RESUMEN
OBJECTIVE: EphrinA2-EphA2 and ephrinB2-EphB4 critically engage in bidirectional signalling to modulate alveolar bone remodelling. The present study aimed to investigate the effects of lipopolysaccharides (LPS) derived from Porphyromonas gingivalis on ephrin/Eph signalling in periodontal ligament fibroblasts (PDLFs). MATERIAL AND METHODS: The primary cultured PDLFs were incubated in the absence (as a control) or presence of P. gingivalisLPS at 0.001-10 µg/mL for 24 hours. The PDLFs were then stimulated with P. gingivalisLPS at the optimal concentration (0.1 µg/mL) for different periods (6-48 hours). The expression of ephrinA2, ephrinB2, EphA2 and EphB4 was assessed by quantitative reverse-transcription real-time polymerase chain reaction and western blotting. The osteoblastic markers alkaline phosphatase, osteocalcin and Runt-related transcription factor 2 (Runx2), and the osteoclastogenesis-related factors receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin were also evaluated. RESULTS: The ephrinA2 and EphA2 expression was upregulated and EphB4 expression was downregulated by stimulation of P. gingivalisLPS. EphrinA2 mRNA expression in the PDLFs was significantly upregulated from 12 to 48 hours (P<.05), whereas EphA2 exhibited no change for the first 24 hours, after which there was a significant increase at 48 hours (P<.05). EphB4 exhibited lower mRNA expression at 12 and 24 hours than did the control (P<.05), but the change was insignificant at 48 hours. In contrast, the expression of ephrinB2 remained unchanged. The expressions of ephrinA2, EphA2, ephrinB2 and EphB4 at the protein level showed a similar pattern to that at the mRNA level. The expression of Runx2 and osteocalcin significantly decreased, whereas that of RANKL/osteoprotegerin increased. CONCLUSION: The present study suggest that P. gingivalisLPS would contribute to a dysregulation of bone remodelling, whereby ephrinA2/EphA2 expression is stimulated and EphB4 expression is inhibited.
Asunto(s)
Efrinas/efectos de los fármacos , Fibroblastos/efectos de los fármacos , Lipopolisacáridos/farmacología , Ligamento Periodontal/efectos de los fármacos , Porphyromonas gingivalis/metabolismo , Receptores de la Familia Eph/efectos de los fármacos , Adolescente , Fosfatasa Alcalina , Remodelación Ósea/efectos de los fármacos , Técnicas de Cultivo de Célula , Niño , Subunidad alfa 1 del Factor de Unión al Sitio Principal , Efrina-A2/efectos de los fármacos , Efrina-A2/genética , Efrina-B2/efectos de los fármacos , Efrina-B2/genética , Efrinas/genética , Regulación de la Expresión Génica , Humanos , Osteoblastos , Osteocalcina , Osteogénesis , Osteoprotegerina , ARN Mensajero/metabolismo , Receptor Activador del Factor Nuclear kappa-B , Receptor EphA2/efectos de los fármacos , Receptor EphA2/genética , Receptor EphB4/efectos de los fármacos , Receptor EphB4/genética , Receptores de la Familia Eph/genéticaRESUMEN
The Eph-ephrin signaling pathway mediates developmental processes and the proper functioning of the adult human body. This distinctive bidirectional signaling pathway includes a canonical downstream signal cascade inside the Eph-bearing cells, as well as a reverse signaling in the ephrin-bearing cells. The signaling is terminated by ADAM metalloproteinase cleavage, internalization, and degradation of the Eph/ephrin complexes. Consequently, the Eph-ephrin-ADAM signaling cascade has emerged as a key target with immense therapeutic potential particularly in the context of cancer. An interesting twist was brought forth by the emergence of ephrins as the entry receptors for the pathological Henipaviruses, which has spurred new studies to target the viral entry. The availability of high-resolution structures of the multi-modular Eph receptors in complexes with ephrins and other binding partners, such as peptides, small molecule inhibitors and antibodies, offers a wealth of information for the structure-guided development of therapeutic intervention. Furthermore, genomic data mining of Eph mutants involved in cancer provides information for targeted drug development. In this review we summarize the distinct avenues for targeting the Eph-ephrin signaling pathway, including its termination by ADAM proteinases. We highlight the latest developments in Eph-related pharmacology in the context of Eph-ephrin-ADAM-based antibodies and small molecules. Finally, the future prospects of genomics- and proteomics-based medicine are discussed.
Asunto(s)
Efrinas/efectos de los fármacos , Efrinas/metabolismo , Receptores de la Familia Eph/efectos de los fármacos , Receptores de la Familia Eph/metabolismo , Proteínas ADAM/efectos de los fármacos , Proteínas ADAM/metabolismo , Anticuerpos/química , Anticuerpos/farmacología , Antineoplásicos/farmacología , Sitios de Unión , Desarrollo de Medicamentos , Efrinas/química , Humanos , Modelos Biológicos , Modelos Moleculares , Mutación , Neoplasias/tratamiento farmacológico , Neoplasias/genética , Neoplasias/metabolismo , Receptores de la Familia Eph/genética , Transducción de Señal/efectos de los fármacosRESUMEN
Eph receptor tyrosine kinases (Ephs) and their membrane anchored ephrin ligands (ephrins) form an essential cell-cell communication system that directs the positioning, adhesion and migration of cells and cell layers during development. While less prominent in normal adult tissues, there is evidence that up-regulated expression and de-regulated function of Ephs and ephrins in a large variety of human cancers may promote a more aggressive and metastatic tumour phenotype. However, in contrast to other RTKs, Ephs do not act as classical proto-oncogenes and do not effect cell proliferation or differentiation. Mounting evidence suggests that Eph receptors, through de-regulated re-emergence of their mode of action in the embryo may direct cell movements and positioning during metastasis, invasion and tumour angiogenesis. This review discusses these and other emerging roles of Eph receptors during oncogenesis.