An Antibody to p16INK4A Recognizes a Modified Form of Galectin-3

Abstract

Galectin-3 is a carbohydrate binding protein involved in multiple processes including cell-cycle regulation and apoptosis. The ability of galectin-3 to protect cells from apoptosis is dependent upon a region of the protein known as a BH-1 domain for its homology to the anti-apoptotic protein Bcl-2. Here, we show that a monoclonal antibody (MAb) to the human tumor suppressor protein p16INK4A recognizes a post-translationally modified form of human galectin-3. The modified form is detectable in only a subset of cell types expressing galectin-3, indicating that the modification is cell-type-specific. Although there is little amino acid sequence homology between p16INK4a and galectin-3, we show by epitope mapping that the modification directly affects the structure of galectin-3's BH-1 domain. Elucidation of the nature of this modification might provide further insight into galectin-3 function.

Epstein-Barr Virus and p16INK4A Methylation in Squamous Cell Carcinoma and Precancerous Lesions of the Cervix Uteri

“…Timmermann et al (32) demonstrated that epithelial cells gained increased activity of beta-galactosidase that is associated with senescence and produced p16 protein with no normal suppressor function. The reexpression of this incomplete protein detected by immnohistochemical method may be explained (33). …”