Anti-Obesity Activities of the Compounds from Perilla frutescens var. acuta and Chemical Profiling of the Extract.

Perilla frutescens var. acuta (Lamiaceae) is widely used not only as an oil or a spice, but also as a traditional medicine to treat colds, coughs, fever, and indigestion. As an ongoing effort, luteolin-7-O-diglucuronide (1), apigenin-7-O-diglucuronide (2), and rosmarinic acid (3) isolated from P. frutescens var. acuta were investigated for their anti-adipogenic and thermogenic activities in 3T3-L1 cells. Compound 1 exhibited a strong inhibition against adipocyte differentiation by suppressing the expression of Pparg and Cebpa over 52.0% and 45.0%, respectively. Moreover, 2 inhibited the expression of those genes in a dose-dependent manner [Pparg: 41.7% (5 µM), 62.0% (10 µM), and 81.6% (50 µM); Cebpa: 13.8% (5 µM), 18.4% (10 µM), and 37.2% (50 µM)]. On the other hand, the P. frutescens var. acuta water extract showed moderate thermogenic activities. Compounds 1 and 3 also induced thermogenesis in a dose-dependent manner by stimulating the mRNA expressions of Ucp1, Pgc1a, and Prdm16. Moreover, an LC-MS/MS chromatogram of the extract was acquired using UHPLC-MS2 and it was analyzed by feature-based molecular networking (FBMN) and the Progenesis QI software (version 3.0). The chemical profiling of the extract demonstrated that flavonoids and their glycoside derivatives, including those isolated earlier as well as rosmarinic acid, are present in P. frutescens var. acuta.

Alternative isoform expression of key thermogenic genes in human beige adipocytes.

Background: The beneficial effect of thermogenic adipocytes in maintaining body weight and protecting against metabolic disorders has raised interest in understanding the regulatory mechanisms defining white and beige adipocyte identity. Although alternative splicing has been shown to propagate adipose browning signals in mice, this has yet to be thoroughly investigated in human adipocytes. Methods: We performed parallel white and beige adipogenic differentiation using primary adipose stem cells from 6 unrelated healthy subjects and assessed differential gene and isoform expression in mature adipocytes by RNA sequencing. Results: We find 777 exon junctions with robust differential usage between white and beige adipocytes in all 6 subjects, mapping to 562 genes. Importantly, only 10% of these differentially spliced genes are also differentially expressed, indicating that alternative splicing constitutes an additional layer of gene expression regulation during beige adipocyte differentiation. Functional classification of alternative isoforms points to a gain of function for key thermogenic transcription factors such as PPARG and CITED1, and enzymes such as PEMT, or LPIN1. We find that a large majority of the splice variants arise from differential TSS usage, with beige-specific TSSs being enriched for PPARγ and MED1 binding compared to white-specific TSSs. Finally, we validate beige specific isoform expression at the protein level for two thermogenic regulators, PPARγ and PEMT. Discussion: These results suggest that differential isoform expression through alternative TSS usage is an important regulatory mechanism for human adipocyte thermogenic specification.

Two-stage evolution of mammalian adipose tissue thermogenesis.

Brown adipose tissue (BAT) is a heater organ that expresses thermogenic uncoupling protein 1 (UCP1) to maintain high body temperatures during cold stress. BAT thermogenesis is considered an overarching mammalian trait, but its evolutionary origin is unknown. We show that adipose tissue of marsupials, which diverged from eutherian mammals ~150 million years ago, expresses a nonthermogenic UCP1 variant governed by a partial transcriptomic BAT signature similar to that found in eutherian beige adipose tissue. We found that the reconstructed UCP1 sequence of the common eutherian ancestor displayed typical thermogenic activity, whereas therian ancestor UCP1 is nonthermogenic. Thus, mammalian adipose tissue thermogenesis may have evolved in two distinct stages, with a prethermogenic stage in the common therian ancestor linking UCP1 expression to adipose tissue and thermal stress. We propose that in a second stage, UCP1 acquired its thermogenic function specifically in eutherians, such that the onset of mammalian BAT thermogenesis occurred only after the divergence from marsupials.

The evolution of thermogenesis in mammals.

Comparative genomics elucidates the steps enabling heat production in fat tissue.

Relative sarcolipin (SLN) and sarcoplasmic reticulum Ca2+ ATPase (SERCA1) transcripts levels in closely related endothermic and ectothermic scombrid fishes: Implications for molecular basis of futile calcium cycle non-shivering thermogenesis (NST).

Regional endothermy is the ability of an animal to elevate the temperature of specific regions of the body above that of the surrounding environment and has evolved independently among several fish lineages. Sarcolipin (SLN) is a small transmembrane protein that uncouples the sarcoplasmic reticulum calcium ATPase pump (SERCA1b) resulting in futile Ca2+ cycling and is thought to play a role in non-shivering thermogenesis (NST) in cold-challenged mammals and possibly some fishes. This study investigated the relative expression of sln and serca1 transcripts in three regionally-endothermic fishes (the skipjack, Katsuwonus pelamis, and yellowfin tuna, Thunnus albacares, both of which elevate the temperatures of their slow-twitch red skeletal muscle (RM) and extraocular muscles (EM), as well as the cranial endothermic swordfish, Xiphias gladius), and closely related ectothermic scombrids (the Eastern Pacific bonito, Sarda chiliensis, and Pacific chub mackerel, Scomber japonicus). Using Reverse Transcription quantitative PCR (RT-qPCR) and species-specific primers, relative sln expression trended higher in both the RM and EM for all four scombrid species compared to white muscle. In addition, relative serca1 expression was found to be higher in RM of skipjack and yellowfin tuna in comparison to white muscle. However, neither sln nor serca1 transcripts were higher in swordfish RM, EM or cranial heater tissue in comparison to white muscle. A key phosphorylation site in sarcolipin, threonine 5, is conserved in the swordfish, but is mutated to alanine or valine in tunas and the endothermic smalleye Pacific opah, Lampris incognitus, which should result in increased uncoupling of the SERCA pump. Our results support the role of potential SLN-NST in endothermic tunas and the lack thereof for swordfish.

The function of brown adipose tissue at different sites of the body in Brandt's voles during cold acclimation.

Ambient temperatures have great impacts on thermoregulation of small mammals. Brown adipose tissue (BAT), an obligative thermogenic tissue for small mammals, is localized not only in the interscapular depot (iBAT), but also in supraclavicular, infra/subscapular, cervical, paravertebral, and periaortic depots. The iBAT is known for its cold-induced thermogenesis, however, less has been paid attention to the function of BAT at other sites. Here, we investigated the function of BAT at different sites of the body during cold acclimation in a small rodent species. As expected, Brandt's voles (Lasiopodomys brandtii) consumed more food and reduced the body mass gain when they were exposed to cold. The voles increased resting metabolic rate and maintained a relatively lower body temperature in the cold (36.5 ± 0.27 °C) compared to those in the warm condition (37.1 ± 0.36 °C). During cold acclimation, the uncoupling protein 1 (UCP1) increased in aBAT (axillary), cBAT (anterior cervical), iBAT (interscapular), nBAT (supraclavicular), and sBAT (suprascapular). The levels of proliferating cell nuclear antigen (PCNA), a marker for cell proliferation, were higher in cBAT and iBAT in the cold than in the warm group. The pAMPK/AMPK and pCREB/CREB were increased in cBAT and iBAT during cold acclimation, respectively. These data indicate that these different sites of BAT play the cold-induced thermogenic function for small mammals.

Dynamic changes of immunocyte subpopulations in thermogenic activation of adipose tissues.

Objectives: The effects of cold exposure on whole-body metabolism in humans have gained increasing attention. Brown or beige adipose tissues are crucial in cold-induced thermogenesis to dissipate energy and thus have the potential to combat metabolic disorders. Despite the immune regulation of thermogenic adipose tissues, the overall changes in vital immune cells during distinct cold periods remain elusive. This study aimed to discuss the overall changes in immune cells under different cold exposure periods and to screen several potential immune cell subpopulations on thermogenic regulation. Methods: Cibersort and mMCP-counter algorithms were employed to analyze immune infiltration in two (brown and beige) thermogenic adipose tissues under distinct cold periods. Changes in some crucial immune cell populations were validated by reanalyzing the single-cell sequencing dataset (GSE207706). Flow cytometry, immunofluorescence, and quantitative real-time PCR assays were performed to detect the proportion or expression changes in mouse immune cells of thermogenic adipose tissues under cold challenge. Results: The proportion of monocytes, naïve, and memory T cells increased, while the proportion of NK cells decreased under cold exposure in brown adipose tissues. Conclusion: Our study revealed dynamic changes in immune cell profiles in thermogenic adipose tissues and identified several novel immune cell subpopulations, which may contribute to thermogenic activation of adipose tissues under cold exposure.

Itaconate alleviates diet-induced obesity via activation of brown adipocyte thermogenesis.

Despite medical advances, there remains an unmet need for better treatment of obesity. Itaconate, a product of the decarboxylation of the tricarboxylic acid cycle intermediate cis-aconitate, plays a regulatory role in both metabolism and immunity. Here, we show that itaconate, as an endogenous compound, counteracts high-fat-diet (HFD)-induced obesity through leptin-independent mechanisms in three mouse models. Specifically, itaconate reduces weight gain, reverses hyperlipidemia, and improves glucose tolerance in HFD-fed mice. Additionally, itaconate enhances energy expenditure and the thermogenic capacity of brown adipose tissue (BAT). Unbiased proteomic analysis reveals that itaconate upregulates key proteins involved in fatty acid oxidation and represses the expression of lipogenic genes. Itaconate may provoke a major metabolic reprogramming by inducing fatty acid oxidation and suppression of fatty acid synthesis in BAT. These findings highlight itaconate as a potential activator of BAT-mediated thermogenesis and a promising candidate for anti-obesity therapy.

Mitochondrial UCP1: Potential thermogenic mechanistic switch for the treatment of obesity and neurodegenerative diseases using natural and epigenetic drug candidates.

BACKGROUND: Brown fat is known to provide non-shivering thermogenesis through mitochondrial uncoupling mediated by uncoupling protein 1 (UCP1). Non-shivering is not dependent on UCP2, UCP4, and BMCP1/UCP5 genes, which are distinct from UCP1 in a way that they are not constitutive uncouplers. Although they are susceptible to free fatty acid and free radical activation, their functioning has a significant impact on the performance of neurons. METHODOLOGY: Using subject-specific keywords (Adipose tissue; Adipocytes; Mitochondria; Obesity; Thermogenesis; UCP's in Neurodegeneration; Alzheimer's disease; Parkinson's disease), research articles and reviews were retrieved from Web of Science, ScienceDirect, Google Scholar, and PubMed. This article includespublications published between 2018 and 2023. The drugs that upregulate UCP1 are included in the study while the drugs that do not impact UCP1 are were not included. RESULTS: Neuronal UCPs have a direct impact on synaptic plasticity, neurodegenerative processes, and neurotransmission, by modulating calcium flux, mitochondrial biogenesis, local temperature, and free radical generation. Numerous significant advances in the study of neuronal UCPs and neuroprotection are still to be made. Identification of the tissue-dependent effects of UCPs is essential first. Pharmacologically targeting neuronal UCPs is a key strategy for preventing both neurodegenerative diseases and physiological aging. Given that UCP2 has activities that are tissue-specific, it will be essential to develop treatments without harmful side effects. The triggering of UCPs by CoQ, an essential cofactor, produces nigral mitochondrial uncoupling, reduces MPTP-induced toxicity, and may even decrease the course of Parkinson's disease, according to early indications. CONCLUSION: Herein, we explore the potential of UCP1 as a therapeutic target for treating obesity, neurodegenerative diseases as well as a potential activator of both synthetic and natural drugs. A deeper knowledge of synaptic signaling and neurodegeneration may pave the way to new discoveries regarding the functioning and controlling of these genes.

Lack of p38 activation in T cells increases IL-35 and protects against obesity by promoting thermogenesis.

Obesity is characterized by low-grade inflammation, energy imbalance and impaired thermogenesis. The role of regulatory T cells (Treg) in inflammation-mediated maladaptive thermogenesis is not well established. Here, we find that the p38 pathway is a key regulator of T cell-mediated adipose tissue (AT) inflammation and browning. Mice with T cells specifically lacking the p38 activators MKK3/6 are protected against diet-induced obesity, leading to an improved metabolic profile, increased browning, and enhanced thermogenesis. We identify IL-35 as a driver of adipocyte thermogenic program through the ATF2/UCP1/FGF21 pathway. IL-35 limits CD8+ T cell infiltration and inflammation in AT. Interestingly, we find that IL-35 levels are reduced in visceral fat from obese patients. Mechanistically, we demonstrate that p38 controls the expression of IL-35 in human and mouse Treg cells through mTOR pathway activation. Our findings highlight p38 signaling as a molecular orchestrator of AT T cell accumulation and function.

Oral supplementation with resveratrol improves hormonal profile and increases expression of genes associated with thermogenesis in oophorectomy mice.

Menopause causes important bodily and metabolic changes, which favor the increased occurrence of cardiovascular diseases, obesity, diabetes, and osteoporosis. Resveratrol exerts proven effects on body metabolism, improving glucose and lipid homeostasis and reducing inflammation and oxidative stress in various organs and tissues. Accordingly, this study evaluates the effects of resveratrol supplementation on the expression of markers associated with thermogenesis in brown adipose tissue, and on the body, metabolic and hormonal parameters of female mice submitted to bilateral oophorectomy. Eighteen female mice were randomized into three groups: G1: control (CONTROL), G2: oophorectomy (OOF), and G3: oophorectomy + resveratrol (OOF + RSV); the animals were kept under treatment for twelve weeks, being fed a standard diet and treated with resveratrol via gavage. Body, biochemical, hormonal, and histological parameters were measured; in addition to the expression of markers associated with thermogenesis in brown adipose tissue. The results showed that animals supplemented with resveratrol showed reduced body weight and visceral adiposity, in addition to glucose, total cholesterol, and triglyceride levels; decreased serum FSH levels and increased estrogen levels were observed compared to the OOF group and mRNA expression of PRDM16, UCP1, and SIRT3 in brown adipose tissue. The findings of this study suggest the important role of resveratrol in terms of improving body, metabolic, and hormonal parameters, as well as modulating markers associated with thermogenesis in brown adipose tissue of female mice submitted to oophorectomy.

Genetic or pharmacological GHSR blockade has sexually dimorphic effects in rodents on a high-fat diet.

The stomach-derived hormone ghrelin regulates essential physiological functions. The ghrelin receptor (GHSR) has ligand-independent actions; therefore, GHSR gene deletion may be a reasonable approach to investigate the role of this system in feeding behaviors and diet-induced obesity (DIO). Here, we investigate the effects of a long-term (12-month) high-fat (HFD) versus regular diet on obesity-related measures in global GHSR-KO and wild-type (WT) Wistar male and female rats. Our main findings are that the GHSR gene deletion protects against DIO and decreases food intake during HFD in male but not in female rats. GHSR gene deletion increases thermogenesis and brain glucose uptake in male rats and modifies the effects of HFD on brain glucose metabolism in a sex-specific manner, as assessed with small animal positron emission tomography. We use RNA-sequencing to show that GHSR-KO rats have upregulated expression of genes responsible for fat oxidation in brown adipose tissue. Central administration of a novel GHSR inverse agonist, PF-5190457, attenuates ghrelin-induced food intake, but only in male, not in female mice. HFD-induced binge-like eating is reduced by inverse agonism in both sexes. Our results support GHSR as a promising target for new pharmacotherapies for obesity.

Transgenic female mice producing trans 10, cis 12-conjugated linoleic acid present excessive prostaglandin E2, adrenaline, corticosterone, glucagon, and FGF21.

Dietary trans 10, cis 12-conjugated linoleic acid (t10c12-CLA) is a potential candidate in anti-obesity trials. A transgenic mouse was previously successfully established to determine the anti-obesity properties of t10c12-CLA in male mice that could produce endogenous t10c12-CLA. To test whether there is a different impact of t10c12-CLA on lipid metabolism in both sexes, this study investigated the adiposity and metabolic profiles of female Pai mice that exhibited a dose-dependent expression of foreign Pai gene and a shift of t10c12-CLA content in tested tissues. Compared to their gender-match wild-type littermates, Pai mice had no fat reduction but exhibited enhanced lipolysis and thermogenesis by phosphorylated hormone-sensitive lipase and up-regulating uncoupling proteins in brown adipose tissue. Simultaneously, Pai mice showed hepatic steatosis and hypertriglyceridemia by decreasing gene expression involved in lipid and glucose metabolism. Further investigations revealed that t10c10-CLA induced excessive prostaglandin E2, adrenaline, corticosterone, glucagon and inflammatory factors in a dose-dependent manner, resulting in less heat release and oxygen consumption in Pai mice. Moreover, fibroblast growth factor 21 overproduction only in monoallelic Pai/wt mice indicates that it was sensitive to low doses of t10c12-CLA. These results suggest that chronic t10c12-CLA has system-wide effects on female health via synergistic actions of various hormones.

Unveiling the Potential of Natural Compounds: A Comprehensive Review on Adipose Thermogenesis Modulation.

The process of adipocyte browning has recently emerged as a novel therapeutic target for combating obesity and obesity-related diseases. Non-shivering thermogenesis is the process of biological heat production in mammals and is primarily mediated via brown adipose tissue (BAT). The recruitment and activation of BAT can be induced through chemical drugs and nutrients, with subsequent beneficial health effects through the utilization of carbohydrates and fats to generate heat to maintain body temperature. However, since potent drugs may show adverse side effects, nutritional or natural substances could be safe and effective as potential adipocyte browning agents. This review aims to provide an extensive overview of the natural food compounds that have been shown to activate brown adipocytes in humans, animals, and in cultured cells. In addition, some key genetic and molecular targets and the mechanisms of action of these natural compounds reported to have therapeutic potential to combat obesity are discussed.

Mitochondrial function in skeletal muscle contributes to reproductive endothermy in tegu lizards (Salvator merianae).

AIM: In cyclic climate variations, including seasonal changes, many animals regulate their energy demands to overcome critical transitory moments, restricting their high-demand activities to phases of resource abundance, enabling rapid growth and reproduction. Tegu lizards (Salvator merianae) are ectotherms with a robust annual cycle, being active during summer, hibernating during winter, and presenting a remarkable endothermy during reproduction in spring. Here, we evaluated whether changes in mitochondrial respiratory physiology in skeletal muscle could serve as a mechanism for the increased thermogenesis observed during the tegu's reproductive endothermy. METHODS: We performed high-resolution respirometry and calorimetry in permeabilized red and white muscle fibers, sampled during summer (activity) and spring (high activity and reproduction), in association with citrate synthase measurements. RESULTS: During spring, the muscle fibers exhibited increased oxidative phosphorylation. They also enhanced uncoupled respiration and heat production via adenine nucleotide translocase (ANT), but not via uncoupling proteins (UCP). Citrate synthase activity was higher during the spring, suggesting greater mitochondrial density compared to the summer. These findings were consistent across both sexes and muscle types (red and white). CONCLUSION: The current results highlight potential cellular thermogenic mechanisms in an ectothermic reptile that contribute to transient endothermy. Our study indicates that the unique feature of transitioning to endothermy through nonshivering thermogenesis during the reproductive phase may be facilitated by higher mitochondrial density, function, and uncoupling within the skeletal muscle. This knowledge contributes significant elements to the broader picture of models for the evolution of endothermy, particularly in relation to the enhancement of aerobic capacity.

Adipsin and adipocyte-derived C3aR1 regulate thermogenic fat in a sex-dependent fashion.

Thermogenesis in beige/brown adipose tissues can be leveraged to combat metabolic disorders such as type 2 diabetes and obesity. The complement system plays pleiotropic roles in metabolic homeostasis and organismal energy balance with canonical effects on immune cells and noncanonical effects on nonimmune cells. The adipsin/C3a/C3a receptor 1 (C3aR1) pathway stimulates insulin secretion and sustains pancreatic ß cell mass. However, its role in adipose thermogenesis has not been defined. Here, we show that male Adipsin/Cfd-knockout mice exhibited increased energy expenditure and white adipose tissue (WAT) browning. In addition, male adipocyte-specific C3aR1-knockout mice exhibited enhanced WAT thermogenesis and increased respiration. In stark contrast, female adipocyte-specific C3aR1-knockout mice displayed decreased brown fat thermogenesis and were cold intolerant. Female mice expressed lower levels of Adipsin in thermogenic adipocytes and adipose tissues than males. C3aR1 was also lower in female subcutaneous adipose tissue than in males. Collectively, these results reveal sexual dimorphism in the adipsin/C3a/C3aR1 axis in regulating adipose thermogenesis and defense against cold stress. Our findings establish a potentially new role of the alternative complement pathway in adaptive thermogenesis and highlight sex-specific considerations in potential therapeutic targets for metabolic diseases.

The histone methyltransferase SUV420H2 regulates brown and beige adipocyte thermogenesis.

Activation of brown adipose tissue (BAT) thermogenesis increases energy expenditure and alleviates obesity. Here we discover that histone methyltransferase suppressor of variegation 4-20 homolog 2 (Suv420h2) expression parallels that of Ucp1 in brown and beige adipocytes and that Suv420h2 knockdown significantly reduces - whereas Suv420h2 overexpression significantly increases - Ucp1 levels in brown adipocytes. Suv420h2 knockout (H2KO) mice exhibit impaired cold-induced thermogenesis and are prone to diet-induced obesity. In contrast, mice with specific overexpression of Suv420h2 in adipocytes display enhanced cold-induced thermogenesis and are resistant to diet-induced obesity. Further study shows that Suv420h2 catalyzes H4K20 trimethylation at eukaryotic translation initiation factor 4E-binding protein 1 (4e-bp1) promoter, leading to downregulated expression of 4e-bp1, a negative regulator of the translation initiation complex. This in turn upregulates PGC1α protein levels, and this upregulation is associated with increased expression of thermogenic program. We conclude that Suv420h2 is a key regulator of brown/beige adipocyte development and thermogenesis.

Angiotensin II participates in mitochondrial thermogenic functions via the activation of glycolysis in chemically induced human brown adipocytes.

Brown adipocytes are potential therapeutic targets for the prevention of obesity-associated metabolic diseases because they consume circulating glucose and fatty acids for heat production. Angiotensin II (Ang II) peptide is involved in the pathogenesis of obesity- and cold-induced hypertension; however, the mechanism underlying the direct effects of Ang II on human brown adipocytes remains unclear. Our transcriptome analysis of chemical compound-induced brown adipocytes (ciBAs) showed that the Ang II type 1 receptor (AGTR1), but not AGTR2 and MAS1 receptors, was expressed. The Ang II/AGTR1 axis downregulated the expression of mitochondrial uncoupling protein 1 (UCP1). The simultaneous treatment with ß-adrenergic receptor agonists and Ang II attenuated UCP1 expression, triglyceride lipolysis, and cAMP levels, although cAMP response element-binding protein (CREB) phosphorylation was enhanced by Ang II mainly through the protein kinase C pathway. Despite reduced lipolysis, both coupled and uncoupled mitochondrial respiration was enhanced in Ang II-treated ciBAs. Instead, glycolysis and glucose uptake were robustly activated upon treatment with Ang II without a comprehensive transcriptional change in glucose metabolic genes. Elevated mitochondrial energy status induced by Ang II was likely associated with UCP1 repression. Our findings suggest that the Ang II/AGTR1 axis participates in mitochondrial thermogenic functions via glycolysis.