title: Pifithrin-α provides neuroprotective effects at the level of mitochondria independently of p53 inhibition.
abstract: Impaired mitochondrial integrity and function are key features of intrinsic death pathways in neuronal cells. Therefore, key regulators of intrinsic death pathways acting upstream of mitochondria are potential targets for therapeutic approaches of neuroprotection. The tumor suppressor p53 is a well-established regulator of cellular responses towards different kinds of lethal stress, including oxidative stress. Recent reports suggested that p53 may affect mitochondrial integrity and function through both, transcriptional activation of mitochondria-targeted pro-death proteins and direct effects at the mitochondrial membrane. In the present study, we compared the effects of pharmacological inhibition of p53 by pifithrin-α with those of selective p53 gene silencing by RNA interference. Using MTT assay and real-time cell impedance measurements we confirmed the protective effect of both strategies against glutamate-induced oxidative stress in immortalized mouse hippocampal HT-22 neurons. Further, we observed full restoration of mitochondrial membrane potential and inhibition of glutamate-induced mitochondrial fragmentation by pifithrin-α which was, in contrast, not achieved by p53 gene silencing. Downregulation of p53 by siRNA decreased p53 transcriptional activity and reduced expression levels of p21 mRNA, while pifithrin-α did not affect these endpoints. These results suggest a neuroprotective effect of pifithrin-α which occurred at the level of mitochondria and independently of p53 inhibition.
authors.affiliation: Institut für Pharmakologie und Klinische Pharmazie, Fachbereich Pharmazie, Philipps-Universität Marburg, Karl-von-Frisch-Straße 1, 35032, Marburg, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Neitemeier
authors.forename: Goutham K
authors.initials: GK
authors.lastname: Ganjam
authors.forename: Sebastian
authors.initials: S
authors.lastname: Diemert
authors.forename: Carsten
authors.initials: C
authors.lastname: Culmsee
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins / Q000235:genetics / Q000378:metabolism; D052160:Benzothiazoles / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D055786:Gene Knockout Techniques; D018698:Glutamic Acid / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D015227:Lipid Peroxidation / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects; D034741:RNA, Small Interfering / Q000235:genetics; D014050:Toluene / Q000031:analogs & derivatives* / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; D052160:Benzothiazoles; D018696:Neuroprotective Agents; D034741:RNA, Small Interfering; D016159:Tumor Suppressor Protein p53; D014050:Toluene; D018698:Glutamic Acid; C121565:pifithrin