Capsaicin, a polyphenol, is known to regulate energy expenditure and thermogenesis in adipocytes and muscles. However, its role in modulating uncoupling proteins (UCPs) and adenosine triphosphate (ATP)-dependent thermogenesis in muscles remains unclear. This study investigated the mechanisms underlying the role of capsaicin in modulating the UCP- and ATP-dependent thermogenesis in C2C12 myoblasts, as well as the gastrocnemius (GM) and soleus muscles (SM) of mice. We employed molecular dynamics (MD), quantitative realtime polymerase chain reactions (qRT-PCR), immunoblots, staining methods, and assay kits to investigate the role of capsaicin on thermogenesis and its modulatory roles on the transient receptor potential cation channel subfamily V member 1 (TRPV1) and alpha-/beta-adrenergic receptors (ARs) using in vitro and in vivo models. Our findings demonstrate that capsaicin treatment in high-fat diet-induced obese mice reduces weight gain and elevates the expression of UCP- and ATP-dependent thermogenic effectors through ATP-consuming calcium and creatine futile cycles. In vitro and in vivo models capsaicin treatment elevated the expression of sarcoendoplasmic/endoplasmic reticulum calcium ATPases (SERCA-1 and -2), ryanodine receptors (RYR-1 and -2), uncoupling proteins (UCP-2 and -3), creatine kinase B (CKB), and creatine kinase mitochondrial 2 (CKMT2), through activation of TRPV1, alpha 1-, beta 2-, and beta 3-AR as well as the suppressed expression of alpha 2-AR. Furthermore, our results also indicate that capsaicin promotes myotube development and enhances lipid metabolism in C2C12 cells. We found that capsaicin increased intracellular Ca2+ levels and the expression of the voltage-dependent anion channel (VDAC) and mitochondrial calcium uniporter (MCU), suggesting that elevated mitochondrial Ca2+ levels boost the expression of oxidative phosphorylation protein complexes via the activation of the ATP-futile cycle. Mechanistic studies in C2C12 cells revealed that TRPV1 is likely dispensable for capsaicin-induced thermogenesis, and TRPV1 and alpha 1-AR may synergistically induce thermogenesis. Collectively, our findings have uncovered a novel mechanism of UCP- and ATP-dependent thermogenesis and its associated pathways in both cellular and animal models which is crucial for designing therapeutic strategies to address obesity and associated metabolic diseases.

It is well documented that the α2 subunit of Na+/K+-ATPase (ATP1A2) positively regulates obesity, cardiovascular disease, and diabetes, and additionally indirectly controls cellular Ca2+ homeostasis. However, the functional role of ATP1A2 in the muscle remains unexplored. Here, we investigated the functional role of ATP1A2 in muscle physiology with a focus on thermogenesis, using mouse-derived C2C12 myoblasts. To this end, we examined the physiological consequences of ATP1A2 by the gene-specific knockdown of ATP1A2 in cultured C2C12 myoblasts. A deficiency of ATP1A2 enhanced the myogenic differentiation, lipid catabolism as well as glucose and fatty acid uptakes in C2C12 myoblasts, as demonstrated by their gene and protein expression levels evaluated with the help of real-time qRT-PCR and immunoblot analysis. Moreover, the silencing of ATP1A2 enhanced the expression of muscle thermogenic effectors, mitochondrial biogenesis markers, and mitochondrial oxidative phosphorylation proteins in C2C12 myoblasts. Further, these results were validated with the cellular-level quantification of sarco-endoplasmic reticulum Ca2+-ATPase1a by immunofluorescence, as well as myogenesis differentiation with myosin heavy chain intensities and Giemsa staining, respectively. A mechanistic study also suggested that ATP1A2 increases myogenesis via activation of the mammalian target of the rapamycin complex 1 signaling pathway. In conclusion, our data suggest a mechanism of action of ATP1A2 in the regulation of myogenic differentiation. The absence of ATP1A2 positively regulates muscle thermogenesis, suggesting that it could be a possible therapeutic target for treating obesity and other metabolic disorders.

Plant-derived compounds have shown potential in combating obesity by promoting thermogenesis in skeletal muscles and adipose tissues. One such compound is homotaurine, a sulfonic acid found in marine red algae, known for its benefits in neurocognitive disorders. However, its impact on adipocyte biology related to energy expenditure regulators remains unexplored. We employed RT-PCR, immunoblot, a staining method, and an assay kit to investigate the role of homotaurine in the regulators of DRD1-mediated ATP-dependent thermogenesis and beiging in C2C12 myoblasts and 3T3–L1 white adipocytes. We also assessed the effects of homotaurine on the expression of target genes and proteins related to ATP-consuming futile and browning processes in both cell models. Our findings revealed that homotaurine suppressed the expression of OXPHOS complexes in 3T3–L1 white adipocytes whereas, in C2C12 myoblasts, it stimulated their expression. Moreover, homotaurine increased intracellular Ca2+ levels in C2C12 myoblasts but not in 3T3–L1 white adipocytes. Furthermore, homotaurine upregulated key effectors of ATP-dependent thermogenesis, such as α1-AR, SLN, CaMKII, VDAC, and MCU, in C2C12 myoblasts. However, in 3T3–L1 white adipocytes, these effectors were downregulated, indicating homotaurine’s suppressing effect on browning and thermogenic characteristics in these cells. Homotaurine exhibited cell-type-specific effects on mitochondrial biogenesis regulators, Ca2+ signaling, and ATP-dependent thermogenesis effectors. It enhanced energy expenditure in C2C12 myoblasts by upregulating key effectors while inhibiting browning and thermogenic characteristics in 3T3–L1 white adipocytes. These in vitro findings suggest that homotaurine holds promise as a therapeutic agent against obesity by promoting energy expenditure regulators in C2C12 myoblasts.

Capsaicin (CAP) is a natural bioactive compound in chili pepper that activates the transient receptor potential vanilloid subfamily 1 (TRPV1) and is known to stimulate uncoupling protein 1 (UCP1)-dependent thermogenesis. However, its effect on ATP-dependent thermogenesis remains unknown. In this study, we employed qRT-PCR, immunoblot, staining method, and assay kit to investigate the role of CAP on ATP-dependent thermogenesis and its modulatory roles on the TRPV1, β3-adrenergic receptor (β3-AR), and α1-AR using in vitro and in vivo models. The studies showed that CAP treatment in high-fat diet-induced obese mice resulted in lower body weight gain and elevated ATP-dependent thermogenic effectors' protein and gene expression through ATP-consuming calcium and creatine futile cycles. In both in vitro and in vivo experiments, CAP treatment elevated the protein and gene expressions of sarcoendoplasmic/endoplasmic reticulum calcium ATPase 2 (SERCA2), ryanodine receptor 2 (RYR2), creatine kinase B (CKB), and creatine kinase mitochondrial 2 (CKMT2) mediated by the activation of β3-AR, α1-AR, and TRPV1. Our study showed that CAP increased intracellular Ca2+ levels and the expression of voltage-dependent anion channel (VDAC) and mitochondrial calcium uniporter (MCU) which indicates that increased mitochondrial Ca2+ levels lead to increased expression of oxidative phosphorylation protein complexes as a result of ATP-futile cycle activation. A mechanistic study in 3T3-L1 adipocytes revealed that CAP induces UCP1- and ATP-dependent thermogenesis mediated by the β3-AR/PKA/p38MAPK/ERK as well as calcium-dependent α1-AR/TRPV1/CaMKII/AMPK/SIRT1 pathway. Taken together, we identified CAP's novel functional and modulatory roles in UCP1- and ATP-dependent thermogenesis, which is important for developing therapeutic strategies for combating obesity and metabolic diseases.

Recent studies have shown that some natural compounds from plants prevent obesity and related disorders, including the loss of skeletal muscle mass and strength. In this study, we investigated the effect of echinacoside (ECH), a caffeic acid glycoside from the phenylpropanoid class, on myogenesis and ATP-dependent thermogenesis in the skeletal muscle and its interaction with the dopaminergic receptors 1 and 5 (DRD1 and DRD5). We applied RT-PCR, immunoblot analysis, a staining method, and an assay kit to determine the effects of ECH on diverse target genes and proteins involved in skeletal muscle myogenesis and ATP-consuming futile processes. Our study demonstrated that ECH enhanced myogenic differentiation, glucose, and fatty acid uptake, as well as lipid catabolism, and induced ATP-dependent thermogenesis in vitro and in vivo. Moreover, ECH upregulated mitochondrial biogenesis proteins, mitochondrial oxidative phosphorylation (OXPHOS) complexes, and intracellular Ca2+ signaling as well as thermogenic proteins. These findings were further elucidated by mechanistic studies which showed that ECH mediates myogenesis via the DRD1/5 in C2C12 muscle cells. In addition, ECH stimulates α1-AR-mediated ATP-dependent thermogenesis via the DRD1/5/cAMP/SLN/SERCA1a pathway in C2C12 muscle cells. To the best of our knowledge, this is the first report that demonstrates the myogenic and thermogenic potential of ECH activity through the dopaminergic receptors. Understanding the novel functions of ECH in terms of its ability to prevent skeletal muscle loss and energy expenditure via ATP-consuming futile processes could help to develop potential alternative strategies to address muscle-related diseases, including combating obesity.

Emerging findings suggest that non-shivering thermogenesis in brown and beige adipocytes may effectively stimulate energy expenditure, thereby contributing to body weight reduction. Our previous report demonstrated that chrysin, a flavone found in honey and propolis, activates uncoupling protein 1 (UCP1)-dependent thermogenesis in brown fat and induces beige adipocytes. However, the effect of chrysin on UCP1-independent thermogenesis remains unexplored. In this study, we examined the effects of chrysin on UCP1-independent thermogenesis in the 3T3-L1 adipocytes and mouse model. This study showed that chrysin elevates the expression of calcium regulatory proteins, including sarcoendoplasmic reticulum Ca2+-ATPase, ryanodine receptor 2, voltage-dependent anion channel, mitochondrial calcium uniporter, and Ca2+/calmodulin-dependent protein kinase 2 in 3T3-L1 adipocytes as well as in inguinal and epididymal white adipose tissues of mice. Furthermore, our results also showed chrysin increased Ca2+ levels in 3T3-L1 adipocytes in a dose-dependent manner. In addition, our study showed chrysin upregulated creatine-mediated thermogenic markers (creatine kinase B and creatine kinase mitochondrial 2) in both in vitro and in vivo models. Mechanistically, we found that chrysin induces UCP1-independent thermogenesis by stimulating creatine- and calcium-mediated ATP-consuming futile cycle through the activation of the α1-adrenergic receptor. Combining the current and previous studies, it can be proposed that chrysin induces both UCP1-dependent and -independent thermogenesis in beige adipocytes, suggesting its possible use for effective intervention for obesity and metabolic disorders.

The activation of brown fat and induction of beige adipocytes, so-called non-shivering thermogenesis, is emerging as a promising target for therapeutic intervention in obesity management. Our previous report demonstrated that β-carotene (BC) induces beige adipocytes to increase UCP1-dependent thermogenic activity. However, the UCP1-independent thermogenic effect of BC on adipose tissues remains unexplored. In this study, we examined the effects of BC on UCP1-independent thermogenic activity with a focus on the ATP-consuming futile cycles in 3T3-L1 adipocytes. BC increased intracellular calcium levels and stimulated the expression of calcium cycling-related proteins, including sarcoendoplasmic reticulum Ca2+-ATPase (SERCA) 2b, ryanodine receptor 2 (RyR2), voltage-dependent anion channel (VDAC), mitochondrial calcium uniporter (MCU), and Ca2+/calmodulin-dependent protein kinase 2 (CaMK2) in 3T3-L1 white adipocytes. In addition, BC stimulated thermogenesis by activating the creatine metabolism-related thermogenic pathway. Moreover, BC activated β-carotene oxygenase 1 (BCO1), which efficiently cleaved BC to retinal and consequently converted to its transcriptionally active form retinoic acid. These BC conversion products also exhibited thermogenic effects comparable to a similar level of BC. The mechanistic study revealed that retinal exhibited thermogenic activity independently of retinoic acid and retinoic acid-mediated thermogenesis was resulted partly from conversion of retinal. Moreover, BC activated α1-AR and UCP1-independent thermogenic effectors independently of UCP1 expression. In conclusion, the thermogenic response to BC and its conversion products in 3T3-L1 white adipocytes involves two interacting pathways, one mediated via β3-adrenergic receptors (β3-AR) and cyclic adenosine monophosphate (cAMP) and the other via α1-AR and increases in cytosolic Ca2+ levels activated by calcium regulatory proteins.

Increasing the number of brite cells (browning) in white adipocytes has attracted considerable attention to combat obesity because brite cells also help elevate energy expenditure. Sodium-potassium adenosine triphosphatase α2 subunit (ATP1A2) has been studied extensively in migraine and cancers. On the other hand, the role of ATP1A2 in adipocytes biology with a focus on fat browning needs to be elucidated. In this study, suppression of ATP1A2 induced browning in white adipocytes. The siRNA-mediated knockdown was used to identify the functional roles of the ATP1A2 gene in white adipocytes browning and the lipid metabolism. A deficiency of ATP1A2 promoted the expression of brown adipocyte-specific proteins and genes, suppressed adipogenesis and lipogenesis, and enhanced lipolysis and fat oxidation, as well as mitochondrial biogenesis. Moreover, silencing of ATP1A2 enhanced the expression of marker proteins for UCPl-dependent (β3-AR, PKA, p38, ATF2, and ERK) and UCP1-independent (α1-AR, SERCA, and RyR) thermogenesis. A mechanistic study showed that a deficiency of ATP1A2 induces browning in white adipocytes by activating the β3-AR/ERK signaling pathways as well as α1-AR/SERCA-based thermogenesis through an ATP-consuming process. In conclusion, ATP1A2 is a previously unrecognized player in thermogenesis in white adipocytes, and downregulating ATP1A2 and activating both UCP1-dependent and UCP1-independent thermogenesis in adipocytes could be a novel pharmacotherapeutic approach to treat obesity.

BACKGROUND As a part of the catecholamines, dopamine receptors (DRs) have not been extensively studied like β3-AR in the thermogenesis process. The present study investigates the effect of DRD5 in browning events and ATP-consuming futile cycles. METHODS siRNA technology, qPCR, immunoblot analysis, immunofluorescence, and staining methods were used to investigate the effect of DRD5 on 3T3-L1 and C2C12 cells. RESULTS siDdr5 increased lipogenesis-associated effectors, and adipogenesis markers while reducing the expression of beige fat effectors. ATP-consuming futile cycle markers were also reduced following the siDrd5. On the contrary, pharmacological activation of DRD5 stimulated these effectors. Our mechanistic studies elucidated that DRD5 mediates fat browning via the cAMP-PKA-p38 MAPK signalling pathway in 3T3-L1 cells as well as the cAMP-SERCA-RyR pathway for the ATP-consuming futile cycles in both cells. CONCLUSIONS siDrd5 positively regulates browning and ATP-consuming futile cycles, and understanding its functions will provide insights into novel strategies to treat obesity.

PDF file - 303K, Supplemental Figure 1. Chemical structure of licochalcone E (LicE). Supplemental Figure 2. Licochalcone E decreases the tube formation of endothelial cells. Supplemental Figure 3. Licochalcone E decreases the secretion of urokinase-type plasminogen activator (uPA), VEGF-A, and MMP-9 in MDA-MB-231 breast cancer cells.

Echinacoside (ECH) is a naturally occurring phenylethanoid glycoside, isolated from Echinacea angustifolia, and this study aimed to analyze its effect on thermogenesis and its interaction with dopaminergic receptors 1 and 5 (DRD1 and DRD5) in 3T3-L1 white adipocytes and mice models. We employed RT-PCR, immunoblot, immunofluorescence, a staining method, and an assay kit to determine its impact. ECH showed a substantial increase in browning signals in vitro and a decrease in adipogenic signals in vivo. Additionally, analysis of the iWAT showed that the key genes involved in beiging, mitochondrial biogenesis, and ATP-dependent thermogenesis were upregulated while adipogenesis and lipogenesis genes were downregulated. OXPHOS complexes, Ca2+ signaling proteins as well as intracellular Ca2+ levels were also upregulated in 3T3-L1 adipocytes following ECH treatment. This was collectively explained by mechanistic studies which showed that ECH mediated the beiging process via the DRD1/5-cAMP-PKA and subsequent downstream molecules, whereas it co-mediated the α1-AR-signaling thermogenesis via the DRD1/5/SERCA2b/RyR2/CKmt pathway in 3T3-L1 adipocytes. Animal experiments revealed that there was a 12.28% reduction in body weight gain after the ECH treatment for six weeks. The effects of ECH treatment on adipose tissue can offer more insights into the treatment of obesity and metabolic syndrome.

PDF file - 167K, Supplemental Table 1. Effect of licochalcone E (LicE) on body weights and organ weights in BALB/c mice injected with 4T1 cells. Supplemental Table 2. Effect of licochalcone E (LicE) on the levels of creatinine and the activity of AST and ALT in the sera of BALB/c mice injected with 4T1 cells. Supplemental Table 3. Oral administration of licochalcone E (LicE) decreases the levels of various cytokines in the lung lysates from 4T1 tumor-bearing BALB/c mice. Supplemental Table 4. Oral administration of licochalcone E (LicE) decreases the levels of various proteins involved in the regulation of angiogenesis/metastasis in the lung lysates from 4T1 tumor-bearing BALB/c mice. Supplemental Table 5. Licochalcone E (LicE) does not inhibit the viability of MDA-MB-231 cells. Supplemental Table 6. Licochalcone E (LicE) does not reduce the viability of 4T1 cells.

The activation of beige fat and muscle tissues is an interesting and encouraging target for therapeutic intervention in obesity owing to their remarkable lipolytic activity and energy-consuming futile cycles. This study examined the effect of dopamine receptor D4 (DRD4) on lipid metabolisms as well as UCP1- and ATP-dependent thermogenesis in Drd4 -silenced 3T3-L1 adipocytes and C2C12 muscle cells. Silencing of Drd4, followed by quantitative real-time PCR, immunoblot analysis, immunofluorescence, and staining methods, were applied to evaluate the effects of DRD4 on diverse target genes and proteins of both cells. The findings showed that DRD4 was expressed in the adipose and muscle tissues of normal and obese mice. Furthermore, the knockdown of Drd4 upregulated the expression of brown adipocyte-specific genes and proteins while downregulating lipogenesis and the adipogenesis marker proteins. Drd4 silencing also upregulated the expression of key signaling molecules involved in ATP-dependent thermogenesis in both cells. This was further elucidated by mechanistic studies showing that a Drd4 knockdown mediates UCP1-dependent thermogenesis via the cAMP/PKA/p38MAPK pathway in 3T3-L1 adipocytes and UCP1-independent thermogenesis via the cAMP/SLN/SERCA2a pathway in C2C12 muscle cells. In addition, si Drd4 also mediates myogenesis via the cAMP/PKA/ERK1/2/Cyclin D3 pathway in C2C12 muscle cells. Silencing of Drd4 promotes β3-AR-dependent browning in 3T3-L1 adipocytes and α1-AR/SERCA-based thermogenesis through an ATP-consuming futile process in C2C12 muscle cells. Understanding the novel functions of DRD4 on adipose and muscle tissues in terms of its ability to enhance energy expenditure and regulate whole-body energy metabolism will aid in developing novel obesity intervention techniques.

Purpose: Peripheral T-cell lymphomas (PTCLs) are a heterogeneous group of non-Hodgkin lymphomas, and their prognoses are still poor because of frequent relapses and the absence of optimal standard therapy. Cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) has been the backbone of frontline chemotherapy for PTCL for many years. However, it is not clear whether anthracycline-based chemotherapies such as CHOP could be standard induction therapy for PTCL. Thus, we conducted a randomized phase II study to compare the efficacy of CHOP with fractionated ifosfamide, carboplatin, etoposide, and dexamethasone (ICED). Patients and Methods: This study was a phase II, multicenter, open-label randomized trial at 21 hospitals that belonged to the Consortium for Improving Survival of Lymphoma (CISL) in Korea (CISL-1504/ROSE study). Eligible participants were patients aged 20–65 years with previously untreated histologically confirmed PTCLs based on the World Health Organization classification 2008 including PTCL-not otherwise specified (NOS), angioimmunoblastic T-cell lymphoma (AITL), ALK-negative anaplastic large-cell lymphoma (ALCL), enteropathy-associated T-cell lymphoma (EATL), and hepatosplenic T-cell lymphoma (HSTL). Patients with ALK-positive ALCL, extranodal NK/T-cell lymphoma, and mycosis fungoides/sezary syndrome were not included in the study. Patients were randomized at a 1:1 ratio to receive either CHOP or ICED every 3 weeks for 6 cycles. Upfront autologous stem cell transplantation (ASCT) was done for patients achieving complete or partial response and the primary end point was progression-free survival (PFS). Results: Between September 2015 and March 2021, 145 patients were screened, and 138 patients were enrolled. The characteristics were not different between CHOP (n = 69) and ICED (n = 66), and PTCL-NOS (n = 60) and AITL (n = 53) were dominant. The objective response rate was not different between CHOP (41/69, 59.4%) and ICED (37/66, 56.1%), and the 3-year PFS was not different between CHOP (36.7%) and ICED (33.1%, P = 0.709). Around 80% of patients who completed either CHOP or ICED followed by upfront ASCT showed 3-year overall survival (Figure 1). There was no statistically significant difference in PFS between the CHOP and ICED arms for any subgroup analyzed except AITL. CHOP was favored over ICED in AITL patients, whereas ICED was favored over CHOP in EATL/HSTL patients. ICED was associated with more anemia, neutropenia, and thrombocytopenia of all grades and grade 3 or worse, and the frequency of febrile neutropenia was higher in the ICED arm. Keywords: aggressive T-cell non-Hodgkin lymphoma, chemotherapy, stem cell transplant No conflicts of interests pertinent to the abstract.

Obesity and related metabolic disorders are epidemic diseases. Promoting thermogenesis and a functional increase in the browning of white adipocytes may counteract obesity. On the other hand, the molecular mechanism that regulates brown and beige fat-mediated thermogenesis is unclear. This article reports a molecular network led by cytoplasmic FMR1-interacting protein 2 (CYFIP2) that negatively regulates adipocyte browning in white adipocytes. Although the function of CYFIP2 in Fragile X Syndrome (FXS) and autism have been reported, its physiological roles in adipocytes remain elusive. Therefore, this study examined the physiological consequences of its deprivation in cultured 3T3-L1 white adipocytes using loss-of-function studies. Combined real-time quantitative reverse-transcription polymerase chain reaction and immunoblot analysis showed that the loss of CYFIP2 induces fat browning, as evidenced by the gene and protein expression levels of the brown fat-associated markers. A deficiency of CYFIP2 promoted mitochondrial biogenesis and significantly enhanced the expression of the core set beige fat-specific genes (Cd137, Cidea, Cited1, Tbx1, and Tmem26) and proteins (PGC-1α, PRDM16, and UCP1). In addition, a CYFIP2 deficiency promoted lipid catabolism and suppressed adipogenesis, lipogenesis, and autophagy. A mechanistic study showed that the loss of CYFIP2 induces browning in white adipocytes, independently via the activation of mTORC1 and suppression of the GABA-BR signaling pathway. The present data revealed a previously unidentified mechanism of CYFIP2 in the browning of white adipocytes and emphasized the potential of CYFIP2 as a pharmacotherapeutic target for treating obesity and other metabolic disorders.