Evidence for the presence of full-length PARK2 mRNA and Parkin protein in human blood

Research on Parkinson's disease fails to pinpoint a single gene or a gene product as the causative factor. However, the early onset form of the disease may be caused by mutations in PARK2 gene. Some studies related to the biochemistry or other aspects of the PARK2 gene or its product mostly used cDNA generated from substantia nigra of the mid-brain. This is essentially because the presence of the 1.4 kb full-length PARK2 cDNA in human leukocytes is, so far, not demonstrated although some splice variants and short RT-PCR products were reported. In this study, we synthesized a 1.4 kb full-length PARK2 cDNA from human leukocytes, cloned and expressed it both in Escherichia coli and in HeLa cells. The presence of Parkin protein was also demonstrated in human serum using Western blotting and MALDI-TOF analysis. The results of this study showed a simple way for routine amplification of PARK2 cDNA from human blood and may become a useful diagnostic tool in the future.