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Autotaxin and its product lysophosphatidic acid suppress brown adipose differentiation and promote diet-induced obesity in mice.

ABSTRACT: Brown adipose tissue is a thermogenic organ that dissipates stored energy as heat to maintain body temperature. This process may also provide protection from development of diet-induced obesity. We report that the bioactive lipid mediator lysophosphatidic acid (LPA) markedly decreases differentiation of cultured primary brown adipocyte precursors, whereas potent selective inhibitors of the LPA-generating enzyme autotaxin (ATX) promote differentiation. Transgenic mice overexpressing ATX exhibit reduced expression of brown adipose tissue-related genes in peripheral white adipose tissue and accumulate significantly more fat than wild-type controls when fed a high-fat diet. Our results indicate that ATX and its product LPA are physiologically relevant negative regulators of brown fat adipogenesis and are consistent with a model in which a decrease in mature peripheral brown adipose tissue results in increased susceptibility to diet-induced obesity in mice.

SUBMITTER: Federico L

PROVIDER: S-EPMC3355557 | biostudies-literature | 2012 May

REPOSITORIES: biostudies-literature

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Autotaxin and its product lysophosphatidic acid suppress brown adipose differentiation and promote diet-induced obesity in mice.

Federico Lorenzo L Ren Hongmei H Mueller Paul A PA Wu Tao T Liu Shuying S Popovic Jelena J Blalock Eric M EM Sunkara Manjula M Ovaa Huib H Albers Harald M HM Mills Gordon B GB Morris Andrew J AJ Smyth Susan S SS

Molecular endocrinology (Baltimore, Md.) 20120403 5

Brown adipose tissue is a thermogenic organ that dissipates stored energy as heat to maintain body temperature. This process may also provide protection from development of diet-induced obesity. We report that the bioactive lipid mediator lysophosphatidic acid (LPA) markedly decreases differentiation of cultured primary brown adipocyte precursors, whereas potent selective inhibitors of the LPA-generating enzyme autotaxin (ATX) promote differentiation. Transgenic mice overexpressing ATX exhibit r ...[more]

PMID: 22474126

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Project description:Brown adipose tissue (BAT) is a thermogenic organ that dissipates stored energy as heat to maintain body temperature in infants and small mammals. This process may also provide protection from development of diet-induced obesity. We found that the bioactive lipid mediator lysophosphatidic acid (LPA) markedly decreases differentiation of cultured primary brown adipocyte precursors, while potent selective inhibitors of the LPA-generating enzyme autotaxin (ATX) promote differentiation. Transgenic mice overexpressing ATX exhibited reduced expression of BAT-related genes in peripheral white adipose tissue and accumulated significantly more fat than wild-type controls when fed a high fat diet. Our results indicate that ATX and its product LPA are physiologically relevant negative regulators of brown fat adipogenesis and suggest that a decrease in peripheral brown adipose tissue results in increased susceptibility to diet-induced obesity in mice. Primary BAT cell cultures were established as previously reported with some minor modifications (Cannon B., 2001; NÃ©chad M., 1983). Four- to 6-week-old mice were euthanized under aseptic conditions and interscapular BAT (IBAT) dissected, finely minced in digestion buffer containing 123 mM NaCl, 5mM HCl, 1.3 mM CaCl2, 5mM glucose, 1.5% (w/v) crude bovine serum albumin fraction V, 100 mM HEPES, 0.2% collagenase type II (Sigma-Aldrich Corp., St. Louis, MO), pH 7.4, and digested in 10 ml of the same buffer for 30 min at 37Â°C. The supernatant obtained was then filtered using a 250 Âµm nylon mesh and kept in ice for 15 minutes to allow fat droplets and mature cells to float. The resulting infranatant was filtered through a 30 Âµm nylon mesh to enrich the fraction with precursor cells and centrifuged at 700g for 10 min. The pellet obtained was washed once in warm DMEM and resuspended in DMEM medium containing 10% newborn calf serum, 10 mM HEPES, 4mM glutamine, 25 Âµg/ml sodium ascorbate (Sigma-Aldrich Corp., St. Louis, MO)., 100U/ml penicillin and 100mg/ml streptomycin. Cells were seeded onto 35mm dish plates. Insulin treatment was started on day 1 at 50 nM and the concentration increased to 100 nM at day 5 and 200 nM at day 7. Differentiated/confluent cells were collected for biochemical analysis (~day 9). To identify genes regulated by ATX and LPA signaling, 9 DIV primary BAT cultures were treated with the vehicle (DMSO), specific ATX inhibitor HA155 (2.5ÂµM), or LPA (1-Oleoly-LPA, 5ÂµM) (Avanti Polar Lipids, AL, USA) during differentiation. Treatment of the BAT cultures did not affect confluence or markers of proliferation. RNA was extracted from three cultures per condition using TRIzol reagent (Invitrogen, Carlsbad, CA) as described previously (Blalock EM., 2003).

Project description:Background/aimsBrown adipose tissue (BAT) dissipates energy stored in triglycerides as heat via the uncoupling protein UCP-1 and is a promising target to combat hyperlipidemia and obesity. BAT is densely innervated by the sympathetic nervous system, which increases BAT differentiation and activity upon cold exposure. Recently, Bone Morphogenetic Protein 7 (BMP7) was identified as an inducer of BAT differentiation. We aimed to elucidate the role of sympathetic activation in the effect of BMP7 on BAT by treating mice with BMP7 at varying ambient temperature, and assessed the therapeutic potential of BMP7 in combating obesity.Methods and resultsHigh-fat diet fed lean C57Bl6/J mice were treated with BMP7 via subcutaneous osmotic minipumps for 4 weeks at 21 °C or 28 °C, the latter being a thermoneutral temperature in which sympathetic activation of BAT is largely diminished. At 21 °C, BMP7 increased BAT weight, increased the expression of Ucp1, Cd36 and hormone-sensitive lipase in BAT, and increased total energy expenditure. BMP7 treatment markedly increased food intake without affecting physical activity. Despite that, BMP7 diminished white adipose tissue (WAT) mass, accompanied by increased expression of genes related to intracellular lipolysis in WAT. All these effects were blunted at 28 °C. Additionally, BMP7 resulted in extensive 'browning' of WAT, as evidenced by increased expression of BAT markers and the appearance of whole clusters of brown adipocytes via immunohistochemistry, independent of environmental temperature. Treatment of diet-induced obese C57Bl6/J mice with BMP7 led to an improved metabolic phenotype, consisting of a decreased fat mass and liver lipids as well as attenuated dyslipidemia and hyperglycemia.ConclusionTogether, these data show that BMP7-mediated recruitment and activation of BAT only occurs at subthermoneutral temperature, and is thus likely dependent on sympathetic activation of BAT, and that BMP7 may be a promising tool to combat obesity and associated disorders.

Project description:Our group has recently demonstrated (Gesta, S., Simon, M., Rey, A., Sibrac, D., Girard, A., Lafontan, M., Valet, P., and Saulnier-Blache, J. S. (2002) J. Lipid Res. 43, 904-910) the presence, in adipocyte conditioned-medium, of a soluble lysophospholipase d-activity (LPLDact) involved in synthesis of the bioactive phospholipid lysophosphatidic acid (LPA). In the present report, LPLDact was purified from 3T3F442A adipocyte-conditioned medium and identified as the type II ecto-nucleotide pyrophosphatase phosphodiesterase, autotaxin (ATX). A unique ATX cDNA was cloned from 3T3F442A adipocytes, and its recombinant expression in COS-7 cells led to extracellular release of LPLDact. ATX mRNA expression was highly up-regulated during adipocyte differentiation of 3T3F442A-preadipocytes. This up-regulation was paralleled by the ability of newly differentiated adipocytes to release LPLDact and LPA. Differentiation-dependent up-regulation of ATX expression was also observed in a primary culture of mouse preadipocytes. Treatment of 3T3F442A-preadipocytes with concentrated conditioned medium from ATX-expressing COS-7 cells led to an increase in cell number as compared with concentrated conditioned medium from ATX non-expressing COS-7 cells. The specific effect of ATX on preadipocyte proliferation was completely suppressed by co-treatment with a LPA-hydrolyzing phospholipase, phospholipase B. Finally, ATX expression was found in mature adipocytes isolated from mouse adipose tissue and was substantially increased in genetically obese-diabetic db/db mice when compared with their lean siblings. In conclusion, the present work shows that ATX is responsible for the LPLDact released by adipocytes and exerts a paracrine control on preadipocyte growth via an LPA-dependent mechanism. Up-regulations of ATX expression with adipocyte differentiation and genetic obesity suggest a possible involvement of this released protein in the development of adipose tissue and obesity-associated pathologies.

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Autotaxin and its product lysophosphatidic acid suppress brown adipose differentiation and promote diet-induced obesity in mice.

Publications

Autotaxin and its product lysophosphatidic acid suppress brown adipose differentiation and promote diet-induced obesity in mice.

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