title: Nuclear factor-κB regulates expression of platelet phospholipase C-β2 (PLCB2).
abstract: Phospholipase C (PLC)-β2 (gene PLCB2) is a critical regulator of platelet responses upon activation. Mechanisms regulating of PLC-β2 expression in platelets/MKs are unknown. Our studies in a patient with platelet PLC-β2 deficiency revealed the PLCB2 coding sequence to be normal and decreased platelet PLC-β2 mRNA, suggesting a defect in transcriptional regulation. PLCB2 5'- upstream region of the patient revealed a heterozygous 13 bp deletion (-1645/-1633 bp) encompassing a consensus sequence for nuclear factor-κB (NF-κB). This was subsequently detected in three of 50 healthy subjects. To understand the mechanisms regulating PLC-β2, we studied the effect of this variation in the PLCB2. Gel-shift studies using nuclear extracts from human erythroleukaemia (HEL) cells or recombinant p65 showed NF-κB binding to oligonucleotide with NF-κB site; in luciferase reporter studies its deletion reduced PLCB2 promoter activity. PLCB2 expression was decreased by siRNA knockdown of NF-κB p65 subunit and increased by p65 overexpression. By immunoblotting platelet PLC-β2 in 17 healthy subjects correlated with p65 (r=0.76, p=0.0005). These studies provide the first evidence that NF-κB regulates MK/platelet PLC-β2 expression. This interaction is important because of the major role of PLC-β2 in platelet activation and of NF-κB in processes, including inflammation and atherosclerosis, where both are intimately involved.
authors.forename: Guangfen
authors.initials: G
authors.lastname: Mao
authors.forename: Jianguo
authors.initials: J
authors.lastname: Jin
authors.forename: Satya P
authors.initials: SP
authors.lastname: Kunapuli
authors.affiliation: A. Koneti Rao, MD, Sol Sherry Thrombosis Research Center, Temple University School of Medicine, 3400 North Broad Street, MRB-204, Philadelphia, PA 19140, USA, Tel.: +1 215 707 4684, Fax: +1 215 707 2783, E-mail: koneti@temple.edu.
authors.forename: A Koneti
authors.initials: AK
authors.lastname: Rao
mesh_terms: D001665:Binding Sites; D001792:Blood Platelets / Q000201:enzymology*; D016384:Consensus Sequence; D005260:Female; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D008297:Male; D008533:Megakaryocytes / Q000201:enzymology; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D054799:Phospholipase C beta / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D017384:Sequence Deletion
chemical_list: D016328:NF-kappa B; C518036:PLCB2 protein, human; D054799:Phospholipase C beta
keywords: Megakaryocytess; nuclear factor-κB; phospholipase C-β2; platelet function defect; platelets