Ralphs, Jim - Cardiff University - School of Biosciences

研究领域

Cellular control of extracellular matrix secretion and organisation in connective tissues The function of connective tissues depends on the organisation of their collagen fibres, arranged in parallel fibres, in parallel sheets (lamellae; annulus fibrosus, cornea, bone), or with more complex or random, orientation (cartilage, dermis, loose connective tissue). My research is on roles of the cytoskeleton and cell-cell interactions in control of secretion and orientation of the extracellular matrix in fibrous connective tissues. In tendons, longitudinal rows of fibroblasts are embedded between parallel collagen fibre bundles. Along a row, cells are connected by gap junctions made of connexins 43 and 32, and by adherens junctions. The adherens junctions link short lengths of actin stress fibres end to end from cell to cell along the cell row. Gap junctions modulate cell response to load: antisense downregulation of of connexin 43 enhances, and connexin 32 depresses, matrix secretion. Adherens junction and stress fibre components are upregulated by load suggesting that cells may bind together more strongly; cell-cell junctions involving cadherins could also be involved in mechanosensation and thus initiation of load responses. The annulus fibrosus consists of concentric collagenous lamellae linking vertebral bodies in the spine. In successive lamellae collagen fibres are tilted, forming a radial ply structure. The cornea has a similar organisation, although with thinner, more numerous lamellae In the annulus, oriented matrix deposition is preceded by orientation of fibroblasts into parallel sheets, with the long axis of the fibroblasts in each layer showing the same alternating angle as the collagen in the lamellae. The orientation process is associated with cadherin based cell-cell interactions, some gap junction expression and the development of prominent longitudinal actin stress fibres in the fibroblasts. In new studies, we are investigating possible associations between the collagen secretory pathway and prominent actin fibres in corneaL stromal fibroblasts, and early stage interactions between connective tissue cells.

近期论文

查看导师新发文章（温馨提示：请注意重名现象，建议点开原文通过作者单位确认）

Beckett, M.et al. 2015. The transmembrane heparan sulphate proteoglycan syndecan-4 is involved in establishment of the lamellar structure of the annulus fibrosus of the intervertebral disc. European Cells and Materials 30, pp. 69-88. Vazquez, M.et al. 2014. A new method to investigate how mechanical loading of osteocytes controls osteoblasts. Frontiers in Endocrinology 5, article number: 208. (10.3389/fendo.2014.00208) pdf Vazquez, M.et al. 2014. Development of a novel in vitro 3D osteoblast-osteocyte co-culture model to investigate mechanically-induced signalling. International Journal of Experimental Pathology 95(3), pp. A34-A35. Young, R.et al. 2014. Three-dimensional aspects of matrix assembly by cells in the developing cornea. Proceedings of the National Academy of Sciences 111(2), pp. 687-692. (10.1073/pnas.1313561110) Czekanska, E.et al. 2014. Enhancing inflammatory and chemotactic signals to regulate bone regeneration. European Cells and Materials 28, pp. 320-334. Czekanska, E.et al. 2014. A phenotypic comparison of osteoblast cell lines versus human primary osteoblasts for biomaterials testing. Journal of Biomedical Materials Research Part A 102(8), pp. 2636-2643. (10.1002/jbm.a.34937) Vazquez, M.et al. 2011. Bone in vitro 3D osteoblast-osteocyte co-culture model. International Journal of Experimental Pathology 92(6), pp. A18-A18. (10.1111/j.1365-2613.2011.00780.x) Hayes, A.et al. 2011. Chondroitin sulphate sulphation motif expression in the ontogeny of the intervertebral disc. European Cells and Materials 21, pp. 1-14. Hayes, A.et al. 2011. Collagen fibrillogenesis in the development of the annulus fibrosus of the intervertebral disc. European Cells and Materials 22, pp. 226-241. Hayes, A. J. and Ralphs, J. R. 2011. The response of foetal annulus fibrosus cells to growth factors: modulation of matrix synthesis by TGF-β1 and IGF-1. Histochemistry and Cell Biology 136(2), pp. 163-175. (10.1007/s00418-011-0835-x) Ralphs, J.et al. 2010. Chondroitin sulphate sulfation motifs in intervertebral disc development [Abstract]. European Cells and Materials 20(Supp 2), pp. 3.