Current topics in pharmacological research on bone metabolism: Promyelotic leukemia zinc finger (PLZF) and tumor necrosis factor-alpha-stimulated gene 6 (TSG-6) identified by gene expression analysis play roles in the pathogenesis of ossification of the posterior longitudinal ligament.
To understand the molecular pathogenesis of ossification of the posterior longitudinal ligament of the spine (OPLL), an ectopic bone formation disease, we performed cDNA microarray analysis on cultured ligament cells from OPLL patients to understand the molecular pathogenesis of OPLL. We identified promyelotic leukemia zinc finger (PLZF) as one of up-regulated genes and tumor necrosis factor-alpha-stimulated gene 6 (TSG-6) as one of down-regulated gene during osteoblastic differentiation. We investigated the roles of PLZF in the regulation of osteoblastic differentiation of human mesenchymal stem cells (hMSCs) and C2C12 cells. siRNA-mediated gene-silencing of PLZF resulted in a reduction of the expression of osteoblast-specific genes such as the alkaline phosphatase, collagen 1A1, Runx2/CBFA1, and osteocalcin genes in the presence of osteogenic differentiation medium (OS) in hMSCs. The overexpression of PLZF induced CBFA1 induction, suggesting that PLZF is an upstream regulator of CBFA1 and thereby participates in promoting the ossification of spinal ligament cells in OPLL patients. Adenovirus-mediated TSG-6 overexpression in hMSCs resulted in suppression of osteoblastic differentiation induced by either BMP-2 or OS. TSG-6 can bind to BMP-2 directly and thereby could inhibit BMP-2 signaling. Taken together, these findings indicate that PLZF and TSG-6 play important roles in early osteoblastic differentiation.
Division of Genetic Diagnosis, The Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan. ituro@ims.u-tokyo.ac.jp
Ituro
I
Inoue
Ryuji
R
Ikeda
So
S
Tsukahara
D000818:Animals; D001483:Base Sequence; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006801:Humans; D051741:Kruppel-Like Transcription Factors; D017846:Longitudinal Ligaments / Q000378:metabolism / Q000473:pathology; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects / Q000473:pathology; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D017887:Ossification of Posterior Longitudinal Ligament / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D010006:Osteoblasts / Q000378:metabolism / Q000473:pathology; D000075722:Promyelocytic Leukemia Zinc Finger Protein; D034622:RNA Interference; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
D019485:Bone Morphogenetic Proteins; D015815:Cell Adhesion Molecules; D004268:DNA-Binding Proteins; D051741:Kruppel-Like Transcription Factors; D000075722:Promyelocytic Leukemia Zinc Finger Protein; C072273:TNFAIP6 protein, human; D014157:Transcription Factors; C092037:ZBTB16 protein, human