title: Prohibitins and the cytoplasmic domain of CD86 cooperate to mediate CD86 signaling in B lymphocytes.
abstract: CD86 engagement on a CD40L/IL-4-primed murine B cell activates signaling intermediates that promote NF-κB activation to increase Oct-2 and mature IgG1 mRNA and protein expression, as well as the rate of IgG1 transcription, without affecting class switch recombination. One of the most proximal signaling intermediates identified is phospholipase Cγ2, a protein reported to bind tyrosine residues, which are absent in the cytoplasmic domain of CD86. Using a proteomics-based identification approach, we show that the tyrosine-containing transmembrane adaptor proteins prohibitin (Phb)1 and Phb2 bind to CD86. The basal expression of Phb1/2 and association with CD86 was low in resting B cells, whereas the level of expression and association increased primarily after priming with CD40. The CD86-induced increase in Oct-2 and IgG1 was less when either Phb1/2 expression was reduced by short hairpin RNA or the cytoplasmic domain of CD86 was truncated or mutated at serine/threonine protein kinase C phosphorylation sites, which did not affect Phb1/2 binding to CD86. Using this approach, we also show that Phb1/2 and the CD86 cytoplasmic domain are required for the CD86-induced phosphorylation of IκBα, which we previously reported leads to NF-κB p50/p65 activation, whereas only Phb1/2 was required for the CD86-induced phosphorylation of phospholipase Cγ2 and protein kinase Cα/β(II), which we have previously reported leads to NF-κB (p65) phosphorylation and subsequent nuclear translocation. Taken together, these findings suggest that Phb1/2 and the CD86 cytoplasmic domain cooperate to mediate CD86 signaling in a B cell through differential phosphorylation of distal signaling intermediates required to increase IgG1.
authors.affiliation: Integrated Biomedical Science Graduate Program, The Ohio State University, Columbus, OH 43210, USA.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Lucas
authors.forename: Hector M
authors.initials: HM
authors.lastname: Cordero-Nieves
authors.forename: Robert S
authors.initials: RS
authors.lastname: Erbe
authors.forename: Jaclyn W
authors.initials: JW
authors.lastname: McAlees
authors.forename: Sumeena
authors.initials: S
authors.lastname: Bhatia
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Hodes
authors.forename: Kerry S
authors.initials: KS
authors.lastname: Campbell
authors.forename: Virginia M
authors.initials: VM
authors.lastname: Sanders
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D001402:B-Lymphocytes / Q000378:metabolism*; D051940:B7-2 Antigen / Q000737:chemistry / Q000378:metabolism*; D019013:CD40 Antigens / Q000378:metabolism; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D051966:Phospholipase C gamma / Q000378:metabolism; D000091402:Prohibitins; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D011493:Protein Kinase C / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D051940:B7-2 Antigen; D019013:CD40 Antigens; D016328:NF-kappa B; C000717333:Phb2 protein, mouse; D000091402:Prohibitins; D012097:Repressor Proteins; D011493:Protein Kinase C; D051966:Phospholipase C gamma