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Biomedical subjects

S Akira

Publications and source records attributed to S Akira.

At least 217 records · Page 12Linked to original sources
PubMed1992

IL-6 and NF-IL6 in acute-phase response and viral infection.

NF-IL6 was originally identified as a DNA-binding protein responsible for IL-1-stimulated IL-6 induction. Direct cloning of NF-IL6 revealed its homology with C/EBP. C/EBP is expressed in liver and adipose tissues and is supposed to regulate several hepatocyte- and adipocyte-specific genes. In contrast, NF-IL6 is suppressed in normal tissues, but is rapidly and drastically induced by LPS or inflammatory cytokines such as IL-1, TNF, and IL-6. NF-IL6 can also bind to the regulatory region of various genes including IL-8, G-CSF, IL-1 and immunoglobulin genes. Furthermore, NF-IL6 is shown to be identical to IL-6DBP, a DNA-binding protein responsible for IL-6-mediated induction in acute-phase proteins, demonstrating that NF-IL6 is responsible for the genes regulated by IL-6. These results indicate that NF-IL6 may be a pleiotropic mediator of many inducible genes involved in acute, immune, and inflammatory responses, like NFkB. In this regard, it is noteworthy that both an NF-IL6 binding site and an NFkB binding site are present in the inducible genes such as IL-6, IL-8, and several acute-phase genes. On the other hand, accumulating evidence has revealed that overproduction of IL-6 may be responsible for the pathogenesis and/or several symptoms of a variety of diseases, including autoimmune diseases, malignancies, and viral diseases. At present, the molecular mechanisms of abnormal expression of the IL-6 gene are not known. Recently it has become evident that interplays between viral proteins and cellular proteins play an important role in viral oncogenesis and infection. The fact that NF-IL6 binds to the enhancer core sequences of various viruses strongly suggests a possible relationship of virus infection and IL-6 expression. In fact some evidence (Mahe et al. 1991, Spergel et al. 1992) indicates that NF-IL6 may interact with viral gene enhancers or viral products, although there are no definite data about the involvement of NF-IL6 in viral pathogenesis. Future studies will be required to clarify whether or not the interplay between NF-IL6 and viral infection is responsible for deregulation of the IL-6 gene.

Acquired Immunodeficiency Syndrome↗
PubMed1992

NF-IL6, a member of the C/EBP family, regulates E1A-responsive promoters in the absence of E1A.

A cDNA encoding NF-IL6, an interleukin-6 (IL-6)-regulated human nuclear factor of the C/EBP family, is demonstrated to complement the transactivation function of E1A. The endogenous NF-IL6 level varies according to cell type and correlates positively with an IL-6-regulated cellular E1A-substituting activity that was described recently (J.M. Spergel and S. Chen-Kiang, Proc. Natl. Acad. Sci. USA 88:6472-6476, 1991). When expressed by transfection in cells which contain low levels of NF-IL6 and are incapable of complementing the function of E1A proteins, NF-IL6 also transactivates the E1A-responsive E2ae and E1B promoters, to the same magnitude as E1A. Activation by NF-IL6 is concentration dependent and sequence specific: mutational studies of the E2ae promoter suggest that the promoter-proximal NF-IL6 recognition site functions as a dominant negative regulatory site whereas the promoter-distal NF-IL6 recognition site is positively regulated at low NF-IL6 concentrations and negatively regulated when the NF-IL6 level is high. Consistent with these functions, NF-IL6 alone is sufficient to complement an E1A deletion mutant dl312 in viral infection, when expressed at appropriate concentrations. These results identify NF-IL6 as a sequence-specific cellular nuclear factor which regulates E1A-responsive genes in the absence of E1A.

Adenovirus Early Proteins↗
PubMed1992

The evidence for interleukin-6 as an autocrine growth factor in malignancy.

Interleukin-6, IL-6, is a pleiotropic cytokine which plays a central role in defense mechanisms, including the immune response, acute phase reaction and hematopoiesis. Abnormal expression of the IL-6 gene has been suggested to be involved in the pathogenesis of a variety of diseases, especially rheumatoid arthritis, Castleman's disease, mesangial proliferative glomerulonephritis, multiple myeloma and Kaposi's sarcoma. In the case of multiple myeloma and Kaposi's sarcoma, the existence of an IL-6-IL-6 receptor autocrine loop has been implicated in the oncogenesis process. On the other hand, IL-6 has a potent anti-tumor activity against certain types of tumors. This anti-tumor effect is mediated by in vivo induction of tumor specific cytotoxic T cells and in part by a growth inhibitory activity of IL-6.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Augmentation of haptoglobin production in Hep3B cell line by a nuclear factor NF-IL6.

The nuclear factor NF-IL6 had been suggested to be responsible for the IL-6-mediated induction of several acute-phase proteins. To obtain evidence for the involvement of NF-IL6 in the induction of acute-phase proteins, we introduced the NF-IL6 gene and its truncated mutant (delNFIL6) gene into a hepatoma cell line Hep3B. Then, we examined the effect of the overproduced NF-IL6 and delNFIL6 on the expression of haptoglobin, fibrinogen and albumin. As a result, basal production as well as induction of haptoglobin by IL-6 were augmented by the expression of NF-IL6, whereas delNFIL6 blocked the production of haptoglobin, fibrinogen and albumin.

Acute-Phase Proteins↗
PubMed1991

Age-associated increase in interleukin 6 in MRL/lpr mice.

It has been demonstrated that abnormal expression of interleukin 6 (IL-6) may be involved in the pathogenesis of a variety of autoimmune diseases and glomerulonephritis. In this study, we demonstrate an age-associated increase in IL-6 in the sera of MRL/lpr mice but not in control congenic MRL/+ mice, normal strains of BALB/c, C3H/HeN mice, and other autoimmune prone mice, such as (NZB x NZW)F1, (NZB x BXSB)F1 mice. IL-6 activity was detected in the sera of MRL/lpr mice by 3 weeks of age and it was neutralized by anti-mouse IL-6 antibody. The serum IL-6 level was gradually increased with age and reached up to 410 pg/ml around 30 weeks of age. The expression of IL-6 mRNA was detected in the spleen and lymph nodes from 8 weeks of age. Expression of IL-6 mRNA was also detected in C57BL/6-lpr mice, indicating the possible linkage of abnormal expression of the IL-6 gene and the lpr gene. Southern blot analysis demonstrated that both the promoter region and 3' untranslated region of the IL-6 gene were apparently normal, suggesting that deregulated production of IL-6 may be due to abnormal transcriptional control. The data suggest that abnormal expression of the IL-6 gene may play a key role in the development of polyclonal B cell activation and glomerulonephritis in MRL/lpr mice.

Age Factors↗
PubMed1991

Reciprocal expression of NF-IL6 and C/EBP in hepatocytes: possible involvement of NF-IL6 in acute phase protein gene expression.

The initial phase of inflammation is accompanied by dramatic changes in the concentrations of certain plasma proteins. Interleukin-6 (IL-6) is an important inducer of these acute phase proteins at the transcriptional level. The recently cloned nuclear factor NF-IL6, a potent trans-acting regulator of IL-6 gene expression, has a region that is highly homologous to the liver-specific transcriptional factor C/EBP. Both factors recognize the same nucleotide sequence. In this study the recombinant NF-IL6 was shown to interact with the IL-6-responsive elements (IL-6REs) identified in the promoter region of several acute phase protein genes whose activity increases during the acute phase reaction. Furthermore, in competition experiments, formation of all the DNA-protein complexes by the IL-6RE and IL-6-treated hepatoma cell extracts was specifically decreased by adding either the 14-bp NF-IL6 binding motif identified in the IL-6 promoter or the antibody against the recombinant NF-IL6. NF-IL6 was expressed at a minor level in mouse liver, but was dramatically induced after stimulation with IL-6. In contrast, the amount of C/EBP mRNA decreased considerably after IL-6 stimulation. These results indicate that the NF-IL6 that regulated IL-6 expression was also involved in regulation of expression of the acute phase protein genes. The ability of NF-IL6 to replace C/EBP may explain the positive and negative acute phase responses induced by IL-6.

Acute-Phase Proteins↗
PubMed1990

A nuclear factor for IL-6 expression (NF-IL6) is a member of a C/EBP family.

NF-IL6 is a nuclear factor that specifically binds to an IL1-responsive element in the IL-6 gene. In this study the gene encoding NF-IL6 has been cloned by direct screening of a lambda gt11 library using NF-IL6 binding sequence as a ligand. The full-length cDNA encoded a 345 amino acid protein with a potential leucine zipper structure and revealed a high degree of homology to a liver-specific transcriptional factor, C/EBP, at the C-terminal portion. The bacterial fusion protein bound to the CCAAT homology as well as the viral enhancer core sequences as in the case of C/EBP. Recombinant NF-IL6 activated the human IL-6 promoter in a sequence-specific manner. Southern blot analysis demonstrated the high-degree conservation of the NF-IL6 gene through evolution and the existence of several other related genes sharing the DNA-binding domain. NF-IL6 mRNA was normally not expressed, but induced by the stimulation with either LPS, IL-1 or IL-6. Interestingly, NF-IL6 was shown to bind to the regulatory regions for various acute-phase protein genes and several other cytokine genes such as TNF, IL-8 and G-CSF, implying that NF-IL6 has a role in regulation not only for the IL-6 gene but also for several other genes involved in acute-phase reaction, inflammation and hemopoiesis.

Acute-Phase Reaction↗
PubMed1990

Biological and clinical aspects of interleukin 6.

Interleukin 6 (IL-6) is a multi-functional cytokine that is produced by a range of cells and plays a central role in host defense mechanisms. Abnormal production of IL-6 has been suggested to be involved in glomerulonephritis, plasmacytomagenesis and in the pathogenesis of autoimmune diseases. In this review, Toshio Hirano and colleagues discuss the possible involvement of IL-6 in a variety of diseases, the regulatory mechanism(s) of expression of the IL-6 gene and the structure and function of the IL-6 receptor.

Acute-Phase Reaction↗
PubMed1990

Constitutive and interleukin-1 (IL-1)-inducible factors interact with the IL-1-responsive element in the IL-6 gene.

The interleukin-6 (IL-6) promoter is rapidly and transiently activated with other cytokines, including IL-1, tumor necrosis factor, and platelet-derived growth factor, as well as phorbol esters and agents that increase intracellular cyclic AMP. In this study, we have investigated cis-acting regulatory elements and trans-acting factors responsible for IL-1-induced IL-6 gene expression. Studies on the 5' deletion mutants of the human IL-6 gene suggested that the IL-1-responsive element was mapped within the IL-6 promoter region (-180 to -123) which was homologous to the c-fos serum-responsive enhancer element. Gel retardation assay identified two types of nuclear factors that bound to this region, one constitutive and the other inducible. These two factors recognized a 14-base-pair (bp) palindromic sequence, ACATTGCACAATCT. Furthermore, three copies of this 14-bp palindrome conferred IL-1 responsiveness to the basal enhancerless IL-6 promoter, indicating that a 14-bp-dyad symmetry sequence was an IL-1-responsive element in the IL-6 gene.

Animals↗
PubMed1990

Biology of multifunctional cytokines: IL 6 and related molecules (IL 1 and TNF).

Interleukin 1 (IL 1), IL 6, and tumor necrosis factor (TNF) are typical examples of multifunctional cytokines involved in the regulation of the immune response, hematopoiesis, and inflammation. Their functions are widely overlapping but each shows its own characteristic properties. IL 6 was originally identified as a B cell differentiation factor, and thus one of the major functions of IL 6 is antibody induction. Transgenic mice have provided much needed information on the pathophysiological role of cytokines. With IL 6 transgenic mice, deregulation of the IL 6 expression was suggested to be involved in the generation of plasmacytoma/myeloma and mesangium proliferative glomerulonephritis. The cis-regulatory elements and trans-acting nuclear factor (or factors) for the IL 6 expression (NF-IL 6) have been identified. NF-IL 6 was shown to be a member of a C/EBP family, and the possible involvement of NF-IL 6 not only in the IL 6 regulation but also in the induction of various acute phase proteins was also observed. The findings suggest the presence of a positive regulatory loop in acute-phase reaction. IL 1 receptor belongs to an Ig superfamily, but the IL 6 receptor is a member of a newly identified cytokine receptor family. The IL 6 receptor system was shown to be composed of a ligand binding chain and a signal-transducing molecule. IL 6 was found to trigger the association of these two polypeptide chains. This unique mechanism may be applied to other cytokine receptor systems.

Animals↗
PubMed1989

IgG1 plasmacytosis in interleukin 6 transgenic mice.

Interleukin 6 (IL-6) has been suggested to be involved in the pathogenesis of polyclonal and monoclonal plasma cell abnormalities. To address this possibility, transgenic mice carrying the human IL-6 genomic gene fused with a human immunoglobulin heavy chain enhancer were generated. High concentrations of human IL-6 and polyclonal increase in IgG1 (120- to 400-fold) in sera of all transgenic mice were observed. A massive plasmacytosis in thymus, lymph node, and spleen and an infiltration of plasma cells in lung, liver, and kidney were observed. However, the plasma cells were not transplantable to syngeneic mice and were found not to contain chromosomal aberrations including c-myc gene rearrangements. The evidence indicates that deregulated gene expression of IL-6 can trigger polyclonal plasmacytosis but cannot induce plasmacytoma. It is suggested that additional genetic changes may be required for the generation of plasma cell neoplasia. Other interesting findings in these transgenic mice were the development of mesangio-proliferative glomerulonephritis and an increase in megakaryocytes in bone marrow.

Animals↗
PubMed1988

Genomic structure of the murine IL-6 gene. High degree conservation of potential regulatory sequences between mouse and human.

The genomic clone of mouse IL-6 was isolated and compared with the human IL-6 gene. The comparison revealed that the mouse IL-6 consists of five exons and four introns and that the overall organization is similar to that of the human IL-6 gene although the third intron is about 2 kb longer. The sequence similarity in the coding region is about 60%, whereas the 3'-untranslated region and the first 300-bp sequence of the 5'-flanking region are highly conserved (greater than 80%). Several sequence blocks with high homology are also found in the introns. Furthermore, sequences similar to transcriptional enhancer elements such as the c-fos serum responsive element and the consensus sequences for cAMP induction, activator protein 1 binding, and the glucocorticoid receptor binding are identified within the highly conserved 5'-flanking regions of the genes from the two species. These sequences may play an important role in transcriptional activation of the IL-6 gene.

Amino Acid Sequence↗
PubMed1988

Effect of testosterone on growth hormone secretion in female rats during a continuous infusion of growth hormone releasing factor.

The effect of testosterone on growth hormone (GH) secretory pattern during a 6-hour continuous infusion of human GH-releasing factor (GRF) (1-44) NH2 was observed in unrestrained adult female Wistar rats. Rats had been ovariectomized or sham operated 6 weeks previously. Three weeks after the ovariectomy, the rats received sesame oil or testosterone propionate at a dose of 1 or 2 mg s.c. daily for 21 days. All rats were provided with two indwelling cannulae: one in the right atrium for undisturbed blood collection and the other in the inferior vena cava for vehicle or GRF infusion. Vehicle or GRF was administered by an infusion pump at a dose of 50 ng/kg/min for 6 h. Serial blood specimens were obtained every 20 min. Sham-operated adult female Wistar rats exhibited a high-frequency, low-amplitude pulsatile GH secretion during a 6-hour vehicle infusion. When they received a 6-hour continuous infusion of GRF, the amplitudes of GH pulses and baseline GH values were markedly augmented, but the pulse frequency remained unaltered. The GH secretory pattern during a 6-hour vehicle infusion among ovariectomized rats was similar to that of sham-operated female rats, whereas the magnitude of elevation of GH pulse and baseline level in ovariectomized rats were significantly lower than in sham-operated rats. The ovariectomized female rats that had received 2 mg testosterone for 21 days showed a low-frequency, regularly timed, high-amplitude pulsatile GH secretion, and GH values during the intervening period were low. This GH secretory pattern was indistinguishable from that in adult male rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

A pre-B cell nuclear protein that specifically interacts with the immunoglobulin V-J recombination sequences.

DNA-nuclear protein interactions were studied with synthetic recombination signal sequences (RSSs) for immunoglobulin V-J joining. With a gel retardation assay, a DNA-binding protein that specifically interacts with RSSs was detected in nuclear extracts from a pre-B cell line, 38B9. This protein was found in all the recombination-competent pre-B cell lines tested in this study, but not in myeloma, mature T cell, monocyte, or fibroblast cell lines. DNA footprint analysis with dimethyl sulfate demonstrated that the 7-mer region of the RSS was strongly protected when complexed with the binding protein. Furthermore, a single base substitution in the 7-mer region totally abolished the binding. The molecular mechanism of V-J joining is discussed in the context of the RSS-binding protein.

Animals↗
PubMed1987

Two pairs of recombination signals are sufficient to cause immunoglobulin V-(D)-J joining.

The minimum sequence requirements for antigen receptor V-(D)-J joining were studied by constructing recombination-substrates containing synthetic recombination signals and introducing them into a recombination-competent pre-B cell line. Two sets of heptamer (CACTGTG) and nonamer (GGTTTTTGT) sequences were shown to be sufficient to cause the V-(D)-J joining, if the 12- and 23-base pair spacer rule is satisfied. A point mutation in the heptamer sequence, or a change in the combination of the two spacer lengths, drastically reduced the recombination.

Animals↗