The enzymatic degradation of heparan sulfate

Glycosaminoglycans (GAGs) such as heparan sulfate (HS) interact with a number of factors in the extracellular matrix (ECM) and as a consequence play a key role in the metabolic processes occurring within the cell. The dynamic synthesis and degradation of HS (and all GAGs) are necessary for ensuring that optimal chains are present for these functions. The degradation of HS begins at the cell surface and finishes in the lysosome, after which components can be recycled. Deficiencies or mutations in the lysosomal enzymes that process GAGs result in rare Mucopolysaccharidoses disorders (MPSs). There are few treatments available for these genetically inherited diseases and those that are available often do not treat the neurological symptoms of the disease. In this review, we discuss the enzymes involved in the degradation of HS and their related diseases, with emphasis on those located in the lysosome.