Adiponectin Receptor-1 in rat heart tissue was detected by
Anti-Adiponectin Receptor-1 (357-375) (Human) Serum
(Catalog No.: H-001-44) (1:200)

New Antibody for Adiponectin Receptor 2 Immunohistochemistry

Adiponectin (also known as 30-kDa adipocyte complement-related protein; Acrp30) is a hormone secreted by adipocytes that acts as an antidiabetic and anti-atherogenic adipokine. Levels of adiponectin in the blood are decreased under conditions of obesity, insulin resistance and type 2 diabetes. Administration of adiponectin causes glucose-lowering effects and ameliorates insulin resistance in mice. Conversely, adiponectin-deficient mice exhibit insulin resistance and diabetes. This insulin-sensitizing effect of adiponectin seems to be mediated by an increase in fatty-acid oxidation through activation of AMP kinase and PPAR-alpha. Here we report the cloning of complementary DNAs encoding adiponectin receptors 1 and 2 (AdipoR1 and AdipoR2) by expression cloning. AdipoR1 is abundantly expressed in skeletal muscle, whereas AdipoR2 is predominantly expressed in the liver. These two adiponectin receptors are predicted to contain seven transmembrane domains, but to be structurally and functionally distinct from G-protein-coupled receptors. Expression of AdipoR1/R2 or suppression of AdipoR1/R2 expression by small-interfering RNA supports our conclusion that they serve as receptors for globular and full-length adiponectin, and that they mediate increased AMP kinase and PPAR-alpha ligand activities, as well as fatty-acid oxidation and glucose uptake by adiponectin.

Expression of adiponectin receptors in human macrophages and regulation by agonists of the nuclear receptors PPARalpha, PPARgamma, and LXR
Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors expressed in macrophages where they control cholesterol homeostasis and inflammation. In an attempt to identify new PPARalpha and PPARgamma target genes in macrophages, a DNA array-based global gene expression profiling experiment was performed on human primary macrophages treated with specific PPARalpha and PPARgamma agonists. Surprisingly, AdipoR2, one of the two recently identified receptors for adiponectin, an adipocyte-specific secreted hormone with anti-diabetic and anti-atherogenic activities, was found to be induced by both PPARalpha and PPARgamma. AdipoR2 induction by PPARalpha and PPARgamma in primary and THP-1 macrophages was confirmed by Q-PCR analysis. Interestingly, treatment with a synthetic LXR agonist induced the expression of both AdipoR1 and AdipoR2. Furthermore, co-incubation with a PPARalpha ligand and adiponectin resulted in an additive effect on the reduction of macrophage cholesteryl ester content. Finally, AdipoR1 and AdipoR2 are both present in human atherosclerotic lesions. Moreover, AdipoR1 is more abundant than AdipoR2 in monocytes and its expression decreases upon differentiation into macrophages, whereas AdipoR2 remains constant. In conclusion, AdipoR1 and AdipoR2 are expressed in human atherosclerotic lesions and macrophages and can be modulated by PPAR and LXR ligands, thus identifying a mechanism of crosstalk between adiponectin and these nuclear receptor signaling pathways.

Chinetti G, et al. Biochem Biophys Res Commun. 2004 Jan 30;314(1):151-8

Growth hormone is a positive regulator of adiponectin receptor 2 in 3T3-L1 adipocytes

The fat-derived protein adiponectin is an important insulin-sensitizing adipocytokine which is downregulated in insulin resistance and obesity. Recently, two receptors of this adipose-expressed protein called adiponectin receptor 1 (AdipoR1) and 2 (AdipoR2) have been cloned. To clarify expression and regulation of these receptors in fat cells, AdipoR1 and AdipoR2 mRNA was measured by quantitative real-time reverse transcription-polymerase chain reaction during differentiation of 3T3-L1 adipocytes and after treatment with various hormones known to induce insulin resistance. Interestingly, AdipoR2 synthesis was significantly increased up to 4.8-fold during differentiation of 3T3-L1 preadipocytes, whereas AdipoR1 expression was only augmented up to 1.4-fold. Furthermore, growth hormone (GH) induced AdipoR2, but not AdipoR1 mRNA by up to 2.4-fold in a dose- and time-dependent fashion with significant stimulation detectable at concentrations as low as 5 ng/ml GH and as early as 2 h after effector addition. The positive effect of GH on AdipoR2 expression could be reversed by withdrawal of the hormone for 24 h. In contrast, other key hormones involved in the regulation of insulin resistance and energy metabolism such as insulin, isoproterenol, dexamethasone, triiodothyronine, angiotensin 2, tumor necrosis factor alpha, and interleukin-6 did not influence AdipoR1 and AdipoR2 synthesis in vitro. Taken together, our results suggest that AdipoR2 expression is differentiation-dependent and selectively regulated by GH implying a potential role of this hormone in adiponectin-associated alterations of insulin sensitivity and energy homeostasis.

Fasshauer M, et al. FEBS Lett. 2004 Jan 30;558(1-3):27-32

Northern blot analysis of AdipoR1 (left panel) and AdipoR2 (right panel) mRNA in human tissues (lanes: 1, brain; 2, heart; 3, skeletal muscle; 4, colon; 5, thymus; 6, spleen;7,kidney 8, liver;9,small intestine; 10, placenta; 11, lung; 12, peripheral blood leukocytes).
Yamauchi T, et al. Nature. 2003 Jun 12;423(6941):762-9

Effects of AdipoRs expression on Adipo binding in 293 cells. Binding of [125I] globular adiponectin (gAd) (a) or [125I] full-length adiponectin (Ad) (b) to 293T transfected with AdipoR1 or AdipoR2.
Yamauchi T, et al. Nature. 2003 Jun 12;423(6941):762-9