Search PubMed⌕ Search

Biomedical subjects

K Miyazawa

Publications and source records attributed to K Miyazawa.

At least 91 records · Page 5Linked to original sources
PubMed1998

Regulation of interleukin-1beta-induced interleukin-6 gene expression in human fibroblast-like synoviocytes by glucocorticoids.

Involvement of interleukin-6 (IL-6) in the pathogenesis of rheumatoid arthritis (RA) has recently been demonstrated. In the present study, the regulation of IL-6 gene expression by glucocorticoids and IL-1beta in fibroblast-like synoviocytes (FLSs) was investigated. Both synthetic and natural glucocorticoids, i.e., dexamethasone (DEX) and hydrocortisone (HC), respectively, concentration-dependently inhibited protein production and gene expression of IL-6 by human FLSs. The effect of DEX was dependent on de novo protein synthesis. DEX significantly reduced the rate of IL-6 gene transcription without affecting the stability of IL-6 mRNA. The IkappaBalpha pathway seemed not to be involved in DEX-mediated inhibition of IL-6 gene expression in IL-1beta-stimulated human FLSs. These findings suggest that glucocorticoids suppress IL-6 gene transcription by an as yet undefined mechanism.

Arthritis, Rheumatoid↗
PubMed1998

Establishment and characterization of a novel human rheumatoid fibroblast-like synoviocyte line, MH7A, immortalized with SV40 T antigen.

A novel immortalized rheumatoid fibroblast-like synoviocyte (FLS) line, MH7A, was established by stably transfecting FLS cells with SV40 T antigen gene. MH7A cells expressed SV40-specific small t and large T antigens as well as an elevated level of p53 protein. They have already reached over 150 population doublings through culture crisis, and have been growing rapidly compared with the parental FLSs. Constitutive activation of p42/p44 mitogen-activated protein (MAP) kinase was detected in MH7A cells. Serum requirements for the growth of MH7A were markedly decreased compared with those for the parental FLSs. MH7A cells were stained positively for interleukin (IL)-1R, intercellular adhesion molecule-1 (ICAM-1), CD16, CD40, CD80, and CD95. IL-1beta enhanced the production of IL-6 and stromelysin-1, and the surface expression of ICAM-1, in a manner similar to that in the parental FLSs. SB203580, a specific inhibitor of p38 MAP kinase, significantly inhibited IL-1beta-induced IL-6 and stromelysin-1 production by both parental FLSs and MH7A cells; although PD098059, an inhibitor of the p42/p44 MAP kinase pathway, did not affect it. Our results clearly indicate the usefulness of MH7A cells for investigating the regulation of rheumatoid FLSs and the IL-1 signal transduction pathway to develop future RA therapy.

Antigens, Polyomavirus Transforming↗
PubMed1998

Role of immunoglobulin-like domains 2-4 of the platelet-derived growth factor alpha-receptor in ligand-receptor complex assembly.

Platelet-derived growth factor (PDGF) is a dimeric protein that exerts its effects through tyrosine kinase alpha- and beta-receptors. The extracellular part of each receptor is composed of five Ig-like domains. Recombinant forms of alpha-receptor domains 1-4 (alphaRD1-4), 1-3 (alphaRD1-3), and 1 and 2 (alphaRD1-2) were prepared after expression in Chinese hamster ovary cells and were used to study the assembly of soluble ligand-receptor complexes. When incubated with micromolar concentrations of PDGF, both alphaRD1-3 and alphaRD1-4 formed complexes of 1:2 molar composition, i.e. one dimeric PDGF molecule bound two soluble receptors. alphaRD1-3, in contrast to alphaRD1-4, formed detectable 1:1 complexes under conditions of ligand excess. alphaRD1-4 displayed an increased ability to form 1:2 complexes as compared with alphaRD1-3 under conditions of limiting concentrations of ligand. We thus conclude that Ig-like domain 4-mediated receptor-receptor interactions contribute to 1:2 PDGF.alphaRD1-4 complex formation. Since alphaRD1-4 and alphaRD1-3 were equipotent in blocking binding of subnanomolar concentrations of PDGF to cell-surface receptors, we also conclude that this effect is predominantly achieved through formation of Ig-like domain 4-independent 1:1 ligand-receptor complexes. Finally, since alphaRD1-2 bound PDGF-BB with high affinity, whereas PDGF-AA was bound only with low affinity, we conclude that Ig-like domain 3 of the PDGF alpha-receptor contains epitopes of particular importance for PDGF-AA binding and that most of the PDGF-BB-binding epitopes reside in Ig-like domains 1 and 2.

Animals↗
PubMed1998

Regulation of interleukin-1beta-induced interleukin-6 gene expression in human fibroblast-like synoviocytes by p38 mitogen-activated protein kinase.

Involvement of p38 mitogen-activated protein (MAP) kinase in interleukin (IL)-6 gene expression of human fibroblast-like synoviocytes (FLSs) was assessed. p38 MAP kinase was constitutively expressed in human FLSs and activated in response to IL-1beta. A pyridinylimidazole compound, SB203580, inhibited p38 MAP kinase activity in vivo, since the activity of MAPKAP kinase-2 (a substrate of p38 MAP kinase) in IL-1beta-stimulated FLSs was totally suppressed by it. SB203580 concentration-dependently inhibited protein production and gene expression of IL-6 by human FLSs. The effect of SB203580 was dependent on de novo protein synthesis. SB203580 significantly reduced the stability of IL-6 mRNA without affecting the rate of IL-6 gene transcription. Here, we provide evidence that p38 MAP kinase is activated in response to IL-1beta in human FLSs and is involved in IL-6 synthesis by stabilizing IL-6 mRNA.

Anti-Inflammatory Agents↗
PubMed1998

Measurement of early pregnancy factor activity for monitoring the viability of the equine embryo.

The viability of embryos before flushing from donor mares (n = 5) and after transfer to recipient mares (n = 7) was monitored in mare serum by detecting early pregnancy factor (EPF) using the rosette inhibition test (RIT). The EPF activity was measured in donor mares before and after natural mating at natural estrus; after ovulation on Days 2, 5 and 8; and after embryo flushing (Day 8) on Days 8, 9, 10 and 13 after ovulation. The collected embryos were transferred immediately after flushing. The EPF activity in recipient mares were measured on the day of transfer and after embryo transfer on Days 1, 2, 3 and 5. Pregnancy was confirmed on Day 12 to 14 after embryo transfer. The mean EPF activity of donor mares was increased to the pregnant level (> an RI titer score of 10) on Day 2 after ovulation. Two days after flushing the embryos, the EPF activity of donor mares had decreased to the nonpregnant level. Among the 7 recipient mares, 3 mares were diagnosed pregnant on Day 12 after embryo transfer with ultrasound. The EPF activity of the pregnant recipient mares was increased above the minimum level observed in pregnant mares on Days 2 to 3 after transfer. However, among the nonpregnant recipient mares after embryo transfer, the EPF activity of 3 mares remained at the pregnant level only 2 to 3 d and then declined to the nonpregnant level. In one recipient mare, EPF activity did not reach the pregnant level throughout the sample collection. The results of this study indicated that equine EPF can be detected in serum of pregnant mares as early as Day 2 after ovulation. From our observation, we conclude that the measurement of EPF activity is useful for monitoring the in vivo viability of equine embryos and early detection of embryonic death.

Animals↗
PubMed1998

Evaluation of fluids from cystic follicles for in vitro maturation and fertilization of bovine oocytes.

Follicular cysts are defined as cystic structures derived from unovulated follicles. The formation of the cysts appears to be related to failure of the oocyte to resume meiosis. The aim of this study was to evaluate in the bovine: 1) the ability of the fluid from cystic follicles to promote in vitro oocyte maturation and fertilization, 2) the predictive value of the morphology of oocytes derived from cystic follicles on the ability of the follicular fluid to promote in vitro maturation/fertilization as well as the oocytes to undergo maturation and fertilization. In Experiment 1, the ability of fluid from cystic (and normal) follicles from live and slaughtered cows (to promote) in vitro maturation and fertilization of bovine cumulus-oocyte-complexes (COC's) was assessed by cumulus expansion, sperm penetration, male pronucleus formation and polyspermy rates. Concentrations of progesterone (P4) and estradiol-17 beta (E2) were measured in the fluid from cystic follicles collected from live and slaughtered cows. In Experiment 2, we investigated the relationship of the morphology of COC's from cystic follicles, and the effect of the follicular fluids on oocyte maturation as well as P4 and E2 concentrations. In Experiment 1, although sperm penetration and male pronucleus formation were inhibited significantly by fluid from some cystic follicles collected from live and slaughtered cows, there were no significant differences in sperm penetration, male pronucleus formation and polyspermy rates between fluid from cystic follicles collected from live cows, from slaughtered cows and from control groups, regardless of the P4/E2 ratio. In Experiment 2, the morphology of cumulus-oocyte complexes from cystic follicles varied and the pronucleus formation of oocytes after in vitro fertilization was abnormal. On the other hand, the male pronucleus formation rates were not significantly different between the cystic follicular fluids and control, regardless, of the P4/E2 ratio. The results of this study suggest that many of the bovine follicular fluids from cystic follicles possess the ability to induce cumulus expansion, nuclear maturation and male pronucleus formation following in vitro maturation and fertilization of bovine oocytes. The morphology of the cumulus-oocytes complexes from cystic follicles seems not to relate to the ability of the cystic follicular fluids to induce oocyte maturation, and oocytes from cystic follicles possess the ability to form male pronucleus even though most were abnormal after in vitro fertilization.

Animals↗
PubMed1998

Oocyte quality of small antral follicles coexisting with cystic follicles in the ovaries of the cow.

The present study was conducted with ovaries to evaluate the effect of the presence of a cystic follicle and its steroid hormone concentration on the oocyte recovery rates, oocyte morphology and in vitro maturation of the oocytes from coexisting small follicles. Ovaries, each bearing a follicular cyst (containing > 10 ml of follicular fluids, > 3 cm in diameter, and without a functional corpus luteum), were collected from each of the 26 Holstein cows from a local slaughterhouse. Small follicles (1-7 mm) from these ovaries were aspirated and their cumulus-oocyte complexes (COCs) classified into one of 5 groups (A to E), depending on oocyte and cumulus cell morphologies. Those oocytes with compact cumulus cells were cultured and their maturation rates determined. Concentrations of estradiol-17 beta (E2) and progesterone (P4) were measured in cystic follicular fluid using double antibody enzyme immunoassays (EIA). The morphology of the COCs and maturation rates of the oocytes were then evaluated using two comparisons. In first comparison, the left and right ovaries obtained from an individual cow were considered as a pair, with each pair being divided into two groups depending on the presence or absence of an E2 dominant or P4 dominant cystic follicle in one or another of the ovaries: E2 dominant cows; and P4 dominant cows. Oocytes collected from the ovaries of cyclic cows at follicular, luteal and post-ovulatory stages served as controls. The oocyte recovery rates, oocyte morphologies and oocyte maturation rates were independent of the presence or absence of a coexisting cystic follicle, or its steroid hormone classification or concentration. In the second comparison, each ovary was consider individually and divided into one of the two classes, depending on the presence or absence of a cystic follicle. Those ovaries with cystic follicles were then divided into three subclasses on the basis of E2 and P4 concentrations in the cystic follicular fluids: P4 dominant (P4/E2 ratio > 1); E2 dominant (P4/E2 ratio < 1); and both P4 and E2 dominant follicles present. The numbers of oocytes obtained from an ovary, their morphology and their maturation rates were not significantly different in the presence or absence of a coexisting cystic follicle. Moreover, the number of the oocytes aspirated from an ovary, their morphology and their maturation rates in small follicles coexisting with P4 dominant, E2 dominant and both P4 and E2 dominant cystic follicles were also not different. These results suggested that neither the presence of a cystic follicle in a cow's ovary nor the cyst's steroid hormone concentrations affected the oocyte recovery rate, oocyte morphology and maturation rates of the coexisting small follicles.

Animals↗
PubMed1998

Features of replicative senescence induced by direct addition of antennapedia-p16INK4A fusion protein to human diploid fibroblasts.

The p16INK4A cyclin-dependent kinase (Cdk) inhibitor is now recognized as a major tumor suppressor that is inactivated by a variety of mechanisms in a wide range of human cancers. It is also implicated in the mechanisms underlying replicative senescence since p16INK4A RNA and protein accumulate as cells approach their proscribed limit of population doublings in tissue culture. To obtain further evidence of its role in senescence, we have sought ways of overexpressing p16INK4A in primary human diploid fibroblasts (HDF). To circumvent the low transfection efficiency of primary cells we have exploited a recombinant form of the full-length p16INK4A protein fused to a 16 amino acid peptide from the Drosophila antennapedia protein. This peptide has the capacity to cross both cytoplasmic and nuclear membranes allowing the direct introduction of the active protein to primary cells. Here, we show that antennapedia-tagged wild-type p16INK4A protein, but not a functionally compromised tumor-specific variant, causes G1 arrest in early passage HDFs by inhibiting the phosphorylation of the retinoblastoma protein. Significantly, the arrested cells display several phenotypic features that are considered characteristic of senescent cells. These data support a role for p16INK4A in replicative senescence and raise the possibility of using the antennapedia-tagged protein therapeutically.

Antennapedia Homeodomain Protein↗
PubMed1998

Effects of follicular fluid on fertilization and embryonic development of bovine oocytes in vitro.

This study was conducted to evaluate the effect of bovine follicular fluid (BFF) on fertilizability and developmental capacity of bovine oocytes matured in vitro. Oocytes were collected from slaughterhouse ovaries, and matured in TCM199 supplemented with 5% superovulated cow serum (SCS), 2 mM pyruvate and 1 IU/mL PMSG. BFF was aspirated from small follicles (1 to 5 mm in diameter). In Experiment 1, BFF was added to the Brackett and Oliphant (BO) fertilization medium at concentrations of 0, 1, 5, 10 and 20%. After insemination with frozen-thawed and heparin-treated (10 micrograms/mL, 15 min) bull spermatozoa for 18 h, some of the oocytes were fixed and stained to evaluate the fertilization rate. The rest of the oocytes were co-cultured in serum-free embryo culture medium (ECM; TCM199 supplemented with 5% SCS, 2 mM pyruvate and 5 micrograms/mL insulin) with bovine oviductal epithelial cells (BOEC) at 38.5 degrees C under 5% CO2 in air, and the developmental capacity of embryos was examined at 2, 7 and 9 d. In Experiment 2, BFF was added to the serum-free ECM with BOEC at 0, 5, 10 and 20% concentrations, and embryos were cultured for 9 d. Fertilization rates and blastocyst rates in low (1 and 5%) BFF in fertilization medium were not significantly different from the control (without BFF). However, high concentrations of BFF (10 and 20%) in the fertilization medium suppressed both fertilization rates and development. Large vesicles with fast monolayer formation were observed at all concentrations of BFF added to ECM with BOEC. There were no significant differences in cleavage or development to blastocyst in different concentrations of BFF added to ECM. However, the rate of development to hatched blastocysts in 20% BFF was significantly lower than that of the control (P < 0.05). The results of the present study indicate that BFF addition to fertilization medium and ECM with BOEC does not improve fertilizability or developmental capacity and that high concentrations of BFF reduce the rate of both fertilization and development.

Animals↗
PubMed1998

Transcriptional roles of CCAAT/enhancer binding protein-beta, nuclear factor-kappaB, and C-promoter binding factor 1 in interleukin (IL)-1beta-induced IL-6 synthesis by human rheumatoid fibroblast-like synoviocytes.

The involvement of interleukin (IL)-6 in the pathogenesis of rheumatoid arthritis (RA) has been recently demonstrated. IL-1beta stimulated rheumatoid fibroblast-like synoviocytes (FLSs) to produce IL-6 in a concentration- and time-dependent manner. In the present study we investigated how the IL-6 promoter is transcriptionally regulated in rheumatoid FLSs in response to a physiologically relevant mediator of inflammation, IL-1beta. Deletion analysis showed that the IL-6 promoter is regulated by two positive elements (located at -159 to -142 base pairs (bp) and -77 to -59 bp). Electrophoretic mobility shift assays revealed that CCAAT/enhancer binding protein-beta (C/EBPbeta) binding to nucleotides -159 to -142 bp was constitutively present. The probe corresponding to nucleotides -77 to -59 bp gave three positive bands. The two slower migrating bands were induced by IL-1beta and comprised an nuclear factor (NF)-kappaB p50/p65 heterodimer and a p65/p65 homodimer. The faster migrating band was constitutively expressed and identified as Epstein-Barr virus C-promoter binding factor 1, CBF1. Site-specific mutagenesis analysis demonstrated that the NF-kappaB and CBF1 binding elements regulated inducible activity of the IL-6 promoter in response to IL-1beta stimulation, whereas the C/EBPbeta binding element mainly regulated basal activity. We also provide the first evidence that CBF1 functions as a positive regulator of human IL-6 gene transcription.

Arthritis, Rheumatoid↗
PubMed1998

Developmental capacity of bovine oocytes matured in two kinds of follicular fluid and fertilized in vitro.

This study was conducted to assess the ability of the follicular fluid derived from large and small follicles to support the in vitro oocyte maturation and subsequent fertilization and developmental capacity. Oocytes were cultured in bovine follicular fluid aspirated from small (SFF; 2-5 mm in diameter), large (LFF; 10 to 20 mm in diameter) follicles and TCM199 as a control under 5% CO2 in air. All maturation media were supplemented with 1 IU ml-1 pregnant mare serum gonadotropin. After 24 h culture, oocytes were fertilized in vitro with frozen-thawed and heparin-treated (10 micrograms ml-1, 15 min) bull spermatozoa and cultured in TCM199 with bovine oviductal epithelial cells (BOEC) for 7 days. Maturation of bovine oocytes cultured in LFF was inhibited and the low of male pronucleus formation was observed when compared with that of SFF (maturation rate: 69 vs. 78%; P < 0.05; male pronucleus formation rate: 58 vs. 80%; P < 0.05). Developmental capacity of bovine oocytes cultured in SFF was significantly (P < 0.05) higher than that of LFF (15 vs. 5%), but significantly (P < 0.05) lower than that of the control. There were no differences in the number of nuclei per blastocyst obtained after each treatment. These results indicate that the inhibitory action of follicular fluid on in vitro maturation, male pronucleus formation and developmental capacity of bovine oocytes is dependent on the developmental stage of the follicles from which fluid was obtained.

Animals↗
PubMed1998

Vitamin K2 selectively induces apoptosis of blastic cells in myelodysplastic syndrome: flow cytometric detection of apoptotic cells using APO2.7 monoclonal antibody.

We have previously reported that vitamin K2 (VK2) but not VK1 has a potent apoptosis-inducing effect on freshly isolated leukemia cells from patients with various types of leukemia. By multi-color flow cytometric analysis using monoclonal antibody (mAb), APO2.7, which detects mitochondrial 7A6 antigen specifically expressed by cells undergoing apoptosis, we further investigated the apoptosis-inducing effect of VK2 on minor populations of leukemic blast cells in bone marrow from patients with myelodysplastic syndrome (MDS) and overt myeloid leukemia (post-MDS AML). Limiting dilution of CD95 (anti-Fas) mAb-treated apoptotic Jurkat cells with nonapoptotic CTB-1 cells revealed that APO2.7-positive Jurkat cells were consistently detectable by flow cytometry when present at levels of at least 5% in the CTB-1 suspension. In patient samples the gating area for leukemic clone was determined using cell surface antigen-specific mAbs conjugated with either fluorescein isothionate (FITC) or phycoerythrin (PE) and subsequently the cells stained with phycoerythrin cyanine (PE-Cy5)-conjugated APO2.7 mAb were assessed within the gating area of the leukemic clone for monitoring apoptosis. Treatment of the bone marrow mononuclear cells with 3-10 microM of VK2 (menaquinone-3, -4 and -5) in vitro potently induced apoptosis of the leukemic blast cells as compared with the untreated control cells in all 15 MDS patients tested. This effect was more prominent on blastic cells than that on mature myeloid cells such as CD34-/CD33+ gated cells. In addition, VK2 performed much less effectively on CD3-positive lymphoid cells. In contrast to VK2, VK1 did not show apoptosis-inducing activity. These data suggest that VK2 may be used for treatment of patients with MDS in blastic transformation.

Antibodies, Monoclonal↗
PubMed1998

Sarcoidosis associated with multiple large pulmonary nodules.

Parenchymal manifestations of pulmonary sarcoidosis include a diffuse, symmetric, reticulonodular interstitial pattern, a fibrotic pattern, and an acinar pattern. Large pulmonary nodules in sarcoidosis are rare, and their frequency (> 1 cm in diameter) has been estimated at 2-4%. We report a rare case of sarcoidosis associated with large bilateral pulmonary nodules. These nodules reached up to 7 cm in diameter, which is larger than any others reported previously. Furthermore, these nodular lesions developed within only 6 months of normal chest X-ray results and were not found to accompany bilateral hilar lymph adenopathy, which is observed in the usual course of sarcoidosis. As described above, this case of pulmonary sarcoidosis was significant not only in terms of the large size of the nodules but also the unique chest X-ray course.

Adult↗
PubMed1998

[Clinical efficacy of fosfomycin in combination with sulbactam/cefoperazone in the treatment of severe infections complicated to blood dyscrasia. Working Group of Kanto Combination Therapy for FOM + SBT/CPZ].

In the treatment of severe infections complicated to blood dyscrasia, the efficacy and usefulness of fosfomycin (FOM) in combination with sulbactam (SBT)/cefoperazone (CPZ) were compared between patients receiving FOM in the first followed by SBT/CPZ (Group A) and those receiving both drugs simultaneously (Group B). The following results were obtained. 1. The efficacy rate was 56.3% for Group A and 47.9% for Group B, with no significant difference. 2. The efficacy for patients suspected of the presence of septicemia, the efficacy rate was 57.9% for Group A and 54.3% for Group B, with no significant difference. 3. As for underlying disease, patients with acute myelogenous leukemia were most prevailing. In these patients, the efficacy rate was 57.1% for Group A and 27.3% for Group B, with no statistically significant difference. However, the efficacy rate tended to be higher in Group A. 4. The administration of antibiotics was effective to restore the neutrophil count to 501/microliters or higher in 77.8% and 45.5% of the cases for Groups A and B, respectively, with significantly higher efficacy for Group A. 5. In the safety evaluation a total of 115 cases were included. Side effects and laboratory abnormalities were seen in 3 cases each, but none of them were serious in degree. From these results, it was confirmed that the combination therapy consisting of administration of FOM followed by SBT/CPZ with some interval is effective for severe infections complicated to blood dyscrasia.

Anti-Bacterial Agents↗
PubMed1998

Hypertension due to coexisting pheochromocytoma and aldosterone-producing adrenal cortical adenoma.

A 49-year-old male was diagnosed as having primary aldosteronism at age 39, and he was treated with antihypertensive drugs. In 1995, a computed tomogram revealed a mass in the right adrenal gland. Radiological examinations and endocrinological data revealed the presence of a pheochromocytoma in the right and an adrenocortical tumor in the left adrenal gland. Right adrenalectomy and left partial adrenalectomy were performed. Histologically, the right adrenal mass was compatible with pheochromocytoma, and the left adrenal mass was an adrenocortical adenoma. Endocrinological data as well as blood pressure returned to normal after operation.

Adrenal Cortex Neoplasms↗
PubMed1998

Studies on agents with vasodilator and beta-blocking activities. V. Synthesis and pharmacological activity of the optical isomers of TZC-5665.

Synthesis of the four optical isomers of TZC-5665 (1), a candidate for the treatment of congestive heart failure, was achieved by the reaction of chiral diaminopyridazinone (2) with chiral glycidyl ether. (3). The hypotensive and beta-blocking activities of 1 and its optical isomers were examined when given intravenously into anesthetized rats. Furthermore these compounds were evaluated for inhibitory activity on cAMP phosphodiesterase III. Among the four optical isomers, Ra,Sb-one (1c) possessed the essential activities of TZC-5665 (1).

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1998

The tetramerization domain-independent Ras activation by BCR-ABL oncoprotein in hematopoietic cells.

BCR-ABL is a chimeric oncoprotein that exhibits deregulated tyrosine kinase activity and is implicated in the pathogenesis of Philadelphia chromosome-positive human leukemias. We have previously shown that BCR-ABL activates Ras signaling pathways required for transformation. To elucidate the mechanisms whereby BCR-ABL induced transformation in hematopoietic cells, we examined the biological effects of expression of a series of BCR-ABL mutants. We found that the Grb2 binding site-deleted BCR-ABL and the SH2 domain-deleted BCR-ABL, as well as the tetramerization domain-deleted BCR-ABL do not diminish the transforming properties of BCR-ABL in hematopoietic cells, although these mutations were previously shown to drastically reduce the transforming activity of BCR-ABL in fibroblasts. The tetramerization domain-deleted BCR-ABL did not induce tyrosine phosphorylation of CrkL, SHP-2, Vav and the interactions of BCR-ABL and Shc. However, Ras is activated, Shc is tyrosine phosphorylated and binds to Grb2 in the tetramerization domain-deleted BCR-ABL expressing hematopoietic cells. These results suggest that the tetramerization domain-independent Ras activation is mediated by Shc proteins and induces the transformation of hematopoietic cells.

Adaptor Proteins, Signal Transducing↗