Analysis of a zebrafish dync1h1 mutant reveals multiple functions for cytoplasmic dynein 1 during retinal photoreceptor development

Insinna, C., Baye, L.M., Amsterdam, A., Besharse, J.C., and Link, B.A.
Neural Development   5: 12 (Journal)
Registered Authors
Amsterdam, Adam, Baye, Lisa, Link, Brian
MeSH Terms
  • Animals
  • Axoneme/metabolism
  • Axoneme/ultrastructure
  • Cell Differentiation/genetics
  • Cytoplasmic Dyneins/antagonists & inhibitors
  • Cytoplasmic Dyneins/genetics*
  • Cytoplasmic Dyneins/metabolism
  • Dyneins/antagonists & inhibitors
  • Dyneins/genetics*
  • Gene Expression Regulation, Developmental/genetics
  • Microscopy, Electron, Transmission
  • Mutation/genetics*
  • Neurogenesis/physiology
  • Oligonucleotides, Antisense/pharmacology
  • Photoreceptor Cells/metabolism*
  • Photoreceptor Cells/ultrastructure
  • Retina/growth & development*
  • Retina/metabolism*
  • Retina/ultrastructure
  • Transport Vesicles/physiology
  • Transport Vesicles/ultrastructure
  • Zebrafish/growth & development*
  • Zebrafish Proteins/genetics*
20412557 Full text @ Neural Dev.
BACKGROUND: Photoreceptors of the retina are highly compartmentalized cells that function as the primary sensory neurons for receiving and initiating transmission of visual information. Proper morphogenesis of photoreceptor neurons is essential for their normal function and survival. We have characterized a zebrafish mutation, cannonball, that completely disrupts photoreceptor morphogenesis. RESULTS: Analysis revealed a non-sense mutation in cytoplasmic dynein heavy chain 1 (dync1h1), a critical subunit in Dynein1, to underlie the cannonball phenotypes. Dynein1 is a large minus-end directed, microtubule motor protein complex that has been implicated in multiple, essential cellular processes. In photoreceptors, Dynein1 is thought to mediate post-Golgi vesicle trafficking, while Dynein2 is thought to be responsible for outer segment maintenance. Surprisingly, cannonball embryos survive until larval stages, owing to wild-type maternal protein stores. Retinal photoreceptor neurons, however, are significantly affected by loss of Dync1h1, as transmission electron microscopy and marker analyses demonstrated defects in organelle positioning and outer segment morphogenesis and suggested defects in post-Golgi vesicle trafficking. Furthermore, dosage-dependent antisense oligonucleotide knock-down of dync1h1 revealed outer segment abnormalities in the absence of overt inner segment polarity and trafficking defects. Consistent with a specific function of Dync1h1 within the outer segment, immunolocalization showed that this protein and other subunits of Dynein1 and Dynactin localized to the ciliary axoneme of the outer segment, in addition to their predicted inner segment localization. However, knock-down of Dynactin subunits suggested that this protein complex, which is known to augment many Dynein1 activities, is only essential for inner segment processes as outer segment morphogenesis was normal. CONCLUSIONS: Our results indicate that Dynein1 is required for multiple cellular processes in photoreceptor neurons, including organelle positioning, proper outer segment morphogenesis, and potentially post-Golgi vesicle trafficking. Titrated knock-down of dync1h1 indicated that outer segment morphogenesis was affected in photoreceptors that showed normal inner segments. These observations, combined with protein localization studies, suggest that Dynein1 may have direct and essential functions in photoreceptor outer segments, in addition to inner segment functions.
Genes / Markers
Mutation and Transgenics
Human Disease / Model Data
Sequence Targeting Reagents
Engineered Foreign Genes
Errata and Notes
Correction in: Neural Dev. 2010 Aug; 5(1): 19
After publication of our recent analysis of the zebrafish dync1h1 gene [1], we discovered a typographical error in the Methods. The sequence listed for the dyn1h1 ATG morpholino omits 2 nucleotides (in bold below).
The correct sequence is:

dyn1h1 ATG morpholino: 5'’-CGCCGCTGTCAGACATTTCCTACAC-3’'

The morpholino oligonucleotide that was synthesized and used for our studies was correct and the results were therefore not affected. We apologize for this typographical error.