ZFIN ID: ZDB-PUB-061020-39
Ubc9 Regulates Mitosis and Cell Survival during Zebrafish Development
Nowak, M., and Hammerschmidt, M.
Date: 2006
Source: Molecular biology of the cell   17(12): 5324-5336 (Journal)
Registered Authors: Hammerschmidt, Matthias, Nowak, Matthias
Keywords: none
MeSH Terms:
  • Animals
  • Body Patterning/physiology
  • Branchial Region/cytology
  • Branchial Region/embryology
  • Cartilage/abnormalities
  • Cell Count
  • Cell Death
  • Cell Proliferation
  • Cell Survival
  • Chondrocytes/cytology
  • DNA/metabolism
  • Embryo, Nonmammalian/abnormalities
  • Embryo, Nonmammalian/cytology*
  • Embryonic Development*
  • Gene Expression Regulation, Developmental
  • Mitosis*
  • RNA, Messenger/genetics
  • RNA, Messenger/metabolism
  • Ubiquitin-Conjugating Enzymes/deficiency
  • Ubiquitin-Conjugating Enzymes/genetics
  • Ubiquitin-Conjugating Enzymes/metabolism*
  • Zebrafish/embryology*
  • Zygote/cytology
PubMed: 17035631 Full text @ Mol. Biol. Cell
Many proteins are modified by conjugation with Sumo, a gene-encoded, ubiquitin-related peptide, which is transferred to its target proteins via an enzymatic cascade. A central component of this cascade is the E2-conjugating enzyme Ubc9, which is highly conserved across species. Loss-of-function studies in yeast, nematode, fruit fly, and mouse blastocystes point to multiple roles of Ubc9 during cell cycle regulation, maintenance of nuclear architecture, chromosome segregation, and viability. Here we show that in zebrafish embryos, reduction of Ubc9 activity by expression of a dominant negative version causes widespread apoptosis, similar to the effect described in Ubc9 deficient mice. However, antisense-based knock down of zygotic ubc9 leads to much more specific defects in late proliferating tissues, such as cranial cartilage and eyes. Affected cartilaginous elements are of relatively normal size and shape, but consist of fewer and larger cells. Stainings with mitotic markers and BrdU incorporation studies indicate that fewer chondrocyte precursors are in mitosis, whereas the proportion of cells in S-phase is unaltered. Consistently, FACS analyses reveal an increase in the number of cells with a DNA content of 4n or even 8n. Our data indicate an in vivo requirement of Ubc9 for G2/M transition and/or progression through mitosis during vertebrate organogenesis. Failed mitosis in the absence of Ubc9 is not necessarily coupled with cell death. Rather, cells can continue to replicate their DNA, grow to a larger size and finish their normal developmental program.