Biomedical subjects

Takeshi Moriishi

Publications and source records attributed to Takeshi Moriishi.

4 recordsLinked to original sources

PubMed2006

Cbf beta regulates Runx2 function isoform-dependently in postnatal bone development.

Runx2 and Cbfbeta are essential for skeletal development during the embryonic stage. Runx2 has two isoforms with different N-termini. We examined the functions of the Runx2 isoforms and Cbfbeta in postnatal bone development. On luciferase and electrophoretic mobility shift assays, Runx2-I was less active than Runx2-II in the absence of Cbfb, but the two Runx2 isoforms had similar activity levels in the presence of Cbfb. We generated Runx2-I transgenic mice under the control of Col1a1 promoter and Runx2-I/Cbfb and Runx2-II/Cbfb double transgenic mice. Runx2-I transgenic mice showed less severe osteopenia and fragility than Runx2-II transgenic mice due to milder inhibition of both osteoblast maturation and transition to osteocytes, even though the former mice showed higher transgene expression. However, Runx2-I/Cbfb and Runx2-II/Cbfb double transgenic mice had enhanced inhibition of osteoblast maturation, resulting in similar severity of osteopenia and fragility, although the latter mice had less osteocytes. These findings indicate that (1) Runx2-II more strongly inhibits osteoblast maturation and transition to osteocytes than Runx2-I; (2) Cbfbeta regulates Runx2 function isoform-dependently; and (3) Runx2-I activity is highly dependent on Cbfbeta. These findings demonstrate that Runx2 isoforms exert their functions through at least partly different mechanisms and Cbfbeta regulates bone development by regulating Runx2 function isoform-dependently.

Animals↗

PubMed2006

Experimental model of tooth movement by orthodontic force in mice and its application to tumor necrosis factor receptor-deficient mice.

Orthodontic tooth movement is achieved by mechanical loading; however, the biological mechanism involved in this process is not clearly understood owing to the lack of a suitable experimental model. In the present study, we established an orthodontic tooth movement model in mice using a Ni-Ti closed coil spring that was inserted between the upper incisors and the upper first molar. Histological examination demonstrated that the orthodontic force moved the first upper molar mesially without necrosis of the periodontium during tooth movement. The number of TRAP-positive osteoclasts on the pressure side significantly increased in a time-dependent manner. Quantitative real time-based reverse transcription-polymerase chain reaction analysis demonstrated increased levels of mRNA for cathepsin K. Immunohistochemical staining revealed the expression of tumor necrosis factor-alpha (TNFalpha) in periodontium on the pressure side of the first molar during orthodontic tooth movement. When this tooth movement system was applied to TNF type 1 receptor-deficient mice and TNF type 2 receptor-deficient mice, tooth movement observed in TNF type 2 receptor-deficient mice was smaller than that in the wild-type mice and TNF type 1 receptor-deficient mice. The number of TRAP-positive osteoclasts on the pressure side was significantly small in TNF type 2 receptor-deficient mice compared with that in TNF type 1 receptor-deficient mice on day 6 after application of the appliance. The present study indicates that TNFalpha signaling plays some important roles in orthodontic tooth movement.

Acid Phosphatase↗

PubMed2005

Expression profile of Xenopus banded hedgehog, a homolog of mouse Indian hedgehog, is related to the late development of endochondral ossification in Xenopus laevis.

Late development of endochondral ossification occurs at the boundary between the growth cartilage and bone marrow during the formation of long bones in Xenopus laevis. Since the Indian hedgehog (Ihh) is involved in endochondral ossification in mouse, we investigated the expression of Xenopus banded hedgehog (X-bhh), which is a homolog of mouse Ihh. RT-PCR analysis demonstrated that the X-bhh mRNA was detected from an early stage of limb formation to formation of femurs in mature frogs, and it was associated with the expression of Xenopus-ptc1 (X-ptc1), Xenopus-gli1 (X-gli1), Xenopus-type II collagen (X-col II), Xenopus-runx2 (X-runx2), and Xenopus-osteocalcin (X-ocn) mRNAs. In situ hybridization revealed that chondrogenic cells observed at early limb development expressed X-bhh and X-gli1. At later stages of limb development, chondrocytes, located slightly away from the boundary between the cartilage and bone marrow, expressed the X-bhh, X-ptc1, and X-gli1 mRNAs; however, the mesenchymal cells at the boundary failed to express these mRNAs. The X-bhh, X-ptc1, and X-gli1 mRNAs as well as those of X-runx2 and X-ocn were expressed by the mesenchymal cells in the periosteal region at the tip of the cortical bone, indicating an intimate relationship between X-bhh expression and bone formation in this region. Considered collectively, the present study suggests that X-bhh evolutionally acquired the function to induce osteogenesis; however, the expression profile of X-bhh in epiphysis is closely related to the late development of endochondral ossification in X. laevis.

Animals↗

PubMed2005

Critical regulation of bone morphogenetic protein-induced osteoblastic differentiation by Delta1/Jagged1-activated Notch1 signaling.

Functional involvement of the Notch pathway in osteoblastic differentiation has been previously investigated using the truncated intracellular domain, which mimics Notch signaling by interacting with the DNA-binding protein CBF-1. However, it is unclear whether Notch ligands Delta1 and Jagged1 also induce an identical cellular response in osteoblastic differentiation. We have shown that both Delta1 and Jagged1 were expressed concomitantly with Notch1 in maturating osteoblastic cells during bone regeneration and that overexpressed and immobilized recombinant Delta1 and Jagged1 alone did not alter the differentiated state of MC3T3-E1 and C2C12 cells. However, they augmented bone morphogenetic protein-2 (BMP2)-induced alkaline phosphatase activity and the expression of several differentiation markers, except for osteocalcin, and ultimately enhanced calcified nodule and in vivo ectopic bone formation of MC3T3-E1. In addition, both ligands transmitted signal through the CBF-1-dependent pathway and stimulated the expression of HES-1, a direct target of Notch pathway. To test the necessity of Notch signaling in BMP2-induced differentiation, Notch signaling was inhibited by the dominant negative extracellular domain of Notch1, specific inhibitor, or small interference RNA. These treatments decreased alkaline phosphatase activity as well as the expression of other differentiation markers and inhibited the promoter activity of Id-1, a target gene of the BMP pathway. These results indicate the functional redundancy between Delta1 and Jagged1 in osteoblastic differentiation whereby Delta1/Jagged1-activated Notch1 enhances BMP2-induced differentiation through the identical signaling pathway. Furthermore, our data also suggest that functional Notch signaling is essential not only for BMP2-induced osteoblast differentiation but also for BMP signaling itself.

Alkaline Phosphatase↗