title: Mechanisms of murine cranial suture patency mediated by a dominant negative transforming growth factor-beta receptor adenovirus.
abstract: Using a physiologic model of mouse cranial suture fusion, the authors' laboratory has previously demonstrated that transforming growth factor (TGF)-betas appear to be more abundantly expressed in the suture complex of the fusing posterior frontal compared with the patent sagittal suture. Furthermore, the authors have shown that by blocking TGF-beta signaling with a replication-deficient adenovirus encoding a defective, dominant negative type II TGF-beta receptor (AdDN-TbetaRII), posterior frontal suture fusion was inhibited. In this study, the authors attempt to further elucidate the role of TGF-beta in cranial suture fusion by investigating possible mechanisms of AdDN-TbetaRII-mediated cranial suture patency using both an established organ culture model and a novel in vitro co-culture system that recapitulates the in vivo anatomic dura mater/cranial suture relationship. In this article, the authors demonstrate that blocking TGF-beta signaling with the AdDN-TbetaRII construct led to inhibition of cellular proliferation in the suture mesenchyme and subjacent dura mater during the early period of predicted posterior frontal suture fusion. Interestingly, co-culture experiments revealed that transfecting osteoblasts with AdDN-TbetaRII led to alterations in the gene expression levels of two important bone-related molecules (Msx2 and osteopontin). Inhibiting TGF-beta signaling prevented time-dependent suppression of Msx2 and prevented induction of osteopontin, thereby retarding osteoblast differentiation. Furthermore, the authors demonstrated that the AdDN-TbetaRII construct was capable of blocking TGF-beta -mediated up-regulation of collagen IalphaI, an extracellular matrix molecule important for bone formation. Collectively, these data strongly suggest that AdDN-TbetaRII maintains posterior frontal patency, in part by altering early events in de novo bone formation, including cellular proliferation and early extracellular matrix production.
authors.affiliation: Department of Surgery, Stanford University School of Medicine, 257 Campus Drive, Stanford, CA 94305-5148, USA.
authors.forename: HanJoon M
authors.initials: HM
authors.lastname: Song
authors.forename: Kenton D
authors.initials: KD
authors.lastname: Fong
authors.forename: Randall P
authors.initials: RP
authors.lastname: Nacamuli
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Warren
authors.forename: Tony D
authors.initials: TD
authors.lastname: Fang
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Mathy
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Cowan
authors.forename: Oliver O
authors.initials: OO
authors.lastname: Aalami
authors.forename: Michael T
authors.initials: MT
authors.lastname: Longaker
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D015152:Blotting, Northern; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D018920:Coculture Techniques; D003393:Cranial Sutures / Q000254:growth & development* / Q000378:metabolism / Q000502:physiology; D004388:Dura Mater / Q000166:cytology / Q000378:metabolism; D005624:Frontal Bone; D005822:Genetic Vectors; D007150:Immunohistochemistry; D051379:Mice; D008815:Mice, Inbred Strains; D009924:Organ Culture Techniques; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D053495:Osteopontin; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D012313:RNA / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics / Q000502:physiology*; D012795:Sialoglycoproteins / Q000378:metabolism; D015398:Signal Transduction; D012886:Skull / Q000166:cytology; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000494:pharmacology / Q000502:physiology*; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: D018809:Proliferating Cell Nuclear Antigen; D018125:Receptors, Transforming Growth Factor beta; D012795:Sialoglycoproteins; C506896:Spp1 protein, mouse; C506897:Spp1 protein, rat; D016212:Transforming Growth Factor beta; D053495:Osteopontin; D012313:RNA; D017346:Protein Serine-Threonine Kinases; D000077294:Receptor, Transforming Growth Factor-beta Type II; D001616:beta-Galactosidase