Prohibitins, novel vitamin K2 target factors in osteoblast

Vitamin K2 (VK2, menaquinone) is a drug for osteoporosis. VK2 acts as a cofactor for γ-glutamyl carboxylase, which catalyzes the carboxylation of specific glutamic acid residues (γ-carboxylation) of substrate proteins. Here we demonstrate that VK2 also regulate osteoblastgenic marker gene expression. Using VK2-immobilzed nanobeads new target proteins were purified and identified from osteoblastic cell line. They are prohibitin 1 and 2 (PHB1 & 2), respectively. To confirm the PHBs function on VK2-dependent transcription, PHB1 & 2 were knock-down and osteocalcin gene 2 transcriptions were analyzed, indicating that PHBs regulate VK2-dependent transcription. Taken together PHBs are VK2 target proteins for osteoblastgenic transcription.

Increased Expression of 11<i>β</i>-Hydroxysteroid Dehydrogenase Type 1 in Experimental Periodontitis Induced by Lipopolysaccharide from <i>Porphyromonas gingivalis</i>

It has been proposed that 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1), which activates glucocorticoids, plays a role in chronic inflammatory diseases including metabolic diseases, rheumatoid arthritis, and ulcerative colitis. We have recently reported that the expression of 11β-HSD1 is increased in the gingiva of patients with chronic periodontitis and in that of rats with ligature-induced periodontitis. In this study, to further demonstrate the involvement of 11β-HSD1 in chronic periodontitis, the expression of 11β-HSD1 was investigated in another rat model of experimental periodontitis induced by intragingival injection of lipopolysaccharide from Porphyromonas gingivalis (LPS-PG). Alveolar bone loss was observed two weeks after intragingival injection of LPS-PG. The level of 11β-HSD1 mRNA assessed by real-time reverse transcriptase-polymerase chain reaction was significantly elevated in LPS-PG-induced periodontitis compared with controls. The expression of 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), which inactivates glucocorticoids, was not significantly different between control and LPS-PG-induced periodontitis. The expression of 11β-HSD1 was significantly correlated with that of TNF in LPS-PG-induced periodontitis. The increased expression of 11β-HSD1 protein in LPS-PG-induced periodontitis was confirmed by immunohistochemistry using anti-11β-HSD1 antibody. These results further suggest a role for 11β-HSD1 in the pathogenesis of chronic periodontitis.

PGJIFs, new mitochondrial PGJ2 target factors, regulate cell proliferation

Our previous study showed that prostaglandin J2 (PGJ2) interacting factor (PGJIF) was purified and identified with magnetic nanobeads. Farther analysis of PGJ2 function shows that PGJ2 inhibits cell proliferation and rhodamine 123 incorporation. Using PGJ2- immobilized nanobeads, two target proteins were also purified and identified as PGJIF1 and PGJIF2. PGJIF1 genetic analysis showed that PGJIF1 regulates cell proliferation as well as rhodamine 123 incorporation in mitochondria, indicating that PGJIF1 is one of the PGJ2 target proteins. The other target protein, PGJIF2, changes its intracellular localization in PGJ2-dependent manner. Using nanobeads technology, two PGJ2 target factors were purified and identified.

Effective cofactor complex purification using nanobeads

Drug target factor complex identification is necessary for evidence based drug discovery. Previous study showed that using small chemical immobilized magnetic nanobeads the chemical target factors were effectively purified and identified. Here we succeeded to purify the chemical target factor complex, so called cofactor(s). Arginine exhibits a variety of biological activities through a complex and highly regulated set of pathways that remain incompletely understood at both the whole-body and the cellular levels. The aim of this study is to develop and validate effective purification system for arginine target complex. New arginine target protein (arginine interacting factor 4, AIF4) was purified and identified. Using recombinant AIF4 protein and arginine-immobilized magnetic nanobeads, AIF4 cofactor, AIF4-BP1, were purified. Interaction of AIF4 and AIF4-BP1 was detected in arginine-dependent manner, suggesting arginine receptor complex formation. This nanobeads technology is more than 30-fold efficient purification efficient than general purification technology.