TITLE:
Prohibitins, novel vitamin K2 target factors in osteoblast
AUTHORS:
Tatsuya Uebi, Makoto Umeda, Naoya Maekawa, Satoshi Karasawa, Hiroshi Handa, Takeshi Imai
KEYWORDS:
Vitamin K2; Prohibitin; Osteoblast; Runt-Related Transcription Factor 2 (Runx2)
JOURNAL NAME:
Journal of Biosciences and Medicines,
Vol.1 No.3,
December
12,
2013
ABSTRACT: 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.