title: Diversity in the glucose transporter-4 gene (SLC2A4) in humans reflects the action of natural selection along the old-world primates evolution.
abstract: BACKGROUND
  Glucose is an important source of energy for living organisms. In vertebrates it is ingested with the diet and transported into the cells by conserved mechanisms and molecules, such as the trans-membrane Glucose Transporters (GLUTs). Members of this family have tissue specific expression, biochemical properties and physiologic functions that together regulate glucose levels and distribution. GLUT4 -coded by SLC2A4 (17p13) is an insulin-sensitive transporter with a critical role in glucose homeostasis and diabetes pathogenesis, preferentially expressed in the adipose tissue, heart muscle and skeletal muscle. We tested the hypothesis that natural selection acted on SLC2A4.
  
  
  RESULTS
  We re-sequenced SLC2A4 and genotyped 104 SNPs along a approximately 1 Mb region flanking this gene in 102 ethnically diverse individuals. Across the studied populations (African, European, Asian and Latin-American), all the eight common SNPs are concentrated in the N-terminal region upstream of exon 7 ( approximately 3700 bp), while the C-terminal region downstream of intron 6 ( approximately 2600 bp) harbors only 6 singletons, a pattern that is not compatible with neutrality for this part of the gene. Tests of neutrality based on comparative genomics suggest that: (1) episodes of natural selection (likely a selective sweep) predating the coalescent of human lineages, within the last 25 million years, account for the observed reduced diversity downstream of intron 6 and, (2) the target of natural selection may not be in the SLC2A4 coding sequence.
  
  
  CONCLUSIONS
  We propose that the contrast in the pattern of genetic variation between the N-terminal and C-terminal regions are signatures of the action of natural selection and thus follow-up studies should investigate the functional importance of different regions of the SLC2A4 gene.
authors.affiliation: Laboratory of Translational Genomics, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America. edutars@icb.ufmg.br
authors.forename: Eduardo
authors.initials: E
authors.lastname: Tarazona-Santos
authors.forename: Cristina
authors.initials: C
authors.lastname: Fabbri
authors.forename: Meredith
authors.initials: M
authors.lastname: Yeager
authors.forename: Wagner C
authors.initials: WC
authors.lastname: Magalhaes
authors.forename: Laurie
authors.initials: L
authors.lastname: Burdett
authors.forename: Andrew
authors.initials: A
authors.lastname: Crenshaw
authors.forename: Davide
authors.initials: D
authors.lastname: Pettener
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Chanock
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D000818:Animals; D005006:Ethnicity; D019143:Evolution, Molecular; D014644:Genetic Variation; D005838:Genotype; D051275:Glucose Transporter Type 4 / Q000235:genetics*; D006801:Humans; D007328:Insulin / Q000378:metabolism; D008253:Macaca mulatta; D018482:Muscle, Skeletal / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D002679:Pan troglodytes; D017434:Protein Structure, Tertiary; D017422:Sequence Analysis, DNA
chemical_list: D051275:Glucose Transporter Type 4; D007328:Insulin; C495692:SLC2A4 protein, human