Targeting the glycolytic pathway in cancer cells: glycolytic and regulatory functions of GAPDH

Abstract

Glyceraldehyde 3‐phosphate dehydrogenase (GAPDH) is a pivotal enzyme of the glycolytic pathway, and a regulatory protein in several cellular networks. Knockdown of GAPDH induces senescence in human cancer cells A549, as revealed by senescence biomarkers SA‐â‐galactosidase and DEC1. To assess the potential role of GAPDH as a molecular target within the cancer energy metabolism network, we (1) characterized structural elements of GAPDH polypeptide pertinent to its intranuclear functions, and (2) evaluated sensitivity of GAPDH‐depleted cells against a panel of chemotherapeutic agents. We performed site‐mutagenesis of the functional domains in GAPDH, and estimated the enzymatic properties, intracellular distribution, and intranuclear mobility of GAPDH mutated variants. The fluorescence recovery after photobleaching experiments revealed that the substitution of Thr and Ser by non‐phosphorylated amino acid residues significantly increased intranuclear mobility of GAPDH. Our results indicate that GAPDH phosphorylation is important both for GAPDH enzymatic activity, and interactions with intranuclear components. Identification of intranuclear functional partners of GAPDH is expected to define targets for development of novel antiproliferative agents.