Ojeok-san enhances platinum sensitivity in ovarian cancer by regulating adipocyte paracrine IGF1 secretion

BACKGROUND

Platinum is a commonly used drug for ovarian cancer (OvCa) treatment, but drug resistance limits its clinical application. This study intended to delineate the effects of adipocytes on platinum resistance in OvCa.

METHODS

OvCa cells were maintained in the adipocyte-conditioned medium. Cell viability and apoptosis were detected by CCK-8 and flow cytometry, separately. Proliferation and apoptosis-related protein expression were assayed by western blot. The IC50 values of cisplatin and carboplatin were determined using CCK-8. IGF1 secretion and expression were assayed via ELISA and western blot, respectively. A xenograft model was established, and pathological changes were detected by H&E staining. Proliferation and apoptosis-associated protein expression was assessed via IHC.

RESULTS

Adipocytes promoted the viability and repressed cell apoptosis in OvCa, as well as enhancing platinum resistance, while the addition of IGF-1 R inhibitor reversed the effects of adipocytes on proliferation, apoptosis, and drug resistance of OvCa cells. Treatment with different concentrations of Ojeok-san (OJS) inhibited the adipocyte-induced platinum resistance in OvCa cells by suppressing IGF1. The combined treatment of OJS and cisplatin significantly inhibited tumour growth in vivo with good mouse tolerance.

CONCLUSION

In summary, OJS inhibited OvCa proliferation and platinum resistance by suppressing adipocyte paracrine IGF1 secretion.

Anti-Obesity Effect of Jeju Roasted Citrus Peel Extract in High-Fat Diet-Induced Obese Mice and 3T3-L1 Adipocytes Via Lipid Metabolism Regulation

Lipid accumulation in adipocytes occurs through multifactorial effects such as overnutrition due to unbalanced eating habits, reduced physical activity, and genetic factors. In addition, obesity can be intensified by the dis-regulation of various metabolic systems such as differentiation, lipogenesis, lipolysis, and energy metabolism of adipocytes. In this study, the Jeju roasted peel extract from Citrus unshiu S.Markov. (JRC), which is discarded as opposed to the pulp of C. unshiu S.Markov., is commonly consumed to ameliorate obesity. To investigate the anti-obesity effect of JRC, these studies were conducted on differentiated 3T3-L1 cells and in high-fat diet-induced mice, and related methods were used to confirm whether it decreased lipid accumulation in adipocytes. The mechanism of inhibiting obesity by JRC was confirmed through mRNA expression studies. JRC suppressed lipid accumulation in adipocytes and adipose tissue, and significantly improved enzymes such as alanine aminotransferase, aspartate aminotransferase, and gamma-glutamyl transferase and serum lipid profiles. In addition, it effectively modulated the expression of genes related to lipid and energy metabolism in adipose tissue. As a result, these findings suggest that JRC could be a therapeutic regulator of body fat accumulation by significantly alleviating the dis-regulation of intracellular lipid metabolism in adipocytes and by enhancement of energy metabolism (Approval No. CNU IACUC-YB-2023-98).

Integrated stress response signaling acts as a metabolic sensor in fat tissues to regulate oocyte maturation and ovulation

Reproduction is an energy-intensive process requiring systemic coordination. However, the inter-organ signaling mechanisms that relay nutrient status to modulate reproductive output are poorly understood. Here, we use Drosophila melanogaster as a model to establish the integrated stress response (ISR) transcription factor, Atf4, as a fat tissue metabolic sensor that instructs oogenesis. We demonstrate that Atf4 regulates lipase activity to mediate yolk lipoprotein synthesis in the fat body. Depletion of Atf4 in the fat body also blunts oogenesis recovery after amino acid deprivation and re-feeding, suggestive of a nutrient-sensing role for Atf4. We also discovered that Atf4 promotes secretion of a fat-body-derived neuropeptide, CNMamide, which modulates neural circuits that promote egg-laying behavior (ovulation). Thus, we posit that ISR signaling in fat tissue acts as a "metabolic sensor" that instructs female reproduction-directly by impacting yolk lipoprotein production and follicle maturation and systemically by regulating ovulation.

Overactivation of the Endocannabinoid System in Adolescence Disrupts Adult Adipose Organ Function in Mice

Cannabis use stimulates calorie intake, but epidemiological studies show that people who regularly use it are leaner than those who don't. Two explanations have been proposed for this paradoxical finding. One posits that Δ9-tetrahydrocannabinol (THC) in cannabis desensitizes adipose CB1 cannabinoid receptors, stopping their stimulating effects on lipogenesis and adipogenesis. Another explanation is that THC exposure in adolescence, when habitual cannabis use typically starts, produces lasting changes in the developing adipose organ, which impacts adult systemic energy use. Here, we consider these possibilities in the light of a study which showed that daily THC administration in adolescent mice produces an adult metabolic phenotype characterized by reduced fat mass, partial resistance to obesity and dyslipidemia, and impaired thermogenesis and lipolysis. The phenotype, whose development requires activation of CB1 receptors in differentiated adipocytes, is associated with overexpression of myocyte proteins in the adipose organ with unchanged CB1 expression. We propose that adolescent exposure to THC causes lasting adipocyte dysfunction and the consequent emergence of a metabolic state that only superficially resembles healthy leanness. A corollary of this hypothesis, which should be addressed in future studies, is that CB1 receptors and their endocannabinoid ligands may contribute to the maintenance of adipocyte differentiation during adolescence.

Multifaceted impact of adipose conditioned media: Obesity-driven promotion of prostate cancer and cancer stem cell dynamics

Obesity is an established risk factor for the development and progression of prostate cancer (PC). This study used adipose conditioned media (ACM) from differentiated adipocytes to assess its effect on PC development and aggressiveness. Due to limited research on ACM's impact on isolated PC stem cells (PCSCs), we also examined CD44+ PCSCs. ACM notably boosted interleukin-1β (IL-1β), IL-6, and IL-8 production in normal prostate epithelial cells and LNCaP cells. It also increased IL-6 and IL-8 production in PC3 and CD44+ LNCaP cells, and IL-1β and IL-6 production in CD44+ PC3 cells. This indicates that ACM induces the production of inflammatory cytokines in both cancer and prostate epithelial cells. Furthermore, ACM promoted proliferation in androgen receptor (AR)-negative PC3 cells, CD44+  PC3 PCSCs, and nonmalignant RWPE cells, without affecting AR-positive LNCaP cells. In addition, ACM-enhanced invasion and migration potential in both PC3 and CD44+  PC3 cells. Western blot analysis indicated the involvement of NF-κB and AKT pathways in ACM-induced proliferation in PC3 cells and NF-κB in PCSCs. In ACM-treated PC3 cells, E-cadherin was downregulated, while N-cadherin, Snail, vimentin, fibronectin, and Twist were upregulated, suggesting ACM-induced invasion via classical epithelial-to-mesenchymal transition (EMT) pathways. In response to ACM, PCSCs exhibited increased expression of E-cadherin, Snail, and vimentin, which are partial EMT markers promoting stemness and resistance to apoptosis. In addition, increased expressions of Nanog, Oct3/4, survivin, and Bcl-2 were observed. Although the molecules we studied have diverse effects on cellular regulation, our data emphasize obesity's multifaceted role in promoting and aggressing PC, notably affecting PCSC populations.

Differential responses to UCP1 ablation in classical brown versus beige fat, despite a parallel increase in sympathetic innervation

In the cold, the absence of the mitochondrial uncoupling protein 1 (UCP1) results in hyper-recruitment of beige fat, but classical brown fat becomes atrophied. Here we examine possible mechanisms underlying this phenomenon. We confirm that in brown fat from UCP1-knockout (UCP1-KO) mice acclimated to the cold, the levels of mitochondrial respiratory chain proteins were diminished; however, in beige fat, the mitochondria seemed to be unaffected. The macrophages that accumulated massively not only in brown fat but also in beige fat of the UCP1-KO mice acclimated to cold did not express tyrosine hydroxylase, the norepinephrine transporter (NET) and monoamine oxidase-A (MAO-A). Consequently, they could not influence the tissues through the synthesis or degradation of norepinephrine. Unexpectedly, in the cold, both brown and beige adipocytes from UCP1-KO mice acquired an ability to express MAO-A. Adipose tissue norepinephrine was exclusively of sympathetic origin, and sympathetic innervation significantly increased in both tissues of UCP1-KO mice. Importantly, the magnitude of sympathetic innervation and the expression levels of genes induced by adrenergic stimulation were much higher in brown fat. Therefore, we conclude that no qualitative differences in innervation or macrophage character could explain the contrasting reactions of brown versus beige adipose tissues to UCP1-ablation. Instead, these contrasting responses may be explained by quantitative differences in sympathetic innervation: the beige adipose depot from the UCP1-KO mice responded to cold acclimation in a canonical manner and displayed enhanced recruitment, while the atrophy of brown fat lacking UCP1 may be seen as a consequence of supraphysiological adrenergic stimulation in this tissue.

Interleukin-6: An Under-Appreciated Inducer of Thermogenic Adipocyte Differentiation

Adipose tissue inflammation is a key factor leading to obesity-associated immune disorders, such as insulin resistance, beta cell loss in the pancreatic islets, meta-inflammation, and autoimmunity. Inhibiting adipose tissue inflammation is considered a straightforward approach to abrogate these diseases. However, recent findings show that certain pro-inflammatory cytokines are essential for the proper differentiation and functioning of adipocytes. Lipolysis is stimulated, and the thermogenic competence of adipocytes is unlocked by interleukin-6 (IL-6), a cytokine that was initially recognized as a key trigger of adipose tissue inflammation. Coherently, signal transducer and activator of transcription 3 (STAT3), which is a signal transducer for IL-6, is necessary for thermogenic adipocyte development. Given the impact of thermogenic adipocytes in increasing energy expenditure and reducing body adiposity, functions of IL-6 in the adipose tissue have gained attention recently. In this review, we show that IL-6 signaling may protect from excess fat accumulation by stimulating thermogenesis in adipocytes.

Orchestration of the Adipose Tissue Immune Landscape by Adipocytes

Obesity is epidemic and of great concern because of its comorbid and costly inflammatory-driven complications. Extensive investigations in mice have elucidated highly coordinated, well-balanced interactions between adipocytes and immune cells in adipose tissue that maintain normal systemic metabolism in the lean state, while in obesity, proinflammatory changes occur in nearly all adipose tissue immune cells. Many of these changes are instigated by adipocytes. However, less is known about obesity-induced adipose-tissue immune cell alterations in humans. Upon high-fat diet feeding, the adipocyte changes its well-known function as a metabolic cell to assume the role of an immune cell, orchestrating proinflammatory changes that escalate inflammation and progress during obesity. This transformation is particularly prominent in humans. In this review, we (a) highlight a leading and early role for adipocytes in promulgating inflammation, (b) discuss immune cell changes and the time course of these changes (comparing humans and mice when possible), and (c) note how reversing proinflammatory changes in most types of immune cells, including adipocytes, rescues adipose tissue from inflammation and obese mice from insulin resistance.

Targeted Overexpression of Claudin 11 in Osteoblasts Increases Trabecular Bone Mass by Stimulating Osteogenesis at the Expense of Adipogenesis in Mice

Mice lacking Claudin11 (Cldn11) manifest reduced trabecular bone mass. However, the impact of Cldn11 expression in osteoblasts in vivo remains understudied. Herein, we generated osteoblast-specific transgenic (Tg) mice expressing Cldn11 and characterized their skeletal phenotype. Micro-CT analyses of the distal metaphysis of the femur showed a 50% and a 38% increase in trabecular bone mass in Tg male and female mice, respectively, due to a significant increase in trabecular number and a reduction in trabecular separation. Histomorphometry and serum biomarker studies uncovered that increased trabecular bone mass in Cldn11 Tg mice was the consequence of enhanced bone formation. Accordingly, an abundance of bone formation (Alp, Bsp), but not bone resorption (Ctsk), markers were augmented in the femurs of Cldn11 Tg mice. Since the trabecular bone density is known to inversely correlate with the amount of marrow adipose tissue (MAT), we measured the MAT in osmium-tetroxide-labeled bones by micro-CT scanning. We found 86% less MAT in the proximal tibia of the Tg males. Consistently, the expression levels of the adipogenic markers, adiponectin and leptin, were 50% lower in the femurs of the Tg males. Our data are consistent with the possibility that claudin11 exerts anabolic effects in osteoblastic lineage cells that act via promoting the differentiation of marrow stem cells towards osteoblasts at the expense of adipocytes.

The Characterization of Subcutaneous Adipose Tissue in Sunit Sheep at Different Growth Stages: A Comprehensive Analysis of the Morphology, Fatty Acid Profile, and Metabolite Profile

Adipose tissue is a crucial economically significant trait that significantly influences the meat quality and growth performance of domestic animals. To reveal the changes in adipose tissue metabolism during the growth of naturally grazing sheep, we evaluated the thickness, adipocyte morphology, fatty acid profile, and metabolite profile of subcutaneous adipose tissue (SAT) from naturally grazing Sunit sheep at 6, 18, and 30 months of age (referred to as Mth-6, Mth-18, and Mth-30, respectively). The fat thickness and adipocyte number were significantly increased with the growth of the sheep (p < 0.05), and the increase of which from Mth-18 to Mth-30 was less than that from Mth-6 to Mth-18. Additionally, the alpha-linolenic acid metabolism was enhanced and fatty acid (FA) elongation increased with growth. The metabolomic analysis revealed 76 differentially expressed metabolites (DEMs) in the SAT in different growth stages. Interestingly, we observed elongation of FAs in lipids correlated with sheep growth. Furthermore, the expression of acylcarnitines was downregulated, and fatty acid amides, aspartic acid, acetic acid and phosphocholine were upregulated in Mth-18 and Mth-30 compared to Mth-6. Altogether, the study found that the difference in SAT in Mth-6 was great compared to Mth-18 and Mth-30. An increase in fat deposition via adipocyte proliferation with the growth of the sheep in naturally grazing. The DEMs of acylcarnitines, fatty acid amides, aspartic acid, acetic acid, and phosphocholine emerged as potential key regulators of adipose tissue metabolism. These findings illustrate the variation in and metabolic mechanism of sheep adipose tissue development under natural grazing, thus providing valuable insights into improving the edible quality of sheep meat and developing the mutton sheep industry.

Age-related changes in the fiber structure around adipocytes in the subcutaneous fat layer and their association with skin viscoelasticity

OBJECTIVE

Age-related changes in the fiber structure around adipocytes were investigated via scanning electron microscopy (SEM) of excised skin tissues. In addition, the viscoelasticity of the subcutaneous fat layer was evaluated via elastography, and the association between the fiber structure and the viscoelastic properties was assessed.

METHODS

Skin tissues excised from the facial cheek area were used. Then, SEM images of these tissues were obtained. The thickness and quantity of the fibers around adipocytes were assessed using a 5-point scale. The score was used to grade 18 tissue samples. Moreover, the viscoelasticity of the subcutaneous fat layer in the same samples was evaluated via ultrasound elastography.

RESULTS

Based on the SEM image score, an association was observed between the fiber status score and age, thereby indicating a tendency toward age-related fibrosis. Fiber structures with high scores, which indicate fibrosis, had a significantly lower viscoelasticity based on ultrasound elastography.

CONCLUSION

The thickness and quantity of fibrous structures around adipocytes in the subcutaneous fat layer increase with age, and these changes can be associated with decreased viscoelasticity in the subcutaneous fat layer.

Transcriptome-wide analysis reveals GYG2 as a mitochondria-related aging biomarker in human subcutaneous adipose tissue

Subcutaneous adipose tissue (SAT), a vital energy reservoir and endocrine organ for maintaining systemic glucose, lipid, and energy homeostasis, undergoes significant changes with age. However, among the existing aging-related markers, only few genes are associated with SAT aging. In this study, weighted gene co-expression network analysis was used on a transcriptome of SAT obtained from the Genotype-Tissue Expression portal to identify biologically relevant, SAT-specific, and age-related marker genes. We found modules that exhibited significant changes with age and identified GYG2 as a novel key aging associated gene. The link between GYG2 and mitochondrial function as well as brown/beige adipocytes was supported using additional bioinformatics and experimental analyses. Additionally, we identified PPARG as the transcription factor of GYG2 expression. The newly discovered GYG2 marker can be used to not only determine the age of SAT but also uncover new mechanisms underlying SAT aging.

Sphingosine 1-Phosphate Regulates Obesity and Glucose Homeostasis

One of the major global health and welfare issues is the treatment of obesity and associated metabolic disorders, such as type 2 diabetes mellitus and nonalcoholic fatty liver disease. Obesity, caused by the excessive accumulation of triglycerides in adipose tissues, induces adipocyte dysfunction, followed by inflammation, in adipose tissues and lipotoxicity in nonadipose tissues. Several studies have shown that obesity and glucose homeostasis are influenced by sphingolipid mediators, including ceramide and sphingosine 1-phosphate (S1P). Cellular accumulation of ceramide impairs pancreatic β-cell survival, confers insulin resistance in the liver and the skeletal muscle, and deteriorates adipose tissue inflammation via unknown molecular mechanisms. The roles of S1P are more complicated, because there are five cell-surface S1P receptors (S1PRs: S1P1-5) which have altered functions, different cellular expression patterns, and inapparent intracellular targets. Recent findings, including those by our group, support the notable concept that the pharmacological activation of S1P1 or S1P3 improves obesity and associated metabolic disorders, whereas that of S1P2 has the opposite effect. In addition, the regulation of S1P production by sphingosine kinase (SphK) is an essential factor affecting glucose homeostasis. This review summarizes the current knowledge on SphK/S1P/S1PR signaling in and against obesity, insulin resistance, and associated disorders.

Diethyl phthalate, a plasticizer, induces adipocyte inflammation and apoptosis in mice after long-term dietary administration

The incidence of metabolic diseases is increasing alarmingly in recent times. Parallel to nutritional excess and sedentary lifestyle, the random usage of several endocrine disrupting chemicals including plasticizers is reported to be closely associated with metabolic diseases. Diethyl phthalate (DEP) is a widely used plasticizer in a host of consumer and daily care products. Adipose tissue plays a central role in energy storage and whole-body metabolism. The impairment of adipose function is critically implicated in the pathogenesis of insulin resistance, diabetes, and related metabolic diseases. Recently, exposure to certain phthalate esters has been linked to the development of obesity and diabetes, although there are contradictions and the mechanisms are not clearly understood. In an effort to ascertain the metabolic consequences of chronic phthalate exposure and the underlying mechanism, the present study was designed to examine the effects of long-term dietary consumption of DEP in adipocytes. DEP-treated mice were hyperglycemic but nonobese; their body weight initially increased which subsequently was reduced compared to control. DEP exposure at lower levels impaired adipogenesis by downregulating the key transcription factor, peroxisome proliferator-activated receptor γ and its downstream insulin-sensitizing adipokine, adiponectin, thereby severely compromising adipocyte function. The activation of master regulator nuclear factor κB led to rise in proinflammatory cytokines. We found that DEP triggered intrinsic apoptotic pathways through activated cytochrome c-Apaf1-caspase 9-caspase 3 axis in adipocytes. Taken together, our data revealed that chronic administration of dietary DEP could unleash adverse metabolic outcomes by initiating oxidative stress, inflammation, and apoptosis in the adipocytes, thus leading to adipose tissue dysfunction.

Metabolome analysis reveals that cyclic adenosine diphosphate ribose contributes to the regulation of differentiation in mice adipocyte

Adipocytes play a key role in energy storage and homeostasis. Although the role of transcription factors in adipocyte differentiation is known, the effect of endogenous metabolites of low molecular weight remains unclear. Here, we analyzed time-dependent changes in the levels of these metabolites throughout adipocyte differentiation, using metabolome analysis, and demonstrated that there is a positive correlation between cyclic adenosine diphosphate ribose (cADPR) and Pparγ mRNA expression used as a marker of differentiation. We also found that the treatment of C3H10T1/2 adipocytes with cADPR increased the mRNA expression of those marker genes and the accumulation of triglycerides. Furthermore, inhibition of ryanodine receptors (RyR), which are activated by cADPR, caused a significant reduction in mRNA expression levels of the marker genes and triglyceride accumulation in adipocytes. Our findings show that cADPR accelerates adipocytic differentiation via RyR pathway.

ITIH5 inhibits proliferation, adipogenic differentiation, and secretion of inflammatory cytokines of human adipose stem cells-A new key in treating obesity?

Inter-α-trypsin inhibitor heavy chain 5 (ITIH5) is widely expressed in the human body, and it is detected to be particularly abundant in adipose tissue. ITIH5 expression is increased in people with obesity compared to lean persons and is decreased by diet-induced weight loss. This suggests that ITIH5 may be involved in the development of adiposity and clinical metabolic variables, although its exact function remains unknown. We measured the protein concentration of ITIH5 in adipose samples from patients undergoing abdominoplasty and tested for correlation with the subjects' BMI as well as inflammatory mediators. We stimulated human adipose stem cells (ASCs) with recombinant (r)ITIH5 protein and tested for an effect on proliferation, differentiation, and immunosuppressive properties when the cells were exposed to an artificial inflammatory environment. We found positive correlations between ITIH5 levels and the BMI (p < .001) as well as concentrations of inflammatory cytokines (TNF-α, IL-6, and MCP-1) in adipose tissue (p < .01). Application of the rITIH5 protein inhibited both proliferation (p < .001) and differentiation of ASCs. Especially, the development of mature adipocytes was reduced by over 50%. Moreover, rITIH5 decreased the release of IL-6 and MCP-1 when the cells were exposed to TNF-α and IL-1β (p < .001). Our data suggest that ITIH5 is an adipokine that is increasingly released during human adipose tissue development, acting as a regulator that inhibits proliferation and adipogenic differentiation of ASCs. ITIH5 thus presents itself as a positive regulator of adipose tissue homeostasis, possibly protecting against both hyperplasia and hypertrophy of adipose tissue and the associated chronic inflammation.

GPER/PKA-Dependent Enhancement of Hormone-Sensitive Lipase Phosphorylation in 3T3-L1 Adipocytes by Piceatannol

We previously reported that piceatannol (PIC) had an anti-obesity effect only in ovariectomized (OVX) postmenopausal obesity mice. PIC was found to induce the phosphorylation of hormone-sensitive lipase (pHSL) in OVX mice. To elucidate the mechanism by which PIC activates HSL, we investigated the effect of PIC using 3T3-L1 adipocytes. PIC induced HSL phosphorylation at Ser563 in 3T3-L1 cells, as in vivo experiments showed. pHSL (Ser563) is believed to be activated through the β-adrenergic receptor (β-AR) and protein kinase A (PKA) pathways; however, the addition of a selective inhibitor of β-AR did not inhibit the effect of PIC. The addition of a PKA inhibitor with PIC blocked pHSL (Ser563), suggesting that the effects are mediated by PKA in a different pathway than β-AR. The addition of G15, a selective inhibitor of the G protein-coupled estrogen receptor (GPER), reduced the activation of HSL by PIC. Furthermore, PIC inhibited insulin signaling and did not induce pHSL (Ser565), which represents its inactive form. These results suggest that PIC acts as a phytoestrogen and phosphorylates HSL through a novel pathway that activates GPER and its downstream PKA, which may be one of the inhibitory actions of PIC on fat accumulation in estrogen deficiency.

Context-dependent regulation of lipid accumulation in adipocytes by a HIF1α-PPARγ feedback network

Hypoxia-induced upregulation of HIF1α triggers adipose tissue dysfunction and insulin resistance in obese patients. HIF1α closely interacts with PPARγ, the master regulator of adipocyte differentiation and lipid accumulation, but there are conflicting results regarding how this interaction controls the excessive lipid accumulation that drives adipocyte dysfunction. To directly address these conflicts, we established a differentiation system that recapitulated prior seemingly opposing observations made across different experimental settings. Using single-cell imaging and coarse-grained mathematical modeling, we show how HIF1α can both promote and repress lipid accumulation during adipogenesis. Our model predicted and our experiments confirmed that the opposing roles of HIF1α are isolated from each other by the positive-feedback-mediated upregulation of PPARγ that drives adipocyte differentiation. Finally, we identify three factors: strength of the differentiation cue, timing of hypoxic perturbation, and strength of HIF1α expression changes that, when considered together, provide an explanation for many of the previous conflicting reports.

MMP11 and MMP14 contribute to the interaction between castration-resistant prostate cancer and adipocytes

Previous studies have demonstrated that adipocytes promote prostate cancer (PCa) cell progression, which facilitates the development of PCa into castration-resistant prostate cancer (CRPC); however, the underlying mechanisms are still not fully understood. Matrix metalloproteinases (MMPs) are a group of proteases responsible for the degradation of extracellular matrix (ECM) and the activation of latent factors. In our study, we detected that MMP11 expression was increased in PCa patients and that a high level of MMP11 was correlated with poor prognosis. Furthermore, siRNA knockdown of MMP11 in CRPC cells not only blocked the delipidation and dedifferentiation of mature adipocytes but also reduced the lipid uptake and utilization of CRPC cells in a cell co-culture model. The number of mitophagosomes and the expression level of Parkin were increased in MMP11-silenced CRPC cells. Moreover, we found that simultaneous downregulation of MMP14 and MMP11 expression may benefit patient survival. Indeed, MMP11/14 knockdown in CRPC cells significantly decreased lipid metabolism and cell invasion, at least partly through the mTOR/HIF1α/MMP2 signaling pathway. Importantly, MMP11/14 knockdown dramatically delayed tumor growth in a xenograft mouse model. Consistently, the decreased lipid metabolism, Ki67 and MMP2 expression, as well as the increased Parkin level were also confirmed in in vivo experiments, further demonstrating the mechanisms responsible for the tumor-promoting effects of MMP11/14. Collectively, our study elucidated the role of MMP11 and MMP14 in the bidirectional crosstalk between adipocytes and CRPC cells and provided the rationale of targeting MMP11/14 for the treatment of CRPC patients.

From a toxin to an obesogen: a review of potential obesogenic roles of acrylamide with a mechanistic approach

Obesity and obesity-related disorders such as cancer, type 2 diabetes, and fatty liver have become a global health problem. It is well known that the primary cause of obesity is positive energy balance. In addition, obesity is the consequence of complex gene and environment interactions that result in excess calorie intake being stored as fat. However, it has been revealed that there are other factors contributing to the worsening of obesity. The presence of nontraditional risk factors, such as environmental endocrine-disrupting chemicals, has recently been associated with obesity and comorbidities caused by obesity. The aim of this review was to examine the evidence and potential mechanisms for acrylamide having endocrine-disrupting properties contributing to obesity and obesity-related comorbidities. Recent studies have suggested that exposure to environmental endocrine-disrupting obesogens may be a risk factor contributing to the current obesity epidemic, and that one of these obesogens is acrylamide, an environmental and industrial compound produced by food processing, particularly the processing of foods such as potato chips, and coffee. In addition to the known harmful effects of acrylamide in humans and experimental animals, such as neurotoxicity, genotoxicity, and carcinogenicity, acrylamide also has an obesogenic effect. It has been shown in the literature to a limited extent that acrylamide may disrupt energy metabolism, lipid metabolism, adipogenesis, adipocyte differentiation, and various signaling pathways, and may exacerbate the disturbances in metabolic and biochemical parameters observed as a result of obesity. Acrylamide exerts its main potential obesogenic effects through body weight increase, worsening of the levels of obesity-related blood biomarkers, and induction of adipocyte differentiation and adipogenesis. Additional mechanisms may be discovered. Further experimental studies and prospective cohorts are needed, both to supplement existing knowledge about acrylamide and its effects, and to clarify its established relationship with obesity and its comorbidities.

Rab18 Drift in Lipid Droplet and Endoplasmic Reticulum Interactions of Adipocytes under Obesogenic Conditions

The adipose tissue stores excess energy in the form of neutral lipids within adipocyte lipid droplets (LDs). The correct function of LDs requires the interaction with other organelles, such as the endoplasmic reticulum (ER) as well as with LD coat-associated proteins, including Rab18, a mediator of intracellular lipid trafficking and ER-LD interaction. Although perturbations of the inter-organelle contact sites have been linked to several diseases, such as cancer, no information regarding ER-LD contact sites in dysfunctional adipocytes from the obese adipose tissue has been published to date. Herein, the ER-LD connection and Rab18 distribution at ER-LD contact sites are examined in adipocytes challenged with fibrosis and inflammatory conditions, which represent known hallmarks of the adipose tissue in obesity. Our results show that adipocytes differentiated in fibrotic conditions caused ER fragmentation, the expansion of ER-LD contact sites, and modified Rab18 dynamics. Likewise, adipocytes exposed to inflammatory conditions favored ER-LD contact, Rab18 accumulation in the ER, and Rab18 redistribution to large LDs. Finally, our studies in human adipocytes supported the suggestion that Rab18 transitions to the LD coat from the ER. Taken together, our results suggest that obesity-related pathogenic processes alter the maintenance of ER-LD interactions and interfere with Rab18 trafficking through these contact sites.

Foxk1 stimulates adipogenic differentiation via a peroxisome proliferator-activated receptor gamma 2-dependent mechanism

Adipogenesis is a tightly regulated process, and its dysfunction has been linked to metabolic disorders such as obesity. Forkhead box k1 (Foxk1) is known to play a role in the differentiation of myogenic precursor cells and tumorigenesis of different types of cancers; however, it is not clear whether and how it influences adipocyte differentiation. Here, we found that Foxk1 was induced in mouse primary bone marrow stromal cells (BMSCs) and established mesenchymal progenitor/stromal cell lines C3H/10T1/2 and ST2 after adipogenic treatment. In addition, obese db/db mice have higher Foxk1 expression in inguinal white adipose tissue than nonobese db/m mice. Foxk1 overexpression promoted adipogenic differentiation of C3H/10T1/2, ST2 cells and BMSCs, along with the enhanced expression of CCAAT/enhancer binding protein-α, peroxisome proliferator-activated receptor γ (Pparγ), and fatty acid binding protein 4. Moreover, Foxk1 overexpression enhanced the expression levels of lipogenic factors during adipogenic differentiation in both C3H/10T1/2 cells and BMSCs. Conversely, Foxk1 silencing impaired these cells from fully differentiating. Furthermore, adipogenic stimulation induced the nuclear translocation of Foxk1, which depended on the mTOR and PI3-kinase signaling pathways. Subsequently, Foxk1 is directly bound to the Pparγ2 promoter, stimulating its transcriptional activity and promoting adipocyte differentiation. Collectively, our study provides the first evidence that Foxk1 promotes adipocyte differentiation from progenitor cells by promoting nuclear translocation and upregulating the transcriptional activity of the Pparγ2 promoter during adipogenic differentiation.

LRRK2 negatively regulates glucose tolerance via regulation of membrane translocation of GLUT4 in adipocytes

Epidemiological studies have shown that abnormalities of glucose metabolism are involved in leucine-rich repeat kinase 2 (LRRK2)-associated Parkinson's disease (PD). However, the physiological significance of this association is unclear. In the present study, we investigated the effect of LRRK2 on high-fat diet (HFD)-induced glucose intolerance using Lrrk2-knockout (KO) mice. We found for the first time that HFD-fed KO mice display improved glucose tolerance compared with their wild-type (WT) counterparts. In addition, high serum insulin and leptin, as well as low serum adiponectin resulting from HFD in WT mice were improved in KO mice. Using western blotting, we found that Lrrk2 is highly expressed in adipose tissues compared with other insulin-related tissues that are thought to be important in glucose tolerance, including skeletal muscle, liver, and pancreas. Lrrk2 expression and phosphorylation of its kinase substrates Rab8a and Rab10 were significantly elevated after HFD treatment in WT mice. In cell culture experiments, treatment with a LRRK2 kinase inhibitor stimulated insulin-dependent membrane translocation of glucose transporter 4 (Glut4) and glucose uptake in mouse 3T3-L1 adipocytes. We conclude that increased LRRK2 kinase activity in adipose tissue exacerbates glucose tolerance by suppressing Rab8- and Rab10-mediated GLUT4 membrane translocation.

Adipocyte traits limiting cellular insulin responsiveness and glucose transport

Adipocyte dysfunction is a hallmark of systemic insulin resistance. Insulin-responsive glucose transporter 4 (GLUT4) is downregulated in the insulin resistant state, and cellular insulin responsiveness varies depending on fat depot origin and degree of adipose expansion. Here, we have resolved factors limiting cellular insulin responsiveness, by examining adipocyte function and traits related to glucose transport at the cellular level. Subcutaneous (inguinal) and visceral (epididymal) adipocytes were isolated from C57BL/6J mice fed either chow or high-fat diet. Cell size was determined using coulter counter method, glucose uptake and cytosolic volume were assessed using glucose tracer assays. Total and GLUT4 protein content expressions were determined by Western blot. We found that basal glucose uptake per cell was preserved independent of diet or fat depot origin. Insulin-stimulated glucose uptake per cell was sustained in visceral adipocytes but decreased with adipose expansion in subcutaneous adipocytes. In parallel, the cytosolic space and total protein increased proportionally to total cellular volumetric expansion in visceral, but not in subcutaneous, adipocytes, whereas GLUT4 content decreased exclusively in expanding subcutaneous adipocytes. Together, these data support the existence of distinct phenotypic adipocyte traits that could limit cellular insulin responsiveness. Potentially, these characteristics account for fat depot-specific differences related to glucose transport capacity.NEW & NOTEWORTHY This work illustrates that adipocyte characteristics related to fat depot origin rather than adipocyte size per se limit cellular insulin responsiveness and glucose uptake in male C57BL/6J mice. These findings contribute to the overall understanding of factors limiting adipocyte function and how adipose progression affects insulin response and glucose transport capacity differently in diverse fat depots. Future studies examining whether the proposed characteristics hold true in adipocytes derived from female mice or human origin are needed.

Traumatic acid inhibits ACSL4 associated lipid accumulation in adipocytes to attenuate high-fat diet-induced obesity

Obesity is a major health concern that lacks effective intervention strategies. Traumatic acid (TA) is a potent wound-healing agent in plants, considered an antioxidant food ingredient. This study demonstrated that TA treatment significantly reduced lipid accumulation in human adipocytes and prevented high-fat diet induced obesity in zebrafish. Transcriptome sequencing revealed TA-activated fatty acid (FA) degradation and FA metabolism signaling pathways. Moreover, western blotting and quantitative polymerase chain reaction showed that TA inhibited the expression of long-chain acyl-CoA synthetase-4 (ACSL4). Overexpression of ACSL4 resulted in the reversal of TA beneficiary effects, indicating that the attenuated lipid accumulation of TA was regulated by ACSL4 expression. Limited proteolysis-mass spectrometry and microscale thermophoresis were then used to confirm hexokinase 2 (HK2) as a direct molecular target of TA. Thus, we demonstrated the molecular basis of TA in regulating lipid accumulation and gave the first evidence that TA may function through the HK2-ACSL4 axis.

10‑Gingerol, a novel ginger compound, exhibits antiadipogenic effects without compromising cell viability in 3T3‑L1 cells

Obesity is defined as excessive fat accumulation that can be detrimental to health and currently affects a large part of the global population. Obesity arises from excessive energy intake along with a sedentary lifestyle and leads to adipocytes with aggravated hypertrophy. Strategies have been designed to prevent and treat obesity. Nutrigenomics may serve a role in prevention of obesity using bioactive compounds present in certain foods with anti-obesogenic effects. Ginger (Zingiber officinale Roscoe) contains gingerols, key bioactive compounds that inhibit hypertrophy and hyperplasia of adipocytes. The present study aimed to evaluate the antiadipogenic activity of 10-gingerol (10-G) in the 3T3-L1 cell line. Three study groups were formed: Negative (3T3-L1 preadipocytes) and positive control (mature 3T3-L1 adipocytes) and 10-G (3T3-L1 preadipocytes stimulated with 10-G during adipogenic differentiation). Cell viability and lipid content were evaluated by MTT assay and Oil Red O staining, respectively. mRNA expression of CCAAT enhancer-binding protein α (C/ebpα), peroxisome proliferator-activated receptor γ (Pparγ), mechanistic target of rapamycin complex (Mtor), sterol regulatory element binding transcription factor 1 (Srebf1), acetyl-coenzyme A carboxylase (Acaca), fatty acid binding protein 4 (Fabp4), and 18S rRNA (Rn18s), was quantified by quantitative PCR. The protein expression of C/EPBα was analyzed by western blot. In the 10-G group, lipid content was decreased by 28.83% (P<0.0001) compared with the positive control; notably, cell viability was not affected (P=0.336). The mRNA expression in the 10-G group was higher for C/ebpα (P<0.001) and lower for Acaca (P<0.001), Fabp4 (P<0.001), Mtor (P<0.0001) and Srebf1 (P<0.0001) compared with the positive control group, while gene expression of Pparγ did not present significant changes. The presence of 10-G notably decreased C/EBPα protein levels in 3T3-L1 adipocytes. In summary, the antiadipogenic effect of 10-G during the differentiation of 3T3-L1 cells into adipocytes may be explained by mRNA downregulation of adipogenic transcriptional factors and lipid metabolism-associated genes.

An optimised protocol for the investigation of insulin signalling in a human cell culture model of adipogenesis

While there is no standardized protocol for the differentiation of human adipocytes in culture, common themes exist in the use of supra-physiological glucose and hormone concentrations, and an absence of exogenous fatty acids. These factors can have detrimental effects on some aspects of adipogenesis and adipocyte function. Here, we present methods for modifying the adipogenic differentiation protocol to overcome impaired glucose uptake and insulin signalling in human adipose-derived stem cell lines derived from the stromal vascular fraction of abdominal and gluteal subcutaneous adipose tissue. By reducing the length of exposure to adipogenic hormones, in combination with a physiological glucose concentration (5 mM), and the provision of exogenous fatty acids (reflecting typical dietary fatty acids), we were able to restore early insulin signalling events and glucose uptake, which were impaired by extended use of hormones and a high glucose concentration, respectively. Furthermore, the addition of exogenous fatty acids greatly increased the storage of triglycerides and removed the artificial demand to synthesize all fatty acids by de novo lipogenesis. Thus, modifying the adipogenic cocktail can enhance functional aspects of human adipocytes in vitro and is an important variable to consider prior to in vitro investigations into adipocyte biology.

Understanding the Role of Adipocytes and Fibroblasts in Cancer

ABSTRACT

Cancer is currently the second leading cause of death in the United States. There is increasing evidence that the tumor microenvironment (TME) is pivotal for tumorigenesis and metastasis. Recently, adipocytes and cancer-associated fibroblasts (CAFs) in the TME have been shown to play a major role in tumorigenesis of different cancers, specifically melanoma. Animal studies have shown that CAFs and adipocytes within the TME help tumors evade the immune system, for example, by releasing chemokines to blunt the effectiveness of the host defense. Although studies have identified that adipocytes and CAFs play a role in tumorigenesis, adipocyte transition to fibroblast within the TME is fairly unknown. This review intends to elucidate the potential that adipocytes may have to transition to fibroblasts and, as part of the TME, a critical role that CAFs may play in affecting the growth and invasion of tumor cells. Future studies that illuminate the function of adipocytes and CAFs in the TME may pave way for new antitumor therapies.

Effect of SARS-CoV-2 spike protein exposure on ACE2 and interleukin 6 productions in human adipocytes: An in-vitro study

Since adipocytes play a crucial role in pathogenesis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection due to their interaction with angiotensin-converting enzyme 2 (ACE2) and interleukin 6 (IL-6), obesity is associated with an increased risk of coronavirus disease 2019 (COVID-19) mortality. Discovery of ACE2 as a SARS-CoV-2 receptor raises a controversy about whether to use ACE inhibitors (ACEIs) could be an optional therapy to prevent cytokine storms. Studies assessing the expressions of ACE2 and IL-6 upon exposure to SARS-CoV-2 is therefore important as a basis for therapeutical trials in the future. The aim of this study was to determine the effect of SARS-CoV-2 spike protein exposure on the production of ACE2 and IL-6 in adipocyte cells. Adipocytes were collected from abdominal adipose tissues of healthy and obese 45-year-old male donor having neither a history of SARS-CoV-2 infection nor COVID-19 vaccination. After being stained using the oil red O protocol, the viable adipocytes were then exposed to S1 subunit of SARS-CoV-2 spike protein. The levels of ACE2 and IL-6 were then examined using the enzyme-linked immunosorbent assay (ELISA). The results showed significant increase of ACE2 (90.22 µg/mL) and IL-6 level (60.01 µg/mL) in human adipocytes upon exposure compared to unexposed control cells (ACE2 13.33 µg/mL; IL-6 21.33 µg/mL), both comparisons had p<0.001). This study provides insight into the basic mechanism of severe COVID-19 symptoms in obese patients and provides a basic information of the potential of ACE inhibitors as an optional therapy for COVID-19 patients with obesity.

Adipose tissue fibrosis: the unwanted houseguest invited by obesity

The prevalence of obesity is increasing exponentially across the globe. The lack of effective treatment options for long-term weight loss has magnified the enormity of this problem. Studies continue to demonstrate that adipose tissue holds a biological memory, one of the most important determinant of long-term weight maintenance. This phenomenon is consistent with the metabolically dynamic role of adipose tissue: it adapts and expands to store for excess energy and serves as an endocrine organ capable of synthesizing a number of biologically active molecules that regulate metabolic homeostasis. An important component of the plasticity of adipose tissue is the extracellular matrix, essential for structural support, mechanical stability, cell signaling and function. Chronic obesity upends a delicate balance of extracellular matrix synthesis and degradation, and the ECM accumulates in such a way that prevents the plasticity and function of the diverse cell types in adipose tissue. A series of maladaptive responses among the cells in adipose tissue leads to inflammation and fibrosis, major mechanisms that explain the link between obesity and insulin resistance, risk of type 2 diabetes, cardiovascular disease, and nonalcoholic fatty liver disease. Adipose tissue fibrosis persists after weight loss and further enhances adipose tissue dysfunction if weight is regained. Here, we highlight the current knowledge of the cellular events governing adipose tissue ECM remodeling during the development of obesity. Our goal is to delineate the relationship more clearly between adipose tissue ECM and metabolic disease, an important step toward better defining the pathophysiology of dysfunctional adipose tissue.

Adipocyte Microenvironment in Ovarian Cancer: A Critical Contributor?

Ovarian cancer is one of the most common gynecological malignancies and has low survival rates. One of the main determinants of this unfavorable prognosis is the high rate of peritoneal metastasis at diagnosis, closely related to its morbidity and mortality. The mechanism underlying peritoneal carcinomatosis is not clearly defined, but a clear preference for omental spread has been described. Growing evidence suggests that adipose tissue plays a role in promoting cancer onset and progression. Moreover, obesity can lead to changes in the original functions of adipocytes, resulting in metabolic and inflammatory changes in the adipose tissue microenvironment, potentially increasing the risk of tumor growth. However, the specific roles of adipocytes in ovarian cancer have not yet been fully elucidated. Due to the undeniable link between obesity and cancer, the adipose tissue microenvironment could also present a promising therapeutic target that warrants further research. This review discusses the complex relationship between ovarian cancer and the adipose tissue microenvironment.

A Review of the Role of an Anthocyanin, Cyanidin-3-O-β-glucoside in Obesity-Related Complications

Obesity has become a major health issue worldwide and obese individuals possess higher levels of adipose tissue when compared with healthy individuals. Obesity is highly associated with the development of different chronic diseases, such as diabetes, cardiovascular diseases, hypertension, cancers, etc. Previous studies established that anthocyanin compounds play an important role in attenuating obesity-related consequences. Among various anthocyanin compounds, cyanidin-3-O-β-glucoside (C3G) is the most important component and is widely distributed in various colored edible plant materials, especially berries, cherries, black rice, purple corn, etc. In recent decades, several studies have reported the therapeutical properties of C3G. C3G has various biological properties and health benefits, such as antioxidant, antimicrobial, anti-inflammatory, antidiabetic, anti-obesity, neuroprotective, anticancer, etc. In this review, we summarized the in vitro and in vivo studies in relation to the role of C3G in obesity-related complications. Several mechanistic studies demonstrated that C3G maintains the metabolism of glucose, fatty acids, and lipids by regulating different genes and signaling pathways. It could be concluded that the consumption of C3G protects healthy individuals from obesity-related issues by maintaining body weight and regulating their metabolism and energy balance. This review provides some important signaling pathways/targets of C3G to facilitate the prevention and treatment of obesity, leading to the development of important food supplements.

STAT3 Signalling Drives LDH Up-Regulation and Adiponectin Down-Regulation in Cachectic Adipocytes

Cachexia is a devastating pathology that worsens the quality of life and antineoplastic treatment outcomes of oncologic patients. Herein, we report that the secretome from murine colon carcinoma CT26 induces cachectic features in both murine and human adipocytes that are associated with metabolic alterations such as enhanced lactate production and decreased oxygen consumption. The use of oxamate, which inhibits lactate dehydrogenase activity, hinders the effects induced by CT26 secretome. Interestingly, the CT26 secretome elicits an increased level of lactate dehydrogenase and decreased expression of adiponectin. These modifications are driven by the STAT3 signalling cascade since the inhibition of STAT3 with WP1066 impedes the formation of the cachectic condition and the alteration of lactate dehydrogenase and adiponectin levels. Collectively, these findings show that STAT3 is responsible for the altered lactate dehydrogenase and adiponectin levels that, in turn, could participate in the worsening of this pathology and highlight a step forward in the comprehension of the mechanisms underlying the onset of the cachectic condition in adipocytes.

Primary Orbital Myxoid Liposarcoma

Although liposarcoma is the most prevalent soft tissue sarcoma in adults, head and neck liposarcomas are rare and account for less than 5% of all liposarcomas. The primary orbital location is even more exceptional, with fewer than 100 cases documented in the medical literature. Given the scarcity of cases of orbital liposarcoma and the limited familiarity of physicians and pathologists with this pathology, there is an increased risk of non-diagnosis or misdiagnosis, which may lead to inappropriate patient management. To address these challenges, we present a case of primary orbital myxoid liposarcoma and subsequently discuss the primary findings of this case based on the evidence documented in the medical literature. This comprehensive text is designed to serve as a valuable resource for healthcare professionals and pathologists, with the goal of promoting both clinical suspicion and accurate diagnosis and treatment of this rare condition in future cases.

LRP1 is the cell-surface endocytosis receptor for vaspin in adipocytes

Vaspin is a serine protease inhibitor that protects against adipose tissue inflammation and insulin resistance, two key drivers of adipocyte dysfunction and metabolic disorders in obesity. Inhibition of target proteases such as KLK7 has been shown to reduce adipose tissue inflammation in obesity, while vaspin binding to cell surface GRP78 has been linked to reduced obesity-induced ER stress and insulin resistance in the liver. However, the molecular mechanisms by which vaspin directly affects cellular processes in adipocytes remain unknown. Using fluorescently labeled vaspin, we found that vaspin is rapidly internalized by mouse and human adipocytes, but less efficiently by endothelial, kidney, liver, and neuronal cells. Internalization occurs by active, clathrin-mediated endocytosis, which is dependent on vaspin binding to the LRP1 receptor, rather than GRP78 as previously thought. This was demonstrated by competition experiments and RNAi-mediated knock-down in adipocytes and by rescuing vaspin internalization in LRP1-deficient Pea13 cells after transfection with a functional LRP1 minireceptor. Vaspin internalization is further increased in mature adipocytes after insulin-stimulated translocation of LRP1. Although vaspin has nanomolar affinity for LRP1 clusters II-IV, binding to cell surface heparan sulfates is required for efficient LRP1-mediated internalization. Native, but not cleaved vaspin, and also vaspin polymers are efficiently endocytosed, and ultimately targeted for lysosomal degradation. Our study provides mechanistic insight into the uptake and degradation of vaspin in adipocytes, thereby broadening our understanding of its functional repertoire. We hypothesize the vaspin-LRP1 axis to be an important mediator of vaspin effects not only in adipose tissue but also in other LRP1-expressing cells.

lncRNA Hnscr Regulates Lipid Metabolism by Mediating Adipocyte Lipolysis

Obesity is a process of fat accumulation due to the imbalance between energy intake and consumption. Long noncoding RNA (lncRNA) Hnscr is crucial for metabolic regulation, but its roles in lipid metabolism during obesity are still unknown. In this article, we found that the expression of Hnscr gradually decreased in adipose tissues of diet-induced obese mice. Furthermore, the deletion of Hnscr promoted an increase in body weight and adipose tissue weight by upregulating the expression of lipogenesis genes and downregulating lipolysis genes in inguinal white adipose tissue (iWAT) and brown adipose tissue. In vitro knockdown of Hnscr in adipocytes resulted in reduced lipolysis of adipocytes. Overexpression of Hnscr by adenovirus or drug mimics showed the opposite. Mechanistically, Hnscr regulated adipose lipid metabolism by mediating the cyclic adenosine monophosphate/protein kinase A signaling pathway. This study identifies the initial characterization of Hnscr as a critical modifier that regulates lipid metabolism, suggesting that lncRNA Hnscr is a potential target for treating obesity.

Metabolic control by AMPK in white adipose tissue

White adipose tissue (WAT) plays an important role in the integration of whole-body metabolism by storing fat and mobilizing triacylglycerol when needed. The released free fatty acids can then be oxidized by other tissues to provide ATP. AMP-activated protein kinase (AMPK) is a key regulator of metabolic pathways, and can be targeted by a new generation of direct, small-molecule activators. AMPK activation in WAT inhibits insulin-stimulated lipogenesis and in some situations also inhibits insulin-stimulated glucose uptake, but AMPK-induced inhibition of β-adrenergic agonist-stimulated lipolysis might need to be re-evaluated in vivo. The lack of dramatic effects of AMPK activation on basal metabolism in WAT could be advantageous when treating type 2 diabetes with pharmacological pan-AMPK activators.

Vitamin D Modulates Lipid Composition of Adipocyte-Derived Extracellular Vesicles Under Inflammatory Conditions

SCOPE

Adipocyte-derived extracellular vesicles (AdEVs) convey lipids that can play a role in the energy homeostasis. Vitamin D (VD) has been shown to limit the metabolic inflammation as it decreases inflammatory markers expression in adipose tissue (AT). However, VD effect on adipocytes-derived EVs has never been investigated.

METHODS AND RESULTS

Thus, the aim of this study is to evaluate the AdEVs lipid composition by LC-MS/MS approach in 3T3-L1 cells treated with VD or/and pro-inflammatory factor (tumor necrosis factor α [TNFα]). Among all lipid species, four are highlighted (glycerolipids, phospholipids, lysophospholipids, and sphingolipids) with a differential content between small (sEVs) and large EVs (lEVs). This study also observes that VD alone modulates EV lipid species involved in membrane fluidity and in the budding of membrane. EVs treated with VD under inflammatory conditions have different lipid profiles than the control group, which is more pronounced in lEVs. Indeed, 25 lipid species are significantly modulated in lEVs, compared with only seven lipid species in sEVs.

CONCLUSIONS

This study concludes that VD, alone or under inflammatory conditions, is associated with specific lipidomic signature of sEVs and lEVs. These observations reinforce current knowledge on the anti-inflammatory effect of VD.

Adipocyte regulation of cancer stem cells

Cancer stem cells (CSCs) are a highly tumorigenic subpopulation of the cancer cells within a tumor that drive tumor initiation, progression, and therapy resistance. In general, stem cell niche provides a specific microenvironment in which stem cells are present in an undifferentiated and self-renewable state. CSC niche is a specialized tumor microenvironment for CSCs which provides cues for their maintenance and propagation. However, molecular mechanisms for the CSC-niche interaction remain to be elucidated. We have revealed that adipsin (complement factor D) and its downstream effector hepatocyte growth factor are secreted from adipocytes and enhance the CSC properties in breast cancers in which tumor initiation and progression are constantly associated with the surrounding adipose tissue. Considering that obesity, characterized by excess adipose tissue, is associated with an increased risk of multiple cancers, it is reasonably speculated that adipocyte-CSC interaction is similarly involved in many types of cancers, such as pancreas, colorectal, and ovarian cancers. In this review, various molecular mechanisms by which adipocytes regulate CSCs, including secretion of adipokines, extracellular matrix production, biosynthesis of estrogen, metabolism, and exosome, are discussed. Uncovering the roles of adipocytes in the CSC niche will propose novel strategies to treat cancers, especially those whose progression is linked to obesity.

The intracellular helical bundle of human glucose transporter GLUT4 is important for complex formation with ASPL

Glucose transporters (GLUTs) are responsible for transporting hexose molecules across cellular membranes. In adipocytes, insulin stimulates glucose uptake by redistributing GLUT4 to the plasma membrane. In unstimulated adipose-like mouse cell lines, GLUT4 is known to be retained intracellularly by binding to TUG protein, while upon insulin stimulation, GLUT4 dissociates from TUG. Here, we report that the TUG homolog in human, ASPL, exerts similar properties, i.e., forms a complex with GLUT4. We describe the structural details of complex formation by combining biochemical assays with cross-linking mass spectrometry and computational modeling. Combined, the data suggest that the intracellular domain of GLUT4 binds to the helical lariat of ASPL and contributes to the regulation of GLUT4 trafficking by cooperative binding.

The emerging role of bile acids in white adipose tissue

The effects of bile acids (BAs) on liver, enteroendocrine function, small intestine, and brown adipose tissue have been described extensively. Outside the liver, BAs in the peripheral circulation system represent a specific but underappreciated physiological compartment. We discuss how systemic BAs can be regarded as specific steroidal hormones that act on white adipocytes, and suggest the name 'bilokines' ('bile hormones') for the specific FXR/TGR5 receptor interaction in adipocytes. Some BAs and their agonists regulate adipocyte differentiation, lipid accumulation, hypoxia, autophagy, adipokine and cytokine secretion, insulin signaling, and glucose uptake. BA signaling could provide a new therapeutic avenue for adipoflammation and metaflammation in visceral obesity, the causal mechanisms underlying insulin resistance and type 2 diabetes mellitus (T2D).

Regulation of Cathelicidin Antimicrobial Peptide (CAMP) Gene Expression by TNFα and cfDNA in Adipocytes

Understanding the complex interactions between metabolism and the immune system ("metaflammation") is crucial for the identification of key immunomodulatory factors as potential therapeutic targets in obesity and in cardiovascular diseases. Cathelicidin antimicrobial peptide (CAMP) is an important factor of innate immunity and is expressed in adipocytes. CAMP, therefore, might play a role as an adipokine in metaflammation and adipose inflammation. TNFα, cell-free nucleic acids (cfDNA), and toll-like receptor (TLR) 9 are components of the innate immune system and are functionally active in adipose tissue. The aim of the present study was to investigate the impact of TNFα and cfDNA on CAMP expression in adipocytes. Since cfDNA acts as a physiological TLR9 agonist, we additionally investigated TLR9-mediated CAMP regulation in adipocytes and adipose tissue. CAMP gene expression in murine 3T3-L1 and human SGBS adipocytes and in murine and human adipose tissues was quantified by real-time PCR. Adipocyte inflammation was induced in vitro by TNFα and cfDNA stimulation. Serum CAMP concentrations in TLR9 knockout (KO) and in wildtype mice were quantified by ELISA. In primary adipocytes of wildtype and TLR9 KO mice, CAMP gene expression was quantified by real-time PCR. CAMP gene expression was considerably increased in 3T3-L1 and SGBS adipocytes during differentiation. TNFα significantly induced CAMP gene expression in mature adipocytes, which was effectively antagonized by inhibition of PI3K signaling. Cell-free nucleic acids (cfDNA) significantly impaired CAMP gene expression, whereas synthetic agonistic and antagonistic TLR9 ligands had no effect. CAMP and TLR9 gene expression were correlated positively in murine and human subcutaneous but not in intra-abdominal/visceral adipose tissues. Male TLR9 knockout mice exhibited lower systemic CAMP concentrations than wildtype mice. CAMP gene expression levels in primary adipocytes did not significantly differ between wildtype and TLR9 KO mice. These findings suggest a regulatory role of inflammatory mediators, such as TNFα and cfDNA, in adipocytic CAMP expression as a novel putative molecular mechanism in adipose tissue innate immunity.

The regulatory role of adipocyte mitochondrial homeostasis in metabolism-related diseases

Adipose tissue is the most important energy storage organ in the body, maintaining its normal energy metabolism function and playing a vital role in keeping the energy balance of the body to avoid the harm caused by obesity and a series of related diseases resulting from abnormal energy metabolism. The dysfunction of adipose tissue is closely related to the occurrence of diseases related to obesity metabolism. Among various organelles, mitochondria are the main site of energy metabolism, and mitochondria maintain their quality through autophagy, biogenesis, transfer, and dynamics, which play an important role in maintaining metabolic homeostasis of adipocytes. On the other hand, mitochondria have mitochondrial genomes which are vulnerable to damage due to the lack of protective structures and their proximity to sites of reactive oxygen species generation, thus affecting mitochondrial function. Notably, mitochondria are closely related to other organelles in adipocytes, such as lipid droplets and the endoplasmic reticulum, which enhances the function of mitochondria and other organelles and regulates energy metabolism processes, thus reducing the occurrence of obesity-related diseases. This article introduces the structure and quality control of mitochondria in adipocytes and their interactions with other organelles in adipocytes, aiming to provide a new perspective on the regulation of mitochondrial homeostasis in adipocytes on the occurrence of obesity-related diseases, and to provide theoretical reference for further revealing the molecular mechanism of mitochondrial homeostasis in adipocytes on the occurrence of obesity-related diseases.

The Pressurized Skin: A Review on the Pathological Effect of Mechanical Pressure on the Skin from the Cellular Perspective

Since human skin is the primary interface responding to external mechanical stimuli, extrinsic forces can disrupt its balanced microenvironment and lead to cutaneous lesions. We performed this review to delve into the pathological effects of mechanical pressure on skin from the cellular perspective. Fibroblasts of different subsets act as heterogeneous responders to mechanical load and express diverse functionalities. Keratinocytes relay mechanical signals through mechanosensitive receptors and the ensuing neurochemical cascades to work collaboratively with other cells and molecules in response to pressure. Mast cells release cytokines and neuropeptides, promoting inflammation and facilitating interaction with sensory neurons, while melanocytes can be regulated by pressure through cellular and molecular crosstalk. Adipocytes and stem cells sense pressure to fine-tune their regulations of mechanical homeostasis and cell differentiation. Applying mechanical pressure to the skin can induce various changes in its microenvironment that potentially lead to pathological alterations, such as ischemia, chronic inflammation, proliferation, regeneration, degeneration, necrosis, and impaired differentiation. The heterogeneity of each cellular lineage and subset from different individuals with various underlying skin conditions must be taken into consideration when discussing the pathological effects of pressure on the skin. Thus, elucidating the mechanotransduction and mechanoresponsive pathways from the cellular viewpoint is crucial in diagnosing and managing relevant dermatological disorders.

The obesity-linked human lncRNA AATBC stimulates mitochondrial function in adipocytes

Adipocytes are critical regulators of metabolism and energy balance. While white adipocyte dysfunction is a hallmark of obesity-associated disorders, thermogenic adipocytes are linked to cardiometabolic health. As adipocytes dynamically adapt to environmental cues by functionally switching between white and thermogenic phenotypes, a molecular understanding of this plasticity could help improving metabolism. Here, we show that the lncRNA Apoptosis associated transcript in bladder cancer (AATBC) is a human-specific regulator of adipocyte plasticity. Comparing transcriptional profiles of human adipose tissues and cultured adipocytes we discovered that AATBC was enriched in thermogenic conditions. Using primary and immortalized human adipocytes we found that AATBC enhanced the thermogenic phenotype, which was linked to increased respiration and a more fragmented mitochondrial network. Expression of AATBC in adipose tissue of mice led to lower plasma leptin levels. Interestingly, this association was also present in human subjects, as AATBC in adipose tissue was inversely correlated with plasma leptin levels, BMI, and other measures of metabolic health. In conclusion, AATBC is a novel obesity-linked regulator of adipocyte plasticity and mitochondrial function in humans.

Skeletal muscles and gut microbiota-derived metabolites: novel modulators of adipocyte thermogenesis

Obesity occurs when overall energy intake surpasses energy expenditure. White adipose tissue is an energy storage site, whereas brown and beige adipose tissues catabolize stored energy to generate heat, which protects against obesity and obesity-associated metabolic disorders. Metabolites are substrates in metabolic reactions that act as signaling molecules, mediating communication between metabolic sites (i.e., adipose tissue, skeletal muscle, and gut microbiota). Although the effects of metabolites from peripheral organs on adipose tissue have been extensively studied, their role in regulating adipocyte thermogenesis requires further investigation. Skeletal muscles and intestinal microorganisms are important metabolic sites in the body, and their metabolites play an important role in obesity. In this review, we consolidated the latest research on skeletal muscles and gut microbiota-derived metabolites that potentially promote adipocyte thermogenesis. Skeletal muscles can release lactate, kynurenic acid, inosine, and β-aminoisobutyric acid, whereas the gut secretes bile acids, butyrate, succinate, cinnabarinic acid, urolithin A, and asparagine. These metabolites function as signaling molecules by interacting with membrane receptors or controlling intracellular enzyme activity. The mechanisms underlying the reciprocal exchange of metabolites between the adipose tissue and other metabolic organs will be a focal point in future studies on obesity. Furthermore, understanding how metabolites regulate adipocyte thermogenesis will provide a basis for establishing new therapeutic targets for obesity.

Delivery of adipose-derived growth factors from heparinized adipose acellular matrix accelerates wound healing

Dermal white adipocytes are closely associated with skin homeostasis and wound healing. However, it has not been fully investigated whether adipose-derived products improve wound healing. Here, we obtained adipose acellular matrix (AAM) and adipose-derived growth factors (ADGFs) from human adipose tissue and fabricated an ADGF-loaded AAM via surface modification with heparin. The product, HEP-ADGF-AAM, contained an adipose-derived scaffold and released ADGFs in a controlled fashion. To test its efficacy in promoting wound healing, mice with full thickness wound received three different treatments: HEP-ADGF-AAM, AAM and ADM. Control mice received no further treatments. Among these treatments, HEP-ADGF-AAM best improved wound healing. It induced adipogenesis in situ after in vivo implantation and provided an adipogenic microenvironment for wounds by releasing ADGFs. HEP-ADGF-AAM not only induced adipocyte regeneration, but also enhanced fibroblast migration, promoted vessel formation, accelerated wound closure, and enhanced wound epithelialization. Moreover, there was a close interaction between HEP-ADGF-AAM and the wound bed, and collagen was turned over in HEP-ADGF-AAM. These results show that HEP-ADGF-AAM might substantially improve re-epithelialization, angiogenesis, and skin appendage regeneration, and is thus a promising therapeutic biomaterial for skin wound healing.

Omentum provides a special cell microenvironment for ovarian cancer

BACKGROUND

Ovarian cancer seriously threatens women's health because of its poor prognosis and high mortality. Due to the lack of efficient early detection and screening methods, when patients seek doctors' help with complaints of abdominal distension, back pain and other nonspecific signs, the clinical results always hint at the widespread metastasis of disease. When referring to the metastasis of this disease, the omentum always takes precedence.

RECENT FINDINGS

The distinguishing feature of the omentum is adipose tissue, which satisfies the energy demand of cancer cells and supplies a more aggressive environment for ovarian cancer cells. In this review, we mainly focus on three important cell types: adipocytes, macrophages, and mesenchymal stem cells. Besides, several mechanisms underlying cancer-associated adipocytes (CAA)-facilitated ovarian cancer cell development have been revealed, including their capacities for storing lipids and endocrine function, and the release of hormones, growth factors, and adipokines. Blocking the reciprocity among cancer cells and various cells located on the omentum might contribute to ovarian cancer therapy. The inhibition of hormones, growth factors and adipokines produced by adipocytes will be a novel therapeutic strategy. However, a sufficient number of trials has not been performed. In spite of this, the therapeutic potential of metformin and the roles of exercise in ovarian cancer will be worth mentioning.

CONCLUSION

It is almost impossible to overcome completely ovarian cancer at the moment. What we can do is trying our best to improve these patients' prognoses. In this process, adipocytes may bring promising future for the therapy of ovarian cancer.

A CRISPR Screen Identifies the E3 Ubiquitin Ligase Rfwd2 as a Negative Regulator of Glucose Uptake in Brown Adipocytes

Brown adipose tissue activation increases energy expenditure and has been shown to improve glucose tolerance, making it a promising target for the treatment of obesity and type 2 diabetes. Brown adipocytes differentiate into cells with multilocular lipid droplets, which can efficiently absorb and oxidize glucose; however, the mechanisms regulating these processes are not completely understood. We conducted a genome-wide loss-of-function screen using a CRISPR-based approach to identify genes that promote or inhibit adipogenesis and glucose uptake in brown adipocytes. We validated genes that negatively or positively regulated these pathways and verified that the E3-ubiquitin ligase Rfwd2 suppressed brown adipocyte glucose uptake. Brown adipocytes with CRISPR-targeted Rfwd2 deletion showed an altered proteomic landscape and increased basal, as well as insulin-stimulated, glucose uptake. These data reveal the complexity of genetic regulation of brown adipogenesis and glucose metabolism.