Post-translational modifications of sibling proteins and their roles in osteogenesis and dentinogenesis.

The Department of Endodontics and Periodontics, University of Texas-Houston Health Science Center, Dental Branch, Houston, TX 77030, USA.
Critical reviews in oral biology and medicine: an official publication of the American Association of Oral Biologists 02/2004; 15(3):126-36. DOI: 10.1177/154411130401500302
Source: PubMed

ABSTRACT The extracellular matrix (ECM) of bone and dentin contains several non-collagenous proteins. One category of non-collagenous protein is termed the SIBLING (Small Integrin-Binding LIgand, N-linked Glycoprotein) family, that includes osteopontin (OPN), bone sialoprotein (BSP), dentin matrix protein 1 (DMP1), dentin sialophosphoprotein (DSPP), and matrix extracellular phosphoglycoprotein (MEPE). These polyanionic SIBLING proteins are believed to play key biological roles in the mineralization of bone and dentin. Although the specific mechanisms involved in controlling bone and dentin formation are still unknown, it is clear that some functions of the SIBLING family members are dependent on the nature and extent of post-translational modifications (PTMs), such as phosphorylation, glycosylation, and proteolytic processing, since these PTMs would have significant effects on their structure. OPN and BSP are present in the ECM of bone and dentin as full-length forms, whereas amino acid sequencing indicates that DMP1 and DSPP exist as proteolytically processed fragments that result from scission of X-Asp bonds. We hypothesized that the processing of DMP1 and DSPP is catalyzed by the PHEX enzyme, since this protein, an endopeptidase that is predominantly expressed in bone and tooth, has a strong preference for cleavage at the NH2-terminus of aspartyl residue. We envision that the proteolytic processing of DMP1 and DSPP may be an activation process that plays a significant, crucial role in osteogenesis and dentinogenesis, and that a failure in this processing would cause defective mineralization in bone and dentin, as observed in X-linked hypophosphatemic rickets.

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    PLoS ONE 02/2015; 10(2):e0117402. DOI:10.1371/journal.pone.0117402 · 3.53 Impact Factor
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    ABSTRACT: The aim of this study is to determine a protocol of gingival crevicular fluid protein extraction used for the first dimension of 2-DE gels. It also aims at conducting a review on the current candidates for protein markers of this pathology, all of which may be used to prevent the disease. Gingival crevicular fluid was collected from two groups of 60 patients each, with and without external root resorption. Samples were extracted by means of various methods of protein extraction. SDS-PAGE gels were used to assess the quality of the method which was subsequently tested during isoelectric focusing of 2-DE gels taken from samples of patients with and without the disease. Milli-Q ultrapure ice cold water, without precipitation for gingival crevicular fluid protein extraction, proved the method with greatest sharpness to detect protein bands. Additionally, it allowed two-dimensional electrophoresis to be performed. The new protein extraction protocol does not interfere in isoeletric focusing of 2-DE gels. Furthermore, it provides the greatest sharpness in detecting protein bands of SDS-PAGE gels. This will allow mapping and searching of new external root resorption markers, particularly due to the difficulty in carrying out molecular tests with the current candidates for protein markers.
    12/2014; 19(6):62-9. DOI:10.1590/2176-9451.19.6.062-069.oar
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    ABSTRACT: Objective: The objective of the study was to systematically review the literature for studies reporting gene expression analyses (GEA) of the biological processes involved in early human peri-implant bone healing. Methods: Electronic databases (MEDLINE, EMBASE) were searched in duplicate. Controlled and uncontrolled studies reporting GEA of human peri-implant tissues - including ≥5 patients and ≥2 time points - during the first 4 weeks of healing were eligible for inclusion. Methodological quality and risk of bias were also assessed. Results: Four exploratory studies were included in reporting GEA of either tissues attached to SLA or SLActive implants after 4 to 14 days or cells attached to TiOBlast or Osseospeed implants after 3 to 7 days. A total of 111 implants from 43 patients were analyzed using validated array methods; however, considerable heterogeneity and risk of bias were detected. A consistent overall pattern of gene expression was observed; genes representing an immuno-inflammatory response were overexpressed at days 3 to 4, followed by genes representing osteogenic processes at day 7. Genes representing bone remodeling, angiogenesis, and neurogenesis were expressed concomitantly with osteogenesis. Several regulators of these processes, such as cytokines, growth factors, transcription factors, and signaling pathways, were identified. Implant surface properties seemed to influence the healing processes at various stages via differential gene expression. Conclusion: Limited evidence from gene expression studies in humans indicates that osteogenic processes commence within the first post-operative week and they appear influenced at various stages by implant surface properties. Keywords: Dental implant; Osseointegration; Gene expression; Molecular assessment

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