Article

Evolution of human-specific neural SRGAP2 genes by incomplete segmental duplication.

Department of Genome Sciences, University of Washington School of Medicine, Seattle, 98195, USA.
Cell (impact factor: 32.4). 05/2012; 149(4):912-22. DOI:10.1016/j.cell.2012.03.033 pp.912-22
Source: PubMed

ABSTRACT Gene duplication is an important source of phenotypic change and adaptive evolution. We leverage a haploid hydatidiform mole to identify highly identical sequences missing from the reference genome, confirming that the cortical development gene Slit-Robo Rho GTPase-activating protein 2 (SRGAP2) duplicated three times exclusively in humans. We show that the promoter and first nine exons of SRGAP2 duplicated from 1q32.1 (SRGAP2A) to 1q21.1 (SRGAP2B) ∼3.4 million years ago (mya). Two larger duplications later copied SRGAP2B to chromosome 1p12 (SRGAP2C) and to proximal 1q21.1 (SRGAP2D) ∼2.4 and ∼1 mya, respectively. Sequence and expression analyses show that SRGAP2C is the most likely duplicate to encode a functional protein and is among the most fixed human-specific duplicate genes. Our data suggest a mechanism where incomplete duplication created a novel gene function-antagonizing parental SRGAP2 function-immediately "at birth" 2-3 mya, which is a time corresponding to the transition from Australopithecus to Homo and the beginning of neocortex expansion.

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    Nature 05/2005; 434(7034):752-5. · 36.28 Impact Factor
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Keywords

adaptive evolution
 
chromosome 1p12
 
cortical development gene Slit-Robo Rho GTPase-activating protein 2
 
encode
 
fixed human-specific duplicate genes
 
functional protein
 
haploid hydatidiform mole
 
identical sequences
 
incomplete duplication
 
larger duplications
 
likely duplicate
 
neocortex expansion
 
novel gene function-antagonizing parental SRGAP2 function-immediately
 
reference genome
 
SRGAP2
 
SRGAP2A
 
SRGAP2B
 
SRGAP2C
 
SRGAP2D
 
time corresponding