Deciphering the Function of Doppel Protein in Astrocytomas

Doppel is a newly recognized prion-like protein encoded by a novel gene locus, PRND, located on the same chromosomal region of the prion coding gene (PRNP); doppel is considered a prion paralogue and together they constitute the prion-gene family, originated through an ancestral gene duplication event. Prion and doppel have different expression patterns, suggesting that the gene products exhibit different biological functions. Actually, doppel is not involved in the etiology of the transmissible spongiform encephalopathies (TSEs) or “prion diseases” and it is highly expressed only within the testicular tissue, where its important physiological role in the process of spermatogenesis and fertilization in human and mouse has been described. Importantly, doppel is toxic when ectopically overexpressed in the central nervous system (CNS), with concomitant prion protein absence: this evidence suggests deeper investigations within particular pathological contexts, such as in Parkinson and Alzheimer’s diseases as well as in cancer. In the latter scenario several studies are showing that doppel represents a novel and attractive diagnostic molecular marker, and that it might provide insights into the regulatory pathways of tumor-cell transformation. In particular, doppel protein has been recently associated with the ability of tumor cells to migrate, as one of the most important hallmarks of cancer. In conclusion, since its discovery, the intriguing spectrum of biological and pathological functions of this new prion-like protein is constantly considered for novel investigations.