Heparan Sulfate Proteoglycans Undergo Differential Expression Alterations in Alzheimer Disease Brains

Previous studies have reported that heparan sulfate proteoglycans (HSPGs) promote amyloid-beta peptide and tau fibrillization in Alzheimer disease (AD) and provide resistance against proteolytic breakdown. We compared the expression levels of 17 HSPG core proteins in 18 AD cases and 6 controls. RT-PCR was used to analyze transcription levels. Immunohistochemistry was performed to localize HSPGs in the brain tissue. We detected expression of all HSPG genes investigated. SDC1, GPC3, and CD44v3 showed the lowest levels of expression, while SDC3 and GPC1 showed the highest. Remarkably, SDC4 and SRGN were overexpressed in most of the areas analyzed. Immunohistochemistry revealed the presence of both SDC4 and SRGN mostly associated with tau and amyloid-β pathology throughout the AD brains. In conclusion, in view of the involvement of HSPGs in AD pathology, especially SDC4 and SRGN, there would seem to be a relationship between the regulation of core protein expression and the pathological features suggesting HSPGs are potential inducers of the disease.