Duplicated Gephyrin Genes Showing Distinct Tissue Distribution and Alternative Splicing Patterns Mediate Molybdenum Cofactor Biosynthesis, Glycine Receptor Clustering, and Escape Behavior in Zebrafish

Ogino, K., Ramsden, S.L., Keib, N., Schwarz, G., Harvey, R.J., and Hirata, H.
The Journal of biological chemistry   286(1): 806-817 (Journal)
Registered Authors
Hirata, Hiromi
Development, Neurobiology, Neuron, Synapses, Zebra fish
MeSH Terms
  • Alternative Splicing*
  • Amino Acid Sequence
  • Animals
  • Carrier Proteins/chemistry
  • Carrier Proteins/genetics*
  • Carrier Proteins/metabolism
  • Coenzymes/biosynthesis*
  • Escape Reaction*
  • Evolution, Molecular
  • Gene Duplication*
  • Gene Expression Regulation
  • Humans
  • Membrane Proteins/chemistry
  • Membrane Proteins/genetics*
  • Membrane Proteins/metabolism
  • Metalloproteins/biosynthesis*
  • Mice
  • Molecular Sequence Data
  • Neurons/metabolism
  • Protein Isoforms/chemistry
  • Protein Isoforms/genetics
  • Protein Isoforms/metabolism
  • Protein Multimerization
  • Protein Structure, Quaternary
  • Pteridines
  • RNA, Messenger/genetics
  • RNA, Messenger/metabolism
  • Rats
  • Receptors, Glycine/chemistry*
  • Receptors, Glycine/metabolism
  • Synapses/genetics
  • Zebrafish/genetics*
  • Zebrafish/metabolism
20843816 Full text @ J. Biol. Chem.
Gephyrin mediates the postsynaptic clustering of glycine receptors (GlyRs) and GABAA receptors at inhibitory synapses and molybdenum-dependent enzyme (molybdoenzyme) activity in non-neuronal tissues. Gephyrin knockout mice show a phenotype resembling both defective glycinergic transmission and molybdenum cofactor (Moco) deficiency and die within one day of birth due to starvation and dyspnea resulting from deficits in motor and respiratory networks, respectively. To address whether gephyrin function is conserved among vertebrates and whether gephyrin deficiency affects molybdoenzyme activity and motor development, we cloned and characterized zebrafish gephyrin genes. We here report that zebrafish have two gephyrin genes, gphna and gphnb. The former is expressed in all tissues and has both C3 and C4 cassette exons, whereas the latter is expressed predominantly in the brain and spinal cord and harbors only C4 cassette exons. We confirmed that all of the gphna and gphnb splicing isoforms have Moco synthetic activity. Antisense morpholino knockdown of either gphna or gphnb alone did not disturb synaptic clusters of GlyRs in the spinal cord and did not affect touch-evoked escape behaviors. However, on knockdown of both gphna and gphnb, embryos showed impairments in GlyR clustering in the spinal cord and, as a consequence, demonstrated touch-evoked startle response behavior, by contracting antagonistic muscles simultaneously, instead of displaying early coiling and late swimming behaviors, which are executed by side-to-side muscle contractions. These data indicate that duplicated gephyrin genes mediate Moco biosynthesis and control postsynaptic clustering of GlyRs, thereby mediating key escape behaviors in zebrafish.
Genes / Markers
Mutation and Transgenics
Human Disease / Model Data
Sequence Targeting Reagents
Engineered Foreign Genes
Errata and Notes