title: Up-regulation of nucleolin mRNA and protein in peripheral blood mononuclear cells by extracellular-regulated kinase.
abstract: The signal transduction pathways regulating nucleolin mRNA and protein production have yet to be elucidated. Peripheral blood mononuclear cells treated with phorbol 12-myristate 13-acetate showed steady state levels of nucleolin mRNA that were 2-2.5-fold greater than untreated control cells. The up-regulation of nucleolin mRNA was substantially repressed by U0126, a specific inhibitor that blocks phosphorylation of extracellular-regulated kinase (ERK). Calcium ionophores and ionomycin also activated ERK and substantially elevated nucleolin mRNA levels, demonstrating phorbol 12-myristate 13-acetate and calcium signaling converge on ERK. Drugs that affected protein kinase C, protein kinase A, and phospholipase C signal transduction pathways did not alter nucleolin mRNA levels significantly. The half-life of nucleolin mRNA increased from 1.8 h in resting cells to 3.2 h with phorbol ester activation, suggesting ERK-mediated posttranscriptional regulation. Concomitantly, full-length nucleolin protein was increased. The higher levels of nucleolin protein were accompanied by increased binding of a 70-kDa nucleolin fragment to the 29-base instability element in the 3'-untranslated region of amyloid precursor protein (APP) mRNA in gel mobility shift assays. Supplementation of rabbit reticulocyte lysate with nucleolin decreased APP mRNA stability and protein production. These data suggest ERK up-regulates nucleolin posttranscriptionally thereby controlling APP production.
authors.affiliation: Institute on Aging and Department of Pathology and Laboratory Medicine, University of Wisconsin Medical School, Madison, Wisconsin 53792, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Westmark
authors.forename: J S
authors.initials: JS
authors.lastname: Malter
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D000262:Adenylyl Cyclases / Q000378:metabolism; D016564:Amyloid beta-Protein Precursor / Q000235:genetics; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000097:blood; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000097:blood*; D009687:Nuclear Proteins / Q000097:blood / Q000235:genetics*; D010750:Phosphoproteins / Q000097:blood / Q000235:genetics*; D014176:Protein Biosynthesis; D011493:Protein Kinase C / Q000097:blood; D012333:RNA, Messenger / Q000097:blood; D016601:RNA-Binding Proteins / Q000097:blood / Q000235:genetics*; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects*; D010738:Type C Phospholipases / Q000097:blood; D000097796:Nucleolin
chemical_list: D020413:3' Untranslated Regions; D000262:Adenylyl Cyclases; D016564:Amyloid beta-Protein Precursor; D000001:Calcimycin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011493:Protein Kinase C; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D013755:Tetradecanoylphorbol Acetate; D010738:Type C Phospholipases; D000097796:Nucleolin