title: Normal Bone Deposition Occurs in Mice Deficient in Factor XIII-A and Transglutaminase 2.
abstract: Transglutaminase activity has been widely implicated in bone deposition. A predominant role has been proposed for factor (F)XIII-A and a subsidiary role suggested for the homologous protein, transglutaminase 2. Full-length FXIII-A is an 83kDa protransglutaminase that is present both in plasma and also in haematopoietic and connective tissue lineages. Several studies have reported expression in murine cells, including osteocytes, of a 37 kDa protein that reacts with the monoclonal anti-FXIII-A antibody AC-1A1. This protein was presumed to be a catalytically active fragment of FXIII-A-83 and to play a major role in bone deposition. We detected a 37 kDa AC-1A1 reactive protein in FXIII-A mRNA negative cell lines and in tissues from FXIII-A(-/-) mice. By mass spectrometric sequencing of AC-1A1 immunoprecipitates, we identified this protein as transaldolase-1, and confirmed that recombinant transaldolase-1 is recognised by AC-1A1. We have also shown that bone deposition is normal in FXIII-A(-/-).TG2(-/-) double knockout mice, casting doubt on the role of transglutaminases in bone mineralisation. Various studies have used antibody AC-1A1 for immunohistochemistry or immunofluorescence. We observe strong FXIII-A dependent staining in paraffin embedded mouse heart sections, with relatively low background in non-expressing mouse cells. In contrast, FXIII-A independent staining predominates in cultured human cells using a standard immunofluorescence procedure. Immunofluorescence is present in membrane compartments that are expected to lack transaldolase, indicating that other off-target antigens are recognised by AC-1A1. This has significant implications for studies that have used this approach to define the subcellular trafficking of FXIII-A in osteocytes.
authors: Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK.
authors: Paul A
authors: PA
authors: Cordell
authors: Bristol Heart Institute, University of Bristol, Level 7, Bristol Royal Infirmary, Bristol BS2 8HW, UK.
authors: Laura M
authors: LM
authors: Newell
authors: Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK.
authors: Kristina F
authors: KF
authors: Standeven
authors: Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK.
authors: Penelope J
authors: PJ
authors: Adamson
authors: Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK.
authors: Kingsley R
authors: KR
authors: Simpson
authors: Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK.
authors: Kerrie A
authors: KA
authors: Smith
authors: Bristol Heart Institute, University of Bristol, Level 7, Bristol Royal Infirmary, Bristol BS2 8HW, UK.
authors: Christopher L
authors: CL
authors: Jackson
authors: Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK.
authors: Peter J
authors: PJ
authors: Grant
authors: Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds LS2 9JT, UK. Electronic address: r.j.pease@leeds.ac.uk.
authors: Richard J
authors: RJ
authors: Pease
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D002113:Calcification, Physiologic; D002460:Cell Line; D026122:Factor XIIIa / Q000235:genetics*; D005260:Female; D019204:GTP-Binding Proteins / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D014153:Transaldolase / Q000276:immunology / Q000378:metabolism*; D011503:Transglutaminases / Q000276:immunology / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D014153:Transaldolase; D026122:Factor XIIIa; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins
keywords: FXIII-A; antibodies; bone development; mice; transaldolase; transglutaminases