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G2 arrest and impaired nucleocytoplasmic transport in mouse embryos lacking the proto-oncogene CAN/Nup214
J van Deursen1, J Boer, L Kasper
1Department of Genetics, St Jude Children's Research Hospital, Memphis, TN 38105, USA.
Abstract:
The vertebrate nucleopore complex (NPC) is a 125 MDa multiprotein assembly that mediates nucleocytoplasmic transport. One of its components, CAN/Nup214, is an FXFG repeat-containing protein known to be involved in myeloid leukemia in humans. We have devised a powerful genetic approach, using maternally derived protein in murine null embryos, to show that CAN/ Nup214 is essential for NPC function in vivo. We demonstrate that CAN-/- mouse embryonic stem (ES) cells are not viable and that CAN-/- embryos die in utero between 4.0 and 4.5 days postcoitum, following the depletion of their CAN from maternal sources. In 3.5-day-old mutant embryos, cultured in vitro, progressive depletion of CAN leads to cell cycle arrest in G2 phase, and eventually to blastocoel collapse, impaired NLS-mediated protein uptake and nuclear accumulation of polyadenylated RNA. Remarkably, these defective CAN-depleted embryos do not display any gross morphological abnormalities in their nuclear envelopes or NPCs. Our data suggest that CAN is critical to cell cycle progression and required for both nuclear protein import and mRNA export.
Insights
The nucleopore complex (NPC) protein CAN/Nup214 is vital for cell survival and function. Its absence causes embryonic lethality, cell cycle arrest, and impaired nuclear transport in mice.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- The vertebrate nucleopore complex (NPC) is a large assembly crucial for nucleocytoplasmic transport.
- CAN/Nup214, an FXFG repeat-containing protein, is a component of the NPC and implicated in human myeloid leukemia.
Purpose of the Study:
- To investigate the in vivo essentiality of CAN/Nup214 for NPC function using a genetic approach in murine models.
- To elucidate the specific cellular processes affected by CAN/Nup214 depletion.
Main Methods:
- Utilized maternally derived protein in murine null embryos to study CAN/Nup214 function.
- Generated and analyzed CAN knockout (CAN-/-) mouse embryonic stem (ES) cells and embryos.
- Cultured mutant embryos in vitro to observe the effects of CAN depletion on cellular processes.
Main Results:
- CAN-/- mouse ES cells are non-viable, and CAN-/- embryos exhibit embryonic lethality between 4.0 and 4.5 days postcoitum.
- CAN depletion in mutant embryos leads to G2 cell cycle arrest, blastocoel collapse, impaired nuclear protein import, and nuclear poly(A) RNA accumulation.
- No gross morphological abnormalities of nuclear envelopes or NPCs were observed in CAN-depleted embryos.
Conclusions:
- CAN/Nup214 is essential for NPC function and viability in vivo.
- CAN/Nup214 plays a critical role in cell cycle progression.
- CAN/Nup214 is required for both nuclear protein import and mRNA export.