Submitted on December 12, 2006
Accepted on February 12, 2007
HSP60 Trafficking in Adult Cardiac Myocytes: Role of the Exosomal Pathway
Sanjiv Gupta1 and Anne A. Knowlton2*
1 Medicine, University of California, Davis, Davis, California, United States
2 Cardiovascular Division, University of California, Davis, Davis, California, United States
* To whom correspondence should be addressed. E-mail: aaknowlton{at}ucdavis.edu.
The heat shock proteins (HSP) are highly conserved family of proteins with critical functions in protein folding, protein trafficking and cell signaling. These proteins also protect the cell against injury. HSP60 has been found in the extracellular space and has been identified in the plasma of some individuals. HSP60 is thought to be a "danger signal" to the immune system and is also highly immunogenic. Thus, extracellular HSP60 is possibly toxic to the cell. The mechanism by which HSP60 is released into the extracellular space is unknown. We investigated several different pathways controlling protein release including the classic, Golgi-mediated pathway. We found that HSP60 is released via exosomes, and that within the exosome, HSP60 is tightly attached to the exosome membrane.
