Protein accumulation is a hallmark of many neurodegenerative disorders. In Alzheimer’s disease (AD), a hyperphosphorylated form of the protein tau (p-tau) forms intracellular inclusions known as neurofibrillary tangles. Deposits of p-tau have also been found in the brains of patients with Down’s syndrome, supranuclear palsy, and prion disease. Mutations in tau have been causally associated with at least one inherited neurologic disorder, frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17), implying that tau abnormalities by themselves can be a primary cause of degenerative diseases of the CNS. Removal of these p-tau species may occur by both chaperone-mediated refolding and degradation. In this issue of the JCI, Dickey and colleagues show that a cochaperone protein, carboxyl terminus of Hsp70-interacting protein (CHIP), in a complex with Hsp90 plays an important role in the removal of p-tau (see the related article beginning on page 648). Pharmacologic manipulation of Hsp90 may be used to alleviate p-tau accumulation in disease.
Dmitry Goryunov, Ronald K.H. Liem
Cellular fates of abnormal tau.