Acetylome regulation by sirtuins in the brain: from normal physiology to aging and pathology.

Our understanding of the magnitude and physiological significance of proteome lysine acetylation remained incipient for five decades since it was first described. State-of-the-art methodologies, ranging from functional genomics to large-scale proteomics, have recently uncovered that this modification is more broadly represented in proteins than previously recognized, thus constituting the "acetylome." At present, it is estimated that acetylome covers only one tenth of the proteome, however, due its potential significance in physiology is capturing great attention. The first components of the cellular machinery, which finely orchestrate acetylome homeostasis, were identified by the end of last century. Since then, the majority of our growing knowledge concerning the physiological relevance of proteome reversible acetylation comes from the study of sirtuins, a unique type of lysine deacetylase that uses NAD(+). Sirtuins participate in a variety of cellular processes, ranging from transcription, DNA repair, energy balance, mitochondrial biogenesis and cell division, to apoptosis, autophagy and aging. Within the brain, besides their widespread epigenetic effects of dynamically modifying histones, sirtuins also target a variety of non-histone proteins either commonly deregulated in pathologies, or that participate in normal cerebral functions. For example, they modulate critical elements of the circadian rhythms, neurogenesis, synapses, cognition, serotonin synthesis, myelination, and proteins involved in neuropathology. Acetylome dynamics, and its regulation by sirtuins, may also help to better understand the molecular mechanisms underlying brain aging. This work reviews the pathways as orchestrated by the interplay between acetylome and sirtuins in the brain, from physiology involvement, to aging processes, and pathological settings.