The transcriptional repressor REST regulates many neuronal genes by binding RE1 motifs. About one third of human RE1s are recently evolved and specific to primates. As changes in the activity of a transcription factor reverberate on its downstream targets, we assessed whether REST displays fast evolutionary rates in primates. We show that REST was targeted by very strong positive selection during primate evolution. Positive selection was also evident in the human lineage, with six selected sites located in a region that surrounds a VNTR in exon 4. Analysis of expression data indicated that REST brain expression peaks during aging in humans but not in other primates. Because a REST coding variant (rs3796529) was previously associated with protection from hippocampal atrophy in elderly subjects with mild cognitive impairment (MCI), we analyzed a cohort of Alzheimer disease (AD) continuum patients. Genotyping of two coding variants (rs3796529 and rs2227902) located in the region surrounding the VNTR indicated a role for rs2227902 in modulation of hippocampal volume loss, indirectly confirming a role for REST in neuroprotection. Experimental studies will be instrumental to determine the functional effect of positively selected sites in REST and the role of REST variants in neuropreservation/neurodegeneration.
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