title: Cellular prion protein mediates early apoptotic proteome alternation and phospho-modification in human neuroblastoma cells.
abstract: Anti-apoptotic properties of physiological and elevated levels of the cellular prion protein (PrPc) under stress conditions are well documented. Yet, detrimental effects of elevated PrPclevels under stress conditions, such as exposure to staurosporine (STS) have also been described. In the present study, we focused on discerning early apoptotic STS-induced proteome and phospho-proteome changes in SH-SY5Y human neuroblastoma cells stably transfected either with an empty or PRNP-containing vector, expressing physiological or supraphysiological levels of PrPc, respectively. PrPc-overexpression per se appears to stress the cells under STS-free conditions as indicated by diminished cell viability of PrPc-overexpressing versus control cells. However, PrPc-overexpression becomes advantageous following exposure to STS. Thus, only a short exposure (2 h) to 1 μM STS results in lower survival rates and significantly higher caspase-3 activity in control versus PrPc-overexpressing cells. Hence, by exposing both experimental groups to the same apoptotic conditions we were able to induce apoptosis in control, but not in PrPc-overexpressing cells (as assessed by caspase-3 activity), which allowed for filtering out proteins possibly contributing to protection against STS-induced apoptosis in PrPc-overexpressing cells. Among other proteins regulated by different PrPclevels following exposure to STS, those involved in maintenance of cytoskeleton integrity caught our attention. In particular, the finding that elevated PrPclevels significantly reduce profilin-1 (PFN-1) expression. PFN-1 is known to facilitate STS-induced apoptosis. Silencing of PFN-1 expression by siRNA significantly increased viability of PrPc-overexpressing versus control cells, under STS treatment. In addition, PrPc-overexpressing cells depleted of PFN-1 exhibited increased viability versus PrPc-overexpressing cells with preserved PFN-1 expression, both subjected to STS. Concomitant increase in caspase-3 activity was observed in control versus PrPc-overexpressing cells after treatment with siRNA- PFN-1 and STS. We suggest that reduction of PFN-1 expression by elevated levels of PrPcmay contribute to protective effects PrPc-overexpressing SH-SY5Y cells confer against STS-induced apoptosis.
authors.affiliation: Department of Neurology, Georg-August University, Goettingen 37075, Germany.
authors.forename: Saima
authors.initials: S
authors.lastname: Zafar
authors.affiliation: Department of Neuropathology, Georg-August University, Goettingen 37075, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Behrens
authors.affiliation: Department of Nephrology and Rheumatology, Georg-August University, Goettingen 37075, Germany.
authors.forename: Hassan
authors.initials: H
authors.lastname: Dihazi
authors.affiliation: Department of Neurology, Georg-August University, Goettingen 37075, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Schmitz
authors.affiliation: Department of Neurology, Georg-August University, Goettingen 37075, Germany.
authors.forename: Inga
authors.initials: I
authors.lastname: Zerr
authors.affiliation: Department of Neuropathology, Georg-August University, Goettingen 37075, Germany.
authors.forename: Walter J
authors.initials: WJ
authors.lastname: Schulz-Schaeffer
authors.affiliation: Sciema UG, An der Hayl 4, Mainz 55130, Germany.
authors.forename: Sanja
authors.initials: S
authors.lastname: Ramljak
authors.affiliation: Institute for Clinical Chemistry / UMG-Laboratories, University Medical Center Goettingen, Georg-August University, Goettingen, Germany.
authors.forename: Abdul R
authors.initials: AR
authors.lastname: Asif
mesh_terms: D017209:Apoptosis / Q000235:genetics*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D009447:Neuroblastoma / Q000235:genetics* / Q000473:pathology; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation / Q000187:drug effects; D000072002:Prion Proteins / Q000235:genetics*; D051304:Profilins / Q000235:genetics*; D020543:Proteome / Q000235:genetics; D019311:Staurosporine / Q000008:administration & dosage; D014162:Transfection
chemical_list: C495738:PFN1 protein, human; D000072002:Prion Proteins; D051304:Profilins; D020543:Proteome; D019311:Staurosporine