PubMed Health⌕ Search

Biomedical subjects

A Nifuji

Publications and source records attributed to A Nifuji.

At least 19 recordsLinked to original sources
PubMed2006

Unloading-induced bone loss was suppressed in gold-thioglucose treated mice.

Loss of mechanical stress causes bone loss. However, the mechanisms underlying the unloading-induced bone loss are largely unknown. Here, we examined the effects of gold-thioglucose (GTG) treatment, which destroys ventromedial hypothalamus (VMH), on unloading-induced bone loss. Unloading reduced bone volume in control (saline-treated) mice. Treatment with GTG-reduced bone mass and in these GTG-treated mice, unloading-induced reduction in bone mass levels was not observed. Unloading reduced the levels of bone formation rate (BFR) and mineral apposition rate (MAR). GTG treatment also reduced these parameters and under this condition, unloading did not further reduce the levels of BFR and MAR. Unloading increased the levels of osteoclast number (Oc.N/BS) and osteoclast surface (Oc.S/BS). GTG treatment did not alter the basal levels of these bone resorption parameters. In contrast to control, GTG treatment suppressed unloading-induced increase in the levels of Oc.N/BS and Oc.S/BS. Unloading reduced the levels of mRNA expression of the genes encoding osteocalcin, type I collagen and Cbfa1 in bone. In contrast, GTG treatment suppressed such unloading-induced reduction of mRNA expression. Unloading also enhanced the levels of fat mass in bone marrow and mRNA expression of the genes encoding PPARgamma2, C/EBPalpha, and C/EBPbeta in bone. In GTG-treated mice, unloading did not increase fat mass and the levels of fat-related mRNA expression. These results indicated that GTG treatment suppressed unloading-induced alteration in bone loss.

Adipocytes↗
PubMed2003

Establishment of tendon-derived cell lines exhibiting pluripotent mesenchymal stem cell-like property.

Development of the musculoskeletal system requires coordinated formation of distinct types of tissues, including bone, cartilage, muscle, and tendon. Compared to muscle, cartilage, and bone, cellular and molecular bases of tendon development have not been well understood due to the lack of tendon cell lines. The purpose of this study was to establish and characterize tendon cell lines. Three clonal tendon cell lines (TT-E4, TT-G11, and TT-D6) were established using transgenic mice harboring a temperature-sensitive mutant of SV40 large T antigen. Proliferation of these cells was significantly enhanced by treatment with bFGF and TGF-beta but not BMP2. Tendon phenotype-related genes such as those encoding scleraxis, Six1, EphA4, COMP, and type I collagen were expressed in these tendon cell clones. In addition to tendon phenotype-related genes, expression of osteopontin and Cbfal was observed. These clonal cell lines formed hard fibrous connective tissue when implanted onto chorioallantoic membrane in ovo. Furthermore, these cells also formed tendon-like tissues when they were implanted into defects made in patella tendon in mice. As these tendon cell lines also produced fibrocartilaginous tissues in tendon defect implantation experiments, mesenchymal stem cell properties were examined. Interestingly, these cells expressed genes related to osteogenic, chondrogenic, and adipogenic lineages at low levels when examined by RT-PCR. TT-G11 and TT-E4 cells differentiated into either osteoblasts or adipocytes, respectively, when they were cultured in cognate differentiation medium. These observations indicated that the established tendon cell line possesses mesenchymal stem cell-like properties, suggesting the existence of mesenchymal stem cell in tendon tissue.

Adipocytes↗
PubMed2003

Bone morphogenetic protein-2 enhances osterix gene expression in chondrocytes.

Osterix is a recently identified zinc-finger-containing transcription factor, which is required for skeletogenesis as no bone formation was observed in osterix-deficient mice. Osterix was first cloned as a gene whose expression was enhanced by BMP in C2C12 cells. As BMP induces ectopic bone formation in vivo via a pathway reminiscent to endochondral bone formation, BMP may also regulate osterix gene expression in chondrocytes. However, no information was available regarding the BMP actions on osterix gene expression in chondrocytes. We therefore examined the effects of BMP-2 on osterix gene expression in chondrocytes in culture. RT-PCR analysis indicated that osterix mRNA was expressed in the primary cultures of chondrocytes derived from mouse rib cartilage. The treatment with BMP-2 enhanced the levels of osterix transcripts within 24 h and the enhancement was still observed at 48 h based on RT-PCR analysis. This BMP effect was specific to this cytokine, as TGF-beta did not alter osterix gene expression. BMP effects on the osterix mRNA levels were also confirmed by Northern blot analysis. The enhancing effect of BMP on osterix gene expression was observed in a dose-dependent manner starting at 200 ng/ml. The BMP enhancement of the osterix gene expression in chondrocytes was blocked in the presence of a protein synthesis inhibitor, cycloheximide, while it was still observed in the presence of 5,6-dichloro-1-beta D-ribofuranosylbenzimidazol (DRB) suggesting the involvement of post-transcriptional events, which require new protein synthesis. These results indicated that osterix gene is expressed in the primary cultures of chondrocytes and its expression is under the control of BMP-2.

Animals↗
PubMed2003

Hedgehog signaling enhances core-binding factor a1 and receptor activator of nuclear factor-kappaB ligand (RANKL) gene expression in chondrocytes.

Hedgehog signaling is considered to play a crucial role in chondrogenesis by regulation through a network of cytokine actions, which is not fully understood. We examined the effect of hedgehog signaling on the expression of core-binding factor a1 (Cbfa1), a critical transcription factor for the development of bone and cartilage. Primary chondrocytes prepared from the costal cartilage of newborn mice were treated with N-terminal fragment of recombinant murine sonic hedgehog (rmShh-N). Northern blot analysis indicated that Cbfa1 mRNA expression levels in the chondrocyte cultures were elevated by the treatment with rmShh-N. rmShh-N treatment enhanced 1.8 kb Cbfa1 promoter activity in chondrocytes, suggesting the presence of transcriptional control. As Cbfa1-binding site(s) have been located in the promoter of the receptor activator of nuclear factor-kappaB (RANK) ligand (RANKL) gene, we also examined RANKL expression. rmShh-N treatment upregulated RANKL and RANK mRNA expression levels in chondrocytes. Interestingly, RANKL suppressed the hedgehog enhancement of alkaline phosphatase activity in chondrocytes, suggesting the presence of a link between these signaling molecules. We conclude that hedgehog signaling activates Cbfa1 gene expression through its promoter in chondrocytes, and also activates and interacts with RANKL to maintain cartilage development.

Analysis of Variance↗
PubMed2002

Defects in growth and bone metabolism in klotho mutant mice are resistant to GH treatment.

Klotho mutant (kl/kl) mice exhibit growth retardation after weaning, and previous electron microscopic examination of GH-producing cells in pituitary glands revealed a reduction in GH granules. However, it has not been known whether growth retardation in klotho mutant mice is related to the loss of GH function. We therefore examined whether treatment with GH could rescue the retardation of growth. At the end of 3 weeks of treatment with human GH, the body weight of wild-type (WT) mice was increased. In contrast, body weight was not increased in klotho mutant mice even after the treatment with human GH. Another feature of klotho mutant mice is the presence of osteopetrosis in the epiphyses of long bones and vertebrae. Treatment with human GH increased trabecular bone volume in the epiphyseal region of WT tibiae. Interestingly, increase in trabecular bone volume by GH treatment was also observed in klotho mutant mice and, therefore, the phenotype of high bone volume in the klotho mice was further enhanced. These findings indicate that a GH receptor system in cancellous bones could operate in mutant mice. Thus, growth retardation in the klotho mutant mice is resistant against GH treatment even when these mice respond to GH treatment in terms of cancellous bone volume.

Animals↗
PubMed2001

Enhancement of osteoclastic bone resorption and suppression of osteoblastic bone formation in response to reduced mechanical stress do not occur in the absence of osteopontin.

Reduced mechanical stress to bone in bedridden patients and astronauts leads to bone loss and increase in fracture risk which is one of the major medical and health issues in modern aging society and space medicine. However, no molecule involved in the mechanisms underlying this phenomenon has been identified to date. Osteopontin (OPN) is one of the major noncollagenous proteins in bone matrix, but its function in mediating physical-force effects on bone in vivo has not been known. To investigate the possible requirement for OPN in the transduction of mechanical signaling in bone metabolism in vivo, we examined the effect of unloading on the bones of OPN(-/-) mice using a tail suspension model. In contrast to the tail suspension-induced bone loss in wild-type mice, OPN(-/-) mice did not lose bone. Elevation of urinary deoxypyridinoline levels due to unloading was observed in wild-type but not in OPN(-/-) mice. Analysis of the mechanisms of OPN deficiency-dependent reduction in bone on the cellular basis resulted in two unexpected findings. First, osteoclasts, which were increased by unloading in wild-type mice, were not increased by tail suspension in OPN(-/-) mice. Second, measures of osteoblastic bone formation, which were decreased in wild-type mice by unloading, were not altered in OPN(-/-) mice. These observations indicate that the presence of OPN is a prerequisite for the activation of osteoclastic bone resorption and for the reduction in osteoblastic bone formation in unloaded mice. Thus, OPN is a molecule required for the bone loss induced by mechanical stress that regulates the functions of osteoblasts and osteoclasts.

Amino Acids↗
PubMed2001

Parathyroid hormone-induced bone resorption does not occur in the absence of osteopontin.

Osteopontin is an RGDS-containing protein that acts as a ligand for the alpha(v)beta(3) integrin, which is abundantly expressed in osteoclasts, cells responsible for bone resorption in osteopenic diseases such as osteoporosis and hyperparathyroidism. However, the role of osteopontin in the process of bone resorption has not yet been fully understood. Therefore, we investigated the direct function of osteopontin in bone resorption using an organ culture system. The amount of (45)Ca released from the osteopontin-deficient bones was not significantly different from the basal release from wild type bones. However, in contrast to the parathyroid hormone (PTH) enhancement of the (45)Ca release from wild type bones, PTH had no effect on (45)Ca release from organ cultures of osteopontin-deficient bones. Because PTH is located upstream of receptor activator of NF-kappaB ligand (RANKL), that directly promotes bone resorption, we also examined the effect of RANKL. Soluble RANKL with macrophage-colony stimulating factor enhanced (45)Ca release from the bones of wild type fetal mice but not from the bones of osteopontin-deficient mice. To obtain insight into the cellular mechanism underlying the phenomena observed in osteopontin-deficient bone, we investigated the number of tartrate-resistant acid phosphatase (TRAP)-positive cells in the bones subjected to PTH treatment in cultures. The number of TRAP-positive cells was increased significantly by PTH in wild type bone; however, no such PTH-induced increase in TRAP-positive cells was observed in osteopontin-deficient bones. These results indicate that the absence of osteopontin suppressed PTH-induced increase in bone resorption via preventing the increase in the number of osteoclasts in the local milieu of bone.

Animals↗
PubMed2001

Osteopontin facilitates angiogenesis, accumulation of osteoclasts, and resorption in ectopic bone.

Osteoclastic bone resorption requires a number of complex steps that are under the control of local regulatory molecules. Osteopontin is expressed in osteoclasts and is also present in bone matrix; however, its biological function has not been fully understood. To elucidate the role of osteopontin in the process of osteoclastic bone resorption, we conducted ectopic bone implantation experiments using wild-type and osteopontin knockout mouse. In the wild-type group, bone discs from calvariae implanted ectopically in muscle were resorbed, and their mass was reduced by 25% within 4 weeks. In contrast, the mass of the bone discs from calvariae of osteopontin knockout mice was reduced by only 5% when implanted in osteopontin knockout mice. Histological analyses indicated that the number of osteoclasts associated with the implanted bones was reduced in the osteopontin knockout mice. As osteopontin deficiency does not suppress osteoclastogenesis per se, we further examined vascularization immunohistologically and found that the number of vessels containing CD31-positive endothelial cells around the bone discs implanted in muscle was reduced in the osteopontin knockout mice. Furthermore, sc implantation assays indicated that the length and branching points of the newly formed vasculatures associated with the bone discs were also reduced in the absence of osteopontin. In this assay, tartrate-resistant acid phosphatase-positive area of the bone discs was also reduced in the osteopontin knockout mice, indicating further the link between the osteopontin-dependent vascularization and osteoclast accumulation. The bone resorption defect could be rescued by topical administration of recombinant osteopontin to the bones implanted in muscle. These observations indicate that osteopontin is required for efficient vascularization by the hemangiogenic endothelial cells and subsequent osteoclastic resorption of bones.

Animals↗
PubMed2001

Bone morphogenetic protein regulation of forkhead/winged helix transcription factor Foxc2 (Mfh1) in a murine mesodermal cell line C1 and in skeletal precursor cells.

Mfh1/Foxc2 is a member of forkhead/winged helix transcription factor family in which its members serve as key regulators in embryogenesis and cell differentiation in various species. Mutant mice null for Mfh1 show defects in axial and cranial skeletogenesis, suggesting requirement of Mfh1 for skeletal tissue development. However, the roles of Mfh1 and its regulation during early skeletogenesis have not been understood fully yet. In this study, we investigated developmental regulation of Mfh1 expression during embryonic skeletogenesis in vivo and in vitro chondrogenic cell differentiation using a mesodermal progenitor-like cell line C1. We first examined expression patterns of Mfh1 in relation to the cartilage phenotype-related molecules including bone morphogenetic proteins (BMPs) during mouse embryogenesis by in situ hybridization. In 10.5 days postcoitum (dpc) mouse limb, Mfh1 messenger RNA (mRNA) was expressed in the mesenchymal cells in the tissues that later give rise to skeleton. In 11.5 dpc embryos, Mfh1 transcripts were expressed in the cell condensation of skeletal blastemas. BMP2 transcripts were expressed in the cell condensation proximal to the Mfh1-expressing cells in the limbs and those of BMP-7 were expressed in the mesenchymal tissue surrounding the Mfh1-positive cell condensation. In 12.5 dpc and 13.5 dpc embryos, the expression of Mfh1 was localized to the perichondrium, which surrounds cells that express noggin and SOX9 mRNA. BMP-2 expression was overlapped with that of Mfh1 in the peripheral layer of 12.5 dpc and 13.5 dpc limb skeletal blastemas. Mfh1 expression persisted in the perichondrium of 15.5 dpc embryos though its level was reduced. We then examined the expression of Mfh1 in the mouse mesodermal cell line C1 that differentiates into chondrocytes in vitro. Mfh1 mRNA was expressed constitutively at low levels in C1 cells before the induction of its differentiation. On the differentiation of C1 cells into chondrocytes by the treatment with dexamethasone (Dex), Mfh1 expression was increased and peaked on day 4 of Dex treatment. Treatment with BMP-4/7 and BMP-7 protein also enhanced Mfh1 expression in C1 cells. To further examine the causative relationship between BMP and Mfh1 in mesenchymal tissue, we performed a mouse limb bud organ culture to implant BMP proteins with carriers into the mesenchymal tissue of the limb bud. Implantation of BMP-7 protein in the limb bud of 11.5 dpc embryos induced Mfh1 expression, suggesting that BMP regulates Mfh1 expression in limb mesenchyme. These results indicate that Mfh1 expression is associated with the early stage of chondrogenic differentiation both in vivo and in vitro and that BMPs regulate Mfh1 expression in skeletal precursor cells.

Animals↗
PubMed2001

Osteopontin deficiency reduces experimental tumor cell metastasis to bone and soft tissues.

Osteopontin has been implicated in the metastasis of tumors, and human tumors with high metastatic activity often express osteopontin at high levels. Osteopontin contains an arginine-glycine-aspartate (RGD) motif that is recognized by integrin family members to promote various cell activities including attachment to substrate and it is abundant in bone, to which certain tumors preferentially metastasize. Therefore, we investigated the role of osteopontin in the experimental metastasis of tumor cells using recently established osteopontin-deficient mice. B16 melanoma cells, which produce little osteopontin, were injected into the left ventricle of osteopontin-deficient mice or wild-type mice. Animals were killed 2 weeks after injection. The number of tumors was reduced in the bones of osteopontin-deficient mice compared with the bones in wild-type mice. The number of tumors in the adrenal gland also was reduced. To investigate the osteopontin effect on metastases via a different route, we injected B16 melanoma cells into the femoral vein. Through this route, the number of lung tumors formed was higher than in the intracardiac route and was again less in osteopontin-deficient mice compared with wild-type mice. In conclusion, in an experimental metastasis assay, the number of tumors found in bone (after intracardiac injection) and lung (after left femoral vein injection) was significantly reduced in osteopontin-deficient mice compared with wild-type mice. Tumor numbers in other organs examined were small and not significantly different in the two situations.

Animals↗
PubMed2001

Klotho-deficient mice are resistant to bone loss induced by unloading due to sciatic neurectomy.

Unloading induces bone loss as seen in experimental animals as well as in space flight or in bed-ridden conditions; however, the mechanisms involved in this phenomenon are not fully understood. Klotho mutant mice exhibit osteopetrosis in the metaphyseal regions indicating that the klotho gene product is involved in the regulation of bone metabolism. To examine whether the klotho gene product is involved in the unloading-induced bone loss, the response of the osteopetrotic cancellous bones in these mice was investigated. Sciatic nerve resection was conducted using klotho mutant (kl/kl) and control heterozygous mice (+/kl) and its effect on bone was examined by micro-computed tomography (microCT). As reported previously for wild-type mice (+/+), about 30% bone loss was induced in heterozygous mice (+/kl) by unloading due to neurectomy within 30 days of the surgery. By contrast, kl/kl mice were resistant against bone loss induced by unloading after neurectomy. Unloading due to neurectomy also induced a small but significant bone loss in the cortical bone of the mid-shaft of the femur in the heterozygous mice; no reduction in the cortical bone was observed in kl/kl mice. These results indicate that klotho mutant mice are resistant against bone loss induced by unloading due to neurectomy in both cortical and trabecular bone and indicate that klotho is one of the molecules involved in the loss of bone by unloading.

Animals↗
PubMed2001

Dexamethasone enhances SOX9 expression in chondrocytes.

SOX9 is a transcription factor that activates type II procollagen (Col2a1) gene expression during chondrocyte differentiation. Glucocorticoids are also known to promote chondrocyte differentiation via unknown molecular mechanisms. We therefore investigated the effects of a synthetic glucocorticoid, dexamethasone (DEX), on Sox9 gene expression in chondrocytes prepared from rib cartilage of newborn mice. Sox9 mRNA was expressed at high levels in these chondrocytes. Treatment with DEX enhanced Sox9 mRNA expression within 24 h and this effect was observed at least up to 48 h. The effect of DEX was dose dependent, starting at 0.1 nM and maximal at 10 nM. The half life of Sox9 mRNA was approximately 45 min in the presence or absence of DEX. Western blot analysis revealed that DEX also enhanced the levels of SOX9 protein expression. Treatment with DEX enhanced Col2a1 mRNA expression in these chondrocytes and furthermore, DEX enhanced the activity of Col2-CAT (chloramphenicol acetyltransferase) construct containing a 1.6 kb intron fragment where chondrocyte-specific Sry/Sox- consensus sequence is located. The enhancing effect of DEX was specific to SOX9, as DEX did not alter the levels of Sox6 mRNA expression. These data suggest that DEX promotes chondrocyte differentiation through enhancement of SOX9.

Animals↗
PubMed2000

Overexpression of Cas-interacting zinc finger protein (CIZ) suppresses proliferation and enhances expression of type I collagen gene in osteoblast-like MC3T3E1 cells.

Osteoblasts are the cells which form bone under the regulation not only by hormones and cytokines but also by ECM molecules via their attachment. To obtain insights into the role of intracellular signaling molecules operating to mediate the attachment-related regulation of osteoblastic functions, we investigated in osteoblast-like MC3T3E1 cells the effects of the overexpression of CIZ, a novel signaling protein which interacts with p130Cas. In MC3T3E1 cells, CIZ mRNA is expressed constitutively. Endogenous CIZ was localized in the MC3T3E1 cells with relatively high levels of accumulation at the attachment sites when the cells were cultured on fibronectin, collagen, or BSA. CIZ overexpression increased the number of adhesion plaques and reduced proliferation of the cells compared to that of control cells transfected with an empty vector. Furthermore, CIZ overexpression enhanced type I collagen mRNA expression, the most abundant constituent of bone matrix and a major product of osteoblasts. Analysis of the promoter region of type I collagen gene identified the presence of a consensus CIZ-binding sequence, which indeed conferred responsiveness to CIZ overexpression to a heterologous promoter. These data indicate that CIZ acts as a novel regulatory molecule in controlling osteoblastic function.

Animals↗
PubMed2000

SOX9 enhances aggrecan gene promoter/enhancer activity and is up-regulated by retinoic acid in a cartilage-derived cell line, TC6.

SOX9 is a transcription factor that plays a key role in chondrogenesis. Aggrecan is one of the major structural components in cartilage; however, the molecular mechanism of aggrecan gene regulation has not yet been fully elucidated. TC6 is a clonal chondrocytic cell line derived from articular cartilage. The purpose of this study was to examine whether SOX9 modulates aggrecan gene expression and to further identify molecules that regulate Sox9 expression in TC6 cells. SOX9 overexpression in TC6 cells enhanced by approximately 3-fold the transcriptional activity of the AgCAT-8 construct containing 8-kilobase (kb) promoter/first exon/first intron fragments of the aggrecan gene. SOX9 enhancement of aggrecan promoter activity was lost when we deleted a 4.5-kb fragment from the 3'-end of the 8-kb fragment corresponding to the region including the first intron. In TC6 cells, SOX9 enhanced the transcriptional activity of a reporter construct containing the Sry/Sox consensus sequence >10-fold. SOX9 enhancement of aggrecan gene promoter activity and SOX9 transactivation through the Sry/Sox consensus sequence were not observed in osteoblastic osteosarcoma cells (ROS17/2.8), indicating the dependence on the cellular background. Northern blot analysis indicated that TC6 cells constitutively express Sox9 mRNA at relatively low levels. To examine regulation of Sox9 gene expression, we investigated the effects of calciotropic hormones and cytokines. Among these, retinoic acid (RA) specifically enhanced Sox9 mRNA expression in TC6 cells. The basal levels of Sox9 expression and its enhancement by RA were observed similarly at both permissive (33 degrees C) and nonpermissive (39 degrees C) temperatures. Furthermore, RA treatment enhanced the transcriptional activity of a reporter construct containing the Sry/Sox consensus sequence in TC6 cells. Moreover, RA treatment also enhanced the transcriptional activity of another reporter construct containing the enhancer region of the type II procollagen gene in TC6 cells. These observations indicate that SOX9 enhances aggrecan promoter activity and that its expression is up-regulated by RA in TC6 cells.

Aggrecans↗
PubMed2000

An osteogenesis-related transcription factor, core-binding factor A1, is constitutively expressed in the chondrocytic cell line TC6, and its expression is upregulated by bone morphogenetic protein-2.

Core-binding factor A1 (Cbfa1), also called Pebp2 alpha A/AML3, is a transcription factor that belongs to the runt-domain gene family. Cbfa1-deficient mice are completely incapable of both endochondral and intramembranous bone formation, indicating that Cbfa1 is indispensable for osteogenesis. Maturation of chondrocytes in these mice is also disorganized, suggesting that Cbfa1 may also play a role in chondrogenesis. The aim of this study was to examine the expression and regulation of Pebp2 alpha A/AML3/Cbfa1 expression in the chondrocyte-like cell line, TC6. Northern blot analysis indicated that Cbfa1 mRNA was constitutively expressed as a 6.3 kb message in TC6 cells and the level of Cbfa1 expression was enhanced by treatment with bone morphogenetic protein-2 (BMP2) in a time- and dose-dependent manner. This effect was blocked by an RNA polymerase inhibitor, 5,6-dichloro-1-beta-d-ribofuranosylbenzimidazole, but not by a protein synthesis inhibitor, cycloheximide. Western blot analysis of the cell lysates using polyclonal antibody raised against Cbfa1 indicated that BMP2 treatment increased the Cbfa1 protein level in TC6 cells. In TC6 cells, BMP2 treatment enhanced expression of alkaline phosphatase and type I collagen mRNAs but suppressed that of type II collagen mRNA. In addition to TC6 cells, Cbfa1 mRNA was also expressed in primary cultures of chondrocytes and BMP2 treatment enhanced Cbfa1 mRNA expression in these cells similarly to its effect on TC6 cells. These data indicate that the Pebp2 alpha A/AML3/Cbfa1 gene is expressed in a chondrocyte-like cell line, TC6, and its expression is enhanced by treatment with BMP.

Animals↗
PubMed1999

Articular cartilage cells immortalized by a temperature sensitive mutant of SV40 large T antigen survive and form cartilage tissue in articular cartilage environment.

A chondrogenic cell line, TC6, was established by using cells derived from articular cartilage of transgenic mice harboring a temperature-sensitive mutant simian virus (SV) 40 large T-antigen gene. TC6 cells express genes encoding proteins related to cartilage phenotypes such as type II collagen. To examine the in vivo behavior of the TC6 cells, these cells were implanted into cavity-shaped full-thickness defects made in the articular cartilage of the central part of the patellar grooves of mouse femora. One week after implantation, the morphology of the cells was still fibroblastic but these cells were just about to start to form a cartilage-like matrix. By 6 weeks after implantation, the cells had produced abundant cartilaginous matrix and their morphology became closer to that of authentic chondrocytes. This was in sharp contrast to the fibroblastic morphology of these cells in an in vitro environment even after long-term culture. These observations indicate that a cartilage-matrix environment provides a scaffold for the TC6 cells to form cartilage tissues. Our data show that the genetically engineered chondrocytic cell line, TC6, can form a cartilage-like matrix in vivo.

Animals↗
PubMed1999

Induction of apoptosis of monocyte-macrophage lineage cells by 5-S-GAD.

We found that 5-S-GAD, an insect-derived antibacterial peptide, inhibited murine osteoclast formation in vitro. We examined the specific time point of the inhibitory action of 5-S-GAD on osteoclast formation and found that it mainly suppressed differentiation of osteoclasts in the middle of the culture period. Using HL60 cells that are able to differentiate into multinucleated macrophage-like cells, we found that 5-S-GAD induced apoptosis of HL60 cells by producing H(2)O(2). Thus, the inhibition of osteoclast formation by 5-S-GAD could be, in part, due to apoptosis of the cells of an osteoclast lineage.

Acid Phosphatase↗