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K. Hosoya, J. Kiyokawa, M. Tachikawa, T. Kondo, S. Ohtsuki, T. Terasaki, M. Tomi; Retinal Pericyte–Secreted Protein: Tropomyosin Plays a Role in Suppressing Retinal Endothelial Cell Growth . Invest. Ophthalmol. Vis. Sci. 2006;47(13):141.
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© ARVO (1962-2015); The Authors (2016-present)
Soluble factors secreted from retinal pericytes play an important role in the regulation of retinal neovascularization. The purpose of this study was to elucidate the suppression mechanism of retinal endothelial cell growth by soluble factors derived from retinal pericytes and identify retinal pericyte–secreted proteins as a suppressor of retinal endothelial cell growth.
Conditionally immortalized rat retinal pericyte cell line (TR–rPCT) was cultured in DMEM. Conditioned medium (CM) of TR–rPCT (rPCT–CM) was concentrated using a Centriprep–3 (3 kDa cut–off). Inhibition activity of cell growth was measured in conditionally immortalized rat retinal endothelial cell line (TR–iBRB). Proteins in rPCT–CM were purified using a 2–D gel electrophoresis and identified by a MALDI–TOFMS/peptide mass fingerprinting method.
rPCT–CM suppressed ischemia–induced retinal neovascularization in vivo. The growth and DNA synthesis of TR–iBRB cells were suppressed in a concentration–dependent manner by rPCT–CM. The levels of expression of G1/S–phase–related proteins, such as cyclin D1, cyclin–dependent kinase (cdk) 4, cdk 6, and proliferating cell nuclear antigen, were reduced in rPCT–CM–treated TR–iBRB cells. Moreover, phosphorylated p44/42 mitogen–activated protein kinase (p44/42 MAPK) in TR–iBRB cells was reduced by rPCT–CM treatment and phosphorylated protein kinase C (PKC)α/ßII was also suppressed. Tropomyosin was identified as a retinal pericyte–secreted protein and had an inhibition activity of cell growth.
CM from retinal pericytes suppresses PKC–p44/42 MAPK signaling and inhibits endothelial cell growth. Tropomyosin may be one of retinal pericyte–secreted proteins as a suppressor of retinal endothelial cell growth.
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