Ngs (notochord granular surface) encodes a novel type of intermediate filament family protein essential for notochord maintenance in zebrafish

Tong, X., Xia, Z., Zu, Y., Telfer, H., Hu, J., Yu, J., Liu, H., Zhang, Q., Sodmergen, D., Lin, S., and Zhang, B.
The Journal of biological chemistry   288(4): 2711-2720 (Journal)
Registered Authors
Hu, Jing, Lin, Shuo, Tong, Xiangjun, Xia, Zhidan, Zhang, Bo, Zu, Yao
cell differentiation, development, intermediate filaments, stress, zebrafish, ngs, notochord
MeSH Terms
  • Animals
  • Apoptosis
  • Cell Differentiation
  • Cell Proliferation
  • Gene Expression Regulation, Developmental*
  • Green Fluorescent Proteins/metabolism
  • In Situ Hybridization
  • Intermediate Filaments/metabolism*
  • Larva/metabolism
  • Microscopy, Electron, Transmission/methods
  • Models, Biological
  • Mutation
  • Notochord/embryology*
  • Notochord/metabolism
  • Phylogeny
  • Polymerase Chain Reaction/methods
  • Tissue Distribution
  • Xenopus
  • Zebrafish
23132861 Full text @ J. Biol. Chem.

Notochord is an important organ involved in embryonic patterning and locomotion. In zebrafish, mature notochord consists of a single stack of fully differentiated, large vacuolated cells called chordocytes, surrounded by a single layer of less differentiated notochordal epithelium cells called chordoblasts. Through genetic analysis of zebrafish lines carrying pseudo-typed retroviral insertions, a mutant exhibiting defective notochord with a granular appearance was isolated and the corresponding gene was identified as ngs (notochord granular surface), which was specifically expressed in notochord. In the mutants, the notochord started to degenerate from 32 hours post fertilization (hpf), and the chordocytes were then gradually replaced by smaller cells derived from chordoblasts. The granular notochord phenotype could be alleviated through anesthetizing the mutant embryos with tricaine to prevent their muscle contraction and locomotion. Phylogenetic analysis showed that ngs encodes a new type of intermediate filament (IF) family protein, thereafter named as chordostatin according to its function. Through transmission electron microcopy, bundles of 10-nm-thick IF like filaments were shown to be enriched in the chordocytes of the wild-type zebrafish embryos, while the chordocytes in ngs mutants lack IF like structures. Furthermore, chordostatin-EGFP fusion protein could assemble into filamentous network specifically in the chordocytes. Taken together, our work demonstrates that ngs encodes a novel type of IF protein and functions to maintain the notochord integrity for larval development and locomotion. Our work should shed light on the in-depth understanding of the mechanism of notochord structural maintenance as well as the evolution and biological function of IF family proteins.

Genes / Markers
Mutation and Transgenics
Human Disease / Model Data
Sequence Targeting Reagents
Engineered Foreign Genes
Errata and Notes