title: Dmp1 Promoter-Driven Diphtheria Toxin Receptor Transgene Expression Directs Unforeseen Effects in Multiple Tissues.
abstract: Mice harbouring a dentin matrix protein 1 (Dmp1) promoter-driven human diphtheria toxin (DT) receptor (HDTR) transgene (Tg) have recently been used to attain targeted ablation of osteocytes by diphtheria toxin (DT) treatment in order to define osteocyte function. Use of these Tg mice has asserted mechano- and novel paracrine regulatory osteocyte functions. To explore osteocyte roles fully, we sought to confirm the selectivity of DT effects in these transgenic mice. However, our findings revealed incomplete DT-induced osteocyte ablation, prevalentHDTRmisexpression, as well as more prominent histopathological DT-induced changes in multiple organs in Tg than in wild-type (WT) littermate mice. Mechanistic evidence for DT action, via prominent regulation of phosphorylation status of elongation factor-2 (EF-2), was also found in many non-skeletal tissues in Tg mice; indicative of direct "off-target" DT action. Finally, very rapid deterioration in health and welfare status in response to DT treatment was observed in these Tg when compared to WT control mice. Together, these data lead us to conclude that alternative models for osteocyte ablation should be sought and caution be exercised when drawing conclusions from experiments using these Tg mice alone.
authors.affiliation: Skeletal Biology Group, Comparative Biomedical Sciences, Royal Veterinary College, Royal College Street, London NW1 0TU, UK. aaljazzar@rvc.ac.uk.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Al-Jazzar
authors.affiliation: Skeletal Biology Group, Comparative Biomedical Sciences, Royal Veterinary College, Royal College Street, London NW1 0TU, UK. bjavaheri@rvc.ac.uk.
authors.forename: Behzad
authors.initials: B
authors.lastname: Javaheri
authors.affiliation: Orthopaedics & Trauma, University of Adelaide, Adelaide, SA 5005, Australia. matt.prideaux@adelaide.edu.au.
authors.forename: Matt
authors.initials: M
authors.lastname: Prideaux
authors.affiliation: Dental Physical Sciences, Institute of Dentistry, Queen Mary University of London, Mile End Campus, London E1 4NS, UK. a.boyde@qmul.ac.uk.
authors.forename: Alan
authors.initials: A
authors.lastname: Boyde
authors.affiliation: Mary Lyon Centre, MRC Harwell, Science & Innovation Campus, Oxfordshire OX11 0RD, UK. c.scudamore@har.mrc.ac.uk.
authors.forename: Cheryl L
authors.initials: CL
authors.lastname: Scudamore
authors.affiliation: Inserm U1132 & Université Sorbonne Paris Cité-Diderot, Rheumatology, Hôpital Lariboisière, Paris 75010, France. cherifichahrazad@gmail.com.
authors.forename: Chahrazad
authors.initials: C
authors.lastname: Cherifi
authors.affiliation: Inserm U1132 & Université Sorbonne Paris Cité-Diderot, Rheumatology, Hôpital Lariboisière, Paris 75010, France. eric.hay@inserm.fr.
authors.forename: Eric
authors.initials: E
authors.lastname: Hay
authors.affiliation: Skeletal Biology Group, Comparative Biomedical Sciences, Royal Veterinary College, Royal College Street, London NW1 0TU, UK. mhopkinson@rvc.ac.uk.
authors.forename: Mark
authors.initials: M
authors.lastname: Hopkinson
authors.affiliation: Skeletal Biology Group, Comparative Biomedical Sciences, Royal Veterinary College, Royal College Street, London NW1 0TU, UK. mboyd@rvc.ac.uk.
authors.forename: Michael
authors.initials: M
authors.lastname: Boyd
authors.affiliation: Inserm U1132 & Université Sorbonne Paris Cité-Diderot, Rheumatology, Hôpital Lariboisière, Paris 75010, France. martine.cohen-solal@inserm.fr.
authors.forename: Martine
authors.initials: M
authors.lastname: Cohen-Solal
authors.affiliation: Roslin Institute, University of Edinburgh, Division of Developmental Biology, Easter Bush, Midlothian EH25 9RG, UK. colin.farquharson@roslin.ed.ac.uk.
authors.forename: Colin
authors.initials: C
authors.lastname: Farquharson
authors.affiliation: Skeletal Biology Group, Comparative Biomedical Sciences, Royal Veterinary College, Royal College Street, London NW1 0TU, UK. apitsillides@rvc.ac.uk.
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Pitsillides
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D004167:Diphtheria Toxin / Q000633:toxicity; D016326:Extracellular Matrix Proteins / Q000235:genetics*; D066257:Heparin-binding EGF-like Growth Factor / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D007668:Kidney / Q000378:metabolism; D051379:Mice; D009206:Myocardium / Q000378:metabolism; D009928:Organ Specificity; D010011:Osteocytes / Q000187:drug effects / Q000378:metabolism; D020652:Peptide Elongation Factor 2 / Q000378:metabolism; D011401:Promoter Regions, Genetic; D019076:Transgenes
chemical_list: D004167:Diphtheria Toxin; C513308:Dmp1 protein, mouse; D016326:Extracellular Matrix Proteins; D066257:Heparin-binding EGF-like Growth Factor; D020652:Peptide Elongation Factor 2
keywords: bone; diphtheria toxin receptor; osteocyte