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FOXP2 , verbal dyspraxia, and the evolution of human language

FOXP2 , verbal dyspraxia, and the evolution of human language. Andrew Tritt. Verbal Dyspraxia. Speech disorder affecting individuals ability to correctly pronounce sounds, syllables, and words Inconsistent speech Trouble ordering things (not just speech)

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FOXP2 , verbal dyspraxia, and the evolution of human language

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  1. FOXP2 , verbal dyspraxia, and the evolution of human language Andrew Tritt

  2. Verbal Dyspraxia • Speech disorder affecting individuals ability to correctly pronounce sounds, syllables, and words • Inconsistent speech • Trouble ordering things (not just speech) • Difficulty learning how to read and spell • Difficulties with other motor tasks • Estimated 5-20% affected • Jewel and Brush

  3. FOXP2 – forkhead box P2 • 715 AA, 78900.04 Da, located on chromosome 7 • Gene Ontology: • Biological processes • Caudate nucleus development • Putamen development • Molecular function • DNA binding • Protein homodimerization • Cellular component • Nucleus

  4. FOXP2 – forkhead box P2 • Member of forkhead box transcription factors • Subgroup of helix-turn-helix class • Forkhead box (a.k.a. winged-helix) • Mutations in FOXP2 linked to verbal dyspraxia • Also thought to play a role in autism • Linked to: • Song in song-birds • Echolocation in bats • Pattern learning in mice

  5. Forkhead box proteins • FOXE1, FOXE2, FOXE3 • FOXF1, FOXF2 • FOXG1 • FOXH1 • FOXI1, FOXI2 • FOXJ1, FOXJ2, FOXJ3 • FOXK1, FOXK2 • FOXL1, FOXL2 • FOXM1 • FOXN1, FOXN2, FOXN3, FOXN4 • FOXO1, FOXO2, FOXO3, FOXO4 • FOXP1, FOXP2, FOXP3, FOXP4 • FOXQ1 • FOXR1, FOXR2 • FOXA1, FOXA2, FOXA3 • FOXB1, FOXB2 • FOXC1, FOXC2 • FOXD1, FOXD2, FOXD3, FOXD4, FOXD5, FOXD6 Image from http://www.neuroscience.ox.ac.uk/directory/simon-fisher

  6. Protein structure • Leucine-zipper domain • Required for dimerization • Forkhead box domain • Required for DNA recognition • Mutations here linked to disease • Similar in other organisms • Polyglutamine tract Image from SMART

  7. Protein Structure • Protein highly conserved given phylogenetic distance Mouse Human Zebra finch Images from SMART

  8. Why FOXP2? • KE family • 30 members across three generations • Roughly half of the family members have impairment • Correlation between FOXP2 and impairment • Genetic origins of language Image from http://www.well.ox.ac.uk/~simon/SPCH1/index.shtml

  9. Root of Human Language • Two mutations since divergence of chimp and humans • Fixation estimated to be within last 200,000 years • Show signs of natural selection • Some targets show signs of natural selection Image from http://www.imagingnotes.com/go/article_free.php?mp_id=1&Udo

  10. Phylogeny • Wooly horseshoe bat and zebra finch ??? • Done using parsimony • Use ML! Image created using PAUP*

  11. Future Directions • Make this harder to read! • Identify other TFs that FOXP2 interacts with • TAP-tag • Look into these proteins further • NFATc2 – Down’s Syndrome

  12. Future Directions • Look into target genes of FOXP2 • Determine function of targets • Tests for selection • Study other organisms with conspicuous traits • Mouse - pattern-learning and vocalization • Zebra finch – singing • ChIP-chip

  13. Questions ???

  14. References • Enard W, Przeworski M, Fisher SE, Lai CSL, Kitano WV, et al. (2002) Molecular evolution of FOXP2, a gene involved in speech and language. Nature 418:869–87. • SMART (2009) http://smart.embl-heidelberg.de/ • Spiteri E, Konopka G, Coppola G, Bornar J, Oldham M, Ou J, Vernes S, Fisher SE, Ren B, Geschwind DH (2007) Identification of transcription targets of FOXP2, a gene linked to speech and language in developing human brain. Cell 81:114-1157 • Swofford, D.L. 2002. PAUP*. Phylogenetic Analysis Using Parsimony (*and Other Methods). Version 4. Sinauer Associates, Sunderland, Massachusetts. • Vargha-Khadem F, Gadian DG, Copp A, Mishkin M (2005) FOXP2 and the neuroanatomy of speech and language. Nat Rev Neurosci 6:131–138.

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