Sialidases as Potential Therapeutic Targets for Treatment of a Number of Human Diseases

Four human sialidases (hNEUs, E.C 3.2.1.18) have been identified. Each is an exosialidase identified as either NEU1, NEU2, NEU3, or NEU4. They exhibit differences in structure, subcellular distribution, substrate specificity, and the diseases with which they are associated. Similarly, microbial sialidases (NAs) may catalyze the release of sialyl residues from the same sialoglycoconjugates as hNEUs, even though they have low sequence homology with human NEUs. Use of sequence homology, plus the crystalline structure of human NEU2, has provided researchers with the basis for developing inhibitors that may differentiate between them. While microbial-induced diseases that use sialidase to complete their infectious cycle have been the driving force behind interrogation of possible NA inhibitors, errors affecting expression of functional hNEUs and their correlation with clinical problems has led to study of the sialidases per se. Information gained about sialidase structure, function, mechanism of action, mutations affecting expression, and their role(s) in disease, has provided the information about the different sialidases needed for development of specific therapies.