Warm-blooded animals such as birds and mammals are able to protect stable body temperature due to various thermogenic mechanisms. These processes can be facultative (occurring only under specific conditions, such as acute cold) and adaptive (adjusting their capacity according to long-term needs). They can represent a substantial part of overall energy expenditure and, therefore, affect energy balance. Classical mechanisms of facultative thermogenesis include shivering of skeletal muscles and (in mammals) non-shivering thermogenesis (NST) in brown adipose tissue (BAT), which depends on uncoupling protein 1 (UCP1). Existence of several alternative thermogenic mechanisms has been suggested. However, their relative contribution to overall heat production and the extent to which they are adaptive and facultative still needs to be better defined. Here we focus on comparison of NST in BAT with thermogenesis in skeletal muscles, including shivering and NST. We present indications that muscle NST may be adaptive but not facultative, unlike UCP1-dependent NST. Due to its slow regulation and low energy efficiency, reflecting in part the anatomical location, induction of muscle NST may counteract development of obesity more effectively than UCP1-dependent thermogenesis in BAT.

• MeSH
• chvění * fyziologie   MeSH
• energetický metabolismus fyziologie   MeSH
• fyziologická adaptace * fyziologie   MeSH
• hnědá tuková tkáň * metabolismus   MeSH
• kosterní svaly * metabolismus   MeSH
• lidé MeSH
• obezita * metabolismus   patofyziologie   MeSH
• termogeneze * fyziologie   MeSH
• uncoupling protein 1 metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

OBJECTIVE: Classical ATP-independent non-shivering thermogenesis enabled by uncoupling protein 1 (UCP1) in brown adipose tissue (BAT) is activated, but not essential for survival, in the cold. It has long been suspected that futile ATP-consuming substrate cycles also contribute to thermogenesis and can partially compensate for the genetic ablation of UCP1 in mouse models. Futile ATP-dependent thermogenesis could thereby enable survival in the cold even when brown fat is less abundant or missing. METHODS: In this study, we explore different potential sources of UCP1-independent thermogenesis and identify a futile ATP-consuming triglyceride/fatty acid cycle as the main contributor to cellular heat production in brown adipocytes lacking UCP1. We uncover the mechanism on a molecular level and pinpoint the key enzymes involved using pharmacological and genetic interference. RESULTS: ATGL is the most important lipase in terms of releasing fatty acids from lipid droplets, while DGAT1 accounts for the majority of fatty acid re-esterification in UCP1-ablated brown adipocytes. Furthermore, we demonstrate that chronic cold exposure causes a pronounced remodeling of adipose tissues and leads to the recruitment of lipid cycling capacity specifically in BAT of UCP1-knockout mice, possibly fueled by fatty acids from white fat. Quantification of triglyceride/fatty acid cycling clearly shows that UCP1-ablated animals significantly increase turnover rates at room temperature and below. CONCLUSION: Our results suggest an important role for futile lipid cycling in adaptive thermogenesis and total energy expenditure.

• MeSH
• adenosintrifosfát metabolismus   MeSH
• hnědá tuková tkáň * metabolismus   MeSH
• mastné kyseliny metabolismus   MeSH
• myši knockoutované MeSH
• myši MeSH
• termogeneze * MeSH
• triglyceridy metabolismus   MeSH
• uncoupling protein 1 genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

The possibility to use leptin therapeutically for lowering glucose levels in patients with type 1 diabetes has attracted interest. However, earlier animal models of type 1 diabetes are severely catabolic with very low endogenous leptin levels, unlike most patients with diabetes. Here, we aim to test glucose-lowering effects of leptin in novel, more human-like murine models. We examined the glucose-lowering potential of leptin in diabetic models of two types: streptozotocin-treated mice and mice treated with the insulin receptor antagonist S961. To prevent hypoleptinemia, we used combinations of thermoneutral temperature and high-fat feeding. Leptin fully normalized hyperglycemia in standard chow-fed streptozotocin-treated diabetic mice. However, more humanized physiological conditions (high-fat diets or thermoneutral temperatures) that increased adiposity - and thus also leptin levels - in the diabetic mice abrogated the effects of leptin, i.e., the mice developed leptin resistance also in this respect. The glucose-lowering effect of leptin was not dependent on the presence of the uncoupling protein-1 and was not associated with alterations in plasma insulin, insulin-like growth factor 1, food intake or corticosterone but fully correlated with decreased plasma glucagon levels and gluconeogenesis. An important implication of these observations is that the therapeutic potential of leptin as an additional treatment in patients with type 1 diabetes is probably limited. This is because such patients are treated with insulin and do not display low leptin levels. Thus, the potential for a glucose-lowering effect of leptin would already have been attained with standard insulin therapy, and further effects on blood glucose level through additional leptin cannot be anticipated.

• MeSH
• bílá tuková tkáň metabolismus   MeSH
• diabetes mellitus 1. typu metabolismus   MeSH
• experimentální diabetes mellitus metabolismus   MeSH
• glukagon metabolismus   MeSH
• glukoneogeneze MeSH
• hnědá tuková tkáň metabolismus   MeSH
• insulinu podobný růstový faktor I metabolismus   MeSH
• inzulin metabolismus   MeSH
• kortikosteron metabolismus   MeSH
• krevní glukóza účinky léků   metabolismus   MeSH
• kyselina pyrohroznová metabolismus   MeSH
• leptin metabolismus   farmakologie   MeSH
• lidé MeSH
• modely nemocí na zvířatech MeSH
• myši knockoutované MeSH
• myši MeSH
• peptidy farmakologie   MeSH
• přijímání potravy MeSH
• receptor inzulinu antagonisté a inhibitory   MeSH
• spotřeba kyslíku MeSH
• transkriptom MeSH
• uncoupling protein 1 genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Adipocytes deficient in fatty acid synthase (iAdFASNKO) emit signals that mimic cold exposure to enhance the appearance of thermogenic beige adipocytes in mouse inguinal white adipose tissues (iWATs). Both cold exposure and iAdFASNKO upregulate the sympathetic nerve fiber (SNF) modulator Neuregulin 4 (Nrg4), activate SNFs, and require adipocyte cyclic AMP/protein kinase A (cAMP/PKA) signaling for beige adipocyte appearance, as it is blocked by adipocyte Gsα deficiency. Surprisingly, however, in contrast to cold-exposed mice, neither iWAT denervation nor Nrg4 loss attenuated adipocyte browning in iAdFASNKO mice. Single-cell transcriptomic analysis of iWAT stromal cells revealed increased macrophages displaying gene expression signatures of the alternately activated type in iAdFASNKO mice, and their depletion abrogated iWAT beiging. Altogether, these findings reveal that divergent cellular pathways are sufficient to cause adipocyte browning. Importantly, adipocyte signaling to enhance alternatively activated macrophages in iAdFASNKO mice is associated with enhanced adipose thermogenesis independent of the sympathetic neuron involvement this process requires in the cold.

• MeSH
• aktivace makrofágů MeSH
• AMP cyklický metabolismus   MeSH
• analýza jednotlivých buněk * MeSH
• béžové tukové buňky metabolismus   MeSH
• bílá tuková tkáň metabolismus   MeSH
• denervace MeSH
• fenotyp MeSH
• hnědá tuková tkáň metabolismus   MeSH
• makrofágy metabolismus   MeSH
• myši inbrední C57BL MeSH
• myši knockoutované MeSH
• neureguliny nedostatek   metabolismus   MeSH
• nízká teplota MeSH
• polarita buněk MeSH
• RNA metabolismus   MeSH
• signální transdukce * MeSH
• syntázy mastných kyselin metabolismus   MeSH
• termogeneze * MeSH
• uncoupling protein 1 genetika   metabolismus   MeSH
• upregulace genetika   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Research Support, N.I.H., Intramural MeSH

Uncoupling protein 1 (UCP1) executes thermogenesis in brown adipose tissue, which is a major focus of human obesity research. Although the UCP1-knockout (UCP1 KO) mouse represents the most frequently applied animal model to judge the anti-obesity effects of UCP1, the assessment is confounded by unknown anti-obesity factors causing paradoxical obesity resistance below thermoneutral temperatures. Here we identify the enigmatic factor as endogenous FGF21, which is primarily mediating obesity resistance. The generation of UCP1/FGF21 double-knockout mice (dKO) fully reverses obesity resistance. Within mild differences in energy metabolism, urine metabolomics uncover increased secretion of acyl-carnitines in UCP1 KOs, suggesting metabolic reprogramming. Strikingly, transcriptomics of metabolically important organs reveal enhanced lipid and oxidative metabolism in specifically white adipose tissue that is fully reversed in dKO mice. Collectively, this study characterizes the effects of endogenous FGF21 that acts as master regulator to protect from diet-induced obesity in the absence of UCP1.

• MeSH
• bílá tuková tkáň metabolismus   MeSH
• energetický metabolismus MeSH
• fibroblastové růstové faktory genetika   metabolismus   MeSH
• hnědá tuková tkáň metabolismus   MeSH
• lidé MeSH
• myši inbrední C57BL MeSH
• myši knockoutované MeSH
• myši MeSH
• obezita genetika   metabolismus   MeSH
• signální transdukce MeSH
• uncoupling protein 1 genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Brown adipose tissue (BAT) and brown in white (brite) adipose tissue, termed also beige adipose tissue, are major sites of mammalian nonshivering thermogenesis. Mitochondrial uncoupling protein 1 (UCP1), specific for these tissues, is the key factor for heat production. Recent molecular aspects of UCP1 structure provide support for the fatty acid cycling model of coupling, i.e. when UCP1 expels fatty acid anions in a uniport mode from the matrix, while uncoupling. Protonophoretic function is ensured by return of the protonated fatty acid to the matrix independent of UCP1. This mechanism is advantageous for mitochondrial uncoupling and compatible with heat production in a pro-thermogenic environment, such as BAT. It must still be verified whether posttranslational modification of UCP1, such as sulfenylation of Cys253, linked to redox activity, promotes UCP1 activity. BAT biogenesis and UCP1 expression, has also been linked to the pro-oxidant state of mitochondria, further endorsing a redox signalling link promoting an establishment of pro-thermogenic state. We discuss circumstances under which promotion of superoxide formation exceeds its attenuation by uncoupling in mitochondria and throughout point out areas of future research into UCP1 function.

• MeSH
• hnědá tuková tkáň chemie   MeSH
• lidé MeSH
• mitochondriální proteiny metabolismus   MeSH
• oxidace-redukce MeSH
• posttranslační úpravy proteinů MeSH
• termogeneze * MeSH
• uncoupling protein 1 metabolismus   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

Phospholipase Dα1 (PLDα1) belongs to phospholipases, a large phospholipid hydrolyzing protein family. PLDα1 has a substrate preference for phosphatidylcholine leading to enzymatic production of phosphatidic acid, a lipid second messenger with multiple cellular functions. PLDα1 itself is implicated in biotic and abiotic stress responses. Here, we present a shot-gun differential proteomic analysis on roots of two Arabidopsis pldα1 mutants compared to the wild type. Interestingly, PLDα1 deficiency leads to altered abundances of proteins involved in diverse processes related to membrane transport including endocytosis and endoplasmic reticulum-Golgi transport. PLDα1 may be involved in the stability of attachment sites of endoplasmic reticulum to the plasma membrane as suggested by increased abundance of synaptotagmin 1, which was validated by immunoblotting and whole-mount immunolabelling analyses. Moreover, we noticed a robust abundance alterations of proteins involved in mitochondrial import and electron transport chain. Notably, the abundances of numerous proteins implicated in glucosinolate biosynthesis were also affected in pldα1 mutants. Our results suggest a broader biological involvement of PLDα1 than anticipated thus far, especially in the processes such as endomembrane transport, mitochondrial protein import and protein quality control, as well as glucosinolate biosynthesis.

• MeSH
• Arabidopsis metabolismus   MeSH
• endocytóza MeSH
• fosfolipasa D genetika   metabolismus   MeSH
• genová ontologie MeSH
• glukosinoláty biosyntéza   MeSH
• kořeny rostlin metabolismus   MeSH
• mitochondriální proteiny metabolismus   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• proteom metabolismus   MeSH
• proteomika * MeSH
• synaptotagmin I metabolismus   MeSH
• tandemová hmotnostní spektrometrie MeSH
• transport proteinů MeSH
• uncoupling protein 1 metabolismus   MeSH
• vysokoúčinná kapalinová chromatografie MeSH
• Publikační typ
• časopisecké články MeSH

RNA-guided, engineered nucleases derived from the prokaryotic adaptive immune system CRISPR-Cas represent a powerful platform for gene deletion and editing. When used as a therapeutic approach, direct delivery of Cas9 protein and single-guide RNA (sgRNA) could circumvent the safety issues associated with plasmid delivery and therefore represents an attractive tool for precision genome engineering. Gene deletion or editing in adipose tissue to enhance its energy expenditure, fatty acid oxidation, and secretion of bioactive factors through a "browning" process presents a potential therapeutic strategy to alleviate metabolic disease. Here, we developed "CRISPR-delivery particles," denoted CriPs, composed of nano-size complexes of Cas9 protein and sgRNA that are coated with an amphipathic peptide called Endo-Porter that mediates entry into cells. Efficient CRISPR-Cas9-mediated gene deletion of ectopically expressed GFP by CriPs was achieved in multiple cell types, including a macrophage cell line, primary macrophages, and primary pre-adipocytes. Significant GFP loss was also observed in peritoneal exudate cells with minimum systemic toxicity in GFP-expressing mice following intraperitoneal injection of CriPs containing Gfp-targeting sgRNA. Furthermore, disruption of a nuclear co-repressor of catabolism, the Nrip1 gene, in white adipocytes by CriPs enhanced adipocyte browning with a marked increase of uncoupling protein 1 (UCP1) expression. Of note, the CriP-mediated Nrip1 deletion did not produce detectable off-target effects. We conclude that CriPs offer an effective Cas9 and sgRNA delivery system for ablating targeted gene products in cultured cells and in vivo, providing a potential therapeutic strategy for metabolic disease.

• MeSH
• bílá tuková tkáň cytologie   metabolismus   MeSH
• buněčné linie MeSH
• CRISPR-Cas systémy MeSH
• editace genu MeSH
• energetický metabolismus * MeSH
• genový targeting metody   MeSH
• lidé MeSH
• myši inbrední C57BL MeSH
• nuclear receptor interacting protein 1 genetika   metabolismus   MeSH
• plazmidy genetika   metabolismus   MeSH
• reportérové geny MeSH
• sekvence CRISPR MeSH
• tukové buňky metabolismus   MeSH
• uncoupling protein 1 genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• hodnotící studie MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH

• Klíčová slova
• irisin,
• MeSH
• bazální metabolismus MeSH
• kodon iniciační metabolismus   MeSH
• lidé MeSH
• membránové proteiny metabolismus   terapeutické užití   MeSH
• modely u zvířat MeSH
• myši MeSH
• obezita * metabolismus   terapie   MeSH
• termogeneze MeSH
• transportní proteiny metabolismus   terapeutické užití   MeSH
• tukové buňky metabolismus   MeSH
• uncoupling protein 1 metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH

BACKGROUND: The de novo biosynthesis of fatty acids (DNL) through fatty acid synthase (FASN) in adipocytes is exquisitely regulated by nutrients, hormones, fasting, and obesity in mice and humans. However, the functions of DNL in adipocyte biology and in the regulation of systemic glucose homeostasis are not fully understood. METHODS & RESULTS: Here we show adipocyte DNL controls crosstalk to localized sympathetic neurons that mediate expansion of beige/brite adipocytes within inguinal white adipose tissue (iWAT). Induced deletion of FASN in white and brown adipocytes of mature mice (iAdFASNKO mice) enhanced glucose tolerance, UCP1 expression, and cAMP signaling in iWAT. Consistent with induction of adipose sympathetic nerve activity, iAdFASNKO mice displayed markedly increased neuronal tyrosine hydroxylase (TH) and neuropeptide Y (NPY) content in iWAT. In contrast, brown adipose tissue (BAT) of iAdFASNKO mice showed no increase in TH or NPY, nor did FASN deletion selectively in brown adipocytes (UCP1-FASNKO mice) cause these effects in iWAT. CONCLUSIONS: These results demonstrate that downregulation of fatty acid synthesis via FASN depletion in white adipocytes of mature mice can stimulate neuronal signaling to control thermogenic programming in iWAT.

• MeSH
• AMP cyklický metabolismus   MeSH
• krevní glukóza metabolismus   MeSH
• kultivované buňky MeSH
• lipogeneze * MeSH
• mastné kyseliny biosyntéza   MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• neurony metabolismus   fyziologie   MeSH
• neuropeptid Y metabolismus   MeSH
• sympatický nervový systém cytologie   fyziologie   MeSH
• syntázy mastných kyselin metabolismus   MeSH
• termogeneze * MeSH
• tukové buňky metabolismus   MeSH
• tyrosin-3-monooxygenasa metabolismus   MeSH
• uncoupling protein 1 metabolismus   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Research Support, N.I.H., Extramural MeSH