Mutations in DMRT3 Affect Locomotion in Horses and Spinal Circuit Function in Mice Lisa S
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University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Faculty Papers and Publications in Animal Science Animal Science Department 8-30-2012 Mutations in DMRT3 Affect Locomotion in Horses and Spinal Circuit Function in Mice Lisa S. Andersson Swedish University of Agricultural Sciences Martin Larhammar Uppsala Universitet Fatima Memic Uppsala Universitet Hanna Wootz Uppsala Universitet Doreen Schwochow Swedish University of Agricultural Sciences See next page for additional authors Follow this and additional works at: http://digitalcommons.unl.edu/animalscifacpub Part of the Biomechanics Commons, Cellular and Molecular Physiology Commons, Genetics Commons, Molecular Genetics Commons, Veterinary Anatomy Commons, and the Zoology Commons Andersson, Lisa S.; Larhammar, Martin; Memic, Fatima; Wootz, Hanna; Schwochow, Doreen; Rubin, Carl-Johan; Patra, Kalicharan; Arnason, Thorvaldur; Wellbring, Lisbeth; Hjälm, Göran; Imsland, Freyja; Petersen, Jessica Lynn; McCue, Molly E.; Mickelson, James R.; Cothran, Gus; Ahituv, Nadav; Roepstorff, Lars; Mikko, Sofia; Vallstedt, Anna; Lindgren, Gabriella; Andersson, Leif; and Kullander, Klas, "Mutations in DMRT3 Affect Locomotion in Horses and Spinal Circuit Function in Mice" (2012). Faculty Papers and Publications in Animal Science. 807. http://digitalcommons.unl.edu/animalscifacpub/807 This Article is brought to you for free and open access by the Animal Science Department at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Faculty Papers and Publications in Animal Science by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Authors Lisa S. Andersson, Martin Larhammar, Fatima Memic, Hanna Wootz, Doreen Schwochow, Carl-Johan Rubin, Kalicharan Patra, Thorvaldur Arnason, Lisbeth Wellbring, Göran Hjälm, Freyja Imsland, Jessica Lynn Petersen, Molly E. McCue, James R. Mickelson, Gus Cothran, Nadav Ahituv, Lars Roepstorff, Sofia Mikko, Anna Vallstedt, Gabriella Lindgren, Leif Andersson, and Klas Kullander This article is available at DigitalCommons@University of Nebraska - Lincoln: http://digitalcommons.unl.edu/animalscifacpub/807 Andersson, Larhammar, Memic, Wootz, Schwochow, Rubin, Patra, Arnason, Wellbring, Hjälm, Imsland, Petersen, McCue, Mickelson, Cothran, Ahituv, Roepstorff, Mikko, Vallstedt, Lindgren, Andersson & Kullander in Nature (August 30, 2012) 488. Copyright 2012, the authors. Used by permission. LETTER doi:10.1038/nature11399 Mutations in DMRT3 affect locomotion in horses and spinal circuit function in mice Lisa S. Andersson1*, Martin Larhammar2*, Fatima Memic2*, Hanna Wootz2*, Doreen Schwochow1, Carl-Johan Rubin3, Kalicharan Patra2, Thorvaldur Arnason4, Lisbeth Wellbring1,Go¨ran Hja¨lm3, Freyja Imsland3, Jessica L. Petersen5, Molly E. McCue5, James R. Mickelson5, Gus Cothran6, Nadav Ahituv7,8, Lars Roepstorff9, Sofia Mikko1, Anna Vallstedt2, Gabriella Lindgren1, Leif Andersson1,3* & Klas Kullander2* Locomotion in mammals relies on a central pattern-generating interval chr23:22628976–23315071. We resequenced selected regions circuitry of spinal interneurons established during development of the 684-kb interval in a panel of four- and five-gaited Icelandic that coordinates limb movement1. These networks produce left– horses. The five-gaited horses were all homozygous for a minimal right alternation of limbs as well as coordinated activation of flexor 438-kb haplotype (chr23:22877015–23315071), that was inferred to and extensor muscles2. Here we show that a premature stop codon be identical-by-descent (IBD; Supplementary Table 2). This region in the DMRT3 gene has a major effect on the pattern of locomotion contains only three genes encoding different isoforms of the doublesex in horses. The mutation is permissive for the ability to perform and mab-3 related transcription factors, DMRT1-3 (Fig. 1e). The alternate gaits and has a favourable effect on harness racing per- DMRT family of transcription factors carry a DM (dsx and mab-3) formance. Examination of wild-type and Dmrt3-null mice demon- DNA-binding domain, conferring sequence-specific DNA binding strates that Dmrt3 is expressed in the dI6 subdivision of spinal cord distinct from a classical zinc-finger4. neurons, takes part in neuronal specification within this subdivi- We performed whole-genome resequencing of one four-gaited and sion, and is critical for the normal development of a coordinated one five-gaited Icelandic horse, homozygous for opposite alleles at the locomotor network controlling limb movements. Our discovery SNP associated with the ability to pace. Average sequence coverage of positions Dmrt3 in a pivotal role for configuring the spinal circuits 303 was obtained and polymorphisms identified in the critical 438-kb controlling stride in vertebrates. The DMRT3 mutation has had a interval were compiled (Supplementary Table 3). Homozygosity major effect on the diversification of the domestic horse, as the mapping using the sequenced five-gaited horse confirmed an IBD altered gait characteristics of a number of breeds apparently region of about 438 kb. In this interval, we identified 65 sequence dif- require this mutation. ferences (60 SNPs and five small insertions/deletions) unique to the Horses show considerable variation in the pattern of locomotion. five-gaited horse when comparing data for the two horses and the The three naturally occurring gaits in all equids are, in order of increas- reference genome (Supplementary Table 4); no structural rearrange- ing speed, walk, trot and canter/gallop. Some horses can use alternate ments were detected. We found five intronic or intragenic SNPs at sites gaits, typically at intermediate speed, and ‘gaitedness’ is a trait upon showing some degree of evolutionary conservation, and a single base which many specialized breeds have been developed. Based on vari- change at nucleotide position chr23:22999655 causing a premature stop ation in footfall pattern, timing and cadence, these alternate gaits can be at codon 301 in DMRT3 (DMRT3_Ser301STOP; Fig. 1f). The allele is generally divided into four categories: pace, regular rhythm ambling, expected to encode a truncated protein lacking 174 amino acid residues lateral ambling and diagonal ambling (Supplementary Notes and of the full-length protein (Fig. 1g), of which 161 (92.5%) are identical Supplementary Table 1). Pace is a two-beat gait in which the horse between human and horse Dmrt3. DMRT3_Ser301STOP was evaluated moves the two legs on the same side of the body in a synchronized, as the candidate causative mutation. lateral movement (Fig. 1a) in contrast to the trot, where the diagonal We genotyped 352 additional Icelandic horses and found that all but front and hind legs move forward and backward together (Fig. 1b). one of the five-gaited horses were homozygous A/A for the DMRT3 Ambling gaits are four-beat gaits in which footfall pattern, foot place- nonsense mutation (Table 1); further investigation of competition ment and timing are often unique to specific breeds (Supplementary records revealed that this single discordant horse was most likely Notes and Supplementary Table 1). To¨lt is a regular ambling gait char- phenotypically misclassified. In contrast, only 31% of the four-gaited acteristic of the Icelandic horse. Many Icelandic horses also have the horses were homozygous A/A (P 5 2.4 3 10214). Thus, homozygosity ability to pace and test scores for pace show a bimodal distribution for the DMRT3 nonsense mutation is required for the ability to pace (Fig. 1c) and high heritability, in the range 0.60–0.73 (ref. 3). in this breed. The observation that a considerable number of A genome-wide association analysis using 30 Icelandic horses homozygous mutant horses are considered four-gaited may reflect classified as four-gaited (walk, to¨lt, trot and gallop) and 40 classified phenotype misclassifications, but more likely incomplete penetrance as five-gaited (walk, to¨lt, trot, gallop and pace) revealed a highly sig- due to other genetic factors, maturity and environmental effects, in nificant association between the ability to pace and a single nucleotide particular training. polymorphism (SNP; BIEC2_620109) at nucleotide position 22967656 The DMRT3 genotype distribution across breeds was markedly on chromosome 23 (Fig. 1d). The two flanking markers showed only dichotomous, with the mutation occurring at high frequency in all weak association to the pacing phenotype, indicating that the muta- gaited breeds, whereas all tested non-gaited horses were homozygous tion(s) underlying the association is located within the 684-kilobases wild type (Table 1), with the exception of horses used for harness 1Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, SE-75124 Uppsala, Sweden. 2Department of Neuroscience, Uppsala University, SE-75124 Uppsala, Sweden. 3Department of Medical Biochemistry and Microbiology, Uppsala University, SE-75123 Uppsala, Sweden. 4Faculty of Land and Animal Resources, The Agricultural University of Iceland, IS-311 Borgarnes, Iceland. 5College of Veterinary Medicine, University of Minnesota, St Paul, Minnesota 55108, USA. 6Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas 77483, USA. 7Department of Bioengineering and Therapeutic Sciences, University of California San Francisco, San Francisco, California 94143, USA. 8Institute for Human Genetics, University of California San Francisco,