T lymphocytes export proteasomes by way of microparticles: a possible mechanism for generation of extracellular proteasomes.

ABSTRACT: The 20S proteasome is almost exclusively localized within cells. High levels of extracellular proteasomes are also found circulating in the blood plasma of patients suffering from a variety of inflammatory, autoimmune and neoplastic diseases. However, the origin of these proteasomes remained enigmatic. Since the proteome of microparticles, small membrane enclosed vesicles released from cells, was shown to contain proteasomal subunits, we studied whether intact proteasomes are actively released into the extracellular space. Using human primary T lymphocytes stimulated with CaCl2 and the calcium ionophore A23187 to induce membrane blebbing we demonstrate that microparticles contain proteolytically active 20S proteasomes as well as the proteasome activator PA28 and subunits of the 19S proteas

SUBMITTER: Bochmann I 

PROVIDER: S-EPMC3916118 | biostudies-literature | 2014 Jan

REPOSITORIES: biostudies-literature