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Extracellular roles for the molecular chaperone, hsp90
Brenda K Eustace1, Daniel G Jay
1Department of Physiology, Tufts University School of Medicine, Boston, Massacusetts, USA.
Cell Cycle (Georgetown, Tex.)
|August 25, 2004
Summary
Heat shock proteins (hsps) function outside cells, aiding tumor invasiveness by activating MMP2. Extracellular hsps and their complexes, like hsp90, hop, and p23, suggest broader roles in health and disease.
Area of Science:
- Molecular biology
- Cell biology
- Biochemistry
Background:
- Heat shock proteins (hsps) are primarily known as intracellular molecular chaperones.
- Emerging evidence indicates hsps also function in the extracellular environment.
- Hsp90alpha has been identified extracellularly, particularly in relation to cancer cell processes.
Purpose of the Study:
- To investigate the extracellular presence and function of hsp90 and its associated proteins.
- To determine the role of extracellular hsps in tumor invasiveness.
- To explore the implications of extracellular chaperoning in biological processes and disease.
Main Methods:
- Analysis of conditioned media from HT-1080 fibrosarcoma cells.
- Identification of extracellular heat shock proteins and their complexes.
- Assessing the role of these proteins in matrix metalloproteinase-2 (MMP2) activation.
Main Results:
- Hsp90alpha was detected on the surface and in conditioned media of HT-1080 cells.
- Extracellular Hsp90alpha was found to activate MMP2, enhancing tumor cell invasiveness.
- Other hsp90 complex components, including hsp90 organizing protein (hop) and p23, were also identified extracellularly.
Conclusions:
- Extracellular heat shock proteins, including hsp90 complexes, play a role in promoting tumor invasiveness.
- The findings support a significant role for extracellular molecular chaperoning in both normal physiology and disease.
- This suggests potential therapeutic targets related to extracellular chaperone activity.