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Heparan sulfate (HS) is a biopolymer consisting of variably sulfated repeating disaccharide units. The anticoagulant heparin is a highly sulfated intracellular variant of HS. HS has demonstrated roles in embryonic development, homeostasis, and human disease via non-covalent interactions with numerous cellular proteins, including growth factors and their receptors. HS can function as a co-receptor by enhancing receptor-complex formation. In other contexts, HS disrupts signaling complexes or serves as a ligand sink. The effects of HS on growth factor signaling are tightly regulated by the actions of sulfyltransferases, sulfatases, and heparanases. HS has important emerging roles in oncogenesis, and heparin derivatives represent potential therapeutic strategies for human cancers. Here we review recent insights into HS signaling in tumor proliferation, angiogenesis, metastasis, and differentiation. A cancer-specific understanding of HS signaling could uncover potential therapeutic targets in this highly actionable signaling network.

Entorhinal cortex neuropathology begins very early in Alzheimer's disease (AD), a disorder characterized by severe memory disruption. Indeed, loss of entorhinal volume is predictive of AD and two of the hallmark neuroanatomical markers of AD, amyloid plaques and neurofibrillary tangles (NFTs), are particularly prevalent in the entorhinal area of AD-afflicted brains. Gene transfer techniques were used to create a model neurofibrillary tauopathy by injecting a recombinant adeno-associated viral vector with a mutated human tau gene (P301L) into the entorhinal cortex of adult rats. The objective of the present investigation was to determine whether adult onset, spatially restricted tauopathy could be sufficient to reproduce progressive deficits in mnemonic function. Spatial memory on a Y-maze was tested for approximately three months post-surgery. Upon completion of behavioral testing the brains were assessed for expression of human tau and evidence of tauopathy. Rats injected with the tau vector became persistently impaired on the task after about six weeks of postoperative testing, whereas the control rats injected with a green fluorescent protein vector performed at criterion levels during that period. Histological analysis confirmed the presence of hyperphosphorylated tau and NFTs in the entorhinal cortex and neighboring retrohippocampal areas as well as limited synaptic degeneration of the perforant path. Thus, highly restricted vector-induced tauopathy in retrohippocampal areas is sufficient for producing progressive impairment in mnemonic ability in rats, successfully mimicking a key aspect of tauopathies such as AD.