[The microtubule-associated protein tau in neurodegenerative diseases. Tauopathies].

INTRODUCTION: Microtubules are the essential components of the cytoskeleton, they are responsible for the formation and maintenance of the neuronal morphology and their specific connections. The microtubule associated proteins (MAPs) contribute to regulate the dynamism and stability of the microtubules, and therefore they are essential to maintain the correct function of the microtubules. Among them, tau is a protein that seems to be crucial in stabilizing the neuronal polarity. DEVELOPMENT: In this paper, factors affecting the affinity of tau to bind microtubules are reviewed, giving special attention to the processes that take place in the neurodegenerative diseases that present neurofibrillary tangles (NFTs), aggregates composed of modified tau in form of paired helical filaments (PHFs). One of the most important tau modification in this aberrant aggregates is the hyperphosphorylation. Thus, kinases and phosphatases responsible for tau modification could be altered in certain pathologies, leading to a decrease in the affinity of tau to bind microtubules and carrying out its self assembling and aberrant aggregation in the neurons of the affected nervous system regions. Those pathologies presenting a tau disfunction are known as tauopathies.