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Prodomain-dependent nuclear localization of the caspase-2 (Nedd2) precursor. A novel function for a caspase prodomain
P A Colussi1, N L Harvey, S Kumar
1Hanson Centre for Cancer Research, Institute of Medical and Veterinary Science, Frome Road, Adelaide, South Australia 5000, Australia.
Abstract:
Caspases are cysteine proteases that play an essential role in apoptosis by cleaving several key cellular proteins. Despite their function in apoptosis, little is known about where in the cell they are localized and whether they are translocated to specific cellular compartments upon activation. In the present paper, using Aequorea victoria green fluorescent protein fusion constructs, we have determined the localization of Nedd2 (mouse caspase-2) and show that both precursor and processed caspase-2 localize to the cytoplasmic and the nuclear compartments. We demonstrate that the nuclear localization of caspase-2 is strictly dependent on the presence of the prodomain. A caspase-2 prodomain-green fluorescent protein localized to dot- and fiber-like structures mostly in the nucleus, whereas a protein lacking the prodomain was largely concentrated in the cytoplasm. We also show that an amino-terminal fusion of the prodomain of caspase-2 to caspase-3 mediates nuclear transport of caspase-3, which is normally localized in the cytoplasm. These results suggest that, in addition to roles in dimerization and recruitment through adaptors, the caspase-2 prodomain has a novel function in nuclear transport.
Insights
The caspase-2 prodomain dictates its nuclear transport, influencing apoptosis. This study reveals a novel nuclear localization function for the caspase-2 prodomain.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Caspases are critical cysteine proteases involved in apoptosis.
- Cellular localization and compartment-specific translocation of caspases upon activation remain largely uncharacterized.
Purpose of the Study:
- To determine the subcellular localization of Nedd2 (mouse caspase-2) and its precursor and processed forms.
- To investigate the role of the caspase-2 prodomain in its cellular localization and nuclear transport.
Main Methods:
- Utilized Aequorea victoria green fluorescent protein (GFP) fusion constructs.
- Examined localization of full-length caspase-2, prodomain-only constructs, and caspase-3 fused with the caspase-2 prodomain.
Main Results:
- Both precursor and processed caspase-2 were found in cytoplasmic and nuclear compartments.
- Nuclear localization of caspase-2 was dependent on the prodomain; the prodomain localized to nuclear structures, while the protein lacking it concentrated in the cytoplasm.
- The caspase-2 prodomain mediated nuclear transport of cytoplasmically localized caspase-3.
Conclusions:
- The caspase-2 prodomain possesses a novel function in mediating nuclear transport.
- This prodomain function extends beyond its known roles in dimerization and adaptor recruitment.
- Findings provide new insights into the regulation of caspase localization and function in apoptosis.