The zebrafish shocked gene encodes a glycine transporter and is essential for the function of early neural circuits in the CNS.
shocked (sho) is a zebrafish mutation that causes motor deficits attributable to CNS defects during the first2dof development. Mutant embryos display reduced spontaneous coiling of the trunk, diminished escape responses when touched, and an absence of swimming. A missense mutation in the slc6a9 gene that encodes a glycine transporter (GlyT1) was identified as the cause of the sho phenotype. Antisense knock-down of GlyT1 in wild-type embryos phenocopies sho, and injection of wild-type GlyT1 mRNA into mutants rescues them. A comparison of glycine-evoked inward currents in Xenopus oocytes expressing either the wild-type or mutant protein found that the missense mutation results in a nonfunctional transporter. glyt1 and the related glyt2 mRNAs are expressed in the hindbrain and spinal cord in nonoverlapping patterns. The fact that these regions are known to be required for generation of early locomotory behaviors suggests that the regulation of extracellular glycine levels in the CNS is important for proper function of neural networks. Furthermore, physiological analysis after manipulation of glycinergic activity in wild-type and sho embryos suggests that the mutant phenotype is attributable to elevated extracellular glycine within the CNS.
Cui
Wilson W
WW
University of Michigan, Ann Arbor, Michigan 48109, USA.
Low
Sean E
SE
Hirata
Hiromi
H
Saint-Amant
Louis
L
Geisler
Robert
R
Hume
Richard I
RI
Kuwada
John Y
JY
D000818:Animals; D002490:Central Nervous System / Q000196:embryology*; D004625:Embryo, Nonmammalian / Q000187:drug effects / Q000473:pathology / Q000503:physiopathology; D045604:Extracellular Fluid / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018390:Gene Targeting; D005998:Glycine / Q000378:metabolism*; D050487:Glycine Plasma Membrane Transport Proteins / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D009132:Muscles / Q000196:embryology / Q000502:physiology; D020125:Mutation, Missense; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D009865:Oocytes; D010641:Phenotype; D010812:Physical Stimulation; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012249:Rhombencephalon / Q000196:embryology / Q000378:metabolism; D012521:Sarcosine / Q000031:analogs & derivatives / Q000494:pharmacology; D013116:Spinal Cord / Q000196:embryology / Q000378:metabolism; D013550:Swimming; D014981:Xenopus; D015027:Zebrafish / Q000196:embryology / Q000235:genetics*; D029961:Zebrafish Proteins / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000235:genetics / Q000502:physiology*
D050487:Glycine Plasma Membrane Transport Proteins; C435025:N-(3-(4'-fluorophenyl)-3-(4'-phenylphenoxy)-3-(4'-phenylphenoxy)propyl)sarcosine; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; C507810:SLC6A5 protein, zebrafish; C507809:SLC6A9 protein, zebrafish; D029961:Zebrafish Proteins; D005998:Glycine; D012521:Sarcosine