Exploring the Biological Connection Between Tau and PrP^C in Neuronal Cells: GSK3β as a Possible Key Player

Cellular prion protein (PrP^C) and tau are highly expressed in the brain and overlap at the cellular level in neurons. Both proteins contribute directly to neurodegeneration processes in a misfolding state, although in their natural conformation, they play important roles in neurogenesis that could have a common link according to the recent literature. In this sense, it is well known that the proteinase-K resistant PrP^C isoform (PrP^Sc), the prion, is the causal agent of prionopathies. And misfolded tau, which is responsible for tauopathies, is considered "prion-like" because it displays similar behavior to prions in terms of self-aggregation and spreading properties. At the physiological level, PrP^C potentiates neuronal differentiation while tau intervenes in axonal maturation and elongation. Likewise, recent studies from our laboratory reported that PrP^C directly affects the alternative splicing of tau through inhibition of GSK3β while tau, in turn, can regulate PRNP transcription. In this review, we first describe the biology and physiological roles of PrP^C and tau in the central nervous system (CNS). Second, in the effort to improve our understanding of a possible cooperation between them in various cellular circumstances, we also discuss the molecular convergence points between PrP^C and tau in neurodegeneration and in natural neuronal physiology.