IMMUNOHISTOCHEMISTRY: GLUTAMINE SYNTHETASE

GLUTAMINE SYNTHETASE (GS) IS AN ENZYME THAT CATALYZES THE ATP-DEPENDENT CONDENSATION OF GLUTAMATE WITH AMMONIA TO FORM GLUTAMINE. GS CAN BE USED WITH A PANEL OF IHC MARKERS LIKE BETA-CATENIN, LIVER FATTY ACID BINDING PROTEIN, C-REACTIVE PROTEIN AND AMYLOID-A TO DISTINGUISH HEPATIC ADENOMA FROM FOCAL NODULAR HYPERPLASIA AND NONNEOPLASTIC LIVER. GS, A TARGET GENE OF BETA-CATENIN, IS EXPRESSED IN HEPATIC ADENOMAS WITH BETA-CATENIN MUTATIONS (TYPE 2), BUT IS NOT EXPRESSED IN HEPATIC ADENOMAS WITHOUT BETA-CATENIN MUTATIONS. GS IS EXPRESSED IN ZONE 3 OF NORMAL LIVER AND HAS A CHARACTERISTIC MAP-LIKE PATTERN IN FOCAL NODULAR HYPERPLASIA.IT IS MAINLY USED FOR THE CLASSIFICATION OF HEPATIC ADENOMAS AND THE IDENTIFICATION OF FOCAL NODULAR HYPERPLASIA.