No abstract

Non-enzymatic modification of proteins by carbohydrates, known as glycation, leads to generation of advanced glycation end-products (AGEs). In our study we used in vitro generated AGEs to model glycation in vivo. We discovered in vivo analogs of unusual melibiose-adducts designated MAGEs (mel-derived AGEs) synthesized in vitro under anhydrous conditions with bovine serum albumin and myoglobin. Using nuclear magnetic resonance spectroscopy we have identified MAGEs as a set of isomers, with open-chain and cyclic structures, of the fructosamine moiety. We generated a mouse anti-MAGE monoclonal antibody and show for the first time that the native and previously undescribed analogous glycation product exists in living organisms and is naturally present in tissues of both invertebrates and vertebrates, including humans. We also report MAGE cross-reactive auto-antibodies in patients with diabetes. We anticipate our approach for modeling glycation in vivo will be a foundational methodology in cell biology. Further studies relevant to the discovery of MAGE may contribute to clarifying disease mechanisms and to the development of novel therapeutic options for diabetic complications, neuropathology, and cancer.

Nuclear ubiquitous casein and cyclin-dependent kinases substrate (NUCKS) is 27 kDa chromosomal protein of unknown function. Its amino acid composition as well as structure of its DNA binding domain resembles that of high-mobility group A, HMGA proteins. HMGA proteins are associated with various malignancies. Since changes in expression of HMGA are considered as marker of tumor progression, it is possible that similar changes in expression of NUCKS could be useful tool in diagnosis and prognosis of breast cancer. For identification and analysis of NUCKS we used proteomic and histochemical methods. Analysis of patient-matched samples of normal and breast cancer by mass spectrometry revealed elevated levels of NUCKS in protein extracts from ductal breast cancers. We elicited specific antibodies against NUCKS and used them for immunohistochemistry in invasive ductal carcinoma of breast. We found high expression of NUCKS in 84.3% of cancer cells. We suggest that such overexpression of NUCKS can play significant role in breast cancer biology.