title: Activated human T cells express alternative mRNA transcripts encoding a secreted form of RANKL.
abstract: Receptor activator of nuclear factor-kappaB-ligand (RANKL), encoded by the gene TNFSF11, is required for osteoclastogenesis, and its expression is upregulated in pathologic bone loss. Transcript variants of TNFSF11 messenger RNA (mRNA) have been described that encode a membrane-bound and a putative secreted form of RANKL. We identify a TNFSF11 transcript variant that extends the originally identified transcript encoding secreted RANKL. We demonstrate that this TNFSF11 transcript variant is expressed by the human osteosarcoma cell line, Saos-2, and by both primary human T cells and Jurkat T cells. Of relevance to the production of RANKL in pathologic bone loss, expression of this secreted TNFSF11 transcript is upregulated in Jurkat T cells and primary human T cells upon activation. Furthermore, this transcript can be translated and secreted in Jurkat T cells in vitro and is able to support osteoclast differentiation. Our data highlight the complexity of the TNFSF11 genomic locus, and demonstrate the potential for the expression of alternate mRNA transcripts encoding membrane-bound and secreted forms of RANKL. Implications of alternate mRNA transcripts encoding different RANKL protein isoforms should be carefully considered and specifically examined in future studies, particularly those implicating RANKL in pathologic bone loss.
authors.affiliation: St Vincent's Institute of Medical Research, Melbourne, Victoria, Australia.
authors.forename: N C
authors.initials: NC
authors.lastname: Walsh
authors.forename: K A
authors.initials: KA
authors.lastname: Alexander
authors.forename: C A
authors.initials: CA
authors.lastname: Manning
authors.forename: S
authors.initials: S
authors.lastname: Karmakar
authors.forename: S K
authors.initials: SK
authors.lastname: Karmakar
authors.forename: J F
authors.initials: JF
authors.lastname: Wang
authors.forename: C M
authors.initials: CM
authors.lastname: Weyand
authors.forename: A R
authors.initials: AR
authors.lastname: Pettit
authors.forename: E M
authors.initials: EM
authors.lastname: Gravallese
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D006801:Humans; D019169:Jurkat Cells; D008213:Lymphocyte Activation; D008264:Macrophages / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D053245:RANK Ligand / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D020033:Protein Isoforms; D053245:RANK Ligand; D012333:RNA, Messenger