregulation in women, the influences of these hormones on responses to cold exposure are not well understood. Both heat conservation and heat production must increase to offset heat losses that decrease body temperature in cold ambient conditions. Cutaneous vasoconstriction conserves heat, whereas shivering and non-shivering thermogenesis produce heat - all as part of reflex physiological responses to cold exposure. Our goal in this brief review is to highlight existing knowledge and recent advances pertaining to sex and sex hormone influences on thermoeffector responses to cold stress. Estrogens have multiple influences that contribute to heat dissipation and a lower body temperature, while the influence of progesterone appears to primarily increase body temperature. Fluctuations in estrogen and progesterone across the menstrual cycle can alter the level at which body temperature is regulated. Recent evidence suggests that female reproductive hormones can modulate the cutaneous vasoconstrictor response, and may influence metabolic mechanisms such as substrate utilization during shivering and non-shivering thermogenesis. Overall, it appears that quantitative differences in cold thermoregulation between sexes are minimal when anthropometric measures are minimized, such that women do not have a strong "advantage" or "disadvantage" in terms of overall ability to tolerate cold. Thermoregulatory physiology in women during cold exposure remains relatively understudied and many mechanisms require further elucidation.

Keywords:  Cold stress; estrogen; progesterone; sex differences; thermogenesis; vasoconstriction; women

DOI:  https://doi.org/10.1080/23328940.2021.1953688
Mol Metab. 2022 May 27. pii: S2212-8778(22)00087-4. [Epub ahead of print] 101518

Proteasome dysfunction disrupts adipogenesis and induces inflammation via ATF3.

Nienke Willemsen, Isabel Arigoni, Maja Studencka-Turski, Elke Krüger, Alexander Bartelt.

   OBJECTIVE: Regulation of proteasomal activity is an essential component of cellular proteostasis and function. This is evident in patients with mutations in proteasome subunits and associated regulators, who suffer from proteasome-associated autoinflammatory syndromes (PRAAS). These patients display lipodystrophy and fevers, which may be partly related to adipocyte malfunction and abnormal thermogenesis in adipose tissue. However, the cell-intrinsic pathways that could underlie these symptoms are unclear. Here, we investigate the impact of two proteasome subunits implicated in PRAAS, Psmb4 and Psmb8, on differentiation, function and proteostasis of brown adipocytes.
METHODS: In immortalized mouse brown pre-adipocytes, levels of Psmb4, Psmb8, and downstream effectors genes were downregulated through reverse transfection with siRNA. Adipocytes were differentiated and analyzed with various assays of adipogenesis, lipogenesis, lipolysis, inflammation, and respiration.
RESULTS: Loss of Psmb4, but not Psmb8, disrupted proteostasis and adipogenesis. Proteasome function was reduced upon Psmb4 loss, but partly recovered by the activation of Nuclear factor, erythroid-2, like-1 (Nfe2l1). In addition, cells displayed higher levels of surrogate inflammation and stress markers, including Activating transcription factor-3 (Atf3). Simultaneous silencing of Psmb4 and Atf3 lowered inflammation and restored adipogenesis.
CONCLUSIONS: Our study shows that Psmb4 is required for adipocyte development and function in cultured adipocytes. These results imply that in humans with PSMB4 mutations, PRAAS-associated lipodystrophy is partly caused by disturbed adipogenesis. While we uncover a role for Nfe2l1 in the maintenance of proteostasis under these conditions, Atf3 is a key effector of inflammation and blocking adipogenesis. In conclusion, our work highlights how proteasome dysfunction is sensed and mitigated by the integrated stress response in adipocytes with potential relevance for PRAAS patients and beyond.

Keywords:  ATF3; NFE2L1; PSMB4; adipocytes; brown adipose tissue; proteasome; proteostasis; ubiquitin

DOI:  https://doi.org/10.1016/j.molmet.2022.101518
Front Physiol. 2022 ;13 865627

Chronic Cold Exposure Leads to Daytime Preference in the Circadian Expression of Hepatic Metabolic Genes.

Zhida Zhang, Le Cheng, Junxian Ma, Xiaomei Wang, Yingying Zhao.

  Circadian control allows organisms to anticipate and adapt to environmental changes through changes in physiology and behavior. The circadian system timing is entrained by cues, such as light, food, and temperature. An ambient temperature dramatically impacts the sleep-wake cycle and metabolic rhythmicity. As endotherms, mammals rely on tissues such as the liver to provide fuel for thermogenesis to maintain body temperature. The adaptive response of the circadian rhythm of liver metabolism to chronic cold exposure remains largely unexplored. Here, we investigated the circadian rhythm adaptation of hepatic metabolism in response to environmental cold stress using a mouse model of chronic cold exposure. We analyzed metabolites and transcripts of mouse livers at 24 h and found that long-term low-temperature exposure resulted in a synergistic and phase synchronization of transcriptional rhythms of many genes associated with metabolic pathways. Notably, transcription peaked in the early light phase when the body temperature was relatively low. Our results suggest that chronic cold does not alter the rhythmic expression of essential core clock genes in the liver, so the rewiring of clock control gene expression is another mechanism that optimizes the circadian rhythm of liver metabolism to meet the energy requirements of animal thermogenesis.

Keywords:  adaption; chronic cold; circadian rhythm; liver; metabolism

DOI:  https://doi.org/10.3389/fphys.2022.865627
N Engl J Med. 2022 Jun 02. pii: 10.1056/NEJMc2204077#sa1. [Epub ahead of print]386(22): e61

Reassessing Human Adipose Tissue.

David A Gorelick.

DOI: https://doi.org/10.1056/NEJMc2204077
Circ Res. 2022 Jun 01. 101161CIRCRESAHA121319582

Endothelial Cells Induced Progenitors Into Brown Fat to Reduce Atherosclerosis.

Kyoungmin Park, Qian Li, Matthew D Lynes, Hisashi Yokomizo, Ernesto Maddaloni, Takanori Shinjo, Ronald St-Louis, Qin Li, Sayaka Katagiri, Jialin Fu, Allen Clermont, Hyunseok Park, I-Hsien Wu, Marc Gregory Yu, Hetal Shah, Yu-Hua Tseng, George L King.

   BACKGROUND: Insulin resistance (IR) can increase atherosclerotic and cardiovascular risk by inducing endothelial dysfunction, decreasing nitric oxide (NO) production, and accelerating arterial inflammation. The aim is to determine the mechanism by which insulin action and NO production in endothelial cells can improve systemic bioenergetics and decrease atherosclerosis via differentiation of perivascular progenitor cells (PPCs) into brown adipocytes (BAT).
METHODS: Studies used various endothelial transgenic and deletion mutant ApoE-/- mice of insulin receptors, eNOS (endothelial NO synthase) and ETB (endothelin receptor type B) receptors for assessments of atherosclerosis. Cells were isolated from perivascular fat and micro-vessels for studies on differentiation and signaling mechanisms in responses to NO, insulin, and lipokines from BAT.
RESULTS: Enhancing insulin's actions on endothelial cells and NO production in ECIRS1 transgenic mice reduced body weight and increased systemic energy expenditure and BAT mass and activity by inducing differentiation of PPCs into beige/BAT even with high-fat diet. However, positive changes in bioenergetics, BAT differentiation from PPCs and weight loss were inhibited by N(gamma)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of eNOS, in ECIRS1 mice and eNOSKO mice. The mechanism mediating NO's action on PPC differentiation into BAT was identified as the activation of solubilized guanylate cyclase/cGMP protein-dependent kinase Iα/GSK3β (glycogen synthase kinase 3β) pathways. Plasma lipidomics from ECIRS1 mice with NO-induced increased BAT mass revealed elevated 12,13-diHOME production. Infusion of 12,13-diHOME improved endothelial dysfunction and decreased atherosclerosis, whereas its reduction had opposite effects in ApoE-/-mice.
CONCLUSIONS: Activation of eNOS and endothelial cells by insulin enhanced the differentiation of PPC to BAT and its lipokines and improved systemic bioenergetics and atherosclerosis, suggesting that endothelial dysfunction is a major contributor of energy disequilibrium in obesity.

Keywords:  atherosclerosis; body weight; cardiovascular disease; fatty acid; obesity

DOI:  https://doi.org/10.1161/CIRCRESAHA.121.319582
Biochim Biophys Acta Bioenerg. 2022 May 28. pii: S0005-2728(22)00047-0. [Epub ahead of print] 148578

Novel targets for ameliorating energy metabolism disorders in depression through stable isotope-resolved metabolomics.

Ting Linghu, Yunhao Zhao, Wenze Wu, Yao Gao, Junsheng Tian, Xuemei Qin.

  The severe harm of depression to human health and life has attracted global attention, but the exact mechanism is not yet known due to the complicated pathogenesis. The existing antidepressants are far from ideal, indicating it is urgently needed to seek safe and effective drugs from a unique perspective. Based on the hypothesis of "mitochondrial dysfunction" proposed recently, we attempt to focus on the substrates supply of energy metabolism. We applied stable isotope-resolved metabolomics, and revealed that significantly decreased TCA cycle and abnormally increased gluconeogenesis pathway in CUMS rats. Pyruvate dehydrogenase (PDH) and pyruvate carboxylase (PC) maybe the key metabolic enzymes. This metabolic reprogramming was confirmed through ELISA assays and Western blot analysis. To explore the causes of substrates supply disorder in depression, we conducted the mitochondrial structure-function evaluation. Interestingly, the levels of the mitochondrial pyruvate carrier (MPC) decreased significantly, which is essential for the entry of pyruvic acid into the TCA cycle. Together, MPC, PDH and PC are expected to become potential novel therapeutic targets for treating depressive disorders. This research provides a unique insight for re-cognizing the pathological mechanisms of depression, the novel targets for development of ideal antidepressants, as well as a paradigm for deciphering abnormal metabolic pathways in other metabolic diseases.

Keywords:  Depression; Energy metabolism; Mitochondrial pyruvate carrier; Pyruvate carboxylase; Pyruvate dehydrogenase; Stable isotope-resolved metabolomics

DOI:  https://doi.org/10.1016/j.bbabio.2022.148578
Elife. 2022 May 30. pii: e72359. [Epub ahead of print]11

Constitutive loss of DNMT3A causes morbid obesity through misregulation of adipogenesis.

Ayala Tovy, Jaime M Reyes, Linda Zhang, Yung-Hsin Huang, Carina Rosas, Alexes C Daquinag, Anna Guzman, Raghav Ramabadran, Chun-Wei Chen, Tianpeng Gu, Sinjini Gupta, Laura Ortinau, Dongsu Park, Aaron R Cox, Rachel E Rau, Sean M Hartig, Mikhail G Kolonin, Margaret A Goodell.

  DNA Methyltransferase 3 A (DNMT3A) is an important facilitator of differentiation of both embryonic and hematopoietic stem cells. Heterozygous germline mutations in DNMT3A lead to Tatton-Brown-Rahman Syndrome (TBRS), characterized by obesity and excessive height. While DNMT3A is known to impact feeding behavior via the hypothalamus, here we investigated a role in adipocyte progenitors utilizing heterozygous knockout mice that recapitulate cardinal TBRS phenotypes. These mice become morbidly obese due to adipocyte enlargement and tissue expansion. Adipose tissue in these mice exhibited defects in preadipocyte maturation and precocious activation of inflammatory gene networks, including interleukin-6 signaling. Adipocyte progenitor cell lines lacking DNMT3A exhibited aberrant differentiation. Furthermore, mice in which Dnmt3a was specifically ablated in adipocyte progenitors showed enlarged fat depots and increased progenitor numbers, partly recapitulating the TBRS obesity phenotypes. Loss of DNMT3A led to constitutive DNA hypomethylation, such that the DNA methylation landscape of young adipocyte progenitors resemble that of older wild-type mice. Together, our results demonstrate that DNMT3A coordinates both the central and local control of energy storage required to maintain normal weight and prevent inflammatory obesity.

Keywords:  CpG; DNA methylation; DNMT3A; Obesity; adipose; developmental biology; epigenetics; mouse; regenerative medicine; stem cells

DOI:  https://doi.org/10.7554/eLife.72359