Fat body, fat pad and adipose tissues in invertebrates and vertebrates: the nexus

Azeez, O. I.; Meintjes, R.A.; Chamunorwa, J. P.

doi:10.1186/1476-511x-13-71

Cited by 81 publications

(45 citation statements)

References 103 publications

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“…8 Thus, adipocytes can also be viewed as integral components of the immune system. 9, 10 Evolutionarily, adipose tissue was derived from the primitive fat body of insects, which simultaneously serves both the animal’s metabolic and immune functions 11 . While higher animals have evolved separate systems to serve these functions (i.e., liver and adipose tissues for metabolism and hematopoietic system for immunity), adipose tissue has retained its basic immune functions.…”

Section: Adipocytes and Inflammationmentioning

confidence: 99%

Proinflammatory Phenotype of Perivascular Adipocytes

Omar

Chatterjee

Tang

et al. 2014

ATVB

140

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Perivascular adipose tissue (PVAT) directly abuts the lamina adventitia of conduit arteries and actively communicates with the vessel wall to regulate vascular function and inflammation. Mounting evidence suggests that the biological activities of PVAT are governed by perivascular (PV) adipocytes, a unique class of adipocyte with distinct molecular and phenotypic characteristics. Perivascular adipocytes surrounding human coronary arteries (pericoronary PV adipocytes) exhibit a reduced state of adipogenic differentiation and a heightened pro-inflammatory state, secreting up to 50-fold higher levels of the pro-inflammatory cytokine MCP-1 as compared with adipocytes from other regional depots. Thus, PV adipocytes may contribute to upregulated inflammation of PVAT observed in atherosclerotic human blood vessels. On the other hand, PV adipocytes also secrete anti-inflammatory molecules such as adiponectin, and elimination of PVAT in rodent models has been shown to augment vascular disease, suggesting that some amount of PVAT is required to maintain vascular homeostasis. Evidence in animal models and in humans suggests that inflammation of PVAT may be modulated by environmental factors, such as high fat diet and tobacco smoke, which are relevant to atherosclerosis. These findings suggest that the inflammatory phenotype of PVAT is diverse depending on species, anatomic location, and environmental factors, and that these differences are fundamentally important in determining a pathogenic versus protective role of PVAT in vascular disease. Further research into the mechanisms that regulate the inflammatory balance of PV adipocytes may yield new insight into, and treatment strategies for, cardiovascular disease.

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Section: Adipocytes and Inflammationmentioning

confidence: 99%

Proinflammatory Phenotype of Perivascular Adipocytes

Omar

Chatterjee

Tang

et al. 2014

ATVB

140

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“…These newly synthesized lipids are distributed to other tissues by the shuttle system mediated by lipophorin, a major circulating lipoprotein present in the hemolymph [5, 10, 15]. Lipids carried by lipophorin are stored mainly as TAG in the fat body [12], an organ functionally analogous to both mammalian liver and adipose tissue [16]. During prolonged starvation, which may be as long as five months for R. prolixus [17], TAG is mobilized to sustain the energy needs of the insect [12, 17], probably by the oxidation of released fatty acids.…”

Section: Introductionmentioning

confidence: 99%

Long-chain acyl-CoA synthetase 2 knockdown leads to decreased fatty acid oxidation in fat body and reduced reproductive capacity in the insect Rhodnius prolixus

Auger

Klett

Paula

et al. 2016

Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biolog

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Long-chain acyl-CoA esters are important intermediates in lipid metabolism and are synthesized from fatty acids by long-chain acyl-CoA synthetases (ACSL). The hematophagous insect Rhodnius prolixus, a vector of Chagas' disease, produces glycerolipids in the midgut after a blood meal, which are stored as triacylglycerol in the fat body and eggs. We identified twenty acyl-CoA synthetase genes in R. prolixus, two encoding ACSL isoforms (RhoprAcsl1 and RhoprAcsl2). RhoprAcsl1 transcripts increased in posterior midgut on the second day after feeding, and RhoprAcsl2 was highly transcribed on the tenth day. Both enzymes were expressed in Escherichia coli. Recombinant RhoprACSL1 and RhoprACSL2 had broad pH optima (7.5-9.5 and 6.5-9.5, respectively), were inhibited by triacsin C, and were rosiglitazone-insensitive. Both showed similar apparent Km for palmitic and oleic acid (2-6 μM), but different Km for arachidonic acid (0.5 and 6 μM for RhoprACSL1-Flag and RhoprACSL2-Flag, respectively). The knockdown of RhoprAcsl1 did not result in noticeable phenotypes. However, RhoprACSL2 deficient insects exhibited a 2.5-fold increase in triacylglycerol content in the fat body, and 90% decrease in fatty acid β-oxidation. RhoprAcsl2 knockdown also resulted in 20% increase in lifespan, delayed digestion, 30% reduced oviposition, and 50% reduction in egg hatching. Laid eggs and hatched nymphs showed remarkable alterations in morphology. In summary, R. prolixus ACSL isoforms have distinct roles on lipid metabolism. Although RhoprACSL1 functions remain unclear, we propose that RhoprACSL2 is the main contributor for the formation of the intracellular acyl-CoA pool channeled for β-oxidation in the fat body, and is also required for normal reproduction.

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“…Similar to mammals, also insects store lipids in the form of triacylglycerides (TGs) and as carbohydrates in the form of glycogen. The main storage organ for lipid and glycogen in insects is the fat body, which can thus be considered as the functional equivalent of mammalian liver and white adipose tissue (Azeez et al 2014). Under energy-demanding conditions, AKHs get released from the organ of their synthesis and storage, the corpora cardiaca (CC), into the hemolymph to reach their cognate G protein-coupled receptors (GPCRs) (called AKH receptors, AKHRs) expressed on the fat body cells.…”

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confidence: 99%

Energy Homeostasis Control in Drosophila Adipokinetic Hormone Mutants

et al. 2015

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Maintenance of biological functions under negative energy balance depends on mobilization of storage lipids and carbohydrates in animals. In mammals, glucagon and glucocorticoid signaling mobilizes energy reserves, whereas adipokinetic hormones (AKHs) play a homologous role in insects. Numerous studies based on AKH injections and correlative studies in a broad range of insect species established the view that AKH acts as master regulator of energy mobilization during development, reproduction, and stress. In contrast to AKH, the second peptide, which is processed from the Akh encoded prohormone [termed "adipokinetic hormone precursor-related peptide" (APRP)] is functionally orphan. APRP is discussed as ecdysiotropic hormone or as scaffold peptide during AKH prohormone processing. However, as in the case of AKH, final evidence for APRP functions requires genetic mutant analysis. Here we employed CRISPR/Cas9-mediated genome engineering to create AKH and AKH plus APRP-specific mutants in the model insect Drosophila melanogaster. Lack of APRP did not affect any of the tested steroid-dependent processes. Similarly, Drosophila AKH signaling is dispensable for ontogenesis, locomotion, oogenesis, and homeostasis of lipid or carbohydrate storage until up to the end of metamorphosis. During adulthood, however, AKH regulates body fat content and the hemolymph sugar level as well as nutritional and oxidative stress responses. Finally, we provide evidence for a negative autoregulatory loop in Akh gene regulation.KEYWORDS Drosophila; adipokinetic hormone; adipokinetic hormone precursor-related peptide; energy homeostasis; stress resistance E NERGY homeostasis requires continuous compensation for fluctuations in the energy expenditure and availability of food resources. Organisms thus build up reserves under positive energy balance and catabolize them when the balance turns negative to retain stable levels of circulating energy fuel. Insulin signaling induces the uptake of excessive circulating sugars, thus promoting reserve accumulation (reviewed, e.g., in Saltiel and Kahn 2001; Cohen 2006), whereas energy mobilization is under the control of glucagon and glucocorticoid signaling in mammals (reviewed, e.g., in Rui 2014;Charron and Vuguin 2015) and adipokinetic hormone (AKH) signaling in insects (reviewed, e.g., in Van der Horst 2003;Lorenz and Gäde 2009;Bednářová et al. 2013a). Consistent with their fundamental physiological function in energy mobilization, AKHs are found not only in insects, but are common in Protostomia, where they have been identified both in Ecdyszoa (in Arthropoda, Tardigrada, and Priapulida) and Lophotrochozoa (in Mollusca, Rotifera, and Annelida) (Gäde 2009;Hauser and Grimmelikhuijzen 2014). Nevertheless, physiological functions of AKHs have been studied mainly in Arthropoda. Similar to mammals, also insects store lipids in the form of triacylglycerides (TGs) and as carbohydrates in the form of glycogen. The main storage organ for lipid and glycogen in insects is the fat body, which can thus b...

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Fat body, fat pad and adipose tissues in invertebrates and vertebrates: the nexus

Cited by 81 publications

References 103 publications

Proinflammatory Phenotype of Perivascular Adipocytes

Proinflammatory Phenotype of Perivascular Adipocytes

Long-chain acyl-CoA synthetase 2 knockdown leads to decreased fatty acid oxidation in fat body and reduced reproductive capacity in the insect Rhodnius prolixus

Energy Homeostasis Control in Drosophila Adipokinetic Hormone Mutants

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