Clusterin/Apo J protein expression in plasma samples of an elderly Sardinian population

Clusterin (CLU) is a glycoprotein with a nearly ubiquitous tissue distribution that has been reported to be implicated in several physiological processes as well as in many pathological conditions including ageing, diabetes, atherosclerosis, degenerative diseases and tumorigenesis. In this work we studied the changes in the CLU protein expression in plasma samples of a Sardinian population divided by age into four groups. We applied a proteomic approach using 2D-PAGE-MS analyses, western immunoblotting and ELISA to perform comparisons between the four groups. The typical train of spots of the Clusterin protein in a 2D plasma map was examined and according to statistical analyses five spots were detected as being differentially expressed within the four groups. Regarding total Clusterin the results agree with the data shown by literature but only values up to 90 years old have been reported for Clusterin protein expression. This work extends to older people showing that after 90 a decrease in plasma Clusterin levels seems to occur especially in centenarians. Considering that Clusterin is a sensitive biosensor of oxidative stress it could be in accordance with the fact that centenarians, considered as a model of successful ageing, are characterized by low levels of ROS (radical oxygen species).