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C Miyaura

Publications and source records attributed to C Miyaura.

At least 37 records · Page 2Linked to original sources
PubMed1997

Activation of cytosolic phospholipase A2 by platelet-derived growth factor is essential for cyclooxygenase-2-dependent prostaglandin E2 synthesis in mouse osteoblasts cultured with interleukin-1.

The synthesis of prostaglandins (PGs) is regulated by the arachidonic acid release by phospholipase A2 (PLA2) and its conversion to PGs by cyclooxygenase (COX). In the present study, we examined the regulation of PG synthesis by interleukin (IL)-1alpha in primary mouse osteoblastic cells isolated from mouse calvaria. Although IL-1alpha greatly enhanced cox-2 mRNA expression and its protein levels, PGE2 was not produced until 24 h. When arachidonic acid was added to osteoblastic cells precultured with IL-1alpha for 24 h, PGE2 was produced within 10 min. Of several growth factors tested, platelet-derived growth factor (PDGF) specifically initiated the rapid synthesis of PGE2, which was markedly suppressed by a selective inhibitor of cox-2 (NS-398). In mouse osteoblastic cells, cytosolic PLA2 (cPLA2) mRNA and its protein were constitutively expressed and increased approximately 2-fold by IL-1alpha, but secretory PLA2 mRNA was not detected. PDGF rapidly stimulated PLA2 activity, which was blocked completely by a cPLA2 inhibitor (arachidonyltrifluoromethyl ketone). The PDGF-induced cPLA2 activation was accompanied by phosphorylation of its protein. These results indicate that cox-2 induction by IL-1alpha is not sufficient, but cPLA2 activation by PDGF is crucial for IL-1alpha-induced PGE2 synthesis in mouse osteoblasts.

Animals↗
PubMed1997

Expression of estrogen receptor beta in rat bone.

A novel estrogen receptor, estrogen receptor beta (ERbeta), has recently been cloned from a rat prostate cDNA library. In bone, which is an important target tissue of estrogen, ER alpha has been reported to be present preferentially in osteoblasts, but the mechanism of action of estrogen in bone is still not known. In the present study, we examined expression of ERbeta mRNA in bone. Expression of ERbeta mRNA was evident in primary osteoblastic cells isolated from 1-day-old rat calvaria and rat osteosarcoma cells (ROS 17/2.8), and its level was higher than that of ER alpha mRNA. When osteoblastic cells were cultured for 28 days to induce differentiation into mature osteoblasts capable of forming bone nodules, ERbeta mRNA was constantly and highly expressed during the entire culture period. In contrast, the level of ER alpha mRNA was very low at the beginning of culture and it gradually increased during the differentiation of osteoblastic cells. Various tissues including bone were isolated from 8-week-old rats of both sexes, and total RNA was extracted to compare the tissue distribution of expression levels of ERbeta mRNA. In cancellous bone of the distal femoral metaphysis and lumbar vertebra, expression of ERbeta mRNA was obvious, and its level was equivalent to those in the uterus and testis, but lower than those in the ovary and prostate. The level of ERbeta mRNA in femoral cortical bone was lower than that in cancellous bone. There was no appreciable differences between female and male rats in the distribution and expression levels of ERbeta mRNA in bone. These results indicate that ERbeta mRNA is highly expressed in osteoblasts in rat bone, suggesting that there is a distinct mechanism of estrogen action mediated by ERbeta in bone.

Animals↗
PubMed1997

Transcriptional induction of cyclooxygenase-2 in osteoblasts is involved in interleukin-6-induced osteoclast formation.

Interleukin-6 (IL-6) induces osteoclast-like cell (osteoclast) formation in a dose-dependent fashion in cocultures of mouse bone marrow cells and osteoblastic cells when soluble IL-6 receptor (sIL-6R) is present. Simultaneous treatment with submaximal doses of IL-1alpha and IL-6 with sIL-6R caused marked induction of osteoclast formation and PGE2 synthesis. These effects were suppressed by adding neutralizing antibodies against IL-1alpha or IL-6R and were totally abolished by adding nonsteroidal antiinflammatory drugs, such as indomethacin and a selective cyclooxygenase-2 (COX-2) inhibitor (NS398). In mouse osteoblastic cells, both IL-1alpha and IL-6 with sIL-6R markedly induced messenger RNA expression of COX-2, but not COX-1, as determined by Northern blot analysis, and luciferase activity in cells stably transfected with a COX-2 promoter-luciferase fusion construct. IL-6 and sIL-6R, when added separately, did not stimulate COX-2 messenger RNA expression. Simultaneous addition of IL-1alpha and IL-6 with sIL-6R to osteoblast cultures cooperatively induced transcription of COX-2, which was associated with a marked increase in COX activity measured by the conversion of arachidonic acid into PGE2. The increased PGE2 synthesis by osteoblasts may play an important role in osteoclastogenesis induced by submaximal doses of IL-1 and IL-6.

Aging↗
PubMed1996

IL-13 and IL-4 inhibit bone resorption by suppressing cyclooxygenase-2-dependent prostaglandin synthesis in osteoblasts.

Activated T cells secrete the cytokine IL-13, which regulates inflammatory and immune responses. To explore the role of IL-13 in bone metabolism, we examined the effects of the cytokine on bone resorption and PG synthesis in osteoblasts. IL-13 suppressed the bone-resorbing activity stimulated by IL-1 alpha, which was determined by the release of 45Ca from prelabeled mouse long bones. Histologic examinations revealed that IL-1 alpha markedly stimulated bone resorption with increased osteoclast recruitment, and that the simultaneous addition of IL-13 considerably inhibited it. The gamma-chain of IL-2 receptors may be functionally involved in the signal transduction of not only IL-2, but also IL-4, IL-7, and IL-13. Of these cytokines, IL-4 similarly suppressed IL-1 alpha-induced bone resorption, but IL-2 and IL-7 did not. Both IL-13 and IL-4 inhibited PGE2 production stimulated by IL-1 alpha in long bone cultures. Suppression of IL-1 alpha-induced bone resorption by IL-13 and IL-4 was recovered by adding exogenous PGE2 to the long bone cultures. Neither IL-4 nor IL-13 further inhibited IL-1 alpha-induced bone resorption in the presence of indomethacin. To examine the effects of IL-13 on PG synthesis, we measured the mRNA levels of cytosolic phospholipase A2 (cPLA2), constitutively expressed cyclooxygenase (COX-1) and inducible COX (COX-2) in mouse osteoblast-like cells. IL-1 alpha markedly stimulated the mRNA expression of COX-2, but not that of COX-1. Both IL-13 and IL-4 dose-dependently suppressed the IL-1 alpha-induced stimulation of both COX-2 mRNA expression and PGE2 synthesis. A small increase (1.7-fold) in cPLA2 mRNA levels was detected in the cultures with IL-1 alpha, but the expression was not affected by IL-13 or IL-4. These results indicated that IL-13 and IL-4 inhibit bone resorption by suppressing COX-2-dependent PG synthesis in osteoblasts.

Animals↗
PubMed1995

Endogenous bone-resorbing factors in estrogen deficiency: cooperative effects of IL-1 and IL-6.

Estrogen deficiency causes a marked bone loss by stimulating osteoclastic bone resorption. To explore the endogenous bone-resorbing factors involved in estrogen deficiency, we examined the bone-resorbing activity present in the supernatant fraction of mouse bone marrow collected from ovariectomized (OVX) mice. Adding bone marrow supernatants at 20-80% to organ cultures of mouse long bones dose-dependently stimulated bone resorption. The endogenous bone-resorbing activity present in bone marrow supernatants from OVX mice was much higher than that from sham-operated mice 2-4 weeks after surgery, and it was significantly diminished by indomethacin in vitro. Anti-IL-1 alpha antibody completely neutralized the bone-resorbing activity present in bone marrow supernatants from OVX mice. Antibodies against IL-1 beta, IL-6, and IL-6 receptors also neutralized it, but partially. The concentration of IL-1 alpha measured by ELISA was much higher in bone marrow supernatants than in sera, but it was not appreciably changed before or after OVX. The concentration of IL-1 beta in bone marrow supernatants from OVX mice was less than the detection limit. OVX stimulated IL-1 activity in bone marrow supernatants measured by means of the proliferation of thymocytes. However, the level of IL-1 alpha present in bone marrow supernatants from OVX mice was insufficient to stimulate bone resorption. Compared with the serum concentration, bone marrow supernatants contained a much higher level of IL-6 as well, and it was further increased by OVX. However, IL-6 alone present in bone marrow supernatants from OVX mice again did not stimulate bone resorption.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Modulation of osteoclast differentiation by local factors.

Bone-resorbing osteoclasts are of hemopoietic cell origin, probably of the CFU-M-derived monocyte-macrophage family. Bone marrow-derived osteoblastic stromal cells play an important role in modulating the differentiation of osteoclast progenitors in two different ways: one is the production of soluble factors, and the other is cell-to-cell recognition between osteoclast progenitors and osteoblastic stromal cells. M-CSF is probably the most important soluble factor, which appears to be necessary for not only proliferation of osteoclast progenitors, but also differentiation into mature osteoclasts and their survival. A number of local factors as well as systemic hormones induce osteoclast differentiation. They are classified into three categories in terms of the signal transduction: vitamin D receptor-mediated signals [1 alpha,25(OH)2D3]; protein kinase A-mediated signals (PTH, PTHrP, PGE2, and IL-1); and gp130-mediated signals (IL-6, IL-11, oncostatin M, and leukemia inhibitory factor). All of these osteoclast-inducing factors appear to act on osteoblastic cells to commonly induce osteoclast differentiation factor (ODF), which recognizes osteoclast progenitors and prepares them to differentiate into mature osteoclasts. This line of approach will undoubtedly produce new ways to treat several metabolic bone diseases caused by abnormal osteoclast recruitment such as osteoporosis, osteopetrosis, Paget's disease, rheumatoid arthritis, and periodontal disease.

Animals↗
PubMed1994

Estrogen deficiency stimulates B lymphopoiesis in mouse bone marrow.

We have found that an estrogen deficiency causes a marked increase in bone marrow cells. To examine the effect of estrogen on hemopoiesis, we characterized the increased population of bone marrow cells after ovariectomy (OVX). In OVX mice, the percentage of myeloid cells and granulocytes was decreased, whereas that of B220-positive B lymphocytes was selectively increased 2-4 wk after surgery. The total number of myeloid cells and granulocytes did not change appreciably, but that of B220-positive cells was greatly increased by OVX. When OVX mice were treated with estrogen, the increased B lymphopoiesis returned to normal. B220-positive cells were classified into two subpopulations, B220low and B220high. The majority of the B220low cells were negative for the IgM mu chain, whereas most of the B220high cells were mu-positive. OVX selectively increased the precursors of B lymphocytes identified by B220low. mu-negative phenotype, suggesting that an estrogen deficiency stimulates accumulation of B lymphocyte precursors. When bone marrow-derived stromal cells (ST2) were pretreated with estrogen then co-cultured with bone marrow cells in the presence of estrogen, the stromal cell-dependent B lymphopoiesis was greatly inhibited. The present study suggests that estrogen plays an important role in the regulation of B lymphocyte development in mouse bone marrow.

Animals↗
PubMed1993

Soluble interleukin-6 receptor triggers osteoclast formation by interleukin 6.

It has been reported that soluble interleukin (IL)-6 receptor (sIL-6R) is detected in the serum of healthy individuals and its level is increased in patients with multiple myeloma and human immunodeficiency virus infection. Although several reports have suggested that sIL-6R potentiates IL-6 action, its physiological role remains unclear. In this study, we examined the role of sIL-6R on osteoclast formation by IL-6, using a coculture of mouse osteoblasts and bone marrow cells. Neither recombinant mouse IL-6 (mIL-6) nor mouse sIL-6R (smIL-6R) induced osteoclast-like multinucleated cell (MNC) formation when they were added separately. In contrast, simultaneous treatment with mIL-6 and smIL-6R strikingly induced MNC formation. These MNCs satisfied major criteria of authentic osteoclasts, such as tartrate-resistant acid phosphatase (TRAP) activity, calcitonin receptors, and pit formation on dentine slices. The MNC formation induced by mIL-6 and smIL-6R was dose-dependently inhibited by adding monoclonal anti-mouse IL-6R antibody (MR16-1). It is likely that osteoblasts and osteoclast progenitors are capable of transducing a signal from a complex of IL-6 and sIL-6R through gp130, even though they may have no or a very small number of IL-6Rs. Factors such as IL-11, oncostatin M, and leukemia inhibitory factor, which are known to exert their functions through gp130 (the signal-transducing chain of IL-6R), also induced MNC formation in our coculture system. These results suggest that increased circulating or locally produced sIL-6R induces osteoclast formation in the presence of IL-6 mediated by a mechanism involving gp130. This may play an important physiological or pathological role in conditions associated with increased osteoclastic bone resorption.

Animals↗
PubMed1993

[Vitamin D].

1 alpha,25-Dihydroxyvitamin D3 [1 alpha,25(OH)2D3], the active form of vitamin D3, stimulates intestinal calcium absorption and osteoclastic bone resorption, resulting in the elevation of plasma calcium. Recent studies have revealed that 1 alpha,25(OH)2D3 also promotes differentiation of various cells such as myeloid leukemia cells, lymphocytes, macrophages and skin keratinocytes. The target cells of 1 alpha,25(OH)2D3 possess 1 alpha,25(OH)2D3 receptors (VDR) which belong to the steroid thyroid retinoic acid receptor gene family. The complex of VDR and 1 alpha,25(OH)2D3 binds to vitamin D3-responsive elements (VDRE) present in the promoter region of target genes of 1 alpha,25(OH)2D3. In bone, osteoblasts possess VDR and synthesize several proteins, such as BGP, osteopontin and the third component of complement (C3), in response to 1 alpha, 25(OH)2D3. 1 alpha, 25(OH)2D3 is involved in the differentiation of osteoclast progenitors into mature osteoclasts directly and also by an indirect mechanism involving some proteins produced by osteoblasts. In this review article, we show the mode of action and the biological function of 1 alpha, 25(OH)2D3.

24,25-Dihydroxyvitamin D 3↗
PubMed1992

Leukemia inhibitory factor/differentiation-stimulating factor (LIF/D-factor): regulation of its production and possible roles in bone metabolism.

Leukemia inhibitory factor/differentiation-stimulating factor (LIF/D-factor), expression of its mRNA, and possible roles in bone metabolism were studied in murine primary and clonal osteoblast-like cells. Local bone-resorbing factors such as IL-1, TNF alpha, and LPS strongly induced expression of LIF/D-factor mRNA in both clonal MC3T3-E1 cells and primary osteoblast-like cells. Neither parathyroid hormone nor 1 alpha,25-dihydroxyvitamin D3 stimulated expression of LIF/D-factor mRNA. LIF/D-factor per se did not stimulate expression of its own mRNA. Appreciable amounts of LIF/D-factor were detected in synovial fluids from rheumatoid arthritis (RA) patients but not in those with osteoarthritis (OA). Simultaneous treatment with LIF/D-factor, IL-1, and IL-6 at the concentrations found in synovial fluids from RA patients greatly enhanced bone resorption, though these cytokines did not stimulate bone resorption when separately applied. This suggests that LIF/D-factor produced by osteoblasts is in concert with other bone-resorbing cytokines such as IL-1 and IL-6 involved in the bone resorption seen in the joints of RA patients. LIF/D-factor specifically bound to MC3T3-E1 cells with an apparent dissociation constant of 161 pM and 1,100 binding sites/cell. LIF/D-factor dose-dependently suppressed incorporation of [3H]thymidine into MC3T3-E1 cells. In addition, it potentiated the alkaline phosphatase activity induced by retinoic acid, though LIF/D-factor alone had no effect on enzyme activity. These results suggest that LIF/D-factor is involved in not only osteoclastic bone resorption but also osteoblast differentiation in conjugation with other osteotropic factors.

Acid Phosphatase↗
PubMed1992

Mechanism of action of amylin in bone.

Amylin is a 37 amino acid peptide produced mainly by beta-cells of the endocrine pancreas. Human amylin has 43% homology with human calcitonin gene-related peptide (CGRP) and 13% homology with human calcitonin (CT). Amylin and CGRP have been reported to have CT-like hypocalcemic activity in vivo. To investigate the role of amylin in bone, we examined the mechanisms of action of human amylin, CGRP, and CT in osteoclasts and osteoblasts. Both human amylin and CGRP inhibited 1 alpha,25-dihydroxyvitamin D3 [1 alpha,25(OH)2D3]- induced bone resorption in an organ culture system, and the potencies of the two peptides were similarly approximately 60-fold lower than that of human CT. Using a recently developed procedure for preparing large numbers of osteoclast-like multinucleated cells (MNCs) formed in co-cultures of mouse osteoblasts and bone marrow cells in the presence of 1 alpha,25(OH)2D3, we found that both human amylin and CGRP stimulated cAMP production in osteoclast-like MNCs, but only at 60-fold higher concentrations than human CT. Specific binding of [125I]-human CT to osteoclast-like MNCs was detected (dissociation constant, 3 x 10(-8) M; binding sites, 3 x 10(7) per cell). To displace the bound [125I]-human CT from osteoclast-like MNCs, about 170-fold higher concentrations of human amylin and CGRP were required. No specific bindings of [125I]-amylin and [125I]-CGRP to osteoclast-like MNCs could be detected. Human CGRP stimulated cAMP production both in established mouse osteoblast-like cells (KS-4) and in mouse primary osteoblast-like cells. Amylin was a weak agonist for cAMP production in KS-4 cells. The increment in cAMP production induced by CGRP and amylin was abolished by the addition of human CGRP(8-37), a selective antagonist for CGRP receptors. CT did not stimulate cAMP production in KS-4 cells. Amylin, but not CT, displaced the bound [125I]-human CGRP from rat brain membranes. These results indicate that amylin binds not only to CT receptors in osteoclast-like MNCs but also to CGRP receptors in osteoblasts. The relative potencies of these compounds to induce cAMP production was CT greater than amylin not equal to CGRP in osteoclast-like MNCs and CGRP greater amylin much greater than CT in osteoblast-like cells.

Amyloid↗
PubMed1991

Expression of reg/PSP, a pancreatic exocrine gene: relationship to changes in islet beta-cell mass.

A cDNA termed reg was recently isolated by differential screening of a library prepared from regenerating islets isolated from pancreatic remnants of rats subjected to 90% pancreatectomy and nicotinamide treatment. This led to speculation that this gene may be involved in expansion of beta-cell mass. In the current study we have measured reg expression after implantation and resection of a solid insulinoma tumor into rats, maneuvers known, respectively, to reduce and reexpand the volume of beta-cells in the islet. Animals with an implanted insulinoma tumor became profoundly hypoglycemic. Islet beta-cells declined from the normal 75% of total islet volume to less than 30%, in concert with a marked reduction in the reg mRNA level. Removal of the tumor resulted in a sharp increase in beta-cell replication, as measured by [3H]thymidine incorporation and a return to normal beta-cell volume within 4 days of tumor resection. This was associated with a transient induction in reg expression compared to that in tumor-bearing animals, effectively returning the amount of reg mRNA to the levels found in normal animals within 48 h; at later time points after tumor removal (3-7 days) reg expression declined, but then rose toward normal. In situ hybridization analysis localized the initial induction in reg mRNA expression to the exocrine pancreas. Continuous infusion of insulin into normal rats for 4 days, a maneuver that does not significantly reduce beta-cell mass, resulted in dramatically reduced insulin mRNA in islets, but no change in the levels of reg mRNA. We conclude that the diminution in pancreatic beta-cell mass caused by subcutaneous implantation of an insulinoma is associated with reduced reg gene expression and that the increase in beta-cell replication after resection of the tumor is preceded by return of reg gene expression toward normal.

Animals↗
PubMed1990

Interleukin 1 regulates the expression of osteopontin mRNA by osteoblasts.

Osteopontin is a matrix protein which belongs to the integrin superfamily and is involved in cell adhesion. In the present study, we examined the regulation of the mRNA expression of osteopontin by interleukin 1 alpha (IL-1 alpha) in osteoblasts. IL-1 alpha greatly increased the steady-state level of osteopontin mRNA in both a mouse osteoblastic cell line (MC3T3-E1) and mouse primary osteoblast-like cells. The increase in the osteopontin mRNA expression by IL-1 alpha was dose-dependent at a range of 0.004-0.2 nM. This was most likely due to an increase in the transcriptional rate, not to an increase in the stability of osteopontin mRNA. The in vitro nuclear transcription experiment showed that IL-1 alpha-treated MC3T3-E1 cells increased the synthesis of osteopontin mRNA. Besides IL-1 alpha, tumor necrosis factor alpha (TNF-alpha), lipopolysaccharides (LPS) and 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25(OH)2D3) increased the osteopontin mRNA expression in both the clonal osteoblasts (MC3T3-E1) and the primary osteoblast-like cells. In response to such bone-resorbing agents, primary osteoblast-like cells expressed osteopontin mRNA much more strongly than primary fibroblast-like cells isolated from mouse calvaria. Both IL-1 alpha and 1 alpha,25(OH)2D3 greatly increased the production of 68 and 62 kDa phosphoproteins in conditioned media of MC3T3-E1 cell cultures, which probably correspond to osteopontin. These results suggest that osteopontin plays an important role in bone remodeling, in particular bone resorption.

Animals↗
PubMed1990

IL-6 is produced by osteoblasts and induces bone resorption.

To examine the possible involvement of IL-6 in bone metabolism, a mouse osteoblastic cell line (MC3T3-E1) and primary osteoblast-like cells from fetal mouse calvaria were cultured with several systemic and local bone-resorbing agents and their expression of IL-6 mRNA was determined. Local bone-resorbing agents such as IL-1 alpha, IL-1 beta, TNF-alpha, and LPS greatly induced IL-6 mRNA expression in both MC3T3-E1 cells and primary osteoblast-like cells. Parathyroid hormone slightly increased expression of IL-6 mRNA in primary osteoblast-like cells but not in MC3T3-E1 cells. Neither IL-6 nor 1 alpha,25-dihydroxyvitamin D3 increased expression of IL-6 mRNA in either of the osteoblast-like cells. In agreement with the expression of IL-6 mRNA, biologically active IL-6 was produced in response to the treatment with IL-1 alpha, TNF-alpha, and LPS in MC3T3-E1 cells. Adding IL-6 dose dependently stimulated the release of 45Ca from prelabeled fetal mouse calvaria. Simultaneously adding suboptimal concentrations of IL-6 and IL-1 alpha induced bone resorption cooperatively. In accord with the increase in the release of 45Ca by IL-6, there were three times as many osteoclasts in the bone sections of calvaria cultured with IL-6 for 5 days as in the controls. IL-6 slightly suppressed alkaline phosphatase activity and collagen synthesis in MC3T3-E1 cells. These results indicate that IL-6 is also produced by osteoblasts, preferentially in response to local bone-resorbing agents, and it induces bone resorption both alone and in concert with other bone-resorbing agents.

Alkaline Phosphatase↗
PubMed1990

Fusion of mouse alveolar macrophages induced by 1 alpha,25-dihydroxyvitamin D3 involves extracellular, but not intracellular, calcium.

We have reported that the active form of vitamin D3, 1 alpha, 25-dihydroxy-vitamin D3 [1 alpha, 25(OH)2D3], directly induces the fusion of mouse alveolar macrophages (Abe et al: Proc. Natl. Acad. Sci. USA 80:5583-5587, 1983). The fusion process can be divided into two phases: the 1 alpha,25(OH)2D3-dependent priming phase (0-18 hr) and the calcium-dependent progression phase (18-72 hr) (Jin et al: J. Cell. Physiol. 137:110-116, 1988). In the present study, we examined the role of calcium in the progression phase of macrophage fusion induced by 1 alpha,25(OH)2D3. Macrophages pretreated with 1 alpha,25(OH)2D3 for 48 hr in a low-calcium (0.13 mM) medium began to fuse quickly 30 min after the culture medium was switched to a normal calcium (1.85 mM) medium. Of various cations tested, calcium was the most effective in inducing fusion, followed by strontium and manganese. Magnesium, potassium, and sodium had no effect. Calcium ionophores such as A23187 and ionomycin did not induce fusion in the low-calcium medium, nor did they potentiate fusion in the media containing higher concentrations of calcium. The intracellular concentration of free Ca2+, measured by a fluorescent method using fura-2 AM, was 116 +/- 1 nM in the macrophages pretreated with 1 alpha,25(OH)2D3 for 48 hr in the low-calcium medium. When calcium chloride was added to the assay system at a final concentration of 1.85 mM, the cytosolic free Ca2+ concentration did not increase appreciably (from 116 to 144 nM). But the macrophages began to fuse quickly when CaCl2 was added. In contrast, adding ionomycin increased cytosolic free Ca2+ from 116 to 440 nM, but no fusion occurred. These results clearly indicate that the extracellular, but not the intracellular, calcium is involved in the progression phase of the fusion of mouse alveolar macrophages primed by 1 alpha,25(OH)2D3.

Animals↗
PubMed1989

Production of interleukin 6 and its relation to the macrophage differentiation of mouse myeloid leukemia cells (M1) treated with differentiation-inducing factor and 1 alpha,25-dihydroxyvitamin D3.

We have studied the production of interleukin 6 (IL-6) and its relation to the macrophage differentiation in murine myeloid leukemia cells (M1). As has been reported, differentiation-inducing factor (D-factor), 1 alpha, 25-dihydroxyvitamin D3 [1 alpha, 25(OH)2D3], and recombinant IL-6 similarly induced differentiation of M1 cells into macrophages. The three compounds also induced mRNA expression of IL-6 in M1 cells. M1 cells treated with D-factor or 1 alpha, 25(OH)2D3 produced biologically active IL-6, but the amounts of IL-6 secreted into culture media did not appear to be enough to induce differentiation of M1 cells. Furthermore, simultaneous addition of anti-IL-6 antibody did not suppress the differentiation of M1 cells induced by D-factor or 1 alpha, 25(OH)2D3. These results show that IL-6 production is an essential property associated with the macrophage differentiation of M1 cells, but it may not be responsible for the D-factor- and 1 alpha, 25(OH)2D3-induced differentiation.

Animals↗