title: Estrogen regulates Bcl-w and Bim expression: role in protection against beta-amyloid peptide-induced neuronal death.
abstract: Estrogen is neuroprotective against a variety of insults, including beta-amyloid peptide (Abeta); however, the underlying mechanism(s) is not fully understood. Here, we report that 17beta-estradiol (E2) selectively regulates neuronal expression of the Bcl-2 family (bcl-2, bcl-x, bcl-w, bax, bak, bad, bik, bnip3, bid, and bim). In primary cerebrocortical neuron cultures under basal conditions, we observe that E2 upregulates expression of antiapoptotic Bcl-w and downregulates expression of proapoptotic Bim in an estrogen receptor (ER)-dependent manner. In the presence of toxic levels of Abeta, we observe that E2 attenuates indices of neuronal apoptosis: c-Jun N-terminal kinase (JNK)-dependent downregulation of Bcl-w and upregulation of Bim, mitochondrial release of cytochrome c and Smac, and cell death. These neuroprotective effects of E2 against Abeta-induced apoptosis are mimicked by the JNK inhibitor SP600125 (anthra[1,9-cd]pyrazol-6(2H)-one). In addition, E2 attenuates Abeta-induced JNK phosphorylation in an ER-dependent manner, but does not affect basal levels of JNK phosphorylation. These results suggest that E2 may reduce Abeta-induced neuronal apoptosis at least in part by two complementary pathways: (1) ER-dependent, JNK-independent upregulation of Bcl-w and downregulation of Bim under basal conditions, and (2) ER-dependent inhibition of Abeta-induced JNK activation and subsequent JNK-dependent downregulation of Bcl-w and upregulation of Bim, resulting in mitochondrial release of cytochrome c and Smac and eventual cell death. These data provide new understanding into the mechanisms contributing to estrogen neuroprotection, a neural function with potential therapeutic relevance to Alzheimer's disease.
authors.affiliation: Davis School of Gerontology, University of Southern California, Los Angeles, California 90089, USA.
authors.forename: Mingzhong
authors.initials: M
authors.lastname: Yao
authors.forename: Thuy-Vi V
authors.initials: TV
authors.lastname: Nguyen
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Pike
mesh_terms: D016229:Amyloid beta-Peptides / Q000633:toxicity*; D000818:Animals; D000873:Anthracenes / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D051017:Apoptosis Regulatory Proteins / Q000096:biosynthesis* / Q000235:genetics; D000072224:Bcl-2-Like Protein 11; D002352:Carrier Proteins / Q000032:analysis; D002540:Cerebral Cortex / Q000166:cytology; D045304:Cytochromes c / Q000032:analysis; D004789:Enzyme Activation / Q000187:drug effects; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology* / Q000502:physiology; D020847:Estrogen Receptor Modulators / Q000494:pharmacology; D000077267:Fulvestrant; D005786:Gene Expression Regulation / Q000187:drug effects; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D008928:Mitochondria / Q000187:drug effects / Q000502:physiology; D024101:Mitochondrial Proteins / Q000032:analysis; D009419:Nerve Tissue Proteins / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D009474:Neurons / Q000187:drug effects* / Q000473:pathology; D018696:Neuroprotective Agents / Q000494:pharmacology*; D010446:Peptide Fragments / Q000633:toxicity*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis* / Q000235:genetics; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger / Q000096:biosynthesis; D034741:RNA, Small Interfering / Q000235:genetics / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D011960:Receptors, Estrogen / Q000187:drug effects / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
chemical_list: D016229:Amyloid beta-Peptides; D000873:Anthracenes; D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; C000606778:Bcl2l11 protein, rat; C491072:Bcl2l2 protein, rat; D002352:Carrier Proteins; C489013:DIABLO protein, rat; D020847:Estrogen Receptor Modulators; D008565:Membrane Proteins; D024101:Mitochondrial Proteins; D009419:Nerve Tissue Proteins; D018696:Neuroprotective Agents; D010446:Peptide Fragments; D047428:Protein Kinase Inhibitors; D011506:Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011960:Receptors, Estrogen; C074636:amyloid beta-protein (25-35); C432165:pyrazolanthrone; D000077267:Fulvestrant; D004958:Estradiol; D045304:Cytochromes c; D048031:JNK Mitogen-Activated Protein Kinases