Zinc-alpha2-glycoprotein (AZGP1) has been implicated in peripheral metabolism; however, its role in regulating energy metabolism in the brain, particularly in POMC neurons, remains unknown. Here, we show that AZGP1 in POMC neurons plays a crucial role in controlling whole-body metabolism. POMC neuron-specific overexpression of Azgp1 under high-fat diet conditions reduces energy intake, raises energy expenditure, elevates peripheral tissue leptin and insulin sensitivity, alleviates liver steatosis, and promotes adipose tissue browning. Conversely, mice with inducible deletion of Azgp1 in POMC neurons exhibit the opposite metabolic phenotypes, showing increased susceptibility to diet-induced obesity. Notably, an increase in AZGP1 signaling in the hypothalamus elevates STAT3 phosphorylation and increases POMC neuron excitability. Mechanistically, AZGP1 enhances leptin-JAK2-STAT3 signaling by interacting with acylglycerol kinase (AGK) to block its ubiquitination degradation. Collectively, these results suggest that AZGP1 plays a crucial role in regulating energy homeostasis and glucose/lipid metabolism by acting on hypothalamic POMC neurons.
Glycoproteins are important biomarkers for cancers, while most glycoproteomics biomarkers suffering from low sensitivity and specificity due to their uncharacterized glycan structures. AZGP1 is a potential biomarker for salivary diagnostics of lung cancer, which is used as a model glycoprotein in this study for method development. We initially analyzed salivary N-glycoproteome by using lectin affinity chromatography and more than 300 N-glycoproteins were identified, including AZGP1. 7 gel spots of AZGP1 were resolved by two-dimensional gel electrophoresis and further confirmed by two-dimensional western blot as well as mass spectrometry. The isomeric glycan structures of AZGP1 in these spots were systematically characterized both at composition level and at structure level. Our results revealed 10 glycan compositions for salivary AZGP1, including core fucosylated glycans on Asn128 and sialylated glycans on Asn109 and Asn112. We further compared the glycan structures of salivary AZGP1 from lung cancer group and control group. Accordingly, 14 and 7 potential glycan structures were successfully revealed, respectively. In total, 15 glycan compositions and 22 potential glycan structures were identified and characterized for AZGP1, including some different structures with the same compositions. In particular, 5 potential glycan structures were identified as lung cancer unique signatures. Our developed strategy holds promise for thorough identification of glycan structures on a target glycoprotein biomarker. In-depth characterization of its glycan structures will ultimately enhance its sensitivity and specificity for cancer detection.
危险品化学品经营许可证（带存储）