@article{oai:repo.qst.go.jp:00046125,
 author = {Nifuji, Akira and Ideno, Hisashi and Ohyama, Yoshio and Takanabe, Rieko and Araki, Ryoko and Abe, Masumi and Noda, Masaki and Shibuya, Hiroshi and 二藤 彰 and 出野 尚 and 高鍋 利依子 and 荒木 良子 and 安倍 真澄},
 issue = {7},
 journal = {Experimental Cell Research},
 month = {Jan},
 note = {Mitogen-activated protein kinases (MAPKs) regulate proliferation and differentiation in osteoblasts. The vertebral homologue of nemo, nemo-like kinase (NLK), is an atypical MAPK that targets several signaling components, including the T-cell factor/lymphoid enhancer factor (TCF/Lef1) transcription factor. Recent studies have shown that NLK forms a complex with the histone H3-K9 methyltransferase SETDB1 and suppresses peroxisome proliferator-activated receptor (PPAR)-gamma:: action in the mesenchymal cell line ST2. Here we investigated whether NLK regulates osteoblastic differentiation. We showed that NLK mRNA is expressed in vivo in osteoblasts at embryonic day 18.5 (E18.5) mouse calvariae. By using retrovirus vectors, we performed forced expression of NLK in primary calvarial osteoblasts (pOB cells) and the mesenchymal cell line ST2. Wild-type NLK (NLK-WT) suppressed alkaline phosphatase activity and expression of bone marker genes such as alkaline phosphatase, type I procollagen, runx2, osterix, steopontin and osteocalcin in these cells. NLK-WT also decreased type I collagen protein expression in pOB and ST2 cells. Furthermore, mineralized nodule formation was reduced in pOB cells overexpressing NLK-WT. In contrast, kinase-negative form of NLK (NLK-KN) did not suppress or partially suppress ALP activity and bone marker gene expression in pOB and ST2 cells. NLK-KN did not suppress nodule formation in pOB cells. In addition to forced expression, suppression of endogenous NLK expression by siRNA increased bone marker gene expression in pOB and ST2 cells. Finally, transcriptional activity analysis of gene promoters revealed that NLK-WT suppressed Wnt1 activation of TOP flash promoter and Runx2 activation of the osteocalcin promoter. Taken together, these results suggest that NLK negatively regulates osteoblastic differentiation.},
 pages = {1127--1136},
 title = {Nemo-like kinase (NLK) expression in osteoblastic cells and suppression of osteoblastic differentiation.},
 volume = {316},
 year = {2010}
}