adipocyte protein 2

About: adipocyte protein 2 is a research topic. Over the lifetime, 1058 publications have been published within this topic receiving 73098 citations. The topic is also known as: A-FABP & AFABP.

A Novel Serum Protein Similar to C1q, Produced Exclusively in Adipocytes

Abstract: We describe a novel 30-kDa secretory protein, Acrp30 (adipocyte complement-related protein of 30 kDa), that is made exclusively in adipocytes and whose mRNA is induced over 100-fold during adipocyte differentiation. Acrp30 is structurally similar to complement factor C1q and to a hibernation-specific protein isolated from the plasma of Siberian chipmunks; it forms large homo-oligomers that undergo a series of post-translational modifications. Like adipsin, secretion of Acrp30 is enhanced by insulin, and Acrp30 is an abundant serum protein. Acrp30 may be a factor that participates in the delicately balanced system of energy homeostasis involving food intake and carbohydrate and lipid catabolism. Our experiments also further corroborate the existence of an insulin-regulated secretory pathway in adipocytes.

Proteolytic cleavage product of 30-kDa adipocyte complement-related protein increases fatty acid oxidation in muscle and causes weight loss in mice

Abstract: Adipocyte complement-related protein (30 kDa) (Acrp30), a secreted protein of unknown function, is exclusively expressed in differentiated adipocytes; its mRNA is decreased in obese humans and mice. Here we describe novel pharmacological properties of the protease-generated globular head domain of Acrp30 (gAcrp30). Acute treatment of mice with gAcrp30 significantly decreased the elevated levels of plasma free fatty acids caused either by administration of a high fat test meal or by i.v. injection of Intralipid. This effect of gAcrp30 was caused, at least in part, by an acute increase in fatty acid oxidation by muscle. As a result, daily administration of a very low dose of gAcrp30 to mice consuming a high-fat/sucrose diet caused profound and sustainable weight reduction without affecting food intake. Thus, gAcrp30 is a novel pharmacological compound that controls energy homeostasis and exerts its effect primarily at the peripheral level.

Myocardial Fatty Acid Metabolism in Health and Disease

Abstract: There is a constant high demand for energy to sustain the continuous contractile activity of the heart, which is met primarily by the β-oxidation of long-chain fatty acids. The control of fatty acid β-oxidation is complex and is aimed at ensuring that the supply and oxidation of the fatty acids is sufficient to meet the energy demands of the heart. The metabolism of fatty acids via β-oxidation is not regulated in isolation; rather, it occurs in response to alterations in contractile work, the presence of competing substrates (i.e., glucose, lactate, ketones, amino acids), changes in hormonal milieu, and limitations in oxygen supply. Alterations in fatty acid metabolism can contribute to cardiac pathology. For instance, the excessive uptake and β-oxidation of fatty acids in obesity and diabetes can compromise cardiac function. Furthermore, alterations in fatty acid β-oxidation both during and after ischemia and in the failing heart can also contribute to cardiac pathology. This paper reviews the regulation of myocardial fatty acid β-oxidation and how alterations in fatty acid β-oxidation can contribute to heart disease. The implications of inhibiting fatty acid β-oxidation as a potential novel therapeutic approach for the treatment of various forms of heart disease are also discussed.

The opposing effects of n-3 and n-6 fatty acids

Abstract: Polyunsaturated fatty acids (PUFAs) can be classified in n-3 fatty acids and n-6 fatty acids, and in westernized diet the predominant dietary PUFAs are n-6 fatty acids. Both types of fatty acids are precursors of signaling molecules with opposing effects, that modulate membrane microdomain composition, receptor signaling and gene expression. The predominant n-6 fatty acid is arachidonic acid, which is converted to prostaglandins, leukotrienes and other lipoxygenase or cyclooxygenase products. These products are important regulators of cellular functions with inflammatory, atherogenic and prothrombotic effects. Typical n-3 fatty acids are docosahexaenoic acid and eicosapentaenoic acid, which are competitive substrates for the enzymes and products of arachidonic acid metabolism. Docosahexaenoic acid- and eicosapentaenoic acid-derived eicosanoids antagonize the pro-inflammatory effects of n-6 fatty acids. n-3 and n-6 fatty acids are ligands/modulators for the nuclear receptors NFkappaB, PPAR and SREBP-1c, which control various genes of inflammatory signaling and lipid metabolism. n-3 Fatty acids down-regulate inflammatory genes and lipid synthesis, and stimulate fatty acid degradation. In addition, the n-3/n-6 PUFA content of cell and organelle membranes, as well as membrane microdomains strongly influences membrane function and numerous cellular processes such as cell death and survival.

ADD1/SREBP1 promotes adipocyte differentiation and gene expression linked to fatty acid metabolism.

Abstract: Adipocyte determination and differentiation-dependent factor 1 (ADD1) is a member of the basic helix-loop-helix leucine zipper (bHLH-LZ) family of transcription factors that binds to two distinct DNA sequences and has been associated with both adipocyte development and cholesterol homeostasis (where it has been termed SREBP1). To investigate the biological role of ADD1, we expressed wild-type and dominant negative forms of this protein with retroviral vectors in preadipocytes and nonadipogenic cells. A dominant-negative form of ADD1 with a point mutation in the DNA-binding domain sharply represses the differentiation of 3T3-L1 cells as observed morphologically or by the expression of adipocyte-specific mRNAs. When NIH-3T3 cells ectopically expressing ADD1 are cultured under hormonal conditions not favoring differentiation, they do not overtly differentiate but still activate expression of mRNAs for fatty acid synthase (FAS) and lipoprotein lipase (LPL), two key genes that regulate fatty acid metabolism. Under culture conditions permissive for differentiation including a PPAR activator, 15%-20% of the cells expressing ADD1 undergo adipogenesis while 2%-3% of cells containing a control vector differentiate. Simultaneous expression of ADD1 with PPARgamma increases the transcriptional activity of this adipogenic nuclear hormone receptor, suggesting involvement of ADD1 in this pathway. These data indicate that ADD1 plays an important role in fat cell gene expression and differentiation, and suggest that it may function by augmenting a step in PPARgamma-mediated transcription.