title: Human recombinant cementum attachment protein (hrPTPLa/CAP) promotes hydroxyapatite crystal formation in vitro and bone healing in vivo.
abstract: Cementum extracellular matrix is similar to other mineralized tissues; however, this unique tissue contains molecules only present in cementum. A cDNA of these molecules, cementum attachment protein (hrPTPLa/CAP) was cloned and expressed in a prokaryotic system. This molecule is an alternative splicing of protein tyrosine phosphatase-like A (PTPLa). In this study, we wanted to determine the structural and functional characteristics of this protein. Our results indicate that hrPTPLa/CAP contains a 43.2% α-helix, 8.9% β-sheet, 2% β-turn and 45.9% random coil secondary structure. Dynamic light scattering shows that this molecule has a size distribution of 4.8 nm and aggregates as an estimated mass of 137 kDa species. AFM characterization and FE-SEM studies indicate that this protein self-assembles into nanospheres with sizes ranging from 7.0 to 27 nm in diameter. Functional studies demonstrate that hrPTPLa/CAP promotes hydroxyapatite crystal nucleation: EDS analysis revealed that hrPTPLa/CAP-induced crystals had a 1.59 ± 0.06 Ca/P ratio. Further confirmation with MicroRaman spectrometry and TEM confirm the presence of hydroxyapatite. In vivo studies using critical-size defects in rat cranium showed that hrPTPLa/CAP promoted 73% ± 2.19% and 87% ± 1.97% new bone formation at 4 and 8 weeks respectively. Although originally identified in cementum, PTPLa/CAP is very effective at inducing bone repair and healing and therefore this novel molecule has a great potential to be used for mineralized tissue bioengineering and tissue regeneration.
authors.affiliation: Laboratorio de Biología Periodontal, Facultad de Odontología, Universidad Nacional Autónoma de México, México.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Montoya
authors.affiliation: Instituto de Física, Universidad Nacional Autónoma de México, México.
authors.forename: Jesús
authors.initials: J
authors.lastname: Arenas
authors.affiliation: Laboratorio de Biología Periodontal, Facultad de Odontología, Universidad Nacional Autónoma de México, México.
authors.forename: Enrique
authors.initials: E
authors.lastname: Romo
authors.affiliation: Ostrow School of Dentistry, University of Southern California, USA.
authors.forename: Margarita
authors.initials: M
authors.lastname: Zeichner-David
authors.affiliation: Laboratorio de Bioingeniería de Tejidos, Facultad de Odontología, Universidad Nacional Autónoma de México, México.
authors.forename: Marco
authors.initials: M
authors.lastname: Alvarez
authors.affiliation: School of Medicine, Department of Pathology, University of Washington, Seattle, USA.
authors.forename: A Sampath
authors.initials: AS
authors.lastname: Narayanan
authors.affiliation: Laboratorio de Biología Periodontal, Facultad de Odontología, Universidad Nacional Autónoma de México, México.
authors.forename: Ulises
authors.initials: U
authors.lastname: Velázquez
authors.affiliation: Laboratorio de Biología Periodontal, Facultad de Odontología, Universidad Nacional Autónoma de México, México.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Mercado
authors.affiliation: Laboratorio de Biología Periodontal, Facultad de Odontología, Universidad Nacional Autónoma de México, México. Electronic address: harzate@unam.mx.
authors.forename: Higinio
authors.initials: H
authors.lastname: Arzate
mesh_terms: D000818:Animals; D001861:Bone Regeneration / Q000187:drug effects*; D002942:Circular Dichroism; D017886:Durapatite / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D018625:Microscopy, Atomic Force; D008854:Microscopy, Electron; D054118:Nanospheres; D011487:Protein Conformation; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry* / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins / Q000737:chemistry / Q000494:pharmacology
chemical_list: D011994:Recombinant Proteins; D017886:Durapatite; C404489:HACD1 protein, human; D017027:Protein Tyrosine Phosphatases
keywords: Biomineralization; Bone regeneration; Cementum attachment protein; Hydroxyapatite; Nanospheres