title: JunB as a potential mediator of PTHrP actions: new gene targets Ephrin B1 and VCAM-1.
abstract: Parathyroid hormone-related protein (PTHrP) is an integral mediator of physiologic and pathologic processes and has demonstrated actions in the periodontium. PTHrP functions via AP-1, and specifically through JunB. This study identified JunB-dependent downstream mediators of PTHrP using OCCM cementoblastic transfectants with JunB over- or reduced expression. Over-expressing cells showed an increase in proliferation, while the opposite was seen in siRNA transfected cells. Microarray analysis of over-expressing cells revealed more than 1000 regulated genes. Three genes were investigated in more detail. The PTH/PTHrP receptor (PTHR1) and ephrin B1 (EfnB1) were down-regulated, and vascular cell adhesion molecule-1 (VCAM-1) was up-regulated with JunB over-expression. JunB siRNA transfectants had increased PTHR1, but reduced ephrin B1 and unaltered VCAM-1 in vitro. To validate these targets, parental OCCM cells and primary osteoblasts were treated with PTHrP, resulting in reduced PTHR1 and ephrin B1, and increased VCAM-1. Cell transfectants were implanted subcutaneously in vivo, and microarray analysis and RT-PCR performed. Over-expression of JunB down-regulated PTHR1 and ephrin B1, and increased VCAM-1. JunB siRNA transfectant implants had increased PTHR1 and ephrin B1, but no altered VCAM-1. These data highlight new gene targets for PTHrP and indicate JunB is a critical mediator of PTHrP actions.
authors.affiliation: Department of Periodontics and Oral Medicine, School of Dentistry, University of Michigan, Ann Arbor, MI 48109-1078, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Berry
authors.forename: G J
authors.initials: GJ
authors.lastname: Pettway
authors.forename: K G
authors.initials: KG
authors.lastname: Cordell
authors.forename: T
authors.initials: T
authors.lastname: Jin
authors.forename: N S
authors.initials: NS
authors.lastname: Datta
authors.forename: L K
authors.initials: LK
authors.lastname: McCauley
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics; D002452:Cell Count; D002460:Cell Line; D049109:Cell Proliferation; D003739:Dental Cementum / Q000473:pathology; D015536:Down-Regulation / Q000235:genetics; D036387:Ephrin-B1 / Q000235:genetics*; D005786:Gene Expression Regulation / Q000235:genetics; D051379:Mice; D008819:Mice, Nude; D010006:Osteoblasts / Q000473:pathology / Q000637:transplantation; D044162:Parathyroid Hormone-Related Protein / Q000235:genetics*; D040081:Protein Array Analysis; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics*; D034741:RNA, Small Interfering / Q000235:genetics; D044168:Receptor, Parathyroid Hormone, Type 1 / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D040521:Subcutaneous Tissue / Q000473:pathology; D018808:Transcription Factor AP-1 / Q000235:genetics; D014162:Transfection; D015854:Up-Regulation / Q000235:genetics; D019010:Vascular Cell Adhesion Molecule-1 / Q000235:genetics*
chemical_list: C092571:Efnb1 protein, mouse; D036387:Ephrin-B1; D044162:Parathyroid Hormone-Related Protein; D016755:Proto-Oncogene Proteins c-jun; D034741:RNA, Small Interfering; D044168:Receptor, Parathyroid Hormone, Type 1; D018808:Transcription Factor AP-1; D019010:Vascular Cell Adhesion Molecule-1