Versatile human cardiac tissues engineered with perfusable heart extracellular microenvironment for biomedical applications.

Engineered human cardiac tissues have been utilized for various biomedical applications, including drug testing, disease modeling, and regenerative medicine. However, the applications of cardiac tissues derived from human pluripotent stem cells are often limited due to their immaturity and lack of functionality. Therefore, in this study, we establish a perfusable culture system based on in vivo-like heart microenvironments to improve human cardiac tissue fabrication. The integrated culture platform of a microfluidic chip and a three-dimensional heart extracellular matrix enhances human cardiac tissue development and their structural and functional maturation. These tissues are comprised of cardiovascular lineage cells, including cardiomyocytes and cardiac fibroblasts derived from human induced pluripotent stem cells, as well as vascular endothelial cells. The resultant macroscale human cardiac tissues exhibit improved efficacy in drug testing (small molecules with various levels of arrhythmia risk), disease modeling (Long QT Syndrome and cardiac fibrosis), and regenerative therapy (myocardial infarction treatment). Therefore, our culture system can serve as a highly effective tissue-engineering platform to provide human cardiac tissues for versatile biomedical applications.

The pathophysiology of visceral adipose tissues in cardiometabolic diseases.

Central pattern of fat distribution, especially fat accumulation within the intraabdominal cavity increases risks for cardiometabolic diseases. Portal hypothesis combined with a pathological remodeling in visceral fat is considered the major etiological factor explaining the independent contribution of visceral obesity to cardiometabolic diseases. Excessive remodeling in visceral fat during development of obesity leads to dysfunctions in the depot, characterized by hypertrophy and death of adipocytes, hypoxia, inflammation, and fibrosis. Dysfunctional visceral fat secretes elevated levels of fatty acids, glycerol, and proinflammatory and profibrotic cytokines into the portal vein directly impacting the liver, the central regulator of systemic metabolism. These metabolic and endocrine products induce ectopic fat accumulation, insulin resistance, inflammation, and fibrosis in the liver, which in turn causes or exacerbates systemic metabolic derangements. Elucidation of underlying mechanisms that lead to the pathological remodeling and higher degree of dysfunctions in visceral adipose tissue is therefore, critical for the development of therapeutics to prevent deleterious sequelae in obesity. We review depot differences in metabolic and endocrine properties and expendabilities as well as underlying mechanisms that contribute to the pathophysiological aspects of visceral adiposity in cardiometabolic diseases. We also discuss impacts of different weight loss interventions on visceral adiposity and cardiometabolic diseases.

Metabolic and structural remodeling during browning of primary human adipocytes derived from omental and subcutaneous depots.

OBJECTIVE: This study investigated remodeling of cellular metabolism and structures during browning of primary human adipocytes derived from both visceral and subcutaneous adipose tissues. Effects of glucocorticoids on the browning were also assessed. METHODS: Differentiated omental and subcutaneous human adipocytes were treated with rosiglitazone, with or without dexamethasone, and expression levels of brite adipocyte markers, lipolysis, and lipid droplet and mitochondrial structures were examined. RESULTS: Both omental and subcutaneous adipocytes acquired brite phenotypes upon peroxisome proliferator-activated receptor-γ agonist treatment, and dexamethasone tended to enhance the remodeling. Although rosiglitazone increased lipolysis during treatment, brite adipocytes exhibited lower basal lipolytic rates and enhanced responses to ß-adrenergic agonists or atrial natriuretic peptide. Transcriptome analysis identified induction of both breakdown and biosynthesis of lipids in brite adipocytes. After 60+ days in culture, lipid droplet size increased to ~50 microns, becoming almost unilocular in control adipocytes, and after browning, they acquired paucilocular morphology, clusters of small lipid droplets (1-2 micron) surrounded by mitochondria appearing on the periphery of the central large one. CONCLUSIONS: Metabolic and structural remodeling during browning of primary human adipocytes is similar to previous findings in human adipocytes in vivo, supporting their uses for mechanical studies investigating browning with translational relevance.

Adhesive Hydrogel Patch-Mediated Combination Drug Therapy Induces Regenerative Wound Healing through Reconstruction of Regenerative Microenvironment.

Regenerative wound healing involves the scarless wound healing as observed in fetal skin. Multiple features of regenerative wound healing have been well studied; however, the practical application of pro-regenerative materials to recapitulate the regenerative wound healing in adult skins has not yet been achieved. In this study, the authors identified that their novel pro-regenerative material, pyrogallol-functionalized hyaluronic acid (HA-PG) patches in combination with protein transduction domain-fused Dishevelled (Dvl)-binding motif (PTD-DBM), a peptide inhibiting the CXXC-type zinc finger protein 5 (CXXC5)-Dvl interaction, promoted regenerative wound healing in mice. The HA-PG patches loaded with this competitor peptide and valproic acid (VPA), a glycogen synthase kinase 3ß (GSK3ß) inhibitor, significantly inhibited scar formation during wound healing. The HA-PG patches with PTD-DBM and/or VPA inhibit the expression of differentiated cell markers such as α-smooth muscle actin (α-SMA) while inducing the expression of stem cell markers such as CD105 and Nestin. Moreover, Collagen III, an important factor for regenerative healing, is critically induced by the HA-PG patches with PTD-DBM and/or VPA, as also seen in VPA-treated Cxxc5-/- mouse fibroblasts. Overall, these findings suggest that the novel regeneration-promoting material can be utilized as a potential therapeutic agent to promote both wound healing and scar attenuation.

l-Arginine supplementation regulates energy-substrate metabolism in skeletal muscle and adipose tissue of diet-induced obese rats.

Dietary supplementation with l-arginine has been reported to reduce white fat mass in diet-induced obese rats and in obese humans. This study was conducted to test the hypothesis that the arginine treatment regulates glucose and fatty acid metabolism in insulin-sensitive tissues. Male Sprague-Dawley rats (4-week-old) were fed either low- or high-fat diets for 15 weeks (n = 16/diet). Thereafter, lean or obese rats were fed their respective diets and received drinking water containing either 1.51% l-arginine-HCl or 2.55% alanine (isonitrogenous control) (n = 8/treatment group). After 12 weeks of treatment, rats were euthanized and tissue samples were collected for biochemical assays. High-fat feeding increased the size of adipocytes isolated from retroperitoneal (RP) adipose tissue, while arginine treatment reduced their size. The total number of adipocytes in the adipose tissue did not differ among the four groups of rats. Glucose oxidation in extensor digitorum longus (EDL) muscle, soleus muscle, and RP adipose tissue were reduced in response to high-fat feeding. On the contrary, oleic acid oxidation in RP adipose tissue was enhanced in rats fed the high-fat diet. Arginine treatment stimulated both glucose and oleic acid oxidation in EDL and soleus muscles, while having no effect on glucose oxidation, oleic acid oxidation, or basal lipolysis per 106 adipocytes in RP adipose tissue. Collectively, these results indicate that oral supplementation with arginine to diet-induced obese rats promoted the oxidation of energy substrates in skeletal muscle, thereby reducing white fat in the body.

Remodeling of Adipose Tissues by Fatty Acids: Mechanistic Update on Browning and Thermogenesis by n-3 Polyunsaturated Fatty Acids.

Enhancing thermogenesis by increasing the amount and activity of brown and brite adipocytes is a potential therapeutic target for obesity and its associated diseases. Diet plays important roles in energy metabolism and a myriad of dietary components including lipids are known to regulate thermogenesis through recruitment and activation of brown and brite adipocytes. Depending on types of fatty acids (FAs), the major constituent in lipids, their health benefits differ. Long-chain polyunsaturated FAs (PUFAs), especially n-3 PUFAs remodel adipose tissues in a healthier manner with reduced inflammation and enhanced thermogenesis, while saturated FAs exhibit contrasting effects. Lipid mediators derived from FAs act as autocrine/paracrine as well as endocrine factors to regulate thermogenesis. We discuss lipid mediators that may contribute to the differential effects of FAs on adipose tissue remodeling and hence, cardiometabolic diseases. We also discuss current understanding of molecular and cellular mechanisms through which n-3 PUFAs enhance thermogenesis. Elucidating molecular details of beneficial effects of n-3 PUFAs on thermogenesis is expected to provide information that can be used for development of novel therapeutics for obesity and its associated diseases.

Evaluation of Barley and Wheat Germplasm for Resistance to Head Blight and Mycotoxin Production by Fusarium asiaticum and F. graminearum.

Fusarium head blight (FHB) is one of the most serious diseases in barley and wheat, as it is usually accompanied by the production of harmful mycotoxins in the grains. To identify FHB-resistant breeding resources, we evaluated 60 elite germplasm accessions of barley (24) and wheat (36) for FHB and mycotoxin accumulation. Assessments were performed in a greenhouse and five heads per accession were inoculated with both Fusarium asiaticum (Fa73, nivalenol producer) and F. graminearum (Fg39, deoxynivalenol producer) strains. While the accessions varied in disease severity and mycotoxin production, four wheat and one barley showed <20% FHB severity repeatedly by both strains. Mycotoxin levels in these accessions ranged up to 3.9 mg/kg. FHB severity was generally higher in barley than in wheat, and Fa73 was more aggressive in both crops than Fg39. Fg39 itself, however, was more aggressive toward wheat and produced more mycotoxin in wheat than in barley. FHB severity by Fa73 and Fg39 were moderately correlated in both crops (r = 0.57/0.60 in barley and 0.42/0.58 in wheat). FHB severity and toxin production were also correlated in both crops, with a stronger correlation for Fa73 (r = 0.42/0.82 in barley, 0.70 in wheat) than for Fg39.

pH-Universal Catechol-Amine Chemistry for Versatile Hyaluronic Acid Bioadhesives.

Catechol, a major mussel-inspired underwater adhesive moiety, has been used to develop functional adhesive hydrogels for biomedical applications. However, oxidative catechol chemistry for interpolymer crosslinking and adhesion is exclusively effective under alkaline conditions, with limited applications in non-alkaline conditions. To overcome this limitation, pH-universal catechol-amine chemistry to recapitulate naturally occurring biochemical events induced by pH variation in the mussel foot is suggested. Aldehyde moieties are introduced to hyaluronic acid (HA) by partial oxidation, which enables dual-mode catechol tethering to the HA via both stable amide and reactive secondary amine bonds. Because of the presence of additional reactive amine groups, the resultant aldehyde-modified HA conjugated with catechol (AH-CA) is effectively crosslinked in acidic and neutral pH conditions. The AH-CA hydrogel exhibits not only fast gelation via active crosslinking regardless of pH conditions, but also strong adhesion and excellent biocompatibility. The hydrogel enables rapid and robust wound sealing and hemostasis in neutral and alkaline conditions. The hydrogel also mediates effective therapeutic stem cell and drug delivery even in dynamic and harsh environments, such as a motile heart and acidic stomach. Therefore, the AH-CA hydrogel can serve as a versatile biomaterial in a wide range of pH conditions in vivo.

Functional roles of all five putative hydrophobin genes in growth, development, and secondary metabolism in Fusarium graminearum.

Fusarium graminearum is the causal agent of Fusarium head blight in cereal crops. As in other filamentous ascomycetes, F. graminearum contains genes encoding putative hydrophobins, which are small secreted amphiphilic proteins with eight conserved cysteine residues. Here, we investigated the roles of all five hydrophobin genes (designated FgHyd1, FgHyd2, FgHyd3, FgHyd4, and FgHyd5) in various mycological traits of F. graminearum. Gene expression analyses revealed that the five FgHyd genes, all of which were under the control of G protein signaling or velvet complex proteins, were differentially expressed under various developmental conditions. Three genes (FgHyd1, FgHyd2, and FgHyd3) were constitutively expressed in all aerial structures examined (hyphae, conidia, and perithecia), and two genes (FgHyd1 and FgHyd2) were also expressed in submerged hyphae. FgHyd3 was exclusively expressed in aerial hyphae on solid surfaces, including rice grains. These genes showed markedly reduced expression in F. asiaticum, which was a closely related to F. graminearum but exhibited different mycological traits from F. graminearum. Phenotypic analyses of various gene deletion strains, including the quintuple deletion (ΔFgHyd12345) strain, confirmed that in addition to their typical functions, all five FgHyd genes were involved in other traits, such as conidiation, pathogenicity, and secondary metabolism in F. graminearum. Both RNA-seq and chemical analyses confirmed that ΔFgHyd led to overproduction of specific terpenoid compounds (e.g., trichothecenes), which has not been reported previously. Nevertheless, the lack of complete phenotypic loss of any of the traits examined, even in the ΔFgHyd12345 strain, and little cumulative action of all five FgHyd genes strongly suggest that all five hydrophobins are redundant in function and are not absolutely essential for these fungal traits in F. graminearum.

Effect of Steam and Smoke Cooking Processes on Web-Foot Octopus (Amphioctopus sp.) Home Meal Replacement Product.

In Korea, the web-foot octopus (Amphioctopus sp.) is commonly consumed as jjukkumi bokkeum, a spicy stir-fried octopus dish. Using steaming and smoking methods, we made jjukkumi bokkeum home meal replacement (HMR) products. The response surface methodology (RSM) was employed to optimize the steam and smoke processes. Quick freezing was applied to freeze the test product at -35 °C. Then, the physicochemical, biological, nutritional characteristics, and shelf-life of the test HMR products were evaluated. The optimal conditions for steaming and smoking were 95 °C for 2 min and 70 °C for 11 min, respectively. The pH, volatile basic nitrogen content, and thiobarbituric acid-reactive substances content decreased after steaming and smoking, indicating that these processes maintained these parameters well. Sensory evaluation revealed that there were no changes in these characteristics after freezing and reheating. Further, the test HMR products contained the daily nutritional requirements of macro and micronutrients, as well as amino acids and fatty acids. The shelf-life of the HMR products was estimated to be 15 months. The findings of this study indicate that the application of steam and smoke processes to produce a jjukkumi bokkeum HMR product results in a high-quality product with a long shelf-life.

Effects of Vacuum Frying on the Preparation of Ready-to-Heat Batter-Fried and Sauced Chub Mackerel (Scomber japonicus).

Chub mackerel (CM) is a commercial fish in Korea, owing to its availability and nutritional values. This study aimed to develop a ready-to-heat (RTH) Korean preparation of CM, known as Godeungo gangjeong. We utilized vacuum frying technology to fry the CM and evaluated its quality. Conventional frying with a deep fryer was performed in parallel to assess the superiority of the vacuum fryer. We optimized the frying conditions of vacuum frying (VBF) and deep frying (DBF) using response surface methodology. At optimum conditions of 95 °C for 7 min 42 s, VBF produced better sensory, chemical, and microbial properties than DBF at 190 °C for 5 min 30 s. The nutritional values, including amino acid and fatty acid contents, were investigated and found to be higher in VBF than in DBF. Sensory properties also showed better scores on VBF than DBF, especially in appearance, aroma, taste, and overall acceptability. The VBF produced lower volatile basic nitrogen (VBN), thiobarbituric acid reactive substances (TBARS), and total bacterial count (TBC) than DBF. The findings confirmed that vacuum frying is a better option to produce RTH Godeungo gangjeong, since it provides less oxidation and maintains the product quality. Using the Arrhenius approach, the product was concluded to preserve both quality and safety for 9 months of storage at -18 °C.

Vitamin D Inhibits Adipokine Production and Inflammatory Signaling Through the Vitamin D Receptor in Human Adipocytes.

OBJECTIVE: The purpose of this study was to investigate the effects of vitamin D on adipokine expression and inflammation in human adipose tissues and adipocytes and evaluate the molecular mechanisms involved. METHODS: Omental and abdominal subcutaneous human adipose tissues were treated with 1,25-dihydroxyvitamin D3 (1,25(OH)2 D3 ), and adipokine levels were measured. Vitamin D effects were measured with or without dexamethasone because glucocorticoids are known to affect vitamin D actions. Using RNA interference, we examined whether the vitamin D receptor (VDR) mediated vitamin D actions on adipokine expression and inflammatory signaling pathways in human adipocytes. RESULTS: mRNA levels and secretion of leptin and IL-6 were suppressed by 1,25(OH)2 D3 in omental adipose tissues. Cotreatment with dexamethasone did not affect these inhibitory actions but partially blocked CYP24A1 induction. Similar results were observed in the subcutaneous depot. In addition, 1,25(OH)2 D3 suppressed leptin and IL-6 expression as well as nuclear factor-κB and extracellular signal-regulated kinase-1/2 phosphorylation in human adipocytes. Adipokine expression also was decreased by 25-hydroxyvitamin D3 (25(OH)D3 ), but not vitamin D3 . Knockdown of VDR increased the inflammatory signaling activity in the control condition and blocked the inhibitory effects of 1,25(OH)2 D3 on adipokine and inflammatory signaling pathways. CONCLUSION: Vitamin D acts through VDR to inhibit inflammatory pathways and adipokine expression in human adipocytes. Increasing vitamin D status may ameliorate obesity-associated metabolic complications by decreasing adipose tissue inflammation.

Vitamin D regulation of adipogenesis and adipose tissue functions.

Vitamin D insufficiency is associated with obesity and its related metabolic diseases. Adipose tissues store and metabolize vitamin D and expression levels of vitamin D metabolizing enzymes are known to be altered in obesity. Sequestration of vitamin D in large amount of adipose tissues and low vitamin D metabolism may contribute to the vitamin D inadequacy in obesity. Vitamin D receptor is expressed in adipose tissues and vitamin D regulates multiple aspects of adipose biology including adipogenesis as well as metabolic and endocrine function of adipose tissues that can contribute to the high risk of metabolic diseases in vitamin D insufficiency. We will review current understanding of vitamin D regulation of adipose biology focusing on vitamin D modulation of adiposity and adipose tissue functions as well as the molecular mechanisms through which vitamin D regulates adipose biology. The effects of supplementation or maintenance of vitamin D on obesity and metabolic diseases are also discussed.

A MicroRNA Linking Human Positive Selection and Metabolic Disorders.

Positive selection in Europeans at the 2q21.3 locus harboring the lactase gene has been attributed to selection for the ability of adults to digest milk to survive famine in ancient times. However, the 2q21.3 locus is also associated with obesity and type 2 diabetes in humans, raising the possibility that additional genetic elements in the locus may have contributed to evolutionary adaptation to famine by promoting energy storage, but which now confer susceptibility to metabolic diseases. We show here that the miR-128-1 microRNA, located at the center of the positively selected locus, represents a crucial metabolic regulator in mammals. Antisense targeting and genetic ablation of miR-128-1 in mouse metabolic disease models result in increased energy expenditure and amelioration of high-fat-diet-induced obesity and markedly improved glucose tolerance. A thrifty phenotype connected to miR-128-1-dependent energy storage may link ancient adaptation to famine and modern metabolic maladaptation associated with nutritional overabundance.

CIDEA Transcriptionally Regulates UCP1 for Britening and Thermogenesis in Human Fat Cells.

Our study identifies a transcriptional role of cell death-inducing DNA fragmentation factor-like effector A (CIDEA), a lipid-droplet-associated protein, whereby it regulates human adipocyte britening/beiging with consequences for the regulation of energy expenditure. The comprehensive transcriptome analysis revealed CIDEA's control over thermogenic function in brite/beige human adipocytes. In the absence of CIDEA, achieved by the modified dual-RNA-based CRISPR-Cas9nD10A system, adipocytes lost their britening capability, which was recovered upon CIDEA re-expression. Uncoupling protein 1 (UCP1), the most upregulated gene in brite human adipocytes, was suppressed in CIDEA knockout (KO) primary human adipocytes. Mechanistically, during induced britening, CIDEA shuttled from lipid droplets to the nucleus via an unusual nuclear bipartite signal in a concentration-dependent manner. In the nucleus, it specifically inhibited LXRα repression of UCP1 enhancer activity and strengthened PPARγ binding to UCP1 enhancer, hence driving UCP1 transcription. Overall, our study defines the role of CIDEA in increasing thermogenesis in human adipocytes.

Rosiglitazone remodels the lipid droplet and britens human visceral and subcutaneous adipocytes ex vivo.

Treatment with PPARγ agonists in vivo improves human adipocyte metabolism, but the cellular mechanisms and possible depot differences in responsiveness to their effects are poorly understood. To examine the ex vivo metabolic effects of rosiglitazone (Rosi), we cultured explants of human visceral (omental) and abdominal subcutaneous adipose tissues for 7 days. Rosi increased mRNA levels of transcriptional regulators of brite/beige adipocytes (PGC1α, PRDM16), triglyceride synthesis (GPAT3, DGAT1), and lipolysis (ATGL) similarly in adipose tissues from both depots. In parallel, Rosi increased key modulators of FA oxidation (UCP1, FABP3, PLIN5 protein), rates of FA oxidation, and protein levels of electron transport complexes, suggesting an enhanced respiratory capacity as confirmed in newly differentiated adipocytes. Rosi led to the formation of small lipid droplets (SLDs) around the adipocyte central lipid droplet; each SLD was decorated with redistributed mitochondria that colocalized with PLIN5. SLD maintenance required lipolysis and FA reesterification. Rosi thus coordinated a structural and metabolic remodeling in adipocytes from both visceral and subcutaneous depots that enhanced oxidative capacity. Selective targeting of these cellular mechanisms to improve adipocyte FA handling may provide a new approach to treat metabolic complications of obesity and diabetes.

Impaired Glucocorticoid Suppression of TGFß Signaling in Human Omental Adipose Tissues Limits Adipogenesis and May Promote Fibrosis.

Visceral obesity is associated with insulin resistance and higher risk of type 2 diabetes and metabolic diseases. A limited ability of adipose tissues to remodel through the recruitment and differentiation of adipose stem cells (ASCs) is associated with adipose tissue inflammation and fibrosis and the metabolic syndrome. We show that the lower adipogenesis of omental (Om) compared with abdominal subcutaneous (Abdsc) ASCs was associated with greater secretion of TGFß ligands that acted in an autocrine/paracrine loop to activate SMAD2 and suppress adipogenesis. Inhibition of TGFß signaling rescued Om ASC differentiation. In Abdsc ASCs, low concentrations of dexamethasone suppressed TGFß signaling and enhanced adipogenesis, at least in part by increasing TGFBR3 protein that can sequester TGFß ligands. Om ASCs were resistant to these dexamethasone effects; recombinant TGFBR3 increased their differentiation. Pericellular fibrosis, a hallmark of dysfunctional adipose tissue, was greater in Om and correlated with higher level of tissue TGFß signaling activity and lower ASC differentiation. We conclude that glucocorticoids restrain cell-autonomous TGFß signaling in ASCs to facilitate adipogenesis and healthy remodeling in Abdsc and these processes are impaired in Om. Therapies directed at overcoming glucocorticoid resistance in visceral adipose tissue may improve remodeling and help prevent metabolic complications of visceral obesity.

Aortic carboxypeptidase-like protein enhances adipose tissue stromal progenitor differentiation into myofibroblasts and is upregulated in fibrotic white adipose tissue.

White adipose tissue expands through both adipocyte hypertrophy and hyperplasia and it is hypothesized that fibrosis or excess accumulation of extracellular matrix within adipose tissue may limit tissue expansion contributing to metabolic dysfunction. The pathways that control adipose tissue remodeling are only partially understood, however it is likely that adipose tissue stromal and perivascular progenitors participate in fibrotic remodeling and also serve as adipocyte progenitors. The goal of this study was to investigate the role of the secreted extracellular matrix protein aortic carboxypeptidase-like protein (ACLP) on adipose progenitor differentiation in the context of adipose tissue fibrosis. Treatment of 10T1/2 mouse cells with recombinant ACLP suppressed adipogenesis and enhanced myofibroblast differentiation, which was dependent on transforming growth factor-ß receptor kinase activity. Mice fed a chronic high fat diet exhibited white adipose tissue fibrosis with elevated ACLP expression and cellular fractionation of these depots revealed that ACLP was co-expressed with collagens primarily in the inflammatory cell depleted stromal-vascular fraction (SVF). SVF cells isolated from mice fed a high fat diet secreted increased amounts of ACLP compared to low fat diet control SVF. These cells also exhibited reduced adipogenic differentiation capacity in vitro. Importantly, differentiation studies in primary human adipose stromal cells revealed that mature adipocytes do not express ACLP and exogenous ACLP administration blunted their differentiation potential while upregulating myofibroblastic markers. Collectively, these studies identify ACLP as a stromal derived mediator of adipose progenitor differentiation that may limit adipocyte expansion during white adipose tissue fibrosis.

A role for long-chain acyl-CoA synthetase-4 (ACSL4) in diet-induced phospholipid remodeling and obesity-associated adipocyte dysfunction.

OBJECTIVE: Regulation of fatty acid (FA) metabolism is central to adipocyte dysfunction during diet-induced obesity (DIO). Long-chain acyl-CoA synthetase-4 (ACSL4) has been hypothesized to modulate the metabolic fates of polyunsaturated FA (PUFA), including arachidonic acid (AA), but the in vivo actions of ACSL4 are unknown. The purpose of our studies was to determine the in vivo role of adipocyte ACSL4 in regulating obesity-associated adipocyte dysfunction. METHODS: We developed a novel mouse model with adipocyte-specific ablation of ACSL4 (Ad-KO) using loxP Cre recombinase technology. Metabolic phenotyping of Ad-KO mice relative to their floxed littermates (ACSL4floxed) was performed, including body weight and body composition over time; insulin and glucose tolerance tests; and energy expenditure, activity, and food intake in metabolic cages. Adipocytes were isolated for ex vivo adipocyte oxygen consumption by Clark electrode and lipidomics analysis. In vitro adipocyte analysis including oxygen consumption by Seahorse and real-time PCR analysis were performed to confirm our in vivo findings. RESULTS: Ad-KO mice were protected against DIO, adipocyte death, and metabolic dysfunction. Adipocytes from Ad-KO mice fed high-fat diet (HFD) had reduced incorporation of AA into phospholipids (PL), free AA, and levels of the AA lipid peroxidation product 4-hydroxynonenal (4-HNE). Additionally, adipocytes from Ad-KO mice fed HFD had reduced p53 activation and increased adipocyte oxygen consumption (OCR), which we demonstrated are direct effects of 4-HNE on adipocytes in vitro. CONCLUSION: These studies are the first to elucidate ACSL4's in vivo actions to regulate the incorporation of AA into PL and downstream effects on DIO-associated adipocyte dysfunction. By reducing the incorporation of AA into PL and free fatty acid pools in adipocytes, Ad-KO mice were significantly protected against HFD-induced increases in adipose and liver fat accumulation, adipocyte death, gonadal white adipose tissue (gWAT) inflammation, and insulin resistance (IR). Additionally, deficiency of adipocyte ACSL4 expression in mice fed a HFD resulted in increased gWAT adipocyte OCR and whole body energy expenditure (EE).

Transforming growth factor beta superfamily regulation of adipose tissue biology in obesity.

Accumulation of dysfunctional white adipose tissues increases risks for cardiometabolic diseases in obesity. In addition to white, brown or brite adipose tissues are also present in adult humans and increasing their amount may be protective. Therefore, understanding factors regulating the amount and function of each adipose depot is crucial for developing therapeutic targets for obesity and its associated metabolic diseases. The transforming growth factor beta (TGFß) superfamily, which consists of TGFß, BMPs, GDFs, and activins, controls multiple aspects of adipose biology. This review focuses on the recent development in understanding the role of TGFß superfamily in the regulation of white, brite and brown adipocyte differentiation, adipose tissue fibrosis, and adipocyte metabolic and endocrine functions. TGFß family and their antagonists are produced locally within adipose tissues and their expression levels are altered in obesity. We also discuss their potential contribution to adipose tissue dysfunction in obesity.