Research ArticleGENETICS

A single splice site mutation in human-specific ARHGAP11B causes basal progenitor amplification

Science Advances  07 Dec 2016:
Vol. 2, no. 12, e1601941
DOI: 10.1126/sciadv.1601941

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Abstract

The gene ARHGAP11B promotes basal progenitor amplification and is implicated in neocortex expansion. It arose on the human evolutionary lineage by partial duplication of ARHGAP11A, which encodes a Rho guanosine triphosphatase–activating protein (RhoGAP). However, a lack of 55 nucleotides in ARHGAP11B mRNA leads to loss of RhoGAP activity by GAP domain truncation and addition of a human-specific carboxy-terminal amino acid sequence. We show that these 55 nucleotides are deleted by mRNA splicing due to a single C→G substitution that creates a novel splice donor site. We reconstructed an ancestral ARHGAP11B complementary DNA without this substitution. Ancestral ARHGAP11B exhibits RhoGAP activity but has no ability to increase basal progenitors during neocortex development. Hence, a single nucleotide substitution underlies the specific properties of ARHGAP11B that likely contributed to the evolutionary expansion of the human neocortex.

Keywords
  • ARHGAP11B
  • neocortical expansion
  • human evolution
  • basal progenitors
  • neurogenesis
  • gene duplication
  • neocortex
  • brain size
  • RhoGAP
  • human-specific gene

This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.

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