Retinol Research Today is a free monthly online journal that collates and summarizes the latest research about Retinol, including details on vitamin a, uses, wrinkle treatment, anti-aging. | ||||||||
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Effect of retinoic acid on transglutaminase and ornithine decarboxylase activities during liver regeneration.Ohtake Y, Maruko A, Ohishi N, Kawaguchi M, Satoh T, Ohkubo Y Department of Radiopharmacy, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai, Miyagi 981-8558, Japan. y-ohtake@tohoku-pharm.ac.jp Liver regeneration is regulated by several factors, including growth factors, cytokines, and post-translational modifications of several proteins. It is suggested that transglutaminase 2 (TG2) and ornithine decarboxylase (ODC) are involved in liver regeneration. To investigate the role of TG2 and ODC activities in regenerating liver, we used retinoic acid (RA), an inducer of TG2 and a suppressor of ODC. Regenerating rat liver was prepared by 70% partial hepatectomy (PH). Rats were sacrificed at 1, 2, 3, 4, and 6 days after surgery. RA was intraperitoneally injected immediately after PH. TG2 and ODC activities and products (epsilon-(gamma-glutamyl) lysine isopeptide (Gln-Lys) and polyamines, respectively) were examined at the indicated times. In RA-treated rat, DNA synthesis and ODC activity declined and the peak shifted to 2 days after PH, whereas TG2 activity increased at 1 day after PH. At that time, protein-polyamine, especially the protein-spermidine (SPD) bond, transiently decreased, whereas the formation of the Gln-Lys bond increased after PH. These results suggested that in regenerating liver, enhanced the formation of Gln-Lys bonds catalyzed by TG2 led to reduced DNA synthesis, whereas when ODC produced newly synthesized SPD, the inhibition of Gln-Lys bond production by the preferential formation of protein-SPD bonds led to an increase in DNA synthesis. Published 14 April 2008 in Cell Biochem Funct, 26(3): 359-65.
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